Oldham County, Kentucky: Energy Resources | Open Energy Information
Climate Zone Number 4 Climate Zone Subtype A. Places in Oldham County, Kentucky Buckner, Kentucky Crestwood, Kentucky Goshen, Kentucky La Grange, Kentucky Orchard Grass...
Gasoline and Diesel Fuel Update (EIA)
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of Hartley Place: Iowa Phone Number: 712-928-2240 Website: www.hartleyiowa.comindex.php? Facebook: https:www.facebook.comHartleychamber Outage Hotline: 712-928-2240...
RADAR OBSERVATIONS OF COMET 103P/HARTLEY 2
Harmon, John K.; Nolan, Michael C.; Howell, Ellen S.; Taylor, Patrick A.; Giorgini, Jon D.
2011-06-10
Comets rarely come close enough to be studied intensively with Earth-based radar. The most recent such occurrence was when Comet 103P/Hartley 2 passed within 0.12 AU in late 2010 October, less than two weeks before the EPOXI flyby. This offered a unique opportunity to improve pre-encounter trajectory knowledge and obtain complementary physical data for a spacecraft-targeted comet. 103P/Hartley 2 is only the fourth comet nucleus to be imaged with radar and already the second to be identified as an elongated, bilobate object based on its delay-Doppler signature. The images show the dominant spin mode to be a rotation about the short axis with a period of 18.2 hr. The nucleus has a low radar albedo consistent with a surface density of 0.5-1.0 g cm{sup -3}. A separate echo component was detected from large (>cm) grains ejected anisotropically with velocities of several to tens of meters per second. Radar shows that, in terms of large-grain production, 103P/Hartley 2 is an unusually active comet for its size.
References Publications Definitions definitions LCA Harmonization Notice: Results for natural gas (conventional and unconventional) will be updated soon, please check back...
Bennett, Charles L.
2009-10-20
A high efficiency harmonic engine based on a resonantly reciprocating piston expander that extracts work from heat and pressurizes working fluid in a reciprocating piston compressor. The engine preferably includes harmonic oscillator valves capable of oscillating at a resonant frequency for controlling the flow of working fluid into and out of the expander, and also preferably includes a shunt line connecting an expansion chamber of the expander to a buffer chamber of the expander for minimizing pressure variations in the fluidic circuit of the engine. The engine is especially designed to operate with very high temperature input to the expander and very low temperature input to the compressor, to produce very high thermal conversion efficiency.
Bennett, Charles L.; Sewall, Noel; Boroa, Carl
2014-08-19
An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into of the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. Upon releasing the inlet valve the inlet valve head undergoes a single oscillation past the equilibrium positio to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. Protrusions carried either by the inlet valve head or piston head are used to bump open the inlet valve from the closed position and initiate the single oscillation of the inlet valve head, and protrusions carried either by the outlet valve head or piston head are used to close the outlet valve ahead of the bump opening of the inlet valve.
Ground-based multiwavelength observations of comet 103P/Hartley 2
Gicquel, A.; Villanueva, G. L.; Cordiner, M. A.; Milam, S. N.; Charnley, S. B.; Remijan, A. J.; Coulson, I. M.; Chuang, Y.-L.; Kuan, Y.-J. E-mail: stefanie.n.milam@nasa.gov E-mail: steven.b.charnley@nasa.gov E-mail: aremijan@nrao.edu E-mail: ylchuang@std.ntnu.edu.tz
2014-10-10
The Jupiter-family comet 103P/Hartley 2 (103P) was the target of the NASA EPOXI mission. In support of this mission, we conducted observations from radio to submillimeter wavelengths of comet 103P in the three weeks preceding the spacecraft rendezvous on UT 2010 November 4.58. This time period included the passage at perihelion and the closest approach of the comet to the Earth. Here, we report detections of HCN, H{sub 2}CO, CS, and OH and upper limits for HNC and DCN toward 103P using the Arizona Radio Observatory Kitt Peak 12 m telescope (ARO 12 m) and submillimeter telescope (SMT), the James Clerk Maxwell Telescope (JCMT), and the Green Bank Telescope (GBT). The water production rate, Q{sub H{sub 2O}} = (0.67-1.07) × 10{sup 28} s{sup –1}, was determined from the GBT OH data. From the average abundance ratios of HCN and H{sub 2}CO relative to water (0.13 ± 0.03% and 0.14 ± 0.03%, respectively), we conclude that H{sub 2}CO is depleted and HCN is normal with respect to typically observed cometary mixing ratios. However, the abundance ratio of HCN with water shows a large diversity with time. Using the JCMT data, we measured an upper limit for the DCN/HCN ratio <0.01. Consecutive observations of ortho-H{sub 2}CO and para-H{sub 2}CO on November 2 (from data obtained at the JCMT) allowed us to derive an ortho:para ratio (OPR) of ?2.12 ± 0.59 (1?), corresponding to T {sub spin} > 8 K (2?).
Harmonization of Biodiesel Specifications
Alleman, T. L.
2008-02-01
Worldwide biodiesel production has grown dramatically over the last several years. Biodiesel standards vary across countries and regions, and there is a call for harmonization. For harmonization to become a reality, standards have to be adapted to cover all feedstocks. Additionally, all feedstocks cannot meet all specifications, so harmonization will require standards to either tighten or relax. For harmonization to succeed, the biodiesel market must be expanded with the alignment of test methods and specification limits, not contracted.
Picconi, David; Grebenshchikov, Sergy Yu.
2014-08-21
Photodissociation of ozone in the near UV is studied quantum mechanically in two excited electronic states coupled at a conical intersection located outside the Franck-Condon zone. The calculations, performed using recent ab initio PESs, provide an accurate description of the photodissociation dynamics across the Hartley/Huggins absorption bands. The observed photofragment distributions are reproduced in the two electronic dissociation channels. The room temperature absorption spectrum, constructed as a Boltzmann average of many absorption spectra of rotationally excited parent ozone, agrees with experiment in terms of widths and intensities of diffuse structures. The exit channel conical intersection contributes to the coherent broadening of the absorption spectrum and directly affects the product vibrational and translational distributions. The photon energy dependences of these distributions are strikingly different for fragments created along the adiabatic and the diabatic paths through the intersection. They can be used to reverse engineer the most probable geometry of the non-adiabatic transition. The angular distributions, quantified in terms of the anisotropy parameter Î², are substantially different in the two channels due to a strong anticorrelation between Î² and the rotational angular momentum of the fragment O{sub 2}.
Josh Harmon | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Josh Harmon About Us Josh Harmon - Intern, EERE International Most Recent Win-Win Opportunities at the Sixth Annual U.S.-China Energy Efficiency Forum October 30
Summers, M.A.; Eimerl, D.; Boyd, R.D.
1982-06-10
A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The extraordinary or e directions of the crystal elements are oriented in the integral assembly to be in quadrature (90/sup 0/). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude o and e components. For a third-harmonic generation, the input fundamental wave has o and e components whose amplitudes are in a ratio of 2:1 (o:e reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10/sup 0/. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axeses (o).
Summers, Mark A.; Eimerl, David; Boyd, Robert D.
1985-01-01
A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The "extraordinary" or "e" directions of the crystal elements are oriented in the integral assembly to be in quadrature (90.degree.). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude "o" and "e" components. For a third-harmonic generation, the input fundamental wave has "o" and "e" components whose amplitudes are in a ratio of 2:1 ("o":"e" reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10.degree.. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axes ("o").
Bennett, Charles L.
2016-03-22
A reciprocating-piston uniflow engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. When released, the inlet valve head undergoes a single oscillation past the equilibrium position to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. In other embodiments, the harmonic oscillator arrangement of the inlet valve enables the uniflow engine to be reversibly operated as a uniflow compressor.
Booster double harmonic setup notes
Gardner, C. J.
2015-02-17
The motivation behind implementing a booster double harmonic include the reduced transverse space charge force from a reduced peak beam current and reduced momentum spread of the beam, both of which can be achieved from flattening the RF bucket. RF capture and acceleration of polarized protons (PP) is first set up in the single harmonic mode with RF harmonic h=1. Once capture and acceleration have been set up in the single harmonic mode, the second harmonic system is brought on and programmed to operate in concert with the single harmonic system.
TEMPORAL AND SPATIAL ASPECTS OF GAS RELEASE DURING THE 2010 APPARITION OF COMET 103P/HARTLEY 2
Mumma, M. J.; Bonev, B. P.; Villanueva, G. L.; Paganini, L.; DiSanti, M. A.; Gibb, E. L.; Keane, J. V.; Meech, K. J.; Blake, G. A.; Ellis, R. S.; Lippi, M.; Boehnhardt, H.; Magee-Sauer, K.
2011-06-10
We report measurements of eight primary volatiles (H{sub 2}O, HCN, CH{sub 4}, C{sub 2}H{sub 6}, CH{sub 3}OH, C{sub 2}H{sub 2}, H{sub 2}CO, and NH{sub 3}) and two product species (OH and NH{sub 2}) in comet 103P/Hartley 2 using high-dispersion infrared spectroscopy. We quantified the long- and short-term behavior of volatile release over a three-month interval that encompassed the comet's close approach to Earth, its perihelion passage, and flyby of the comet by the Deep Impact spacecraft during the EPOXI mission. We present production rates for individual species, their mixing ratios relative to water, and their spatial distributions in the coma on multiple dates. The production rates for water, ethane, HCN, and methanol vary in a manner consistent with independent measures of nucleus rotation, but mixing ratios for HCN, C{sub 2}H{sub 6}, and CH{sub 3}OH are independent of rotational phase. Our results demonstrate that the ensemble average composition of gas released from the nucleus is well defined and relatively constant over the three-month interval (September 18 through December 17). If individual vents vary in composition, enough diverse vents must be active simultaneously to approximate (in sum) the bulk composition of the nucleus. The released primary volatiles exhibit diverse spatial properties which favor the presence of separate polar and apolar ice phases in the nucleus, establish dust and gas release from icy clumps (and from the nucleus), and provide insights into the driver for the cyanogen (CN) polar jet. The spatial distributions of C{sub 2}H{sub 6} and HCN along the near-polar jet (UT October 19.5) and nearly orthogonal to it (UT October 22.5) are discussed relative to the origin of CN. The ortho-para ratio (OPR) of water was 2.85 {+-} 0.20; the lower bound (2.65) defines T{sub spin} > 32 K. These values are consistent with results returned from the Infrared Space Observatory in 1997.
Quaternionic Harmonic Analysis of Texture
Energy Science and Technology Software Center (OSTI)
2012-10-01
QHAT uses various functions and data structures native to MATLAB to analyze crystallographic texture information using harmonic functions on the space of rotations represented as normalized quaternions. These harmonic functions generalize the spherical harmonics in three dimensions, and form the basis for the irreducible representations of the four-dimensional rotation group. This allows the basis of harmonic functions to be reduced to linearly independent combinations that satisfy the crystal and sample symmetry point groups.
Echo-Enabled Harmonic Generation
Stupakov, Gennady; /SLAC
2012-06-28
A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.
Echo-Enabled Harmonic Generation
Stupakov, Gennady
2010-08-25
A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.
Harmonic analysis of electrical distribution systems
1996-03-01
This report presents data pertaining to research on harmonics of electric power distribution systems. Harmonic data is presented on RMS and average measurements for determination of harmonics in buildings; fluorescent ballast; variable frequency drive; georator geosine harmonic data; uninterruptible power supply; delta-wye transformer; westinghouse suresine; liebert datawave; and active injection mode filter data.
Drahus, Michal; Jewitt, David; Guilbert-Lepoutre, Aurelie; Waniak, Waclaw; Sievers, Albrecht
2012-09-01
One of the least understood properties of comets is the compositional structure of their nuclei, which can either be homogeneous or heterogeneous. The nucleus structure can be conveniently studied at millimeter wavelengths, using velocity-resolved spectral time series of the emission lines, obtained simultaneously for multiple molecules as the body rotates. Using this technique, we investigated the sources of CH{sub 3}OH and HCN in comet 103P/Hartley 2, the target of NASA's EPOXI mission, which had an exceptionally favorable apparition in late 2010. Our monitoring with the IRAM 30 m telescope shows short-term variability of the spectral lines caused by nucleus rotation. The varying production rates generate changes in brightness by a factor of four for HCN and by a factor of two for CH{sub 3}OH, and they are remarkably well correlated in time. With the addition of the velocity information from the line profiles, we identify the main sources of outgassing: two jets, oppositely directed in a radial sense, and icy grains, injected into the coma primarily through one of the jets. The mixing ratio of CH{sub 3}OH and HCN is dramatically different in the two jets, which evidently shows large-scale chemical heterogeneity of the nucleus. We propose a network of identities linking the two jets with morphological features reported elsewhere and postulate that the chemical heterogeneity may result from thermal evolution. The model-dependent average production rates are 3.5 Multiplication-Sign 10{sup 26} molecules s{sup -1} for CH{sub 3}OH and 1.25 Multiplication-Sign 10{sup 25} molecules s{sup -1} for HCN, and their ratio of 28 is rather high but not abnormal. The rotational temperature from CH{sub 3}OH varied strongly, presumably due to nucleus rotation, with the average value being 47 K.
Harmonics and Resonance Issues with Wind Plants
Bradt, M.; Badrzadeh, Babak; Camm, E H; Castillo, Nestor; Mueller, David; Siebert, T.; Schoene, Jens; Smith, Travis M; Starke, Michael R; Walling, R.
2011-01-01
Wind plants are susceptible to lightly-damped resonances which can attract and amplify ambient grid harmonic distortion and magnify wind turbine harmonic generation. Long-accepted harmonic modeling assumptions and practices are not appropriate for wind plants. VSCs are not ideal current sources and grid impedance is important. Attention to modeling detail and thorough evaluation over range of conditions is critical to meaningful analysis. In general, wind turbines are very slight sources of harmonics. Most harmonic issues are a result of resonance, caused by capacitor banks (for reactive power compensation) or from the extensive underground cabling in a collector system. Converter controls instability can be exacerbated by power system resonances. In some cases this has caused severe voltage distorDon and other problems. The IEEE 519 recommended guidelines are very restrictive. I recommend that they are used to resolve serious harmonic issues, and not to create petty problems.
Killing vector fields and harmonic superfield theories
Groeger, Josua
2014-09-15
The harmonic action functional allows a natural generalisation to semi-Riemannian supergeometry, also referred to as harmonic, which resembles the supersymmetric sigma models studied in high energy physics. We show that Killing vector fields are infinitesimal supersymmetries of this harmonic action and prove three different Noether theorems in this context. En passant, we provide a homogeneous treatment of five characterisations of Killing vector fields on semi-Riemannian supermanifolds, thus filling a gap in the literature.
Nucleon-nucleon scattering in a harmonic potential (Journal Article...
Office of Scientific and Technical Information (OSTI)
Journal Article: Nucleon-nucleon scattering in a harmonic potential Citation Details In-Document Search Title: Nucleon-nucleon scattering in a harmonic potential Authors: Luu, T ; ...
Half-harmonic Kelvin probe force microscopy with transfer function...
Office of Scientific and Technical Information (OSTI)
Using linear and half-harmonic BE enables quantitative correction of the cantilever transfer function. Half-harmonic band excitation Kelvin probe force microscopy (HBE KPFM) thus ...
Generation of even harmonics in coupled quantum dots (Journal...
Office of Scientific and Technical Information (OSTI)
Generation of even harmonics in coupled quantum dots Citation Details In-Document Search Title: Generation of even harmonics in coupled quantum dots Using the spatial-temporal...
A high-fidelity harmonic drive model.
Preissner, C.; Royston, T. J.; Shu, D.
2012-01-01
In this paper, a new model of the harmonic drive transmission is presented. The purpose of this work is to better understand the transmission hysteresis behavior while constructing a new type of comprehensive harmonic drive model. The four dominant aspects of harmonic drive behavior - nonlinear viscous friction, nonlinear stiffness, hysteresis, and kinematic error - are all included in the model. The harmonic drive is taken to be a black box, and a dynamometer is used to observe the input/output relations of the transmission. This phenomenological approach does not require any specific knowledge of the internal kinematics. In a novel application, the Maxwell resistive-capacitor hysteresis model is applied to the harmonic drive. In this model, sets of linear stiffness elements in series with Coulomb friction elements are arranged in parallel to capture the hysteresis behavior of the transmission. The causal hysteresis model is combined with nonlinear viscous friction and spectral kinematic error models to accurately represent the harmonic drive behavior. Empirical measurements are presented to quantify all four aspects of the transmission behavior. These measurements motivate the formulation of the complete model. Simulation results are then compared to additional measurements of the harmonic drive performance.
Harmonics in a Wind Power Plant: Preprint
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
... At the same time, the wind turbine should be able to operate immune to small disturbances coming from the grid. Harmonics are one of the more common power quality issues presented ...
Harmon, Illinois: Energy Resources | Open Energy Information
Map This article is a stub. You can help OpenEI by expanding it. Harmon is a village in Lee County, Illinois. It falls under Illinois' 14th congressional district.12...
SEVENTH HARMONIC 20 GHz CO-GENERATOR
Hirshfield, Jay L
2014-04-08
To satisfy the need for multi-MW rf sources in frequency ranges where commercial sources do not exist, a study was undertaken on a class of devices based on gyro-harmonic frequency multiplication. This mechanism relies upon adding energy in gyrating motion to a linear electron beam that traverses a rotating-mode TE111-mode drive cavity in a dc magnetic field. The beam then drifts along the magnetic field into a second cavity, operating in the TEn11-mode tuned to the nth harmonic of the drive cavity. Studies of this configuration have been carried out for 2 < n < 7. Results are given for multi-MW, efficient operation of a 7th harmonic device operating at 20 GHz, and a 2nd harmonic device operating at 22.4 GHz.
NREL: Energy Analysis - Life Cycle Assessment Harmonization
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Energy Analysis Printable Version Life Cycle Assessment Harmonization Life Cycle Greenhouse Gas Emissions from Electricity Generation (Fact Sheet) Cover of the Life Cycle Greenhouse Gas Emissions from Electricity Generation factsheet Download the Fact Sheet The U.S. Department of Energy enlisted NREL to review and "harmonize" life cycle assessments (LCA) of electricity generation technologies. Hundreds of assessments have been published, often with considerable variability in results.
Quantum harmonic oscillator with superoscillating initial datum
Buniy, R. V.; Struppa, D. C.; Colombo, F.; Sabadini, I.
2014-11-15
In this paper, we study the evolution of superoscillating initial data for the quantum driven harmonic oscillator. Our main result shows that superoscillations are amplified by the harmonic potential and that the analytic solution develops a singularity in finite time. We also show that for a large class of solutions of the SchrÃ¶dinger equation, superoscillating behavior at any given time implies superoscillating behavior at any other time.
HARMONIC CAVITY PERFORMANCE FOR NSLS-II
BLEDNYKH, A.; KRINSKY, S.; PODOBEDOV, B.; ROSE, J.; TOWNE, N.; WANG, J.M.
2005-05-15
NSLS-II is a 3 GeV ultra-high brightness storage ring planned to succeed the present NSLS rings at BNL. Ultralow emittance combined with short bunch length means that it is critical to minimize the effects of Touschek scattering and coherent instabilities. Improved lifetime and stability can be achieved by including a third-harmonic RF cavity in the baseline design. This paper describes the required harmonic RF parameters and the expected system performance.
Microsoft Word - Global Harmonization Classifications.docx
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Harmonization Classifications: The following is prepared for your understanding of the new Global Harmonization System Physical hazards ï‚· H200: Unstable explosive ï‚· H201: Explosive; mass explosion hazard ï‚· H202: Explosive; severe projection hazard ï‚· H203: Explosive; fire, blast or projection hazard ï‚· H204: Fire or projection hazard ï‚· H205: May mass explode in fire ï‚· H220: Extremely flammable gas ï‚· H221: Flammable gas ï‚· H222: Extremely flammable aerosol ï‚· H223: Flammable
Voltage and current transducer harmonic sensitivity analysis
Domijan, A. Jr.
1998-10-01
This work presents the results of a study on the sensitivity of real power as a function of harmonic magnitudes and angles. These transducers are ones that are typical of those used, in combination with metering instruments, to measure the performance of variable-speed drives. Frequency response tests were performed on two different signal transducers (voltage and current) up to the 50th harmonic in accordance with Institute of Electrical and Electronics engineers (IEEE) Standard 519-1992. Results from these tests gave maximum magnitude percentage errors of {minus}2.2% (at 15th harmonic) and maximum phase shifts of +3.3 (at 50th harmonic) for voltage (at 120 V) and maximum percentage error of {minus}1.9% (at 2d harmonic) and maximum phase shift of {minus}4.3 for current (at 5 A). Using the percentage errors at 120 V and 5 A throughout the 60 Hz through 3,000 Hz range, in harmonic magnitudes and harmonic angles exhibited by the transducers, mathematical analysis was done on two sets of distorted signals and a sensitivity analysis was done to determine what would be the impact of the actual transducers` errors on the final calculation of real power. Variations of {minus}1.48% and {minus}1.60% were obtained. Then, assuming a maximum 5% change in current harmonic magnitudes and angles, a maximum real power percent variation of 0.02% and 2.47% were obtained for the same two sets of field-recorded voltage and current waveforms sets.
Dual aperture dipole magnet with second harmonic component
Praeg, W.F.
1983-08-31
An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.
Dual aperture dipole magnet with second harmonic component
Praeg, Walter F.
1985-01-01
An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.
High harmonic phase in molecular nitrogen
McFarland, Brian K.
2009-10-17
Electronic structure in atoms and molecules modulates the amplitude and phase of high harmonic generation (HHG). We report measurements of the high harmonic spectral amplitude and phase in N{sub 2}. The phase is measured interferometrically by beating the N{sub 2} harmonics with those of an Ar reference oscillator in a gas mixture. A rapid phase shift of 0.2{pi} is observed in the vicinity of the HHG spectral minimum, where a shift of {pi} had been presumed [J. Itatani et al., Nature 432, 867 (2004)]. We compare the phase measurements to a simulation of the HHG recombination step in N{sub 2} that is based on a simple interference model. The results of the simulation suggest that modifications beyond the simple interference model are needed to explain HHG spectra in molecules.
Quantum stochastic thermodynamic on harmonic networks
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Deffner, Sebastian
2016-01-04
Fluctuation theorems are symmetry relations for the probability to observe an amount of entropy production in a finite-time process. In a recent paper Pigeon et al (2016 New. J. Phys. 18 013009) derived fluctuation theorems for harmonic networks by means of the large deviation theory. Furthermore, their novel approach is illustrated with various examples of experimentally relevant systems. As a main result, however, Pigeon et al provide new insight how to consistently formulate quantum stochastic thermodynamics, and provide new and robust tools for the study of the thermodynamics of quantum harmonic networks.
Harmonic generation with multiple wiggler schemes
Bonifacio, R.; De Salvo, L.; Pierini, P.
1995-02-01
In this paper the authors give a simple theoretical description of the basic physics of the single pass high gain free electron laser (FEL), describing in some detail the FEL bunching properties and the harmonic generation technique with a multiple-wiggler scheme or a high gain optical klystron configuration.
Strong Second Harmonic Generation from the Tantalum Thioarsenates...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Strong Second Harmonic Generation from the Tantalum Thioarsenates A3Ta2AsS11 (A K and ... and exhibit strong nonlinear optical (NLO) second harmonic generation (SHG) response. ...
Strongly Dispersive Transient Bragg Grating for High Harmonics
Farrell, J.; Spector, L.S.; Gaarde, M.B.; McFarland, B.K.; Bucksbaum, P.H.; Guhr, Markus; /SLAC, PULSE /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.
2010-06-04
We create a transient Bragg grating in a high harmonic generation medium using two counterpropagating pulses. The Bragg grating disperses the harmonics in angle and can diffract a large bandwidth with temporal resolution limited only by the source size.
Reduced Switching Frequency Active Harmonic Elimination for Multilevel Converters
Du, Zhong; Tolbert, Leon M; Chiasson, John N; Ozpineci, Burak
2008-01-01
This paper presents a reduced switching-frequency active-harmonic-elimination method (RAHEM) to eliminate any number of specific order harmonics of multilevel converters. First, resultant theory is applied to transcendental equations to eliminate low-order harmonics and to determine switching angles for a fundamental frequency-switching scheme. Next, based on the number of harmonics to be eliminated, Newton climbing method is applied to transcendental equations to eliminate high-order harmonics and to determine switching angles for the fundamental frequency-switching scheme. Third, the magnitudes and phases of the residual lower order harmonics are computed, generated, and subtracted from the original voltage waveform to eliminate these low-order harmonics. Compared to the active-harmonic-elimination method (AHEM), which generates square waves to cancel high-order harmonics, RAHEM has lower switching frequency. The simulation results show that the method can effectively eliminate all the specific harmonics, and a low total harmonic distortion (THD) near sine wave is produced. An experimental 11-level H-bridge multilevel converter with a field-programmable gate-array controller is employed to experimentally validate the method. The experimental results show that RAHEM does effectively eliminate any number of specific harmonics, and the output voltage waveform has low switching frequency and low THD.
Harmonic generation by circularly polarized laser beams propagating in plasma
Agrawal, Ekta; Hemlata,; Jha, Pallavi
2015-04-15
An analytical theory is developed for studying the phenomenon of generation of harmonics by the propagation of an obliquely incident, circularly polarized laser beam in homogeneous, underdense plasma. The amplitudes of second and third harmonic radiation as well as detuning distance have been obtained and their variation with the angle of incidence is analyzed. The amplitude of harmonic radiation increases with the angle of incidence while the detuning distance decreases, for a given plasma electron density. It is observed that the generated second and third harmonic radiation is linearly and elliptically polarized, respectively. The harmonic radiation vanishes at normal incidence of the circularly polarized laser beam.
Harmonics in a Wind Power Plant: Preprint
Preciado, V.; Madrigal, M.; Muljadi, E.; Gevorgian, V.
2015-04-02
Wind power generation has been growing at a very fast pace for the past decade, and its influence and impact on the electric power grid is significant. As in a conventional power plant, a wind power plant (WPP) must ensure that the quality of the power being delivered to the grid is excellent. At the same time, the wind turbine should be able to operate immune to small disturbances coming from the grid. Harmonics are one of the more common power quality issues presented by large WPPs because of the high switching frequency of the power converters and the possible nonlinear behavior from electric machines (generator, transformer, reactors) within a power plant. This paper presents a summary of the most important issues related to harmonics in WPPs and discusses practical experiences with actual Type 1 and Type 3 wind turbines in two WPPs.
Prolate spheroidal harmonic expansion of gravitational field
Fukushima, Toshio
2014-06-01
As a modification of the oblate spheroidal case, a recursive method is developed to compute the point value and a few low-order derivatives of the prolate spheroidal harmonics of the second kind, Q{sub nm} (y), namely the unnormalized associated Legendre function (ALF) of the second kind with its argument in the domain, 1 < y < âˆž. They are required in evaluating the prolate spheroidal harmonic expansion of the gravitational field in addition to the point value and the low-order derivatives of P-bar {sub nm}(t), the 4Ï€ fully normalized ALF of the first kind with its argument in the domain, |t| â‰¤ 1. The new method will be useful in the gravitational field computation of elongated celestial objects.
Dark-matter harmonics beyond annual modulation
Lee, Samuel K.; Lisanti, Mariangela; Safdi, Benjamin R. E-mail: mlisanti@princeton.edu
2013-11-01
The count rate at dark-matter direct-detection experiments should modulate annually due to the motion of the Earth around the Sun. We show that higher-frequency modulations, including daily modulation, are also present and in some cases are nearly as strong as the annual modulation. These higher-order modes are particularly relevant if (i) the dark matter is light, O(10) GeV, (ii) the scattering is inelastic, or (iii) velocity substructure is present; for these cases, the higher-frequency modes are potentially observable at current and ton-scale detectors. We derive simple expressions for the harmonic modes as functions of the astrophysical and geophysical parameters describing the Earth's orbit, using an updated expression for the Earth's velocity that corrects a common error in the literature. For an isotropic halo velocity distribution, certain ratios of the modes are approximately constant as a function of nuclear recoil energy. Anisotropic distributions can also leave observable features in the harmonic spectrum. Consequently, the higher-order harmonic modes are a powerful tool for identifying a potential signal from interactions with the Galactic dark-matter halo.
Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R
1982-09-01
Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.
Algal Supply System Design - Harmonized Version
Abodeely, Jared; Stevens, Daniel; Ray, Allison; Newby, Deborah; Schaller, Kastli
2013-03-01
The objective of this design report is to provide an assessment of current technologies used for production, dewatering, and converting microalgae cultivated in open-pond systems to biofuel. The original draft design was created in 2011 and has subsequently been brought into agreement with the DOE harmonized model. The design report extends beyond this harmonized model to discuss some of the challenges with assessing algal production systems, including the ability to (1) quickly assess alternative algal production system designs, (2) assess spatial and temporal variability, and (3) perform large-scale assessments considering multiple scenarios for thousands of potential sites. The Algae Logistics Model (ALM) was developed to address each of these limitations of current modeling efforts to enable assessment of the economic feasibility of algal production systems across the United States. The (ALM) enables (1) dynamic assessments using spatiotemporal conditions, (2) exploration of algal production system design configurations, (3) investigation of algal production system operating assumptions, and (4) trade-off assessments with technology decisions and operating assumptions. The report discusses results from the ALM, which is used to assess the baseline design determined by harmonization efforts between U.S. DOE national laboratories. Productivity and resource assessment data is provided by coupling the ALM with the Biomass Assessment Tool developed at PNNL. This high-fidelity data is dynamically passed to the ALM and used to help better understand the impacts of spatial and temporal constraints on algal production systems by providing a cost for producing extracted algal lipids annually for each potential site.
Separation of High Order Harmonics with Fluoride Windows
Allison, Tom; van Tilborg, Jeroen; Wright, Travis; Hertlein, Marcus; Falcone, Roger; Belkacem, Ali
2010-08-02
The lower orders produced in high order harmonic generation can be effciently temporally separated into monochromatic pulses by propagation in a Fluoride window while still preserving their femtosecond pulse duration. We present calculations for MgF2, CaF2, and LiF windows for the third, fifth, and seventh harmonics of 800 nm. We demonstrate the use of this simple and inexpensive technique in a femtosecond pump/probe experiment using the fifth harmonic.
Harmonization of Federal and International Regulations | Department of
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Energy Harmonization of Federal and International Regulations Harmonization of Federal and International Regulations Update of the U.S. Department of Transportation (DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA). Harmonization of Federal and International Regulations (636.69 KB) More Documents & Publications DOE-STD-5507-2013 Department of Transportation Pipeline and Hazardous Materials Safety Administration Activities FAQS Reference Guide - NNSA Package
Numerical Verification of Bounce Harmonic Resonances in Neoclassical
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Toroidal Viscosity for Tokamaks (Technical Report) | SciTech Connect Numerical Verification of Bounce Harmonic Resonances in Neoclassical Toroidal Viscosity for Tokamaks Citation Details In-Document Search Title: Numerical Verification of Bounce Harmonic Resonances in Neoclassical Toroidal Viscosity for Tokamaks This Letter presents the rst numerical veri cation for the bounce-harmonic (BH) resonance phenomena of the neoclassical transport in a tokamak perturbed by non-axisymmetric magnetic
Generation of even harmonics in coupled quantum dots
Guo Shifang; Duan Suqing; Yang Ning; Chu Weidong; Zhang Wei
2011-07-15
Using the spatial-temporal symmetry principle we developed recently, we propose an effective scheme for even-harmonics generation in coupled quantum dots. The relative intensity of odd and even harmonic components in the emission spectrum can be controlled by tuning the dipole couplings among the dots, which can be realized in experiments by careful design of the nanostructures. In particular, pure 2nth harmonics and (2n+1)th harmonics (where n is an integer) can be generated simultaneously with polarizations in two mutual perpendicular directions in our systems. An experimental design of the coupled dots system is presented.
Optical Third-Harmonic Generation in Graphene (Journal Article...
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Published Article: Optical Third-Harmonic Generation in Graphene Title: Optical ... Sponsoring Org: USDOE Country of Publication: United States Language: English Word Cloud ...
A Simple Harmonic Universe (Technical Report) | SciTech Connect
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RELATIVITY THEORY; HARMONICS; PARTICLE PRODUCTION; UNIVERSE Theory-HEP,HEPPH, HEPTH, ASTRO, GRQC Word Cloud More Like This Full Text preview image File size NAView Full Text...
Limitations and improvements for harmonic generation measurements
Best, Steven; Croxford, Anthony; Neild, Simon
2014-02-18
A typical acoustic harmonic generation measurement comes with certain limitations. Firstly, the use of the plane wave-based analysis used to extract the nonlinear parameter, Î², ignores the effects of diffraction, attenuation and receiver averaging which are common to most experiments, and may therefore limit the accuracy of a measurement. Secondly, the method usually requires data obtained from a through-transmission type setup, which may not be practical in a field measurement scenario where access to the component is limited. Thirdly, the technique lacks a means of pinpointing areas of damage in a component, as the measured nonlinearity represents an average over the length of signal propagation. Here we describe a three-dimensional model of harmonic generation in a sound beam, which is intended to provide a more realistic representation of a typical experiment. The presence of a reflecting boundary is then incorporated into the model to assess the feasibility of performing single-sided measurements. Experimental validation is provided where possible. Finally, a focusing acoustic source is modelled to provide a theoretical indication of the afforded advantages when the nonlinearity is localized.
Higher order harmonic detection for exploring nonlinear interactions
Vasudevan, Rama K; Okatan, M. B.; Rajapaksa, Indrajit; Kim, Yunseok; Marincel, Dan; Trolier-McKinstry, Susan; Jesse, Stephen; Nagarajan, Valanoor; Kalinin, Sergei V
2013-01-01
Nonlinear dynamics underpin a vast array of physical phenomena ranging from interfacial motion to jamming transitions. In many cases, decoupling the contributions of competing or co-existing mechanisms to the system response can be achieved through investigation of higher order harmonics. Here, a method using band excitation scanning probe microscopy to investigate higher order harmonics of the electromechanical response, with nanometer scale spatial resolution is presented. The utility of the technique is demonstrated by probing the first three harmonics of strain for a well-known system, a model Pb(Zr1-xTix)O3 ferroelectric capacitor. It is shown that the second order harmonic response is correlated with the first harmonic response, whereas the third harmonic is not. Additionally, nanoscale measurements of the second harmonic response with field reveal significant deviations from Rayleigh-type models in the form of a much more complicated field dependence than is observed in the spatially averaged data. These results illustrate the versatility of combining proximal probe techniques with nth harmonic detection methods in exploring and decoupling nonlinear dynamics in a wide variety of nanoscale materials.
Basic principles of the surface harmonics method: Flat geometry
Kovalishin, A. A.
2011-12-15
The basic principles of the surface harmonics method are described. A one-dimensional problem is used to exemplify the specific features of the method and the algorithms for construction of finite-difference equations. The objective of this study is to popularize the surface harmonics method among specialists.
Xiang, D.; Colby, E.; Dunning, M.; Gilevich, S.; Hast, C.; Jobe, K.; McCormick, D.; Nelson, J.; Raubenheimer, T.O.; Soong, K.; Stupakov, G.; Szalata, Z.; Walz, D.; Weathersby, S.; Woodle, M.; ,
2012-02-15
Echo-enabled harmonic generation free electron lasers hold great promise for the generation of fully coherent radiation in x-ray wavelengths. Here we report the first evidence of high harmonics from the echo-enabled harmonic generation technique in the realistic scenario where the laser energy modulation is comparable to the beam slice energy spread. In this experiment, coherent radiation at the seventh harmonic of the second seed laser is generated when the energy modulation amplitude is about 2-3 times the slice energy spread. The experiment confirms the underlying physics of echo-enabled harmonic generation and may have a strong impact on emerging seeded x-ray free electron lasers that are capable of generating laserlike x rays which will advance many areas of science.
High-harmonic generation in a dense medium
Strelkov, V.V.; Platonenko, V.T.; Becker, A.
2005-05-15
The high-harmonic generation in a plasma or gas under conditions when the single-atom response is affected by neighboring ions or atoms of the medium is studied theoretically. We solve numerically the three-dimensional Schroedinger equation for a single-electron atom in the combined fields of the neighboring particles and the laser, and average the results over different random positions of the particles using the Monte Carlo method. Harmonic spectra are calculated for different medium densities and laser intensities. We observe a change of the harmonic properties due to a random variation of the harmonic phase induced by the field of the medium, when the medium density exceeds a certain transition density. The transition density is found to depend on the harmonic order, but it is almost independent of the fundamental intensity. It also differs for the two (shorter and longer) quantum paths. The latter effect leads for ionic densities in the transition regime to a narrowing of the harmonic lines and a shortening of the attosecond pulses generated using a group of harmonics.
Relativistic high harmonic generation in gas jet targets
Pirozhkov, A.S.; Kando, M.; Esirkepov, T.Zh.; and others
2012-07-11
We experimentally demonstrate a new regime of high-order harmonic generation by relativistic-irradiance lasers in gas jet targets. Bright harmonics with both odd and even orders, generated by linearly as well as circularly polarized pulses, are emitted in the forward direction, while the base harmonic frequency is downshifted. A 9 TW laser generates harmonics up to 360 eV, within the 'water window' spectral region. With a 120 TW laser producing 40 uJ/sr per harmonic at 120 eV, we demonstrate the photon number scalability. The observed harmonics cannot be explained by previously suggested scenarios. A novel high-order harmonics generation mechanism [T. Zh. Esirkepov et al., AIP Proceedings, this volume], which explains our experimental findings, is based on the phenomena inherent in the relativistic laser - underdense plasma interactions (self-focusing, cavity evacuation, and bow wave generation), mathematical catastrophe theory which explains formation of electron density singularities (cusps), and collective radiation due to nonlinear oscillations of a compact charge.
Revenue and harmonics: An evaluation of some proposed rate structures
McEachern, A.; Grady, W.M.; Moncrief, W.A.; Heydt, G.T.; McGranaghan, M.
1995-01-01
IEEE Recommended Practice 519 sets specific limits on harmonic voltages and currents at the ``point of common coupling``, which is usually interpreted as the revenue meter. Although most utilities will employ these limits simply to persuade and encourage their customers to reduce harmonics (and vice versa), it is also possible to construct economic incentives to encourage both the utility and the consumer to remain within the limits described in IEEE 519. 7his paper discusses seven approaches to this challenge, and discusses the advantages and disadvantages of each. It appears that the ``Harmonic-Adjusted Power Factor`` approach is practical, justifiable, compatible with existing rate structures, and relatively easy to implement.
High order harmonic generation in dual gas multi-jets
Tosa, Valer E-mail: calin.hojbota@itim-cj.ro; Hojbota, Calin E-mail: calin.hojbota@itim-cj.ro
2013-11-13
High order harmonic generation (HHG) in gas media suffers from a low conversion efficiency that has its origins in the interaction of the atom/molecule with the laser field. Phase matching is the main way to enhance the harmonic flux and several solutions have been designed to achieve it. Here we present numerical results modeling HHG in a system of multi-jets in which two gases alternate: the first gas jet (for example Ne) generates harmonics and the second one which ionizes easier, recover the phase matching condition. We obtain configurations which are experimentally feasible with respect to pressures and dimensions of the jets.
Investigation of plasma diagnostics using a dual frequency harmonic technique
Kim, Dong-Hwan; Kim, Young-Do; Cho, Sung-Won; Kim, Yu-Sin; Chung, Chin-Wook
2014-09-07
Plasma diagnostic methods using harmonic currents analysis of electrostatic probes were experimentally investigated to understand the differences in their measurement of the plasma parameters. When dual frequency voltage (Ï‰{sub 1},Ï‰{sub 2}) was applied to a probe, various harmonic currents (Ï‰{sub 1},â€‰2Ï‰{sub 1},Ï‰{sub 2},â€‰2Ï‰{sub 2},Ï‰{sub 2}Â±Ï‰{sub 1},Ï‰{sub 2}Â±2Ï‰{sub 1}) were generated due to the non-linearity of the probe sheath. The electron temperature can be obtained from the ratio of the two harmonics of the probe currents. According to the combinations of the two harmonics, the sensitivities in the measurement of the electron temperature differed, and this results in a difference of the electron temperature. From experiments and simulation, it is shown that this difference is caused by the systematic and random noise.
Harmonic gyrotrons operating in high-order symmetric modes
Nusinovich, Gregory S.; Kashyn, Dmytro G.; Antonsen, T. M.
2015-01-05
It is shown that gyrotrons operating at cyclotron harmonics can be designed for operation in symmetric TE{sub 0,p}-modes. Such operation in fundamental harmonic gyrotrons is possible only at small radial indices (pâ‰¤3) because of the severe mode competition with TE{sub 2,p}-modes, which are equally coupled to annular beams as the symmetric modes. At cyclotron harmonics, however, this â€œdegeneracyâ€ of coupling is absent, and there is a region in the parameter space where harmonic gyrotrons can steadily operate in symmetric modes. This fact is especially important for sub-THz and THz-range gyrotrons where ohmic losses limit the power achievable in continuous-wave and high duty cycle regimes.
Reconstruction of local neutron physical functionals in surface harmonics method
Boyarinov, V. F. Nevinitsa, V. A.
2010-12-15
Formulas for reconstruction of local neutron physical functionals for a three-stage calculation of a 2D VVER-1000 core using the surface harmonics method are obtained, implemented in the SUHAM code, and verified.
Harmonic mode competition in a terahertz gyrotron backward-wave...
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The viability of a harmonic gyro-BWO is assessed on the basis of the results obtained. Authors: Kao, S. H. ; Chiu, C. C. ; Chang, P. C. ; Wu, K. L. ; Chu, K. R. 1 + Show Author ...
A Massively Parallel Solver for the Mechanical Harmonic Analysis...
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Details In-Document Search Title: A Massively Parallel Solver for the Mechanical Harmonic Analysis of Accelerator Cavities ACE3P is a 3D massively parallel simulation suite that...
Nonlinearly driven harmonics of AlfvÃ©n modes
Zhang, B. Breizman, B. N.; Zheng, L. J.; Berk, H. L.
2014-01-15
In order to study the leading order nonlinear magneto-hydrodynamic (MHD) harmonic response of a plasma in realistic geometry, the AEGIS code has been generalized to account for inhomogeneous source terms. These source terms are expressed in terms of the quadratic corrections that depend on the functional form of a linear MHD eigenmode, such as the Toroidal AlfvÃ©n Eigenmode. The solution of the resultant equation gives the second order harmonic response. Preliminary results are presented here.
Wind LCA Harmonization (Fact Sheet), NREL (National Renewable Energy Laboratory)
Not Available
2013-06-01
NREL recently led the Life Cycle Assessment (LCA) Harmonization Project, a study that provides more exact estimates of GHG emissions for renewable and conventional generation, clarifying inconsistent and conflicting estimates in the published literature, and reducing uncertainty. This involved a systematic review and harmonization of life cycle assessment (LCA) literature of utility-scale wind power systems in order to determine the causes of life cycle greenhouse gases (GHG) emissions and, where possible, reduce variability in GHG estimates.
OBTAINING POTENTIAL FIELD SOLUTIONS WITH SPHERICAL HARMONICS AND FINITE DIFFERENCES
Toth, Gabor; Van der Holst, Bart; Huang Zhenguang
2011-05-10
Potential magnetic field solutions can be obtained based on the synoptic magnetograms of the Sun. Traditionally, a spherical harmonics decomposition of the magnetogram is used to construct the current- and divergence-free magnetic field solution. This method works reasonably well when the order of spherical harmonics is limited to be small relative to the resolution of the magnetogram, although some artifacts, such as ringing, can arise around sharp features. When the number of spherical harmonics is increased, however, using the raw magnetogram data given on a grid that is uniform in the sine of the latitude coordinate can result in inaccurate and unreliable results, especially in the polar regions close to the Sun. We discuss here two approaches that can mitigate or completely avoid these problems: (1) remeshing the magnetogram onto a grid with uniform resolution in latitude and limiting the highest order of the spherical harmonics to the anti-alias limit; (2) using an iterative finite difference algorithm to solve for the potential field. The naive and the improved numerical solutions are compared for actual magnetograms and the differences are found to be rather dramatic. We made our new Finite Difference Iterative Potential-field Solver (FDIPS) a publicly available code so that other researchers can also use it as an alternative to the spherical harmonics approach.
Efficiency enhancement of a harmonic lasing free-electron laser
Salehi, E.; Maraghechi, B.; Mirian, N. S.
2015-03-15
The harmonic lasing free-electron laser amplifier, in which two wigglers is employed in order for the fundamental resonance of the second wiggler to coincide with the third harmonic of the first wiggler to generate ultraviolet radiation, is studied. A set of coupled nonlinear first-order differential equations describing the nonlinear evolution of the system, for a long electron bunch, is solved numerically by CYRUS code. Solutions for the non-averaged and averaged equations are compared. Remarkable agreement is found between the averaged and non-averaged simulations for the evolution of the third harmonic. Thermal effects in the form of longitudinal velocity spread are also investigated. For efficiency enhancement, the second wiggler field is set to decrease linearly and nonlinearly at the point where the radiation of the third harmonic saturates. The optimum starting point and the slope of the tapering of the amplitude of the wiggler are found by a successive run of the code. It is found that tapering can increase the saturated power of the third harmonic considerably. In order to reduce the length of the wiggler, the prebunched electron beam is considered.
Efficient Forward Second-Harmonic Generation from Planar Archimedean Nanospirals
Davidson, Roderick B.; Ziegler, Jed I.; Vargas, Guillermo; Avanesyan, Sergey M.; Gong, Yu; Hess, Wayne P.; Haglund Jr., Richard F.
2015-01-21
The enhanced electric field at plasmonic resonances in nanoscale antennas can lead to efficient harmonic generation, especially when the plasmonic geometry is asymmetric on either inter-particle or intra-particle levels. The planar Archimedean nanospiral offers a unique geometrical asymmetry for second-harmonic generation (SHG) because the SHG results neither from arranging centrosymmetric nanoparticles in asymmetric groupings, nor from noncentrosymmetric nanoparticles that retain a local axis of symmetry. Here we report forward SHG from planar arrays of Archimedean nanospirals using 15 fs pulse from a Ti:sapphire oscillator tuned to 800 nm wavelength. The measured harmonic-generation efficiencies are 2.6â€¢10-9, 8â€¢10-9 and 1.3â€¢10-8 for left-handed circular, linear, and right-handed circular polarizations, respectively.
Development of the third harmonic SC cavity at Fermilab
Nikolay Solyak et al.
2004-08-05
The third harmonic 3.9 GHz superconducting cavity was recently proposed by DESY for a new generation of high brightness photo-injector (TTF photoinjector-2) to compensate nonlinear distortion of the longitudinal phase space due to RF curvature of the 1.3 GHz TESLA cavities [1,2]. Installation of the 3rd harmonic cavity will allow us to generate ultra-short (<50 {micro}m rms) highly charged electron bunches with an extremely small transverse normalized emittance (<1 {micro}m). This is required to support a new generation of linear colliders, free electron lasers and synchrotron radiation sources. In this paper we present the current status of the 3rd harmonic cavity being developed at Fermilab. We discuss the design procedure, the building and testing of the copper and niobium half-cells and components, the design of input and HOM couplers.
High-order harmonic generation in a capillary discharge
Rocca, Jorge J.; Kapteyn, Henry C.; Mumane, Margaret M.; Gaudiosi, David; Grisham, Michael E.; Popmintchev, Tenio V.; Reagan, Brendan A.
2010-06-01
A pre-ionized medium created by a capillary discharge results in more efficient use of laser energy in high-order harmonic generation (HHG) from ions. It extends the cutoff photon energy, and reduces the distortion of the laser pulse as it propagates down the waveguide. The observed enhancements result from a combination of reduced ionization energy loss and reduced ionization-induced defocusing of the driving laser as well as waveguiding of the driving laser pulse. The discharge plasma also provides a means to spectrally tune the harmonics by tailoring the initial level of ionization of the medium.
Propagation of nonlinearly generated harmonic spin waves in microscopic stripes
Rousseau, O.; Yamada, M.; Miura, K.; Ogawa, S.; Otani, Y.
2014-02-07
We report on the experimental study of the propagation of nonlinearly generated harmonic spin waves in microscopic CoFeB stripes. Using an all electrical technique with coplanar waveguides, we find that two kinds of spin waves can be generated by nonlinear frequency multiplication. One has a non-uniform spatial geometry and thus requires appropriate detector geometry to be identified. The other corresponds to the resonant fundamental propagative spin waves and can be efficiently excited by double- or triple-frequency harmonics with any geometry. Nonlinear excited spin waves are particularly efficient in providing an electrical signal arising from spin wave propagation.
Harmonic and interharmonic distortion modeling in multiconverter systems
Carbone, R.; Morrison, R.E.; Testa, A.; Menniti, D.
1995-07-01
The problem of modeling multiconverter systems in presence of harmonic and interharmonic distortion is considered. Specifically, current source rectifiers are considered as distortion sources some supply d.c. motors and the remaining supplying inverters feeding a.c. machines. The classical analogue, frequency domain and time domain models proposed in the literature to study harmonic distortion in a multiconverter system are considered and for each model suitable extension to include the interharmonic distortion are presented and critically analyzed. The results of several experiments are reported to show the usefulness and to compare the accuracy of the different extensions considered.
Nonlinear Trivelpiece--Gould waves: Recurrence, harmonic cascade, and sidebands
Cabral, J.A.C.; Lapao, L.M.; Mendonca, J.T. )
1993-03-01
A theoretical and experimental study of Trivelpiece--Gould waves propagating in a magnetized plasma column is presented in this paper. In the experiments, these waves are excited by a radio frequency (rf) source, which also serves to create the plasma. Observation of nonlinear effects includes space and time recurrence effects, a wave spectrum containing a large number (up to 25) harmonics, and low-frequency sidebands. The theoretical model explains the recurrence effects as a consequence of multiple nonlinear interactions between the fundamental wave and its harmonics. A good agreement is found between theory and the experiments.
Loganathan, Muthukumaran; Bristow, Douglas A.
2014-04-15
This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields.
WAVEMOTH-FAST SPHERICAL HARMONIC TRANSFORMS BY BUTTERFLY MATRIX COMPRESSION
Seljebotn, D. S.
2012-03-01
We present Wavemoth, an experimental open source code for computing scalar spherical harmonic transforms (SHTs). Such transforms are ubiquitous in astronomical data analysis. Our code performs substantially better than existing publicly available codes owing to improvements on two fronts. First, the computational core is made more efficient by using small amounts of pre-computed data, as well as paying attention to CPU instruction pipelining and cache usage. Second, Wavemoth makes use of a fast and numerically stable algorithm based on compressing a set of linear operators in a pre-computation step. The resulting SHT scales as O(L{sup 2}log{sup 2} L) for the resolution range of practical interest, where L denotes the spherical harmonic truncation degree. For low- and medium-range resolutions, Wavemoth tends to be twice as fast as libpsht, which is the current state-of-the-art implementation for the HEALPix grid. At the resolution of the Planck experiment, L {approx} 4000, Wavemoth is between three and six times faster than libpsht, depending on the computer architecture and the required precision. Because of the experimental nature of the project, only spherical harmonic synthesis is currently supported, although adding support for spherical harmonic analysis should be trivial.
Excitation of electron Langmuir frequency harmonics in the solar atmosphere
Fomichev, V. V.; Fainshtein, S. M.; Chernov, G. P.
2013-05-15
An alternative mechanism for the excitation of electron Langmuir frequency harmonics as a result of the development of explosive instability in a weakly relativistic beam-plasma system in the solar atmosphere is proposed. The efficiency of the new mechanism as compared to the previously discussed ones is analyzed.
Experimental study of a fourth-harmonic gyromultiplier
Bandurkin, I. V.; Bratman, V. L.; Savilov, A. V.; Samsonov, S. V.; Volkov, A. B.
2009-07-15
Simultaneous generation at the second and fourth cyclotron harmonics has been obtained from a single-cavity self-excited gyromultiplier. Output power of the short-wavelength radiation amounts to 100 W at a frequency of 75 GHz. The proposed scheme seems to be promising for the terahertz frequency range.
Wave kernels for the Dirac, Euler operators and the harmonic oscillator
Mohameden, Ahmedou Yahya Ould Moustapha, Mohamed Vall Ould
2014-03-15
Explicit solutions for the wave equations associated to the Dirac, Euler operators and the harmonic oscillator are given.
Enhanced Harmonic Up-Conversion Using a Hybrid HGHG-EEHG Scheme
Marksteiner, Quinn R.; Bishofberger, Kip A.; Carlsten, Bruce E.; Freund, Henry P.; Yampolsky, Nikolai A.
2012-04-30
We introduce a novel harmonic generation scheme which can be used, for a given desired harmonic, to achieve higher bunching factors, weaker chicanes, and/or less final energy spread than can be achieved using Echo-Enabled Harmonic Generation. This scheme only requires a single laser with relatively low power, and is a hybrid of High-Gain Harmonic Generation and EEHG. We present a design of this scheme applied to the Next Generation Light Source (NGLS).
Study on higher harmonic suppression using edge filter and polished Si wafer
Gupta, R. K. Singh, Amol Modi, Mohammed H. Lodha, G. S.
2014-04-24
Higher harmonics contamination is a severe problem in synchrotron beamlines where grating monochromators are used. In these beamlines, absorption edge filters and critical angle mirrors are used to suppress the harmonic contaminations. In the present study, carried out using Indus-1 reflectivity beamline, a harmonic suppression characteristic of Al edge filter and polished silicon wafer are determined. It is found that the Al filter suppresses higher harmonics in 2â€“7% range whereas the polished silicon wafer can suppress the higher harmonics below 1%. The results of comparative study are discussed.
Kaur, Sukhdeep; Sharma, A. K.; Salih, Hyder A.
2009-04-15
Second harmonic generation of a right circularly polarized Gaussian electromagnetic beam in a magnetized plasma is investigated. The beam causes Ohmic heating of electrons and subsequent redistribution of the plasma, leading to self-defocusing. The radial density gradient, in conjunction with the oscillatory electron velocity, produces density oscillation at the wave frequency. The density oscillation beats with the oscillatory velocity to produce second harmonic current density, giving rise to resonant second harmonic radiation when the wave frequency is one-third of electron cyclotron frequency. The second harmonic field has azimuthal dependence as exp(i{theta}). The self-defocusing causes a reduction in the efficiency of harmonic generation.
Continuous third harmonic generation in a terahertz driven modulated nanowire
Hamilton, Kathleen E. De, Amrit; Pryadko, Leonid P.; Kovalev, Alexey A.
2015-06-07
We consider the possibility of observing continuous third-harmonic generation using a strongly driven, single-band one-dimensional metal. In the absence of scattering, the quantum efficiency of frequency tripling for such a system can be as high as 93%. Combining the Floquet quasi-energy spectrum with the Keldysh Green's function technique, we derive a semiclassical master equation for a one-dimensional band of strongly and rapidly driven electrons in the presence of weak scattering by phonons. The power absorbed from the driving field is continuously dissipated by phonon modes, leading to a quasi-equilibrium in the electron distribution. We use the Kronig-Penney model with varying effective mass to establish the growth parameters of an InAs/InP nanowire near optimal for third harmonic generation at terahertz frequency range.
Monitoring microstructural evolution in irradiated steel with second harmonic generation
Matlack, Kathryn H.; Kim, Jin-Yeon; Jacobs, Laurence J.; Wall, James J.; Qu, Jianmin
2015-03-31
Material damage in structural components is driven by microstructural evolution that occurs at low length scales and begins early in component life. In metals, these microstructural features are known to cause measurable changes in the acoustic nonlinearity parameter. Physically, the interaction of a monochromatic ultrasonic wave with microstructural features such as dislocations, precipitates, and vacancies, generates a second harmonic wave that is proportional to the acoustic nonlinearity parameter. These nonlinear ultrasonic techniques thus have the capability to evaluate initial material damage, particularly before crack initiation and propagation occur. This paper discusses how the nonlinear ultrasonic technique of second harmonic generation can be used as a nondestructive evaluation tool to monitor microstructural changes in steel, focusing on characterizing neutron radiation embrittlement in nuclear reactor pressure vessel steels. Current experimental evidence and analytical models linking microstructural evolution with changes in the acoustic nonlinearity parameter are summarized.
Echo-enabled Harmonic Generation Free Electron Laser
Xiang, D; Stupakov, G.; /SLAC
2008-12-18
In this paper, we systematically study the echo-enabled harmonic generation (EEHG) free electron laser (FEL). The EEHG FEL uses two modulators in combination with two dispersion sections that allow to generate in the beam a high harmonic density modulation starting with a relatively small initial energy modulation of the beam. After presenting analytical theory of the phenomenon, we address several practically important issues, such as the effect of incoherent synchrotron radiation in the dispersion sections, and the beam transverse size effect in the modulator. Using a representative realistic set of beam parameters, we show how the EEHG scheme enhances the FEL performance and allows to generate a fully (both longitudinally and transversely) coherent radiation. As an example, we demonstrate that 5 nm coherent soft x-rays with GW peak power can be generated directly from the 240 nm seeding laser using the proposed EEHG scheme.
Higher harmonics generation in relativistic electron beam with virtual cathode
Kurkin, S. A. Badarin, A. A.; Koronovskii, A. A.; Hramov, A. E.
2014-09-15
The study of the microwave generation regimes with intense higher harmonics taking place in a high-power vircator consisting of a relativistic electron beam with a virtual cathode has been made. The characteristics of these regimes, in particular, the typical spectra and their variations with the change of the system parameters (beam current, the induction of external magnetic field) as well as physical processes occurring in the system have been analyzed by means of 3D electromagnetic simulation. It has been shown that the system under study demonstrates the tendency to the sufficient growth of the amplitudes of higher harmonics in the spectrum of current oscillations in the VC region with the increase of beam current. The obtained results allow us to consider virtual cathode oscillators as promising high power mmw-to-THz sources.
Discrete quadratic solitons with competing second-harmonic components
Setzpfandt, Frank; Pertsch, Thomas; Sukhorukov, Andrey A.
2011-11-15
We describe families of discrete solitons in quadratic waveguide arrays supported by competing cascaded nonlinear interactions between one fundamental and two second-harmonic modes. We characterize the existence, stability, and excitation dynamics of these solitons and show that their features may resemble those of solitons in saturable media. Our results also demonstrate that a power threshold may appear for soliton formation, leading to a suppression of beam self-focusing which explains recent experimental observations.
Using Coupled Harmonic Oscillators to Model Some Greenhouse Gas Molecules
Go, Clark Kendrick C.; Maquiling, Joel T.
2010-07-28
Common greenhouse gas molecules SF{sub 6}, NO{sub 2}, CH{sub 4}, and CO{sub 2} are modeled as harmonic oscillators whose potential and kinetic energies are derived. Using the Euler-Lagrange equation, their equations of motion are derived and their phase portraits are plotted. The authors use these data to attempt to explain the lifespan of these gases in the atmosphere.
On the moment of inertia of a quantum harmonic oscillator
Khamzin, A. A. Sitdikov, A. S.; Nikitin, A. S.; Roganov, D. A.
2013-04-15
An original method for calculating the moment of inertia of the collective rotation of a nucleus on the basis of the cranking model with the harmonic-oscillator Hamiltonian at arbitrary frequencies of rotation and finite temperature is proposed. In the adiabatic limit, an oscillating chemical-potential dependence of the moment of inertia is obtained by means of analytic calculations. The oscillations of the moment of inertia become more pronounced as deformations approach the spherical limit and decrease exponentially with increasing temperature.
Background and Reflections on the Life Cycle Assessment Harmonization Project
Broader source: Energy.gov [DOE]
Despite the ever-growing body of life cycle assessment literature on electricity generation technologies, inconsistent methods and assumptions hamper comparison across studies and pooling of published results. Synthesis of the body of previous research is necessary to generate robust results to assess and compare environmental performance of different energy technologies for the benefit of policy makers, managers, investors, and citizens. With funding from the U.S. Department of Energy, the National Renewable Energy Laboratory initiated the LCA Harmonization Project in an effort to rigorously leverage the numerous individual studies to develop collective insights.
STARS A Two Stage High Gain Harmonic Generation FEL Demonstrator
M. Abo-Bakr; W. Anders; J. Bahrdt; P. Budz; K.B. Buerkmann-Gehrlein; O. Dressler; H.A. Duerr; V. Duerr; W. Eberhardt; S. Eisebitt; J. Feikes; R. Follath; A. Gaupp; R. Goergen; K. Goldammer; S.C. Hessler; K. Holldack; E. Jaeschke; Thorsten Kamps; S. Klauke; J. Knobloch; O. Kugeler; B.C. Kuske; P. Kuske; A. Meseck; R. Mitzner; R. Mueller; M. Neeb; A. Neumann; K. Ott; D. Pfluckhahn; T. Quast; M. Scheer; Th. Schroeter; M. Schuster; F. Senf; G. Wuestefeld; D. Kramer; Frank Marhauser
2007-08-01
BESSY is proposing a demonstration facility, called STARS, for a two-stage high-gain harmonic generation free electron laser (HGHG FEL). STARS is planned for lasing in the wavelength range 40 to 70 nm, requiring a beam energy of 325 MeV. The facility consists of a normal conducting gun, three superconducting TESLA-type acceleration modules modified for CW operation, a single stage bunch compressor and finally a two-stage HGHG cascaded FEL. This paper describes the faciliy layout and the rationale behind the operation parameters.
A non-conforming 3D spherical harmonic transport solver
Van Criekingen, S.
2006-07-01
A new 3D transport solver for the time-independent Boltzmann transport equation has been developed. This solver is based on the second-order even-parity form of the transport equation. The angular discretization is performed through the expansion of the angular neutron flux in spherical harmonics (PN method). The novelty of this solver is the use of non-conforming finite elements for the spatial discretization. Such elements lead to a discontinuous flux approximation. This interface continuity requirement relaxation property is shared with mixed-dual formulations such as the ones based on Raviart-Thomas finite elements. Encouraging numerical results are presented. (authors)
Temperature-insensitive phase-matched optical harmonic conversion crystal
Barker, C.E.; Eimerl, D.; Velsko, S.P.; Roberts, D.
1993-11-23
Temperature-insensitive, phase-matched harmonic frequency conversion of laser light at a preferred wavelength of 1.064 microns can be achieved by use of a crystal of deuterated l-arginine phosphate. The crystal is cut and oriented so that the laser light propagates inside the crystal along one of several required directions, which correspond to a temperature-insensitive, phase-matching locus. The method of measuring and calculating the temperature-insensitive, phase-matching angles can be extended to other fundamental wavelengths and other crystal compositions. 12 figures.
Uncertainties in compliance with harmonic current distortion limits in electric power systems
Gruzs, T.M. )
1991-07-01
The harmonic distortion of any repetitive voltage or current waveform is typically described by the quantity total harmonic distortion (THD). With the proliferation of nonlinear loads, such as static power converters, there has been increasing concern over the generation of harmonic currents and the effects of these currents on the power system. Proposals have been made to limit harmonic currents in power systems using the total harmonic distortion of the current as the criterion. This criterion, although it may be necessary, can be ambiguous and lead to compliance uncertainties. In this paper a discussion is presented on several of the practical problems by applying total harmonic current distortion limits to industrial and commercial power systems.
Ganeev, R. A.; Abdelrahman, Z. Frank, F.; Witting, T.; Okell, W. A.; Fabris, D.; Hutchison, C.; Marangos, J. P.; Tisch, J. W. G.
2014-01-13
We present measurements of the spatial coherence of the high-order harmonics generated in laser-produced ablation plumes. Harmonics were generated using 4 fs, 775â€‰nm pulses with peak intensity 3â€‰Ã—â€‰10{sup 14}â€‰Wâ€‰cm{sup âˆ’2}. Double-slit fringe visibilities in the range of â‰ˆ0.6â€“0.75 were measured for non-resonant harmonics in carbon and resonantly enhanced harmonics in zinc and indium. These are somewhat higher than the visibility obtained for harmonics generated in argon gas under similar conditions. This is attributed to lower time-dependent ionization of the plasma ablation targets compared to argon during the high harmonics generation process.
Braenzel, J.; SchnÃ¼rer, M.; Steinke, S.; Priebe, G.; Sandner, W.; Andreev, A.; Vavilov State Optical Institute, Birzhevaya line 4, 199034 St. Petersburg ; Platonov, K.
2013-08-15
Theoretical and experimental investigations of the dynamics of a relativistically oscillating plasma slab reveal spectral line splitting in laser driven harmonic spectra, leading to double harmonic series. Both series are well characterized with harmonics arising by two fundamental frequencies. While a relativistic oscillation of the critical density drives the harmonic emission, the splitting is a result of an additional acceleration during the laser pulse duration. In comparison with the oscillatory movement, this acceleration is rather weak and can be described by a plasma shock wave driven by the pressure of light. We introduce particle in cell simulations and an analytical model explaining the harmonic line splitting. The derived analytical formula gives direct access between the splitting in the harmonic spectrum and the acceleration of the plasma surface.
Tracing the structure of asymmetric molecules from high-order harmonic generation
Chen Yanjun; Zhang, Bing
2011-11-15
We investigate high-order harmonic generation (HHG) from asymmetric molecules exposed to intense laser fields. We show that the emissions of odd and even harmonics depend differently on the orientation angle, the internuclear distance, as well as the effective charge. This difference mainly comes from different roles of intramolecular interference in the HHG of odd and even harmonics. These roles map the structure of the asymmetric molecule to the odd vs even HHG spectra.
N = 4 supersymmetric mechanics: Harmonic superspace as a universal tool of model-building
Ivanov, E. A.
2013-08-15
We overview applications of the harmonic superspace approach in models of N = 4supersymmetric mechanics, with emphasis on some recent results.
A multiple deep attenuation frequency window for harmonic analysis in power systems
Daponte, P.; Falcomata, G. . Dept. di Elettronica Informatica e Sistemistica); Testa, A. . Dipt. di Ingegneria Elettrica)
1994-04-01
A novel window is presented and applied in electrical power system harmonic analysis. The goal of increasing the resolvability of low magnitude non-harmonic tones close in frequency to higher magnitude harmonics and the detectability of very low magnitude high frequency harmonics is pursued. The proposed window is derived from the Tseng window; its spectrum can be modeled in the synthesis stage and it is characterized by a narrow width main lobe and by sidelobes which are very low in correspondence to some specified frequencies. Numerical experiments demonstrate the performances and the usefulness of the new window in resolving periodic distorted waveforms in power systems.
Numerical studies of third-harmonic generation in laser filament in air perturbed by plasma spot
Feng Liubin; Lu Xin; Liu Xiaolong; Li Yutong; Chen Liming; Ma Jinglong; Dong Quanli; Wang Weimin; Xi Tingting; Sheng Zhengming; Zhang Jie; He Duanwei
2012-07-15
Third-harmonic emission from laser filament intercepted by plasma spot is studied by numerical simulations. Significant enhancement of the third-harmonic generation is obtained due to the disturbance of the additional plasma. The contribution of the pure plasma effect and the possible plasma-enhanced third-order susceptibility on the third-harmonic generation enhancement are compared. It is shown that the plasma induced cancellation of destructive interference [Y. Liu et al., Opt. Commun. 284, 4706 (2011)] of two-colored filament is the dominant mechanism of the enhancement of third-harmonic generation.
Reconsidering harmonic and anharmonic coherent states: Partial differential equations approach
Toutounji, Mohamad
2015-02-15
This article presents a new approach to dealing with time dependent quantities such as autocorrelation function of harmonic and anharmonic systems using coherent states and partial differential equations. The approach that is normally used to evaluate dynamical quantities involves formidable operator algebra. That operator algebra becomes insurmountable when employing Morse oscillator coherent states. This problem becomes even more complicated in case of Morse oscillator as it tends to exhibit divergent dynamics. This approach employs linear partial differential equations, some of which may be solved exactly and analytically, thereby avoiding the cumbersome noncommutative algebra required to manipulate coherent states of Morse oscillator. Additionally, the arising integrals while using the herein presented method feature stability and high numerical efficiency. The correctness, applicability, and utility of the above approach are tested by reproducing the partition and optical autocorrelation function of the harmonic oscillator. A closed-form expression for the equilibrium canonical partition function of the Morse oscillator is derived using its coherent states and partial differential equations. Also, a nonequilibrium autocorrelation function expression for weak electronâ€“phonon coupling in condensed systems is derived for displaced Morse oscillator in electronic state. Finally, the utility of the method is demonstrated through further simplifying the Morse oscillator partition function or autocorrelation function expressions reported by other researchers in unevaluated form of second-order derivative exponential. Comparison with exact dynamics shows identical results.
Structural characterization of particle systems using spherical harmonics
Feinauer, Julian; Spettl, Aaron; Manke, Ingo; Strege, Stefan; Kwade, Arno; Pott, Andres; Schmidt, Volker
2015-08-15
Many important properties of particulate materials are heavily influenced by the size and shape of the constituent particles. Thus, in order to control and improve product quality, it is important to develop a good understanding of the shape and size of the particles that make up a given particulate material. In this paper, we show how the spherical harmonics expansion can be used to approximate particles obtained from tomographic 3D images. This yields an analytic representation of the particles which can be used to calculate structural characteristics. We present an estimation method for the optimal length of expansion depending on individual particle shapes, based on statistical hypothesis testing. A suitable choice of this parameter leads to a smooth approximation that preserves the main shape features of the original particle. To show the wide applicability of this procedure, we use it to approximate particles obtained from two different tomographic 3D datasets of particulate materials. The first one describes an anode material from lithium-ion cells that consists of sphere-like particles with different sizes. The second dataset describes a powder of highly non-spherical titanium dioxide particles. - Highlights: â€¢ Complex particle shapes are described analytically by spherical harmonics expansion. â€¢ The optimal length of the expansion is estimated for each particle individually. â€¢ Characteristics like, e.g., particle surface areas can be calculated efficiently. â€¢ The method is applied to two tomographic datasets of particulate materials.
Longitudinal instabilities with a non-harmonic rf potential
Krinsky, S.; Wang, J.M.
1983-01-01
We consider the longitudinal instabilities of a bunched beam subject to a non-harmonic rf potential. Assuming the unperturbed bunch to be described by a Maxwell-Boltzmann distribution, our treatment is based upon the linearized Vlasov equation. The formalism developed is exact, and in particular, correctly describes the effect of the dependence on amplitude of the synchrotron oscillation frequency. We discuss the fast blowup limit, and extend Wang and Pellegrini's treatment of the microwave instability to include the case of a non-Gaussian bunch. Next, within the short bunch approximation, we derive the dispersion relation describing the Landau damping of the coupled bunch modes, resulting from the use of a Landau cavity.
Cai, Jiandong; Zhang, Li; Wang, Michael Yu
2015-12-15
In multifrequency atomic force microscopy (AFM), probeâ€™s characteristic of assigning resonance frequencies to integer harmonics results in a remarkable improvement of detection sensitivity at specific harmonic components. The selection criterion of harmonic order is based on its amplitudeâ€™s sensitivity on material properties, e.g., elasticity. Previous studies on designing harmonic probe are unable to provide a large design capability along with maintaining the structural integrity. Herein, we propose a harmonic probe with step cross section, in which it has variable width in top and bottom steps, while the middle step in cross section is kept constant. Higher order resonance frequencies are tailored to be integer times of fundamental resonance frequency. The probe design is implemented within a structural optimization framework. The optimally designed probe is micromachined using focused ion beam milling technique, and then measured with an AFM. The measurement results agree well with our resonance frequency assignment requirement.
Resonant second harmonic generation in a gallium nitride two-dimensional photonic crystal on silicon
Zeng, Y.; Roland, I.; Checoury, X.; Han, Z.; El Kurdi, M.; Sauvage, S.; Boucaud, P.; Gayral, B.; Brimont, C.; Guillet, T.; Mexis, M.; Semond, F.
2015-02-23
We demonstrate second harmonic generation in a gallium nitride photonic crystal cavity embedded in a two-dimensional free-standing photonic crystal platform on silicon. The photonic crystal nanocavity is optically pumped with a continuous-wave laser at telecom wavelengths in the transparency window of the nitride material. The harmonic generation is evidenced by the spectral range of the emitted signal, the quadratic power dependence vs. input power, and the spectral dependence of second harmonic signal. The harmonic emission pattern is correlated to the harmonic polarization generated by the second-order nonlinear susceptibilities Ï‡{sub zxx}{sup (2)},â€‰Ï‡{sub zyy}{sup (2)} and the electric fields of the fundamental cavity mode.
Singh, Mamta; Gupta, D. N.; Suk, H.
2015-06-15
We propose an idea to enhance the efficiency of second- and third-harmonic generation by considering the amplitude-modulation of the fundamental laser pulse. A short-pulse laser of finite spot size is modeled as amplitude modulated in time. Amplitude-modulation of fundamental laser contributes in quiver velocity of the plasma electrons and produces the strong plasma-density perturbations, thereby increase in current density at second- and third-harmonic frequency. In a result, the conversion efficiency of harmonic generation increases significantly. Power conversion efficiency of harmonic generation process is the increasing function of the amplitude-modulation parameter of the fundamental laser beam. Harmonic power generated by an amplitude modulated laser is many folds higher than the power obtained in an ordinary case.
Third harmonic generation in air ambient and laser ablated carbon plasma
Singh, Ravi Pratap Gupta, Shyam L.; Thareja, Raj K.
2015-12-15
We report the third harmonic generation of a nanosecond laser pulse (1.06â€‰Î¼m) in air ambient and in the presence of nanoparticles from laser ablated carbon plasma. Significant decrease in the threshold of third harmonic generation and multi-fold increment in the intensity of generated third harmonic is observed in presence of carbon plasma. The third harmonic in air is due to the quasi-resonant four photon process involving vibrationally excited states of molecular ion of nitrogen due to electron impact ionization and laser pulse. Following optical emission spectroscopic observations we conclude that the presence of C{sub 2} and CN in the ablated plume play a vital role in the observed third harmonic signals.
Improvement of nonlinear harmonics in free electron laser with planar wiggler
Bazouband, F.; Maraghechi, B.
2012-11-15
Spontaneous emission of free electron laser with planar wiggler and ion-channel guiding is calculated analytically and possibility of emission at up-shifted wiggler or ion-channel betatron frequency and their harmonics has been found. To investigate the nonlinear odd harmonics, a set of self-consistent nonlinear differential equations that governs the evolution of radiation and electron beam are derived and solved numerically by Runge-Kutta method. Using the simulation code, gain improvement of third harmonic is studied in the range of microwave frequency by applying ion-channel guiding for a cold beam. It is shown that the combination of the ion-channel and a prebunched electron beam increases the amplitude of the third harmonic of the radiation and decreases its saturation length. The relation between the linear and nonlinear harmonics is discussed.
Controlling harmonic instability of HVDC links connected to weak ac systems
Bodger, P.S. ); Irwin, G.D.; Woodford, D.A. )
1990-10-01
Time domain digital simulation of HVDC transmission enables harmonic stability of a system to be studied. This paper reports two alternative measures of controlling harmonic instability were investigated; the use of C-type ac filters and a simple addition of a harmonic damping circuit in the rectifier converter control. The design of a C-type filter is described and its effectiveness presented. Harmonic damping by controls consists of taking the output from a fast response dc current transducer, passing it through a filter and a gain and adding the output to the firing angle order. Both methods result in stable recovery from faults at both rectifier and inverter terminal busbars for a dc system inherently harmonically unstable.
Harmonization - Two Years' of Transportation Regulation Lessons Learned
Colborn, K.
2007-07-01
The U.S. Department of Transportation issued modifications to the Hazardous Materials Regulations in October, 2004 as part of an ongoing effort to 'harmonize' U.S. regulations with those of the International Atomic Energy Agency. The harmonization effort had several predictable effects on low level radioactive materials shipment that were anticipated even prior to their implementation. However, after two years' experience with the new regulations, transporters have identified several effects on transportation which were not entirely apparent when the regulations were first implemented. This paper presents several case studies in the transportation of low level radioactive materials since the harmonization rules took effect. In each case, an analysis of the challenge posed by the regulatory revision is provided. In some cases, more than one strategy for compliance was considered, and the advantages and disadvantages of each are discussed. In several cases, regulatory interpretations were sought and obtained, and these are presented to clarify the legitimacy of the compliance approach. The presentation of interpretations will be accompanied by reports of clarifying discussions with the U.S. DOT about the interpretation and scope of the regulatory change. Specific transportation issues raised by the revised hazardous materials regulations are reviewed, including: The new definition of radioactive material in accordance with isotope-specific concentration and total activity limits. The new hazardous materials regulations (HMR) created a new definition for radioactive material. A case study is presented for soils contaminated with low levels of Th-230. These soils had been being shipped for years as exempt material under the old 2,000 pCi/g concentration limit. Under the new HMR, these same soils were radioactive material. Further, in rail-car quantities their activity exceeded an A2 value, so shipment of the material in gondolas appeared to require an IP-2 package
Mitigation of harmonic disturbance at pumped storage power station with static frequency converter
Chiang, J.C.; Wu, C.J.; Yen, S.S.
1997-09-01
This paper investigates the harmonic distortion problem and mitigation method at the Mingtan Pumped Storage Power Station in Taiwan, where six 300 MVA synchronous generators/motors are started by a static frequency converter (SFC) before the pumping stage. Since the SFC uses 6-pulse rectifier technique, a large amount of harmonic currents are produced during the starting period. The harmonic distortion level at each bus of the power plant was very high. Especially, the total harmonic distortion (THD) of current at the lighting feeder reached up to 184%, so that power fuses were burned out. At first a 5 mH reactor was inserted in the SFC feeder and a 5th order and high pass filter was installed. However, the harmonic distortion levels were still too high, but there is no space for additional higher-order filters. Finally, the SFC is fed with an individual transformer, and the harmonic disturbance problem is avoided. This paper also gives computer simulations to investigate the harmonic distortion problems and verify the mitigation methods.
Madsen, C. B.; Madsen, L. B.
2007-10-15
Using a quantum-mechanical three-step model, we present numerical calculations of the high-order harmonic generation from four polyatomic molecules. Ethylene (C{sub 2}H{sub 4}) serves as an example where orbital symmetry directly affects the harmonic yield. We treat the case of methane (CH{sub 4}) to address the high-order harmonic generation resulting from a molecule with degenerate orbitals. To this end we illustrate how the single-orbital contributions show up in the total high-order harmonic signal. This example illustrates the importance of adding coherently the amplitude contributions from the individual degenerate orbitals. Finally, we study the high-order harmonic generation from propane (C{sub 3}H{sub 8}) and butane (C{sub 4}H{sub 10}). These two molecules, being extended and far from spherical in structure, produce harmonics with nontrivial orientational dependencies. In particular, propane can be oriented so that very high-frequency harmonics are favored, and thus the molecule contains prospects for the generation of uv attosecond pulses.
Analysis of higher harmonic contamination with a modified approach using a grating analyser
Gupta, Rajkumar Modi, Mohammed H.; Lodha, G. S.; Kumar, M.; Chakera, J. A.
2014-04-15
Soft x-ray spectra of the toroidal grating monochromator (TGM) at the reflectivity beamline of Indus-1 synchrotron source are analyzed for higher harmonic contribution. A diffraction grating of central line spacing 1200 l/mm is used to disperse the monochromatic beam received from TGM to quantify the harmonic contents in the 50â€“360 Ã… wavelength range. In order to calculate the harmonic contamination, conventionally the intensity of higher order peak is divided by first order peak intensity of the desired wavelength. This approach is found to give wrong estimate as first order peak itself is overlapped by higher order peaks. In the present study, a modified approach has been proposed to calculate harmonic contamination where the intensity contributions of overlapping orders have been removed from the first order diffraction peak of the desired wavelength. It is found that the order contamination in the TGM spectra is less than 15% in the wavelength range of 90â€“180 Ã…. The total harmonic contribution increases from 6%â€“60% in the wavelength range of 150â€“260 Ã…. The critical wavelength of Indus-1 is 61 Ã… hence the harmonic contamination below 90 Ã… is significantly low. The results obtained with modified approach match well with those obtained by quantitative analysis of multilayer reflectivity data. The obtained higher harmonics data are used to fit the transmission of aluminum edge filter in the 120â€“360 Ã… wavelength range.
RF physics of ICWC discharge at high cyclotron harmonics
Lyssoivan, A.; Van Eester, D.; Wauters, T.; Vervier, M.; Van Schoor, M.; Bobkov, V.; Rohde, V.; Schneider, P.; Douai, D.; Kogut, D.; Kreter, A.; MÃ¶ller, S.; Philipps, V.; Sergienko, G.; Moiseenko, V.; Noterdaeme, J.-M.; Collaboration: TEXTOR Team; ASDEX Upgrade Team
2014-02-12
Recent experiments on Ion Cyclotron Wall Conditioning (ICWC) performed in tokamaks TEXTOR and ASDEX Upgrade with standard ICRF antennas operated at fixed frequencies but variable toroidal magnetic field demonstrated rather contrasting parameters of ICWC discharge in scenarios with on-axis fundamental ion cyclotron resonance (ICR) for protons,Ï‰=Ï‰{sub H+}, and with its high cyclotron harmonics (HCH), Ï‰=10Ï‰{sub cH+}â‹… HCH scenario: very high antenna coupling to low density RF plasmas (P{sub pl}â‰ˆ0.9P{sub RF-G}) and low energy Maxwellian distribution of CX hydrogen atoms with temperature T{sub H}â‰ˆ350 eV. Fundamental ICR: lower antenna-plasma coupling efficiency (by factor of about 1.5 times) and generation of high energy non-Maxwellian CX hydrogen atoms (with local energy E{sub âŠ¥H} â‰¥1.0 keV). In the present paper, we analyze the obtained experimental results numerically using (i) newly developed 0-D transport code describing the process of plasma production with electron and ion collisional ionization in helium-hydrogen gas mixture and (ii) earlier developed 1-D Dispersion Relation Solver accounting for finite temperature effects and collision absorption mechanisms for all plasma species in addition to conventionally examined Landau/TTPM damping for electrons and cyclotron absorption for ions. The numerical study of plasma production in helium with minor hydrogen content in low and high toroidal magnetic fields is presented. The investigation of the excitation, conversion and absorption of plasma waves as function of B{sub T}-field suggests that only fast waves (FW) may give a crucial impact on antenna coupling and characteristics of the ICWC discharge using standard poloidally polarized ICRF antennas designed to couple RF power mainly to FW. The collisional (non-resonant) absorption by electrons and ions and IC absorption by resonant ions of minor concentration in low T{sub e} plasmas is studied at fundamental ICR and its high harmonics.
Surface plasma wave assisted second harmonic generation of laser over a metal film
Chauhan, Santosh; Parashar, J.
2015-01-15
Second harmonic generation of laser mode converted surface plasma wave (SPW) over a corrugated metal film is studied. The laser, impinged on the metal film, under attenuated total reflection configuration, excites SPW over the metalâ€“vacuum interface. The excited SPW extends over a much wider surface area than the laser spot cross-section. It exerts a second harmonic ponderomotive force on metal electrons, imparting them velocity that beats with the surface ripple to produce a nonlinear current, driving resonant second harmonic surface plasma wave.
Calculation of voltage harmonic distortion caused by small non-linear loads
Hegazy, Y.G.; Salama, M.M.A.
1995-10-01
This paper presents an accurate method to evaluate the harmonic distortion in distribution systems. This method overcomes most of the drawbacks of the traditional methods. The main idea of the proposed method is to represent the harmonic effects of small non-linear loads by an equivalent large load. A case study is presented in the paper to illustrate the proposed method. The total harmonic distortion factor is evaluated at different busses of a distribution system using the proposed method. The results are then compared to those obtained using the traditional methods.
Li, Dongsheng; Khaleel, Mohammad A.; Sun, Xin; Garmestani, Hamid
2010-03-01
Statistical correlation function, including two-point function, is one of the popular methods to digitize microstructure quantitatively. This paper investigated how to represent statistical correlations using layered fast spherical harmonics expansion. A set of spherical harmonics coefficients may be used to represent the corresponding microstructures. It is applied to represent carbon nanotube composite microstructures to demonstrate how efficiently and precisely the harmonics coefficients will characterize the microstructure. This microstructure representation methodology will dramatically improve the computational efficiencies for future works in microstructure reconstruction and property prediction.
Approach of spherical harmonics to the representation of the deformed su(1,1) algebra
Fakhri, H.; Ghaneh, T.
2008-11-15
The m-shifting generators of su(2) algebra together with a pair of l-shifting ladder symmetry operators have been used in the space of all spherical harmonics Y{sub l}{sup m}({theta},{phi}) in order to introduce a new set of operators, expressing the transitions between them. It is shown that the space of spherical harmonics whose l+2m or l-2m is given presents negative and positive irreducible representations of a deformed su(1,1) algebra, respectively. These internal symmetries also suggest new algebraic methods to construct the spherical harmonics in the framework of the spectrum-generating algebras.
Boyarinov, V. F.; Kondrushin, A. E.; Fomichenko, P. A.
2012-07-01
Finite-difference time-dependent equations of Surface Harmonics method have been obtained for plane geometry. Verification of these equations has been carried out by calculations of tasks from 'Benchmark Problem Book ANL-7416'. The capacity and efficiency of the Surface Harmonics method have been demonstrated by solution of the time-dependent neutron transport equation in diffusion approximation. The results of studies showed that implementation of Surface Harmonics method for full-scale calculations will lead to a significant progress in the efficient solution of the time-dependent neutron transport problems in nuclear reactors. (authors)
Effect of the resonant growth of harmonics on the electron density in capacitively coupled plasma
Yamazawa, Yohei
2009-11-09
The growth of harmonics is known to occur under the condition of plasma series resonance (PSR). In an actual plasma process chamber, the external circuit also affects the PSR. We experimentally demonstrated the resonant growth of the third and fourth harmonics by tuning a variable capacitor attached to the electrode, and investigated the influence of the growth on the electron density. We observed significant increases in electron density as the amplitude of harmonics grows. The result clearly shows that nonlinear electron resonance heating actually takes place.
Third harmonic stimulated Raman backscattering of laser in a magnetized plasma
Paknezhad, Alireza; Dorranian, Davoud
2013-09-15
This article studies the nonlinear Raman shifted third harmonic backscattering of an intense extraordinary laser wave through a homogenous transversely magnetized cold plasma. Due to the relativistic nonlinearity, the plasma dynamic is modified in the presence of transversely magnetic field, and this can generate the third harmonic scattered wave and an electrostatic upper hybrid wave via the Raman scattering process. Using the nonlinear wave equation, the mechanism of nonlinear third harmonic Raman scattering is discussed in detail to obtain the maximum growth rate of instability in the mildly relativistic regime. The growth rate decreases as the static magnetic field increases. It also increases with the pump wave amplitude.
Electro-optic harmonic conversion to switch a laser beam out of a cavity
Haas, Roger A.; Henesian, Mark A.
1987-01-01
The invention is a switch to permit a laser beam to escape a laser cavity through the use of an externally applied electric field across a harmonic conversion crystal. Amplification takes place in the laser cavity, and then the laser beam is switched out by the laser light being harmonically converted with dichroic or polarization sensitive elements present to alter the optical path of the harmonically converted laser light. Modulation of the laser beam can also be accomplished by varying the external electric field.
A new frequency domain arc furnace model for iterative harmonic analysis
Mayordomo, J.G.; Beites, L.F.; Asensi, R.; Izzeddine, M.; Zabala, L.; Amantegui, J.
1997-10-01
This paper presents a new frequency domain Arc Furnace model for Iterative Harmonic Analysis (IHA) by means of a Newton method. Powerful analytical expressions for harmonic currents and their derivatives are obtained under the balanced conditions of the system. The model offers a three phase configuration where there is no path for homopolar currents. Moreover, it contemplates continuous and discontinuous evolution of the arc current. The solution obtained is validated by means of time domain simulations. Finally, the model was integrated in a harmonic power flow where studies have been performed in a network with more than 700 busbars and 7 actual Arc Furnace Loads.
Third-harmonic performance of the Beamlet prototype laser
Wegner, P.J.; Barker, C.E.; Caird, J.A.; Dixit, S.N.; Henesian, M.A.; Seppala, L.G.; Thompson, C.E.; Van Wonterghem, B.V.
1997-01-31
The Beamlet laser is a nearly full-scale, single-aperture prototype of the driver design for the National Ignition Facility (NIF). As part of a test and validation plan for the NIF design, Beamlet was recently equipped with final focusing optics and diagnostics for the purpose of evaluating integrated component performance and equivalent target-plane irradiance conditions at the 0.351-{mu}m output wavelength specified for NIF targets. A 37-cm aperture two-crystal converter scheme generates the third harmonic of the Nd:glass 1.053-{mu}m wavelength with high efficiency. The efficiency of the converter has been characterized and is reported, along with detailed measurements of the near-field and far-field UV irradiance distributions at operating conditions up to and exceeding red-line levels for the NIF. Dependences of observed beam quality on critical laser parameters including output power, B-integral, and spatial filtering are discussed and compared with numerical simulations.
All-sky interferometry with spherical harmonic transit telescopes
Shaw, J. Richard; Pen, Ue-Li; Sigurdson, Kris; Sitwell, Michael; Stebbins, Albert
2014-02-01
In this paper, we describe the spherical harmonic transit telescope through the use of a novel formalism for the analysis of transit radio telescopes. This all-sky approach bypasses the curved-sky complications of traditional interferometry and so is particularly well-suited to the analysis of wide-field radio interferometers. It enables compact and computationally efficient representations of the data and its statistics, which allow new ways of approaching important problems like map-making and foreground removal. In particular, we show how it enables the use of the Karhunen-LoÃ¨ve transform as a highly effective foreground filter, suppressing realistic foreground residuals for our fiducial example by at least a factor 20 below the 21 cm signal, even in highly contaminated regions of the sky. This is despite the presence of the mode-mixing inherent in real-world instruments with frequency-dependent beams. We show, using Fisher forecasting, that foreground cleaning has little effect on power spectrum constraints compared to hypothetical foreground-free measurements. Beyond providing a natural real-world data analysis framework for 21 cm telescopes now under construction and future experiments, this formalism allows accurate power spectrum forecasts to be made that include the interplay of design constraints and realistic experimental systematics with 21st century 21 cm science.
High-order harmonic generation using a high-repetition-rate turnkey laser
Lorek, E. Larsen, E. W.; Heyl, C. M.; CarlstrÃ¶m, S.; Mauritsson, J.; PaleÄek, D.; Zigmantas, D.
2014-12-15
We generate high-order harmonics at high pulse repetition rates using a turnkey laser. High-order harmonics at 400 kHz are observed when argon is used as target gas. In neon, we achieve generation of photons with energies exceeding 90 eV (âˆ¼13 nm) at 20 kHz. We measure a photon flux of up to 4.4 Ã— 10{sup 10} photons per second per harmonic in argon at 100 kHz. Many experiments employing high-order harmonics would benefit from higher repetition rates, and the user-friendly operation opens up for applications of coherent extreme ultra-violet pulses in new research areas.
Resonant third harmonic generation of KrF laser in Ar gas
Rakowski, R.; Barna, A.; Suta, T.; FÃ¶ldes, I. B.; Bohus, J.; SzatmÃ¡ri, S.; MikoÅ‚ajczyk, J.; Bartnik, A.; Fiedorowicz, H.; Verona, C.; Verona Rinati, G.; Margarone, D.; Nowak, T.; and others
2014-12-15
Investigations of emission of harmonics from argon gas jet irradiated by 700 fs, 5 mJ pulses from a KrF laser are presented. Harmonics conversion was optimized by varying the experimental geometry and the nozzle size. For the collection of the harmonic radiation silicon and solar-blind diamond semiconductor detectors equipped with charge preamplifiers were applied. The possibility of using a single-crystal CVD diamond detector for separate measurement of the 3rd harmonic in the presence of a strong pumping radiation was explored. Our experiments show that the earlier suggested 0.7% conversion efficiency can really be obtained, but only in the case when phase matching is optimized with an elongated gas target length corresponding to the length of coherence.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Bansal, Dipanshu; Aref, Amjad; Dargush, Gary; Delaire, Olivier A.
2016-07-20
Based on thermodynamic principles, we derive expressions quantifying the non-harmonic vibrational behavior of materials, which are rigorous yet easily evaluated from experimentally available data for the thermal expansion coefficient and the phonon density of states. These experimentally-derived quantities are valuable to benchmark first-principles theoretical predictions of harmonic and non-harmonic thermal behaviors using perturbation theory, ab initio molecular-dynamics, or Monte-Carlo simulations. In this study, we illustrate this analysis by computing the harmonic, dilational, and anharmonic contributions to the entropy, internal energy, and free energy of elemental aluminum and the ordered compound FeSi over a wide range of temperature. Our results agreemoreÂ Â» well with previous data in the literature and provide an efficient approach to estimate anharmonic effects in materials.Â«Â less
de Rooij, Michael Andrew; Steigerwald, Robert Louis; Delgado, Eladio Clemente
2008-12-16
Photovoltaic power converter system including a controller configured to reduce load harmonics is provided. The system comprises a photovoltaic array and an inverter electrically coupled to the array to generate an output current for energizing a load connected to the inverter and to a mains grid supply voltage. The system further comprises a controller including a first circuit coupled to receive a load current to measure a harmonic current in the load current. The controller includes a second circuit to generate a fundamental reference drawn by the load. The controller further includes a third circuit for combining the measured harmonic current and the fundamental reference to generate a command output signal for generating the output current for energizing the load connected to the inverter. The photovoltaic system may be configured to compensate harmonic currents that may be drawn by the load.
Compensation for phase mismatch of high harmonics by the group-velocity mismatch
Kulagin, I A; Kim, V V; Usmanov, T
2011-09-30
A mechanism providing an essential enhancement of the conversion efficiency of a single high harmonic in gaseous media is first proposed using an appropriate change in the phase mismatch and group-velocity mismatch in the vicinity of resonance.
Heath, G.
2012-06-01
This powerpoint presentation to be presented at the World Renewable Energy Forum on May 14, 2012, in Denver, CO, discusses systematic review and harmonization of life cycle GHG emission estimates for electricity generation technologies.
A Proof-of-Principle Echo-enabled Harmonic Generation Free Electron...
Office of Scientific and Technical Information (OSTI)
ThesisDissertation: A Proof-of-Principle Echo-enabled Harmonic Generation Free Electron Laser Experiment at SLAC Citation Details In-Document Search Title: A Proof-of-Principle...
Optical Third-Harmonic Generation in Graphene Hong, Sung-Young...
Office of Scientific and Technical Information (OSTI)
Third-Harmonic Generation in Graphene Hong, Sung-Young; Dadap, Jerry I.; Petrone, Nicholas; Yeh, Po-Chun; Hone, James; Osgood, Richard M. American Physical Society None USDOE...
Second-harmonic generation of upper-hybrid radiation in a plasma
Tewari, D.P.; Tripathi, V.K.
1980-05-01
Employing the fluid model for the nonlinear response of electrons, we have studied the phenomenon of second-harmonic generation of upper-hybrid electromagnetic radiation in an inhomogeneous plasma. In the case of laser-pallet fusion, the maximum contribution for harmonic generation comes from the vicinity of the upper-hybrid layer, and the harmonic conversion efficiency turns out to be approx.0.1% at the power densities approx.10/sup 14/ W/cm/sup 2/ (CO/sub 2/ laser), the same order as observed experimentally. In the case of electron cyclotron heating experiments of tokamak, a strong second harmonic must be generated at the cyclotron resonance layer. The wave-number-matching condition could be satisfied in a tokamak, which adds to the conversion efficiency.
High harmonic generation in underdense plasmas by intense laser pulses with orbital angular momentum
MendonÃ§a, J. T.; Vieira, J.
2015-12-15
We study high harmonic generation produced by twisted laser pulses, with orbital angular momentum in the relativistic regime, for pulse propagation in underdense plasma. We consider fast time scale processes associated with an ultra-short pulse, where the ion motion can be neglected. We use both analytical models and numerical simulations using a relativistic particle-in-cell code. The present description is valid for relativistic laser intensities, when the normalized field amplitude is much larger than one, a â‰« 1. We also discuss two distinct processes associated with linear and circular polarization. Using both analytical solutions and particle-in-cell simulations, we are able to show that, for laser pulses in a well defined Laguerre-Gauss mode, angular momentum conservation is observed during the process of harmonic generation. Intensity modulation of the harmonic spectrum is also verified, as imposed by the nonlinear time-scale for energy transfer between different harmonics.
Second harmonic generation from direct band gap quantum dots pumped by femtosecond laser pulses
Liu, Liwei Wang, Yue; Hu, Siyi; Ren, Yu; Huang, Chen
2014-02-21
We report on nonlinear optical experiments performed on Cu{sub 2}S quantum dots (QDs) pumped by femtosecond laser pulses. We conduct a theoretical simulation and experiments to determine their second harmonic generation characteristics. Furthermore, we demonstrate that the QDs have a second harmonic generation conversion efficiency of up to 76%. Our studies suggest that these Cu{sub 2}S QDs can be used for solar cells, bioimaging, biosensing, and electric detection.
Attachment of second harmonic-active moiety to molecules for detection of molecules at interfaces
Salafsky, Joshua S.; Eisenthal, Kenneth B.
2005-10-11
This invention provides methods of detecting molecules at an interface, which comprise labeling the molecules with a second harmonic-active moiety and detecting the labeled molecules at the interface using a surface selective technique. The invention also provides methods for detecting a molecule in a medium and for determining the orientation of a molecular species within a planar surface using a second harmonic-active moiety and a surface selective technique.
Fluid simulations of frequency effects on nonlinear harmonics in inductively coupled plasma
Si Xuejiao; Xu Xiang; Wang Younian [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Zhao Shuxia [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Department of Chemistry, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, BE-2610 Wilrijk-Antwerp (Belgium); Bogaerts, A. [Department of Chemistry, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, BE-2610 Wilrijk-Antwerp (Belgium)
2011-03-15
A fluid model is self-consistently established to investigate the harmonic effects in an inductively coupled plasma, where the electromagnetic field is solved by the finite difference time domain technique. The spatiotemporal distribution of harmonic current density, harmonic potential, and other plasma quantities, such as radio frequency power deposition, plasma density, and electron temperature, have been investigated. Distinct differences in current density have been observed when calculated with and without Lorentz force, which indicates that the nonlinear Lorentz force plays an important role in the harmonic effects, especially at low frequencies. Moreover, the even harmonics are larger than the odd harmonics both in the current density and the potential. Finally, the dependence of various plasma quantities with and without the Lorentz force on various driving frequencies is also examined. It is shown that the deposited power density decreases and the depth of penetration increases slightly because of the Lorentz force. The electron density increases distinctly while the electron temperature remains almost the same when the Lorentz force is taken into account.
Harmonic mode competition in a terahertz gyrotron backward-wave oscillator
Kao, S. H.; Chiu, C. C.; Chang, P. C.; Wu, K. L.; Chu, K. R.
2012-10-15
Electron cyclotron maser interactions at terahertz (THz) frequencies require a high-order-mode structure to reduce the wall loss to a tolerable level. To generate THz radiation, it is also essential to employ cyclotron harmonic resonances to reduce the required magnetic field strength to a value within the capability of the superconducting magnets. However, much weaker harmonic interactions in a high-order-mode structure lead to serious mode competition problems. The current paper addresses harmonic mode competition in the gyrotron backward wave oscillator (gyro-BWO). We begin with a comparative study of the mode formation and oscillation thresholds in the gyro-BWO and gyromonotron. Differences in linear features result in far fewer 'windows' for harmonic operation of the gyro-BWO. Nonlinear consequences of these differences are examined in particle simulations of the multimode competition processes in the gyro-BWO, which shed light on the competition criteria between modes of different as well as the same cyclotron harmonic numbers. The viability of a harmonic gyro-BWO is assessed on the basis of the results obtained.
Electron cyclotron harmonic resonances in high-frequency heating of the ionosphere
Kuo, Spencer P.
2013-09-15
Electron acceleration by upper hybrid waves under cyclotron harmonic resonance interaction is studied. Theory is formulated; the analytical solutions in the second and fourth harmonic cyclotron resonance cases are obtained, and in the third harmonic case, a first order differential equation governing the evolution of the electron energy is derived. The theory is applied for explaining the generation of artificial ionization layers observed in high-frequency (HF) ionospheric heating experiments. The upper hybrid waves are assumed to be excited parametrically by the O-mode HF heating wave. As the decay mode is the lower hybrid wave, the excited upper hybrid waves have wavelengths ranging from 0.25 to 0.5 m, which are short enough to effectively incorporate the finite Larmour radius effect for the harmonic cyclotron resonance interactions as well as have a frequency bandwidth of about 20 kHz, which provides an altitude region of about 10 km for continuous harmonic cyclotron resonance interaction between electrons and descending waves in the slightly inhomogeneous geomagnetic field. The numerical results on electron acceleration show that electron fluxes with energies larger than 14 eV are generated in the three harmonic cases. These energetic electrons cause impact ionizations, which are descending to form artificial ionization layers at the bottom of the ionospheric F region.
Global Harmonization of Quality Assurance Naming Conventions in Radiation Therapy Clinical Trials
Melidis, Christos; Bosch, Walther R.; Izewska, Joanna; Fidarova, Elena; Zubizarreta, Eduardo; Ulin, Kenneth; Ishikura, Satoshi; Followill, David; Galvin, James; Haworth, Annette; Besuijen, Deidre; Clark, Clark H.; Miles, Elizabeth; Aird, Edwin; and others
2014-12-01
Purpose: ToÂ review the various radiation therapy quality assurance (RTQA) procedures used by the Global Clinical Trials RTQA Harmonization Group (GHG) steering committee members and present the harmonized RTQA naming conventions by amalgamating procedures with similar objectives. Methods and Materials: A survey of the GHG steering committee members' RTQA procedures, their goals, and naming conventions was conducted. The RTQA procedures were classified as baseline, preaccrual, and prospective/retrospective data capture and analysis. After all the procedures were accumulated and described, extensive discussions took place to come to harmonized RTQA procedures and names. Results: The RTQA procedures implemented within a trial by the GHG steering committee members vary in quantity, timing, name, and compliance criteria. The procedures of each member are based on perceived chances of noncompliance, so that the quality of radiation therapy planning and treatment does not negatively influence the trial measured outcomes. A comparison of these procedures demonstrated similarities among the goals of the various methods, but the naming given to each differed. After thorough discussions, the GHG steering committee members amalgamated the 27 RTQA procedures to 10 harmonized ones with corresponding names: facilityÂ questionnaire, beam output audit, benchmark case, dummy run, complex treatment dosimetry check, virtual phantom, individual case review, review of patients' treatment records, and protocol compliance and dosimetry site visit. Conclusions: Harmonized RTQA harmonized naming conventions, which can be used in all future clinical trials involving radiation therapy, have been established. Harmonized procedures will facilitate future intergroup trial collaboration and help to ensure comparable RTQA between international trials, which enables meta-analyses and reduces RTQA workload for intergroup studies.
Density- and wavefunction-normalized Cartesian spherical harmonics for l ? 20
Michael, J. Robert; Volkov, Anatoliy
2015-03-01
The widely used pseudoatom formalism in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l ? 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens. It was shown that the analytical form for normalization coefficients is available primarily for
G-band harmonic multiplying gyrotron traveling-wave amplifier with a mode-selective circuit
Yeh, Y. S.; Chen, Chang-Hong; Wang, Z. W.; Kao, B. H.; Chen, Chien-Hsiang; Lin, T. Y.; Guo, Y. W.
2014-12-15
Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) permit for magnetic field reduction and frequency multiplication. A high-order-mode harmonic multiplying gyro-TWA with large circuit dimensions and low ohmic loss can achieve a high average power. By amplifying a fundamental harmonic TE{sub 01} drive wave, the second harmonic component of the beam current initiates a TE{sub 02} wave to be amplified. Wall losses can suppress some competing modes because they act as an effective sink of the energy of the modes. However, such wall losses do not suppress all competing modes as the fields are contracted in the copper section in the gyro-TWA. An improved mode-selective circuit, using circular waveguides with the specified radii, can provide the rejection points within the frequency range to suppress the competing modes. The simulated results reveal that the mode-selective circuit can provide an attenuation of more than 10â€‰dB to suppress the competing modes (TE{sub 21}, TE{sub 51}, TE{sub 22}, and TE{sub 03}). A G-band second harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 50â€‰kW at 198.8â€‰GHz, corresponding to a saturated gain of 55â€‰dB at an interaction efficiency of 10%. The full width at half maximum bandwidth is 5â€‰GHz.
Control of high-order harmonics for attoscience using a static-electric-field pattern
Serrat, Carles
2011-12-15
Quantum control in high-order-harmonic generation is considered theoretically by using a spatial distribution of static electric fields along the propagation direction of the driving field. It is shown that the trajectories of the electrons during its acceleration by the laser field in the high-harmonics-generation process can be controlled by periodically distributed static electric fields, which conveniently shape the driving laser field during propagation. Applying this mechanism, a quasi-phase-matching scheme that leads to filtered enhanced high harmonics is achieved. The harmonics in the plateau region are enhanced due to periodical phase variations in the long quantum trajectories as a consequence of the faster change experienced by the intensity-dependent phase along the longer electron trajectories. This effect should be observed in all quasi-phase-matching schemes based on perturbation of the microscopic quantum phase. The richness of adding a static-electric-field spatial pattern in the interaction region suggests a general scheme for feedback loop control in high-order-harmonic generation.
Density- and wavefunction-normalized Cartesian spherical harmonics for l â‰¤ 20
Michael, J. Robert; Volkov, Anatoliy
2015-03-01
The widely used pseudoatom formalism in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l â‰¤ 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens. It was shown that the analytical form for normalization coefficients is available primarily for
Kolakoski sequence as an element to radiate giant forward and backward second harmonic signals
Parvini, T. S.; Tehranchi, M. M. E-mail: teranchi@sbu.ac.ir; Hamidi, S. M. E-mail: teranchi@sbu.ac.ir; Sarkarati, S.
2015-11-14
We propose a novel type of aperiodic one-dimensional photonic crystal structures which can be used for generating giant forward and backward second harmonic signals. The studied structure is formed by stacking together the air and nonlinear layers according to the Kolakoski self-generation scheme in which each nonlinear layer contains a pair of antiparallel 180Â° poled LiNbO{sub 3} crystal layers. For different generation stages of the structure, conversion efficiencies of forward and backward second harmonic waves have been calculated by nonlinear transfer matrix method. Numerical simulations show that conversion efficiencies in the Kolakoski-based multilayer are larger than the perfect ones for at least one order of magnitude. Especially for 33rd and 39th generation stages, forward second harmonic wave are 42 and 19 times larger, respectively. In this paper, we validate the strong fundamental field enhancement and localization within Kolakoski-based multilayer due to periodicity breaking which consequently leads to very strong radiation of backward and forward second harmonic signals. Following the applications of analogous aperiodic structures, we expect that Kolakosi-based multilayer can play a role in optical parametric devices such as multicolor second harmonic generators with high efficiency.
Experimental investigation of a phased-locked harmonic multiplying inverted gyrotwystron
Guo, H.; Rodgers, J.; Chen, S.; Walter, M.; Granatstein, V.L.
1996-12-31
The University of Maryland is investigating harmonic multiplication as a means of generating high frequency, large bandwidth, high power microwaves with reduced magnetic field and high subharmonic injection gain. The current experimental efforts are concentrated don two-stage devices. One of them is the phase-locked, harmonic-multiplying inverted gyrotwystron (phigtron) which uses a MIG produced electron beam (60 kV, 10 A), a combined mode launcher/input coupler, a Ku band fundamental gyro-TWT prebunching section, a radiation-free drift section, and a Ka band special complex cavity as output section. The bandwidth of this phigtron is expected to be improved over that of a gyroklystron since the input cavity is replaced by a traveling wave interaction structure. The second harmonic content of the beam may develop within both the input section and the drift space, and this allows the use of a smaller input signal. For a proof-of-principle experiment, a hot test tube was built. Initial experimental data will be provided in this presentation and will be compared with theoretical predictions. Finally, the feasibility of using a phigtron configuration with second harmonic prebunching and fourth harmonic output to realize a compact, high performance MMW power source at 94 GHz is discussed.
Experimental investigation of a phase-locked harmonic multiplying inverted gyrotwystron
Guo, H.; Rodgers, J.; Chen, S.; Walter, M.; Granatstein, V.L.
1996-12-31
The University of Maryland is investigating harmonic multiplication as a means of generating high frequency, large bandwidth, high power microwaves with reduced magnetic fields and high subharmonic injection gain. The current experimental efforts are concentrated on two-stage devices. One of them is the phase-locked, harmonic-multiplying inverted gyrotwystron (phigtron) which uses a MIG produced electron beam (60 kV, 10 A), a combined mode launcher/input coupler, a Ku band fundamental gyro-TWT prebunching section, a radiation-free drift section, and a Ka band special complex cavity as output section. The bandwidth of this phigtron is expected to be improved over that of a gyroklystron since the input cavity is replaced by a traveling wave interaction structure. The second harmonic content of the beam may develop within both the input section and the drift space, and this allows the use of a smaller input signal. For a proof-of-principle experiment, a hot test tube was built. Initial experimental data will be provided in this presentation and will be compared with theoretical predictions. Finally, the feasibility of sing a phigtron configuration with second harmonic prebunching and fourth harmonic output to realize a compact, high performance MMW power source at 94 GHz will be discussed.
Low-voltage harmonic multiplying gyrotron traveling-wave amplifier in G band
Yeh, Y. S.; Guo, Y. W.; Kao, B. H.; Chen, C. H.; Wang, Z. W.; Hung, C. L.; Chang, T. H.
2015-12-15
Harmonic multiplying operation in a gyrotron traveling-wave amplifier (gyro-TWA) permits for magnetic field reduction and frequency multiplication. Lowering a beam voltage is an important step toward miniaturization of a harmonic multiplying gyro-TWA. However, the additional degree of freedom that is provided by the multitude cyclotron harmonics in a low-voltage harmonic multiplying gyro-TWA still easily generates various competing modes. An improved mode-selective circuit, using circular waveguides with various radii, can provide the rejection points within the frequency range to suppress competing modes. Simulated results reveal that the mode-selective circuit can provide an attenuation of more than 14â€‰dB to suppress the competing modes. Furthermore, the performance of the gyro-TWA is analyzed for studying the sensitivity of the saturated output power and full width at half maximum bandwidth of the gyro-TWA to the beam voltage and the magnetic field. A stable low-voltage harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 24â€‰kW at 200.4â€‰GHz, corresponding to a saturated gain of 56â€‰dB at an interaction efficiency of 20%. The full width at half maximum bandwidth is 3.0â€‰GHz.
Density- and wavefunction-normalized Cartesian spherical harmonics for l â‰¤ 20
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Michael, J. Robert; Volkov, Anatoliy
2015-03-01
The widely used pseudoatom formalism in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l â‰¤ 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens. It was shown that the analytical form for normalization coefficients is available primarily forl â‰¤ 4. Only in very special cases it is possible to derive an analytical representation of the normalization coefficients for 4 < l â‰¤ 7.moreÂ Â» In most cases for l > 4 the density normalization coefficients were calculated numerically to within seven significant figures. In this study we review the literature on the density-normalized spherical harmonics, clarify the existing notations, use the Paturleâ€“Coppens method in the Wolfram Mathematicasoftware to derive the Cartesian spherical harmonics for l â‰¤ 20 and determine the density normalization coefficients to 35 significant figures, and computer-generate a Fortran90 code. The article primarily targets researchers who work in the field of experimental X-ray electron density, but may be of some use to all who are interested in Cartesian spherical harmonics.Â«Â less
Harmonic superspace geometry of (4,4) supersymmetric {sigma} models with torsion
Ivanov, E.A.
1996-02-01
Starting from the dual action of (4,4) two-dimensional (2D) twisted multiplets in the harmonic superspace with two independent sets of SU(2) harmonic variables, we present its generalization which hopefully provides an off-shell description of general (4,4) supersymmetric {sigma} models with torsion. Like the action of the torsionless (4,4) hyper-K{umlt a}hler {sigma} models in the standard harmonic superspace, it is characterized by a number of superfield potentials. They depend on {ital n} copies of a triple of analytic harmonic (4,4) superfields. As distinct from the hyper-K{umlt a}hler case, the potentials prove to be severely constrained by the self-consistency condition which stems from the commutativity of the left and right harmonic derivatives. We show that for {ital n}=1 these constraints reduce the general action to that of the (4,4) twisted multiplet, while for {ital n}{ge}2 there exists a wide class of new actions which cannot be written only via twisted multiplets. Their most strikng feature is the non-Abelian and in general nonlinear gauge invariance which substitutes the Abelian gauge symmetry of the dual action of twisted multiplets and ensures the correct number of physical degrees of freedom. We show, on a simple example, that these actions describe {sigma} models with noncommuting left and right complex structures on the bosonic target. {copyright} {ital 1996 The American Physical Society.}
Jha, Pallavi; Agrawal, Ekta
2014-05-15
An analytical study of second harmonic generation due to interaction an intense, p-polarized laser beam propagating obliquely in homogeneous underdense plasma, in the mildly relativistic regime, has been presented. The efficiency of the second harmonic radiation as well as its detuning length has been obtained and their variation with the angle of incidence is analyzed. It is shown that, for a given plasma electron density, the second harmonic efficiency increases with the angle of incidence while the detuning length decreases. The second harmonic amplitude vanishes at normal incidence of the laser beam.
Ganeev, R. A.; Baba, M.; Suzuki, M.; Yoneya, S.; Kuroda, H.
2014-12-28
The systematic studies of the harmonic generation of ultrashort laser pulses in the 5-mm-long Zn and Mn plasmas (i.e., application of nanosecond, picosecond, and femtosecond pulses for ablation, comparison of harmonic generation from atomic, ionic, and cluster-contained species of plasma, variation of plasma length, two-color pump of plasmas, etc.) are presented. The conversion efficiency of the 11thâ€“19th harmonics generated in the Zn plasma was âˆ¼5â€‰Ã—â€‰10{sup âˆ’5}. The role of the ionic resonances of Zn near the 9th and 10th harmonics on the enhancement of harmonics is discussed. The enhancement of harmonics was also analyzed using the two-color pump of extended plasmas, which showed similar intensities of the odd and even harmonics along the whole range of generation. The harmonics up to the 107th order were demonstrated in the case of manganese plasma. The comparison of harmonic generation in the 5-mm-long and commonly used short (â‰¤0.5â€‰mm) plasma plumes showed the advanced properties of extended media.
Nonlinear absorption and harmonic generation of laser in a gas with anharmonic clusters
Kumar, Manoj; Tripathi, V. K.
2013-02-15
The nonlinear absorption and harmonic generation of intense short pulse laser in a gas embedded with anharmonic clusters are investigated theoretically. When the laser induced excursion of cluster electrons becomes comparable to cluster radius, the restoration force on electrons no longer remains linearly proportional to the excursion. As a consequence, the plasmon resonance is broadened, leading to broadband laser absorption. It also leads to second and third harmonic generations, at much higher level than the one due to ponderomotive nonlinearity. The harmonic yield is resonantly enhanced at the plasmon resonance {omega}={omega}{sub pe}/{radical}(3), where {omega} is the frequency of the laser and {omega}{sub pe} is the plasma frequency of cluster electrons.
Pressure-induced phase matching in high-order harmonic generation
Kazamias, S.; Daboussi, S.; Guilbaud, O.; Cassou, K.; Ros, D.; Cros, B.; Maynard, G.
2011-06-15
We present an alternative explanation of the high-order-harmonic-generation experimental results published recently by Seres et al. [Nature Phys. 6, 455 (2010)]. We show that the physical interpretation can be comprehensively done in the frame of classical theory of high-order harmonic generation without referring to a parametric effect in the XUV domain. The experimental conditions explored by Seres et al. indeed correspond to the case of long-pulse, low-infrared-energy laser beams for which tight focusing is necessary to reach the minimum intensity required for high atomic response. The positive atomic dispersion can compensate for the Gouy phase and explains the behavior of the experimental variation of the harmonic signal presented. We will show that our interpretation explains not only the global behavior of the curves but also the second-order variation of the signal as a function of experimental parameters.
Cho, Suwon; Kwak, Jong-Gu
2014-04-15
The propagation and absorption of high harmonic fast waves is of interest for non-inductive current drives in fusion experiments. The fast wave can be coupled with the ion Bernstein wave that propagates in the high magnetic field side of an ion cyclotron harmonic resonance layer. This coupling and the absorption are analyzed using the hot plasma dispersion relation and a wave equation that was converted from an approximate dispersion relation for the case where Î»{sub i}=k{sub âŠ¥}{sup 2}Ï{sub i}{sup 2}/2â‰³1 (where k{sub âŠ¥} is the perpendicular wave number and Ï{sub i} is the ion Larmor radius). It is found that both reflection and conversion may occur near the harmonic resonance layer but that they decrease rapidly, giving rise to a sharp increase in the absorption as the parallel wave number increases.
Influence of gas pressure on high-order-harmonic generation of Ar and Ne
Wang Guoli; Jin Cheng; Le, Anh-Thu; Lin, C. D.
2011-11-15
We study the effect of gas pressure on the generation of high-order harmonics where harmonics due to individual atoms are calculated using the recently developed quantitative rescattering theory, and the propagation of the laser and harmonics in the medium is calculated by solving the Maxwell's wave equation. We illustrate that the simulated spectra are very sensitive to the laser focusing conditions at high laser intensity and high pressure since the fundamental laser field is severely reshaped during the propagation. By comparing the simulated results with several experiments we show that the pressure dependence can be qualitatively explained. The lack of quantitative agreement is tentatively attributed to the failure of the complete knowledge of the experimental conditions.
Zhu, Hong-Ming; Chen, Jin-Wang; Pan, Xiao-Yin; Sahni, Viraht
2014-01-14
We derive via the interaction â€œrepresentationâ€ the many-body wave function for harmonically confined electrons in the presence of a magnetostatic field and perturbed by a spatially homogeneous time-dependent electric fieldâ€”the Generalized Kohn Theorem (GKT) wave function. In the absence of the harmonic confinement â€“ the uniform electron gas â€“ the GKT wave function reduces to the Kohn Theorem wave function. Without the magnetostatic field, the GKT wave function is the Harmonic Potential Theorem wave function. We further prove the validity of the connection between the GKT wave function derived and the system in an accelerated frame of reference. Finally, we provide examples of the application of the GKT wave function.
Guo, Y.; Keller, J.; Parker, R. G.
2012-06-01
The dynamics of wind turbine planetary gears with gravity effects are investigated using an extended harmonic balance method that extends established harmonic balance formulations to include simultaneous internal and external excitations. The extended harmonic balance method with arc-length continuation and Floquet theory is applied to a lumped-parameter planetary gear model including gravity, fluctuating mesh stiffness, bearing clearance, and nonlinear tooth contact to obtain the planetary gear dynamic response. The calculated responses compare well with time domain integrated mathematical models and experimental results. Gravity is a fundamental vibration source in wind turbine planetary gears and plays an important role in system dynamics, causing hardening effects induced by tooth wedging and bearing-raceway contacts. Bearing clearance significantly reduces the lowest resonant frequencies of translational modes. Gravity and bearing clearance together lowers the speed at which tooth wedging occurs lower than the resonant frequency.
Trull, J.; Wang, B.; Parra, A.; Vilaseca, R.; Cojocaru, C.; Sola, I.; Sheng, Y.
2015-06-01
Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system.
Second harmonic generation in photonic crystal cavities in (111)-oriented GaAs
Buckley, Sonia Radulaski, Marina; VuÄkoviÄ‡, Jelena; Biermann, Klaus
2013-11-18
We demonstrate second harmonic generation at telecommunications wavelengths in photonic crystal cavities in (111)-oriented GaAs. We fabricate 30 photonic crystal structures in both (111)- and (100)-oriented GaAs and observe an increase in generated second harmonic power in the (111) orientation, with the mean power increased by a factor of 3, although there is a large scatter in the measured values. We discuss possible reasons for this increase, in particular, the reduced two photon absorption for transverse electric modes in (111) orientation, as well as a potential increase due to improved mode overlap.
Beam test of a grid-less multi-harmonic buncher.
Ostroumov, P. N.; Aseev, V. N.; Barcikowski, A.; Clifft, B.; Pardo, R.; Sharamentov, S. I.; Sengupta, M.; Physics
2008-01-01
The Argonne Tandem Linear Accelerator System (ATLAS) is the first superconducting heavy-ion linac in the world. Currently ATLAS is being upgraded with the Californium Rare Ion Breeder Upgrade (CARIBU). The latter is a funded project to expand the range of shortlived, neutron-rich rare isotope beams available for nuclear physics research at ATLAS. To avoid beam losses associated with the existing gridded multi-harmonic buncher (MHB), we have developed and built a grid-less four-harmonic buncher with fundamental frequency of 12.125 MHz. In this paper, we report the results of the MHB commissioning and ATLAS beam performance with the new buncher.
Ising antiferromagnet with ultracold bosonic mixtures confined in a harmonic trap
Guglielmino, M.; Penna, V.; Capogrosso-Sansone, B.
2011-09-15
We present accurate results based on quantum Monte Carlo simulations of two-component bosonic systems on a square lattice and in the presence of an external harmonic confinement. Starting from hopping parameters and interaction strengths which stabilize the Ising antiferromagnetic phase in the homogeneous case and at half-integer filling factor, we study how the presence of the harmonic confinement challenges the realization of such a phase. We consider realistic trapping frequencies and number of particles, and we establish under which conditions, i.e., total number of particles and population imbalance, the antiferromagnetic phase can be observed in the trap.
High-order harmonic generation at a repetition rate of 100 kHz
Lindner, F.; Stremme, W.; Schaetzel, M. G.; Grasbon, F.; Paulus, G. G.; Walther, H.; Hartmann, R.; Strueder, L.
2003-07-01
We report high-order harmonic generation (HHG) in rare gases using a femtosecond laser system with a very high repetition rate (100 kHz) and low pulse energy (7 {mu}J). To our knowledge, this is the highest repetition rate reported to date for HHG. The tight focusing geometry required to reach sufficiently high intensities implies low efficiency of the process. Harmonics up to the 45th order are nevertheless generated and detected. We show evidence of clear separation and selection of quantum trajectories by moving the gas jet with respect to the focus, in agreement with the theoretical predictions of the semiclassical model of HHG.
Heath, G.; O'Donoughue, P.; Whitaker, M.
2012-12-01
This research provides a systematic review and harmonization of the life cycle assessment (LCA) literature of electricity generated from conventionally produced natural gas. We focus on estimates of greenhouse gases (GHGs) emitted in the life cycle of electricity generation from conventionally produced natural gas in combustion turbines (NGCT) and combined-cycle (NGCC) systems. A process we term "harmonization" was employed to align several common system performance parameters and assumptions to better allow for cross-study comparisons, with the goal of clarifying central tendency and reducing variability in estimates of life cycle GHG emissions. This presentation summarizes preliminary results.
Zhang Xiaofei |; Yang Qin |; Zhang Jiefang; Chen, X. Z.; Liu, W. M.
2008-02-15
We present how to control interactions between solitons, either bright or dark, in Bose-Einstein condensates by synchronizing Feshbach resonance and harmonic trap. Our results show that as long as the scattering length is to be modulated in time via a changing magnetic field near the Feshbach resonance, and the harmonic trapping frequencies are also modulated in time, exact solutions of the one-dimensional nonlinear Schroedinger equation can be found in a general closed form, and interactions between two solitons are modulated in detail in currently experimental conditions. We also propose experimental protocols to observe the phenomena such as fusion, fission, warp, oscillation, elastic collision in future experiments.
Hayes, R.M.; Kirkpatrick, T.L.; Lauletta, J.L.; Shuter, T.C.; Vollkommer, H.T. Jr.
1987-05-19
A system is described for determining directions of locations of sources of power harmonics relative to a node interconnecting n branches of a power distribution network, where n is an integer greater than or equal to 2, comprising: voltage transducer means for monitoring voltage waveforms in at least (n-1) of the n branches; current transducer means for monitoring current waveforms in at least (n-1) branches; means for sampling the current and voltage waveforms to obtain analog current and voltage waveform samples; A/D converter means for digitizing the analog waveform samples; and spectrum analyzer means for resolving the digitized samples into their respective harmonic components.
Kumar, M.; Singhal, H.; Chakera, J. A.; Naik, P. A.; Khan, R. A.; Gupta, P. D.
2013-07-21
A study of the spatial coherence of the high order harmonic radiation generated by the interaction of 45 fs Ti:sapphire laser beam with carbon (graphite) plasma plume has been carried out using Young's double slit interferometry. It is observed that the spatial coherence varies with harmonic order, laser focal spot size in plasma plume, and peaks at an optimal spot size. It is also observed that the spatial coherence is higher when the laser pulse is focused before the plasma plume than when focused after the plume, and it decreases with increase in the harmonic order. The optimum laser parameters and the focusing conditions to achieve good spatial coherence with high harmonic conversion have been identified, which is desirable for practical applications of the harmonic radiation.
Samet Y. Kadioglu; Robert R. Nourgaliev; Vincent A. Mousseau
2008-03-01
We perform a comparative study for the harmonic versus arithmetic averaging of the heat conduction coefficient when solving non-linear heat transfer problems. In literature, the harmonic average is the method of choice, because it is widely believed that the harmonic average is more accurate model. However, our analysis reveals that this is not necessarily true. For instance, we show a case in which the harmonic average is less accurate when a coarser mesh is used. More importantly, we demonstrated that if the boundary layers are finely resolved, then the harmonic and arithmetic averaging techniques are identical in the truncation error sense. Our analysis further reveals that the accuracy of these two techniques depends on how the physical problem is modeled.
Campione, Salvatore; Benz, Alexander; Brener, Igal; Sinclair, Michael B.; Capolino, Filippo
2014-03-31
We theoretically analyze the second harmonic generation capacity of two-dimensional periodic metamaterials comprising sub-wavelength resonators strongly coupled to intersubband transitions in quantum wells (QWs) at mid-infrared frequencies. The metamaterial is designed to support a fundamental resonance at âˆ¼30â€‰THz and an orthogonally polarized resonance at the second harmonic frequency (âˆ¼60â€‰THz), while the asymmetric quantum well structure is designed to provide a large second order susceptibility. Upon continuous wave illumination at the fundamental frequency we observe second harmonic signals in both the forward and backward directions, with the forward efficiency being larger. We calculate the overall second harmonic conversion efficiency of the forward wave to be âˆ¼1.3â€‰Ã—â€‰10{sup âˆ’2} W/W{sup 2}â€”a remarkably large value, given the deep sub-wavelength dimensions of the QW structure (about 1/15th of the free space wavelength of 10â€‰Î¼m). The results shown in this Letter provide a strategy for designing easily fabricated sources across the entire infrared spectrum through proper choice of QW and resonator designs.
Stabilizing effect of a double-harmonic RF system in the CERN PS
Bhat, C.; Caspers, F.; Damerau, H.; Hancock, S.; Mahner, E.; Zimmermann, F.; /CERN
2009-04-01
Motivated by the discussions on scenarios for LHC upgrades, beam studies on the stability of flat bunches in a double-harmonic RF system have been conducted in the CERN Proton Synchrotron (PS). Injecting nearly nominal LHC beam intensity per cycle, 18 bunches are accelerated on harmonic h = 21 to 26GeV with the 10MHz RF system. On the flat-top, all bunches are then transformed to flat bunches by adiabatically adding RF voltage at h = 42 from a 20 MHz cavity in anti-phase to the h = 21 system. The voltage ratio V (h42)/V (h21) of about 0.5 was set according to simulations. For the next 140 ms, longitudinal profiles show stable bunches in the double-harmonic RF bucket until extraction. Without the second harmonic component, coupled-bunch oscillations are observed. The flatness of the bunches along the batch is analyzed as a measure of the relative phase error between the RF systems due to beam loading. The results of beam dynamics simulations and their comparison with the measured data are presented.
Krebs, I.; HÃ¶lzl, M.; Lackner, K.; GÃ¼nter, S.
2013-08-15
Nonlinear simulations of the early edge-localized mode (ELM) phase based on a typical type-I ELMy ASDEX Upgrade discharge have been carried out using the reduced MHD code JOREK. The analysis is focused on the evolution of the toroidal Fourier spectrum. It is found that during the nonlinear evolution, linearly subdominant low-n Fourier components, in particular the n = 1, grow to energies comparable with linearly dominant harmonics. A simple model is developed, based on the idea that energy is transferred among the toroidal harmonics via second order nonlinear interaction. The simple model reproduces and explains very well the early nonlinear evolution of the toroidal spectrum in the JOREK simulations. Furthermore, it is shown for the n = 1 harmonic, that its spatial structure changes significantly during the transition from linear to nonlinearly driven growth. The rigidly growing structure of the linearly barely unstable n = 1 reaches far into the plasma core. In contrast, the nonlinearly driven n= 1 has a rigidly growing structure localized at the plasma edge, where the dominant toroidal harmonics driving the n = 1 are maximal and in phase. The presented quadratic coupling model might explain the recent experimental observation of strong low-n components in magnetic measurements [Wenninger et al., â€œNon-linear magnetic perturbations during edge localized modes in TCV dominated by low n mode components,â€ Nucl. Fusion (submitted)].
Sherratt, Paul A. J.; Ramakrishna, S.; Seideman, Tamar
2011-05-15
We explore the information content of the polarization of high-order harmonics emitted from aligned molecules driven by a linearly polarized field. The study builds upon our previous work [Ramakrishna et al., Phys. Rev. A 81, 021802(R) (2010)], which illustrated that the phase of the continuum electronic wave function, and hence the underlying molecular potential, is responsible, at least in part, for the ellipticity observed in harmonic spectra. We use a simple model potential and systematically vary the potential parameters to investigate the sense in which, and the degree to which, the shape of the molecular potential is imprinted onto the polarization of the emitted harmonics. Strong ellipticity is observed over a wide range of potential parameters, suggesting that the emission of elliptically polarized harmonics is a general phenomenon, yet qualitatively determined by the molecular properties. The sensitivity of the ellipticity to the model parameters invites the use of ellipticity measurements as a probe of the continuum wave function and the underlying molecular potential.
High-order harmonics from bow wave caustics driven by a high-intensity laser
Pirozhkov, A.S.; Kando, M.; Esirkepov, T.Zh.; and others
2012-07-11
We propose a new mechanism of high-order harmonic generation during an interaction of a high-intensity laser pulse with underdense plasma. A tightly focused laser pulse creates a cavity in plasma pushing electrons aside and exciting the wake wave and the bow wave. At the joint of the cavity wall and the bow wave boundary, an annular spike of electron density is formed. This spike surrounds the cavity and moves together with the laser pulse. Collective motion of electrons in the spike driven by the laser field generates high-order harmonics. A strong localization of the electron spike, its robustness to oscillations imposed by the laser field and, consequently, its ability to produce high-order harmonics is explained by catastrophe theory. The proposed mechanism explains the experimental observations of high-order harmonics with the 9 TW J-KAREN laser (JAEA, Japan) and the 120 TW Astra Gemini laser (CLF RAL, UK) [A. S. Pirozhkov, et al., arXiv:1004.4514 (2010); A. S. Pirozhkov et al, AIP Proceedings, this volume]. The theory is corroborated by high-resolution two-and three-dimensional particle-in-cell simulations.
X-ray FEL based on harmonics generation and electron beam outcoupling
Litvinenko, V.N.; Burnham, B.
1995-12-31
Electron beam outcoupling was suggested by N. A. Vinokurov as a method of optics independent outcoupling for high power FELs. The bunching of the electron beam is provided in a master oscillator. The prebunched electron beam then radiates coherently into an additional wiggler called the radiator. The electron beam is turned by an achromatic bend into this wiggler and its radiation propagates with a small angle with respect to the OK-4 optical axis. Thus, the radiation will pass around the mirror of the master oscillator optical cavity and can then be utilized. This scheme is perfectly suited for harmonic generation if the radiator wiggler is tuned on one of the master oscillator wavelength harmonics. This system is reminiscent of a klystron operating on a harmonic of the reference frequency. In this paper we present the theory of this device, its spectral and spatial characteristics of radiation, the optimization of the master oscillator, the achromatic bend and bunching for harmonic generation, and influence of beam parameters (energy spread, emittance, etc.) on generated power. Examples of possible storage ring and linac driven systems are discussed.
Vejling Andersen, SÃ¸ren; Lund Trolle, Mads; Pedersen, Kjeld
2013-12-02
Oblique angle deposited (OAD) silicon monoxide (SiO) thin films forming tilted columnar structures have been characterized by second-harmonic generation. It was found that OAD SiO leads to a rotationally anisotropic second-harmonic response, depending on the optical angle of incidence. A model for the observed dependence of the second-harmonic signal on optical angle of incidence allows extraction of the growth direction of OAD films. The optically determined growth directions show convincing agreement with cross-sectional scanning electron microscopy images. In addition to a powerful characterization tool, these results demonstrate the possibilities for designing nonlinear optical devices through SiO OAD.
Arpin, P.; Popmintchev, T.; Kapteyn, H. C.; Murnane, M. M.; Wagner, N. L.; Cohen, O.
2009-10-02
By combining laser pulse self-compression and high harmonic generation within a single waveguide, we demonstrate high harmonic emission from multiply charged ions for the first time. This approach enhances the laser intensity and counteracts ionization-induced defocusing, extending the cutoff photon energy in argon above 500 eV for the first time, with higher spectral intensity and cutoff energy than He for the same input laser parameters. This Letter demonstrates a pathway for extending high harmonic emission to very high photon energies using large, multiply charged, ions with high ionization potentials.
A Massively Parallel Solver for the Mechanical Harmonic Analysis of Accelerator Cavities
O. Kononenko
2015-02-17
ACE3P is a 3D massively parallel simulation suite that developed at SLAC National Accelerator Laboratory that can perform coupled electromagnetic, thermal and mechanical study. Effectively utilizing supercomputer resources, ACE3P has become a key simulation tool for particle accelerator R and D. A new frequency domain solver to perform mechanical harmonic response analysis of accelerator components is developed within the existing parallel framework. This solver is designed to determine the frequency response of the mechanical system to external harmonic excitations for time-efficient accurate analysis of the large-scale problems. Coupled with the ACE3P electromagnetic modules, this capability complements a set of multi-physics tools for a comprehensive study of microphonics in superconducting accelerating cavities in order to understand the RF response and feedback requirements for the operational reliability of a particle accelerator. (auth)
Advanced properties of extended plasmas for efficient high-order harmonic generation
Ganeev, R. A.; Physics Department, Voronezh State University, Voronezh 394006 ; Suzuki, M.; Kuroda, H.
2014-05-15
We demonstrate the advanced properties of extended plasma plumes (5â€‰mm) for efficient harmonic generation of laser radiation compared with the short lengths of plasmas (âˆ¼0.3â€“0.5â€‰mm) used in previous studies. The harmonic conversion efficiency quadratically increased with the growth of plasma length. The studies of this process along the whole extreme ultraviolet range using the long plasma jets produced on various metal surfaces, particularly including the resonance-enhanced laser frequency conversion and two-color pump, are presented. Such plasmas could be used for the quasi-phase matching experiments by proper modulation of the spatial characteristics of extended ablating area and formation of separated plasma jets.
Radice, David; Abdikamalov, Ernazar; Rezzolla, Luciano; Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA ; Ott, Christian D.
2013-06-01
Recent work by McClarren and Hauck (2010) [31] suggests that the filtered spherical harmonics method represents an efficient, robust, and accurate method for radiation transport, at least in the two-dimensional (2D) case. We extend their work to the three-dimensional (3D) case and find that all of the advantages of the filtering approach identified in 2D are present also in the 3D case. We reformulate the filter operation in a way that is independent of the timestep and of the spatial discretization. We also explore different second- and fourth-order filters and find that the second-order ones yield significantly better results. Overall, our findings suggest that the filtered spherical harmonics approach represents a very promising method for 3D radiation transport calculations.
LeiÃŸner, Till; KostiuÄenko, Oksana; Rubahn, Horst-GÃ¼nter; Fiutowski, Jacek; Brewer, Jonathan R.
2015-12-21
In this letter we show that the optical response of organic nanofibers, grown from functionalized para-quaterphenylene molecules, can be controlled by forming organic-plasmonic hybrid systems. The interaction between nanofibers and supporting regular arrays of nanostructures leads to a strongly enhanced second harmonic response. At the same time, the fluorescence lifetime of the nanofibers is reduced from 0.32â€‰ns for unstructured gold films to 0.22â€‰ns for gold nanosquare arrays, demonstrating efficient organicâ€“plasmonic interaction. To study the origin of these effects, we applied two-photon laser scanning microscopy and fluorescence lifetime imaging microscopy. These findings provide an effective approach for plasmon-enhanced second-harmonic generation at the nanoscale, which is attractive for nanophotonic circuitry.
Multiple layer optical memory system using second-harmonic-generation readout
Boyd, Gary T.; Shen, Yuen-Ron
1989-01-01
A novel optical read and write information storage system is described which comprises a radiation source such as a laser for writing and illumination, the radiation source being capable of radiating a preselected first frequency; a storage medium including at least one layer of material for receiving radiation from the radiation source and capable of being surface modified in response to said radiation source when operated in a writing mode and capable of generating a pattern of radiation of the second harmonic of the preselected frequency when illuminated by the radiation source at the preselected frequency corresponding to the surface modifications on the storage medium; and a detector to receive the pattern of second harmonic frequency generated.
Zhang, Xiaoshi; Lytle, Amy L.; Cohen, Oren; Kapteyn, Henry C.; Murnane, Margaret M.
2010-11-09
All-optical quasi-phase matching (QPM) uses a train of counterpropagating pulses to enhance high-order harmonic generation (HHG) in a hollow waveguide. A pump pulse enters one end of the waveguide, and causes HHG in the waveguide. The counterpropagation pulses enter the other end of the waveguide and interact with the pump pulses to cause QPM within the waveguide, enhancing the HHG.
Application of IEEE Standard 519-1992 harmonic limits for revenue billing meters
Arseneau, R.; Heydt, G.T.; Kempker, M.J.
1997-01-01
This paper identifies the potential for billing inequities at harmonic generating loads due to different measuring methods implemented in revenue meters. Potential problems are almost exclusively in the commercial and industrial sectors where demand and power factor charges are common. Field data are used to illustrate that compliance with IEEE Standard 519-1992 reduces the possibility of meter reading differences thus promoting a more equitable treatment of all customers.
Campo, V. L. Jr.; Capelle, K.
2005-12-15
We construct the complete U-{mu} phase diagram for harmonically confined ultracold fermionic atoms with repulsive and attractive interactions({mu} is the chemical potential and U the interaction strength). Our approach is based on density-functional theory, and employs analytical expressions for the kinetic and correlation energy functionals, permitting us to obtain closed expressions for all phase boundaries and characteristic lines of the phase diagram, both for repulsive and attractive interactions.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Rubinstein, Robert; Kurien, Susan; Cambon, Claude
2015-06-22
The representation theory of the rotation group is applied to construct a series expansion of the correlation tensor in homogeneous anisotropic turbulence. The resolution of angular dependence is the main analytical difficulty posed by anisotropic turbulence; representation theory parametrises this dependence by a tensor analogue of the standard spherical harmonics expansion of a scalar. As a result, the series expansion is formulated in terms of explicitly constructed tensor bases with scalar coefficients determined by angular moments of the correlation tensor.
Vignolo, Patrizia; Minguzzi, Anna
2003-05-01
We develop a Green's function method to evaluate the exact equilibrium particle-density profiles of noninteracting Fermi gases in external harmonic confinement in any spatial dimension and for arbitrary trap anisotropy. While in a spherically symmetric configuration the shell effects are negligible in the case of a large number of particles, we find that for very anisotropic traps the quantum effects due to single-level occupancy and the deviations from the Thomas-Fermi approximation are also visible for mesoscopic clouds.
Whitaker, M.; Heath, G. A.; O'Donoughue, P.; Vorum, M.
2012-04-01
This systematic review and harmonization of life cycle assessments (LCAs) of utility-scale coal-fired electricity generation systems focuses on reducing variability and clarifying central tendencies in estimates of life cycle greenhouse gas (GHG) emissions. Screening 270 references for quality LCA methods, transparency, and completeness yielded 53 that reported 164 estimates of life cycle GHG emissions. These estimates for subcritical pulverized, integrated gasification combined cycle, fluidized bed, and supercritical pulverized coal combustion technologies vary from 675 to 1,689 grams CO{sub 2}-equivalent per kilowatt-hour (g CO{sub 2}-eq/kWh) (interquartile range [IQR]= 890-1,130 g CO{sub 2}-eq/kWh; median = 1,001) leading to confusion over reasonable estimates of life cycle GHG emissions from coal-fired electricity generation. By adjusting published estimates to common gross system boundaries and consistent values for key operational input parameters (most importantly, combustion carbon dioxide emission factor [CEF]), the meta-analytical process called harmonization clarifies the existing literature in ways useful for decision makers and analysts by significantly reducing the variability of estimates ({approx}53% in IQR magnitude) while maintaining a nearly constant central tendency ({approx}2.2% in median). Life cycle GHG emissions of a specific power plant depend on many factors and can differ from the generic estimates generated by the harmonization approach, but the tightness of distribution of harmonized estimates across several key coal combustion technologies implies, for some purposes, first-order estimates of life cycle GHG emissions could be based on knowledge of the technology type, coal mine emissions, thermal efficiency, and CEF alone without requiring full LCAs. Areas where new research is necessary to ensure accuracy are also discussed.
The Ultraviolet Surprise. Efficient Soft X-Ray High Harmonic Generation in Multiply-Ionized Plasmas
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Popmintchev, Dimitar; Hernandez-Garcia, Carlos; Dollar, Franklin; Mancuso, Christopher; Perez-Hernandez, Jose A.; Chen, Ming-Chang; Hankla, Amelia; Gao, Xiaohui; Shim, Bonggu; Gaeta, Alexander L.; et al
2015-12-04
High-harmonic generation is a universal response of matter to strong femtosecond laser fields, coherently upconverting light to much shorter wavelengths. Optimizing the conversion of laser light into soft x-rays typically demands a trade-off between two competing factors. Reduced quantum diffusion of the radiating electron wave function results in emission from each species which is highest when a short-wavelength ultraviolet driving laser is used. But, phase matchingâ€”the constructive addition of x-ray waves from a large number of atomsâ€”favors longer-wavelength mid-infrared lasers. We identified a regime of high-harmonic generation driven by 40-cycle ultraviolet lasers in waveguides that can generate bright beams inmoreÂ Â» the soft x-ray region of the spectrum, up to photon energies of 280 electron volts. Surprisingly, the high ultraviolet refractive indices of both neutral atoms and ions enabled effective phase matching, even in a multiply ionized plasma. We observed harmonics with very narrow linewidths, while calculations show that the x-rays emerge as nearly time-bandwidthâ€“limited pulse trains of ~100 attoseconds.Â«Â less
Shao, Yan-Lin Faltinsen, Odd M.
2014-10-01
We propose a new efficient and accurate numerical method based on harmonic polynomials to solve boundary value problems governed by 3D Laplace equation. The computational domain is discretized by overlapping cells. Within each cell, the velocity potential is represented by the linear superposition of a complete set of harmonic polynomials, which are the elementary solutions of Laplace equation. By its definition, the method is named as Harmonic Polynomial Cell (HPC) method. The characteristics of the accuracy and efficiency of the HPC method are demonstrated by studying analytical cases. Comparisons will be made with some other existing boundary element based methods, e.g. Quadratic Boundary Element Method (QBEM) and the Fast Multipole Accelerated QBEM (FMA-QBEM) and a fourth order Finite Difference Method (FDM). To demonstrate the applications of the method, it is applied to some studies relevant for marine hydrodynamics. Sloshing in 3D rectangular tanks, a fully-nonlinear numerical wave tank, fully-nonlinear wave focusing on a semi-circular shoal, and the nonlinear wave diffraction of a bottom-mounted cylinder in regular waves are studied. The comparisons with the experimental results and other numerical results are all in satisfactory agreement, indicating that the present HPC method is a promising method in solving potential-flow problems. The underlying procedure of the HPC method could also be useful in other fields than marine hydrodynamics involved with solving Laplace equation.
Quantum efficiency harmonic analysis of exciton annihilation in organic light emitting diodes
Price, J. S.; Giebink, N. C.
2015-06-29
Various exciton annihilation processes are known to impact the efficiency roll-off of organic light emitting diodes (OLEDs); however, isolating and quantifying their contribution in the presence of other factors such as changing charge balance continue to be a challenge for routine device characterization. Here, we analyze OLED electroluminescence resulting from a sinusoidal dither superimposed on the device bias and show that nonlinearity between recombination current and light output arising from annihilation mixes the quantum efficiency measured at different dither harmonics in a manner that depends uniquely on the type and magnitude of the annihilation process. We derive a series of analytical relations involving the DC and first harmonic external quantum efficiency that enable annihilation rates to be quantified through linear regression independent of changing charge balance and evaluate them for prototypical fluorescent and phosphorescent OLEDs based on the emitters 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran and platinum octaethylporphyrin, respectively. We go on to show that, in most cases, it is sufficient to calculate the needed quantum efficiency harmonics directly from derivatives of the DC light versus current curve, thus enabling this analysis to be conducted solely from standard light-current-voltage measurement data.
A variable-width harmonic probe for multifrequency atomic force microscopy
Cai, Jiandong; Zhang, Li; Xia, Qi E-mail: michael.wang@nus.edu.sg; Luo, Yangjun; Wang, Michael Yu E-mail: michael.wang@nus.edu.sg
2015-02-16
In multifrequency atomic force microscopy (AFM) to simultaneously measure topography and material properties of specimens, it is highly desirable that the higher order resonance frequencies of the cantilever probe are assigned to be integer harmonics of the excitation frequency. The harmonic resonances are essential for significant enhancement of the probe's response at the specified harmonic frequencies. In this letter, a structural optimization technique is employed to design cantilever probes so that the ratios between one or more higher order resonance frequencies and the fundamental natural frequency are ensured to be equal to specified integers and, in the meantime, that the fundamental natural frequency is maximized. Width profile of the cantilever probe is the design variable in optimization. Thereafter, the probes were prepared by modifying a commercial probe through the focused ion beam (FIB) milling. The resonance frequencies of the FIB fabricated probes were measured with an AFM. Results of the measurement show that the optimal design of probe is as effective as design prediction.
Han, Yong-Chang; Madsen, Lars Bojer
2010-06-15
We solve the time-dependent Schroedinger equation for atomic hydrogen in an intense field using spherical coordinates with a radial grid and a spherical harmonic basis for the angular part. We present the high-order harmonic spectra based on three different forms, the dipole, dipole velocity, and acceleration forms, and two gauges, the length and velocity gauges. The relationships among the harmonic phases obtained from the Fourier transform of the three forms are discussed in detail. Although quantum mechanics is gauge invariant and the length and velocity gauges should give identical results, the two gauges present different computation efficiencies, which reflects the different behavior in terms of characteristics of the physical couplings acting in the two gauges. In order to obtain convergence, more angular momentum states are required in the length gauge, while more grid points are required in the velocity gauge. At lower laser intensity, the calculation in the length gauge is faster than that in the velocity gauge, while at high laser intensity, the calculation in the velocity gauge is more efficient. The velocity gauge is also expected to be more efficient in higher-dimensional calculations.
The Ultraviolet Surprise. Efficient Soft X-Ray High Harmonic Generation in Multiply-Ionized Plasmas
Popmintchev, Dimitar; Hernandez-Garcia, Carlos; Dollar, Franklin; Mancuso, Christopher; Perez-Hernandez, Jose A.; Chen, Ming-Chang; Hankla, Amelia; Gao, Xiaohui; Shim, Bonggu; Gaeta, Alexander L.; Tarazkar, Maryam; Romanov, Dmitri A.; Levis, Robert J.; Gaffney, Jim A.; Foord, Mark; Libby, Stephen B.; Jaron-Becker, Agnieskzka; Becker, Andreas; Plaja, Luis; Muranane, Margaret M.; Kapteyn, Henry C.; Popmintchev, Tenio
2015-12-04
High-harmonic generation is a universal response of matter to strong femtosecond laser fields, coherently upconverting light to much shorter wavelengths. Optimizing the conversion of laser light into soft x-rays typically demands a trade-off between two competing factors. Reduced quantum diffusion of the radiating electron wave function results in emission from each species which is highest when a short-wavelength ultraviolet driving laser is used. But, phase matchingâ€”the constructive addition of x-ray waves from a large number of atomsâ€”favors longer-wavelength mid-infrared lasers. We identified a regime of high-harmonic generation driven by 40-cycle ultraviolet lasers in waveguides that can generate bright beams in the soft x-ray region of the spectrum, up to photon energies of 280 electron volts. Surprisingly, the high ultraviolet refractive indices of both neutral atoms and ions enabled effective phase matching, even in a multiply ionized plasma. We observed harmonics with very narrow linewidths, while calculations show that the x-rays emerge as nearly time-bandwidthâ€“limited pulse trains of ~100 attoseconds.
Meliopoulos, A.P.S.; Zhang, Fan ); Cokkinides, G.J. ); Coffeen, L.; Burnett, R.; McBride, J. ); Zelingher, S.; Stillman, G.
1993-07-01
This paper presents a technique for laboratory characterization of instrument transformers designed for transmission level voltage and current measurements. The technique is also extended to Transient Event Recorders (TERs). The objective of the method is to determine the suitability of existing substation instrument transformers for harmonic measurements, particularly in the frequency range of 60 to 1500 Hz covering the first 25 harmonics. Specifically, the following characteristics are of interest in the frequency range of 60 to 1500 Hz: transfer function magnitude and phase, linearity, and sensitivity of the frequency response to burdens. The measurement technique is based on exciting the instrument transformer primary with an impulsive waveform. Both input and output waveforms are recorded using laboratory grade probes and digitizers. Subsequently, digital signal processing techniques are used to compute the instrument transformer frequency response. Several voltage transformers (both PTs and CCVTs) and current transformers in the 230kV-765kV voltage range were tested. The results of these tests are described in the paper. Conclusions are presented regarding the suitability of the instrument transformers and transient event recorders for harmonic measurement and the requirements for such a system. A quantitative analysis of the measurement accuracy and software based methods to enhance the measurement accuracy is also presented.
Efficiency enhancement of nonlinear odd harmonics in thermal free electron laser
Bazouband, F.; Maraghechi, B.
2013-05-07
The effect of axial energy spread on the radiation of third harmonic is studied in the free electron laser with planar wiggler and ion-channel guiding. Spread in the longitudinal momentum and so in the initial energy of electron beam, without any spread in the transverse velocity, is assumed in the form of Gaussian distribution function. The technique that is employed is a one-dimensional and steady-state simulation. A set of self consistent nonlinear differential equations that describes the system is solved numerically by Runge-Kutta method. Due to the sensitivity of harmonics to thermal effects, gain improvement of third harmonic radiation is achieved by using ion-channel guiding technique and efficiency enhancement is applied by tapering the magnetic field of wiggler to optimize radiation. The bunching parameter of the electron beam is also studied. It is found that the growth of the magnitude of the bunching parameter that is caused by the ponderomotive wave stops before the saturation point of the radiation. This means that ponderomotive wave saturates at a shorter distance compared to the radiation.
Theory of third-harmonic generation using Bessel beams, and self-phase-matching
Tewari, S.P.; Huang, H.; Boyd, R.W.
1996-09-01
Taking Bessel beams ({ital J}{sub 0} beam) as a representation of a conical beam, and a slowly varying envelope approximation (SVEA) we obtain the results for the theory of third-harmonic generation from an atomic medium. We demonstrate how the phenomenon of self-phase-matching is contained in the transverse-phase-matching integral of the theory. A method to calculate the transverse-phase-matching integral containing four Bessel functions is described which avoids the computer calculations of the Bessel functions. In order to consolidate the SVEA result an alternate method is used to obtain the exact result for the third-harmonic generation. The conditions are identified in which the exact result goes over to the result of the SVEA. The theory for multiple Bessel beams is also discussed which has been shown to be the source of the wide width of the efficiency curve of the third-harmonic generation observed in experiments. {copyright} {ital 1996 The American Physical Society.}
Bierbach, Jana; Yeung, Mark; Eckner, Erich; Roedel, Christian; Kuschel, Stephan; Zepf, Matt; Paulus, Gerhard G.
2015-05-01
Surface high-harmonic generation in the relativistic regime is demonstrated as a source of extreme ultra-violet (XUV) pulses with extended operation time. Relativistic high-harmonic generation is driven by a frequency-doubled high-power Ti:Sapphire laser focused to a peak intensity of 3Â·1019 W/cm2 onto spooling tapes. We demonstrate continuous operation over up to one hour runtime at a repetition rate of 1 Hz. Harmonic spectra ranging from 20 eV to 70 eV (62 nm to 18 nm) were consecutively recorded by an XUV spectrometer. An average XUV pulse energy in the ÂµJ range is measured. With the presented setup, relativistic surface high-harmonic generation becomes a powerful source of coherent XUV pulses that might enable applications in, e.g. attosecond laser physics and the seeding of free-electron lasers, when the laser issues causing 80-% pulse energy fluctuations are overcome.
Ransom, Ray M.; Gallegos-Lopez, Gabriel; Kinoshita, Michael H.
2012-07-31
Methods, system and apparatus are provided for quickly approximating a peak summed magnitude (A) of a phase voltage (Vph) waveform in a multi-phase system that implements third harmonic injection.
Erba, A. Dovesi, R.; Shahrokhi, M.; Moradian, R.
2015-01-28
Harmonic and quasi-harmonic thermal properties of two isostructural simple oxides (periclase, MgO, and lime, CaO) are computed with ab initio periodic simulations based on the density-functional-theory (DFT). The more polarizable character of calcium with respect to magnesium cations is found to dramatically affect the validity domain of the quasi-harmonic approximation that, for thermal structural properties (such as temperature dependence of volume, V(T), bulk modulus, K(T), and thermal expansion coefficient, Î±(T)), reduces from [0 K-1000 K] for MgO to just [0 K-100 K] for CaO. On the contrary, thermodynamic properties (such as entropy, S(T), and constant-volume specific heat, C{sub V}(T)) are described reliably at least up to 2000 K and quasi-harmonic constant-pressure specific heat, C{sub P}(T), up to about 1000 K in both cases. The effect of the adopted approximation to the exchange-correlation functional of the DFT is here explicitly investigated by considering five different expressions of three different classes (local-density approximation, generalized-gradient approximation, and hybrids). Computed harmonic thermodynamic properties are found to be almost independent of the adopted functional, whereas quasi-harmonic structural properties are more affected by the choice of the functional, with differences that increase as the system becomes softer.
Opportunities for regional harmonization of appliance standards and l abeling program
McNeil, Michael A.
2003-09-01
The South Asian Regional Initiative for Energy (SARI/Energy) calls for a series of activities to promote Energy Efficiency Standards and Labeling (EES&L) of end use appliances in the region. In pursuit of this goal, the project supports several seminars and meetings that bring together policymakers and stakeholders from throughout the region. The purpose of these gatherings is to encourage a dialogue among participants as to the benefits and barriers associated with EES&L programs. In addition, it is the role of the program organizers to provide participants with the technical details necessary to make progress towards effective efficiency programs. One component of the initiative is to encourage the harmonization (alignment) of existing program components, and the pursuit of new programs coordinated at the regional level. In support of this goal, the report provides information aimed at motivating and enabling cooperative activities which will provide concrete benefits to programs in each country, whether well developed, or still in the initial planning stage. It should be emphasized that the underlying objective of the harmonization component of the SARI/Energy project is to increase the potential for success of EES&L programs of all countries involved, and to reduce burdens on manufacturers, exporters and importers in each country. Harmonization ''for it's own sake'' is not desirable, nor is it suggested that policymakers should bring their programs in line with international norms if doing so would present a disadvantage to their own efficiency programs, or to commercial interests within their country. If there is no such disadvantage, however, the program encourages alignment of policies and provides a forum at which this alignment can be pursued. The report covers several main topics, with varying emphasis. First, a general discussion of the motivation for an explicit policy of regional harmonization is given. Next, the current status of existing programs in
Evidence of the 2s2p({sup 1}P) doubly excited state in the harmonic generation spectrum of helium
Ngoko Djiokap, J. M.; Starace, Anthony F.
2011-07-15
By solving the two-active-electron time-dependent Schroedinger equation in an intense, ultrashort laser field, we investigate evidence of electron correlations in the high-order harmonic generation spectrum of helium. As the frequency of the driving laser pulse varies from 4.6 to 6.6 eV, the 13th, 11th, and 9th harmonics sequentially become resonant with the transition between the ground state and the isolated 2s2p({sup 1}P) autoionizing state of helium, which dramatically enhances these harmonics and changes their profiles. When each of the 9th and 13th harmonics are in resonance with this autoionizing state, there is also a low-order multiphoton resonance with a Rydberg state, resulting in a particularly large enhancement of these harmonics relative to neighboring harmonics. When the 11th harmonic is in resonance with the 2s2p({sup 1}P) autoionizing state, the 13th harmonic is simultaneously in resonance with numerous higher-energy autoionizing states, resulting in a competition between these two harmonics for intensity. These results demonstrate that even electron correlations occurring over a narrow energy interval can have a significant effect on strong-field processes such as harmonic generation.
Nusinovich, Gregory S.; Pu, Ruifeng; Granatstein, Victor L.
2015-07-06
In recent years, there was an active development of high-power, sub-terahertz (sub-THz) gyrotrons for numerous applications. For example, a 0.67 THz gyrotron delivering more than 200â€‰kW with about 20% efficiency was developed. This record high efficiency was achieved because the gyrotron operated in a high-order TE{sub 31,8}-mode with the power of ohmic losses less than 10% of the power of outgoing radiation. That gyrotron operated at the fundamental cyclotron resonance, and a high magnetic field of about 27â€‰T was created by a pulse solenoid. For numerous applications, it is beneficial to use gyrotrons at cyclotron harmonics which can operate in available cryomagnets with fields not exceeding 15â€‰T. However, typically, the gyrotron operation at harmonics faces severe competition from parasitic modes at the fundamental resonance. In the present paper, we consider a similar 0.67 THz gyrotron designed for operation in the same TE{sub 31,8}-mode, but at the second harmonic. We focus on two nonlinear effects typical for interaction between the fundamental and second harmonic modes, viz., the mode suppression and the nonlinear excitation of the mode at the fundamental harmonic by the second harmonic oscillations. Our study includes both the analytical theory and numerical simulations performed with the self-consistent code MAGY. The simulations show that stable second harmonic operation in the TE{sub 31,8} mode is possible with only modest sacrifice of efficiency and power.
Warner, E. S.; Heath, G. A.
2012-04-01
A systematic review and harmonization of life cycle assessment (LCA) literature of nuclear electricity generation technologies was performed to determine causes of and, where possible, reduce variability in estimates of life cycle greenhouse gas (GHG) emissions to clarify the state of knowledge and inform decision making. LCA literature indicates that life cycle GHG emissions from nuclear power are a fraction of traditional fossil sources, but the conditions and assumptions under which nuclear power are deployed can have a significant impact on the magnitude of life cycle GHG emissions relative to renewable technologies. Screening 274 references yielded 27 that reported 99 independent estimates of life cycle GHG emissions from light water reactors (LWRs). The published median, interquartile range (IQR), and range for the pool of LWR life cycle GHG emission estimates were 13, 23, and 220 grams of carbon dioxide equivalent per kilowatt-hour (g CO{sub 2}-eq/kWh), respectively. After harmonizing methods to use consistent gross system boundaries and values for several important system parameters, the same statistics were 12, 17, and 110 g CO{sub 2}-eq/kWh, respectively. Harmonization (especially of performance characteristics) clarifies the estimation of central tendency and variability. To explain the remaining variability, several additional, highly influential consequential factors were examined using other methods. These factors included the primary source energy mix, uranium ore grade, and the selected LCA method. For example, a scenario analysis of future global nuclear development examined the effects of a decreasing global uranium market-average ore grade on life cycle GHG emissions. Depending on conditions, median life cycle GHG emissions could be 9 to 110 g CO{sub 2}-eq/kWh by 2050.
iHarmonizer: improving the disk efficiency of I/O-intensive multithreaded codes
Davis, Marion Kei; Wang, Yizhe; Jiang, Song
2010-01-01
Challenged by serious power and thermal constraints, and limited by available instruction-level parallelism, processor designs have evolved to multi-core architectures. These architectures, many augmented with native simultaneous multithreading, are driving software developers to use multithreaded programs to exploit thread-level parallelism. While multithreading is well-known to introduce concerns of data dependency and CPU load balance, less known is that the uncertainty of relative progress of thread execution can cause patterns of I/O requests, issued by different threads, to be effectively random and so significantly degrade hard-disk efficiency. This effect can severely offset the performance gains from parallel execution, especially for I/O-intensive programs. Retaining the benefits of multithreading while not reducing I/O efficiency is an urgent and challenging problem. We propose a user-level scheme, iHarmonizer, to streamline the servicing of I/O requests from multiple threads in OpenMP programs. Specifically, we use the compiler to insert code into OpenMP programs so that data usage can be transmitted at run time to a supporting run-time library; this library in turn prefetches data in a disk-friendly way and coordinates threads execution according to the availability of their requested data. Transparently to the programmer, iHarmonizer makes a multithreaded program I/O efficient while maintaining the benefits of parallelism. Our experiments show that iHarmonizer can significantly speed up the execution of a representative set of I/O-intensive scientific benchmarks.
Approximate local magnetic-to-electric surface operators for time-harmonic Maxwell's equations
El Bouajaji, M.
2014-12-15
The aim of this paper is to propose new local and accurate approximate magnetic-to-electric surface boundary operators for the three-dimensional time-harmonic Maxwell's equations. After their construction where their accuracy is improved through a regularization process, a localization of these operators and a full finite element approximation is introduced. Next, their numerical efficiency and accuracy is investigated in detail for different scatterers when these operators are used in the extreme situation of On-Surface Radiation Conditions methods.
Molecular Solid EOS based on Quasi-Harmonic Oscillator approximation for phonons
Menikoff, Ralph
2014-09-02
A complete equation of state (EOS) for a molecular solid is derived utilizing a Helmholtz free energy. Assuming that the solid is nonconducting, phonon excitations dominate the specific heat. Phonons are approximated as independent quasi-harmonic oscillators with vibrational frequencies depending on the specific volume. The model is suitable for calibrating an EOS based on isothermal compression data and infrared/Raman spectroscopy data from high pressure measurements utilizing a diamond anvil cell. In contrast to a Mie-Gr Ìˆuneisen EOS developed for an atomic solid, the specific heat and Gr Ìˆuneisen coefficient depend on both density and temperature.
Enhanced third harmonic generation from the epsilon-near-zero modes of ultrathin films
Luk, Ting S. Liu, Sheng; Campione, Salvatore; Ceglia, Domenico de; Vincenti, Maria A.; Keeler, Gordon A.; Sinclair, Michael B.; Prasankumar, Rohit P.; Scalora, Michael
2015-04-13
We experimentally demonstrate efficient third harmonic generation from an indium tin oxide nanofilm (Î»/42 thick) on a glass substrate for a pump wavelength of 1.4â€‰Î¼m. A conversion efficiency of 3.3 Ã— 10{sup âˆ’6} is achieved by exploiting the field enhancement properties of the epsilon-near-zero mode with an enhancement factor of 200. This nanoscale frequency conversion method is applicable to other plasmonic materials and reststrahlen materials in proximity of the longitudinal optical phonon frequencies.
Coherent states for nonlinear harmonic oscillator and some of its properties
Amir, Naila E-mail: naila.amir@sns.nust.edu.pk; Iqbal, Shahid E-mail: siqbal@sns.nust.edu.pk
2015-06-15
A one-dimensional nonlinear harmonic oscillator is studied in the context of generalized coherent states. We develop a perturbative framework to compute the eigenvalues and eigenstates for the quantum nonlinear oscillator and construct the generalized coherent states based on Gazeau-Klauder formalism. We analyze their statistical properties by means of Mandel parameter and second order correlation function. Our analysis reveals that the constructed coherent states exhibit super-Poissonian statistics. Moreover, it is shown that the coherent states mimic the phenomena of quantum revivals and fractional revivals during their time evolution. The validity of our results has been discussed in terms of various parametric bounds imposed by our computational scheme.
Label-free three-dimensional imaging of cell nucleus using third-harmonic generation microscopy
Lin, Jian; Zheng, Wei; Wang, Zi; Huang, Zhiwei
2014-09-08
We report the implementation of the combined third-harmonic generation (THG) and two-photon excited fluorescence (TPEF) microscopy for label-free three-dimensional (3-D) imaging of cell nucleus morphological changes in liver tissue. THG imaging shows regular spherical shapes of normal hepatocytes nuclei with inner chromatin structures while revealing the condensation of chromatins and nuclear fragmentations in hepatocytes of diseased liver tissue. Colocalized THG and TPEF imaging provides complementary information of cell nuclei and cytoplasm in tissue. This work suggests that 3-D THG microscopy has the potential for quantitative analysis of nuclear morphology in cells at a submicron-resolution without the need for DNA staining.
Two-wave regime of operation of the high-harmonic gyrotron
Savilov, A. V.; Denisov, G. G.; Kalynov, Yu. K.; Osharin, I. V.
2015-04-15
The use of the two-wave co-generation is proposed as a way to decrease the effective Q-factor of the operating near-cutoff wave of the gyrotron. In this two-wave regime, the operating wave represents a â€œhotâ€ wave mode formed by two partial â€œcoldâ€ modes (near-cutoff and far-from-cutoff ones) coupled on the electron beam. It is shown that the use of this regime can provide a significant decrease of the Ohmic losses in low-relativistic high-harmonic gyrotrons operating in the THz frequency range.
Reliability of IGBT in a STATCOM for Harmonic Compensation and Power Factor Correction
Gopi Reddy, Lakshmi Reddy; Tolbert, Leon M; Ozpineci, Burak; Xu, Yan; Rizy, D Tom
2012-01-01
With smart grid integration, there is a need to characterize reliability of a power system by including reliability of power semiconductors in grid related applications. In this paper, the reliability of IGBTs in a STATCOM application is presented for two different applications, power factor correction and harmonic elimination. The STATCOM model is developed in EMTP, and analytical equations for average conduction losses in an IGBT and a diode are derived and compared with experimental data. A commonly used reliability model is used to predict reliability of IGBT.
Office of Energy Efficiency and Renewable Energy (EERE)
As clean energy increasingly becomes part of the national dialogue, lenders, utilities, and lawmakers need the most comprehensive and accurate information on GHG emissions from various sources of energy to inform policy, planning, and investment decisions. The National Renewable Energy Laboratory (NREL) recently led the Life Cycle Assessment (LCA) Harmonization Project, a study that gives decision makers and investors more precise estimates of life cycle GHG emissions for renewable and conventional generation, clarifying inconsistent and conflicting estimates in the published literature, and reducing uncertainty.
Office of Energy Efficiency and Renewable Energy (EERE)
As clean energy increasingly becomes part of the national dialogue, lenders, utilities, and lawmakers need the most comprehensive and accurate information on GHG emissions from various sources of energy to inform policy, planning, and investment decisions. The National Renewable Energy Laboratory (NREL) recently led the Life Cycle Assessment (LCA) Harmonization Project, a study that gives decision makers and investors more precise estimates of life cycle GHG emissions for renewable and conventional generation, clarifying inconsistent and conflicting estimates in the published literature, and reducing uncertainty.
Study of the second harmonic generation and optical rectification in a cBN crystal
Dou Qingping; Ma Haitao; Jia Gang; Chen Zhanguo; Cao Kun; Zhang Tiechen
2007-02-28
Cubic boron nitride (cBN) - a kind of an artificial (synthetic) crystal with the band gap of {approx}6.3 eV, which has the zinc blende structure and the 4-bar 3m symmetry, is studied. The optical rectification is obtained and the second harmonic generation (SHG) is observed in the cBN crystal for the first time by using a 1064-nm Q-switched Nd:YAG laser. The green light at 532 nm from the cBN sample can be seen with a naked eye. (nonlinear optical phenomena)
Life Cycle Greenhouse Gas Emissions of Utility-Scale Wind Power: Systematic Review and Harmonization
Broader source: Energy.gov [DOE]
As clean energy increasingly becomes part of the national dialogue, lenders, utilities, and lawmakers need the most comprehensive and accurate information on GHG emissions from various sources of energy to inform policy, planning, and investment decisions. The National Renewable Energy Laboratory (NREL) recently led the Life Cycle Assessment (LCA) Harmonization Project, a study that gives decision makers and investors more precise estimates of life cycle GHG emissions for renewable and conventional generation, clarifying inconsistent and conflicting estimates in the published literature, and reducing uncertainty.
Broader source: Energy.gov [DOE]
As clean energy increasingly becomes part of the national dialogue, lenders, utilities, and lawmakers need the most comprehensive and accurate information on GHG emissions from various sources of energy to inform policy, planning, and investment decisions. The National Renewable Energy Laboratory (NREL) recently led the Life Cycle Assessment (LCA) Harmonization Project, a study that gives decision makers and investors more precise estimates of life cycle GHG emissions for renewable and conventional generation, clarifying inconsistent and conflicting estimates in the published literature, and reducing uncertainty.
Enhanced third harmonic generation from the epsilon-near-zero modes of ultrathin films
Luk, Ting S.; De Ceglia, Domenico; Liu, Sheng; Keeler, Gordon Arthur; Prasankumar, Rohit; Los Alamos National Lab. , Los Alamos, NM ; Vincenti, Maria A; Scalora, Michael; Sinclair, Michael B.; campione, salvatore
2015-04-13
We demonstrate, through our experimentation, efficient third harmonic generation from an indium tin oxide nanofilm (Î»/42 thick) on a glass substrate for a pump wavelength of 1.4 Î¼m. A conversion efficiency of 3.3 Ã— 10^{-6} is achieved by exploiting the field enhancement properties of the epsilon-near-zero mode with an enhancement factor of 200. Furthermore, this nanoscale frequency conversion method is applicable to other plasmonic materials and reststrahlen materials in proximity of the longitudinal optical phonon frequencies.
CORRELATED AND ZONAL ERRORS OF GLOBAL ASTROMETRIC MISSIONS: A SPHERICAL HARMONIC SOLUTION
Makarov, V. V.; Dorland, B. N.; Gaume, R. A.; Hennessy, G. S.; Berghea, C. T.; Dudik, R. P.; Schmitt, H. R.
2012-07-15
We propose a computer-efficient and accurate method of estimating spatially correlated errors in astrometric positions, parallaxes, and proper motions obtained by space- and ground-based astrometry missions. In our method, the simulated observational equations are set up and solved for the coefficients of scalar and vector spherical harmonics representing the output errors rather than for individual objects in the output catalog. Both accidental and systematic correlated errors of astrometric parameters can be accurately estimated. The method is demonstrated on the example of the JMAPS mission, but can be used for other projects in space astrometry, such as SIM or JASMINE.
Method and apparatus for reducing the harmonic currents in alternating-current distribution networks
Beverly, L.H.; Hance, R.D.; Kristalinski, A.L.; Visser, A.T.
1996-11-19
An improved apparatus and method reduce the harmonic content of AC line and neutral line currents in polyphase AC source distribution networks. The apparatus and method employ a polyphase Zig-Zag transformer connected between the AC source distribution network and a load. The apparatus and method also employs a mechanism for increasing the source neutral impedance of the AC source distribution network. This mechanism can consist of a choke installed in the neutral line between the AC source and the Zig-Zag transformer. 23 figs.
Method and apparatus for reducing the harmonic currents in alternating-current distribution networks
Beverly, Leon H.; Hance, Richard D.; Kristalinski, Alexandr L.; Visser, Age T.
1996-01-01
An improved apparatus and method reduce the harmonic content of AC line and neutral line currents in polyphase AC source distribution networks. The apparatus and method employ a polyphase Zig-Zag transformer connected between the AC source distribution network and a load. The apparatus and method also employs a mechanism for increasing the source neutral impedance of the AC source distribution network. This mechanism can consist of a choke installed in the neutral line between the AC source and the Zig-Zag transformer.
Restricted thermalization for two interacting atoms in a multimode harmonic waveguide
Yurovsky, V. A.; Olshanii, M. [School of Chemistry, Tel Aviv University, IL-69978 Tel Aviv (Israel); Department of Physics, University of Massachusetts Boston, Boston, Massachusetts 02125 (United States)
2010-04-15
In this article, we study the thermalizability of a system consisting of two atoms in a circular, transversely harmonic waveguide in the multimode regime. While showing some signatures of quantum-chaotic behavior, the system fails to reach a thermal equilibrium in a relaxation from an initial state, even when the interaction between the atoms is infinitely strong. We relate this phenomenon to the previously addressed unattainability of a complete quantum chaos in the Seba billiard [P. Seba, Phys. Rev. Lett. 64, 1855 (1990)], and we conjecture the absence of a complete thermalization to be a generic property of integrable quantum systems perturbed by a nonintegrable but well-localized perturbation.
Broader source: Energy.gov [DOE]
As clean energy increasingly becomes part of the national dialogue, lenders, utilities, and lawmakers need the most comprehensive and accurate information on GHG emissions from various sources of energy to inform policy, planning, and investment decisions. The National Renewable Energy Laboratory (NREL) recently led the Life Cycle Assessment (LCA) Harmonization Project, a study that gives decision makers and investors more precise estimates of life cycle GHG emissions for renewable and conventional generation, clarifying inconsistent and conflicting estimates in the published literature, and reducing uncertainty.
Zhang, Xiao-Fei; Du, Zhi-Jing; Tan, Ren-Bing; Dong, Rui-Fang; Chang, Hong; Zhang, Shou-Gang
2014-07-15
We consider a pair of coupled nonlinear SchrÃ¶dinger equations modeling a rotating two-component Boseâ€“Einstein condensate with tunable interactions and harmonic potential, with emphasis on the structure of vortex states by varying the strength of inter-component interaction, rotational frequency, and the aspect ratio of the harmonic potential. Our results show that the inter-component interaction greatly enhances the effect of rotation. For the case of isotropic harmonic potential and small inter-component interaction, the initial vortex structure remains unchanged. As the ratio of inter- to intra-component interactions increases, each component undergoes a transition from a vortex lattice (vortex line) in an isotropic (anisotropic) harmonic potential to an alternatively arranged stripe pattern, and eventually to the interwoven â€œserpentineâ€ vortex sheets. Moreover, in the case of anisotropic harmonic potential the system can develop to a rotating droplet structure. -- Highlights: â€¢Different vortex structures are obtained within the full parameter space. â€¢Effects of system parameters on the ground state structure are discussed. â€¢Phase transition between different vortex structures is also examined. â€¢Present one possible way to obtain the rotating droplet structure. â€¢Provide many possibilities to manipulate vortex in two-component BEC.
Roles of poloidal rotation in the q = 1 high-order harmonic tearing modes in a tokamak plasma
Wei Lai; Wang Zhengxiong
2013-01-15
Roles of poloidal rotation in stabilizing the m/n=1/1 kink-tearing mode and exciting its high-order harmonic tearing modes are numerically investigated by using a reduced magnetohydrodynamic model. It is found that the high-order harmonic tearing modes, such as m/n=2/2, m/n=3/3, or even much higher-m harmonics, can be destabilized so significantly by rotation shear as to be more unstable than or comparable to the m/n=1/1 mode. Moreover, the short wave-length Kelvin- Helmholtz (KH) instabilities can be excited in the large rotation shear regime. The scaling power laws of the linear growth rate for each harmonic mode in different rotation shear regimes are verified by the previous relevant theoretical results based on the non-constant-{psi} and constant-{psi} behavior categories in tearing modes. During the nonlinear evolution, the m/n=2/2 mode dominated phase first appears and then is followed by the m/n=1/1 mode dominated nonlinear phase instead. Afterward, some smaller sub-islands due to the high-order harmonics are produced in the large irregular m=1 crescent-shaped island, and then a coalescence process of turbulent island chains occurs before the decay phase.
Multi-MW 22.8 GHz Harmonic Multiplier - RF Power Source for High-Gradient Accelerator R&D
Jay L. Hirshfield
2012-07-26
Electrodynamic and particle simulation studies have been carried out to optimize design of a two-cavity harmonic frequency multiplier, in which a linear electron beam is energized by rotating fields near cyclotron resonance in a TE111 cavity in a uniform magnetic field, and in which the beam then radiates coherently at the nth harmonic into a TEn11 output cavity. Examples are worked out in detail for 7th and 2nd harmonic converters, showing RF-to-RF conversion efficiencies of 45% and 88%, respectively at 19.992 GHz (K-band) and 5.712 GHz (C-band), for a drive frequency of 2.856 GHz. Details are shown of RF infrastructure (S-band klystron, modulator) and harmonic converter components (drive cavity, output cavities, electron beam source and modulator, beam collector) for the two harmonic converters to be tested. Details are also given for the two-frequency (S- and C-band) coherent multi-MW test stand for RF breakdown and RF gun studies.
Combining harmonic generation and laser chirping to achieve high spectral density in Compton sources
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
TerziÄ‡, BalÅ¡a; Reeves, Cody; Krafft, Geoffrey A.
2016-04-25
Recently various laser-chirping schemes have been investigated with the goal of reducing or eliminating ponderomotive line broadening in Compton or Thomson scattering occurring at high laser intensities. Moreover, as a next level of detail in the spectrum calculations, we have calculated the line smoothing and broadening expected due to incident beam energy spread within a one-dimensional plane wave model for the incident laser pulse, both for compensated (chirped) and unchirped cases. The scattered compensated distributions are treatable analytically within three models for the envelope of the incident laser pulses: Gaussian, Lorentzian, or hyperbolic secant. We use the new results tomoreÂ Â» demonstrate that the laser chirping in Compton sources at high laser intensities: (i) enables the use of higher order harmonics, thereby reducing the required electron beam energies; and (ii) increases the photon yield in a small frequency band beyond that possible with the fundamental without chirping. We found that this combination of chirping and higher harmonics can lead to substantial savings in the design, construction and operational costs of the new Compton sources. This is of particular importance to the widely popular laser-plasma accelerator based Compton sources, as the improvement in their beam quality enters the regime where chirping is most effective.Â«Â less
Bertelli, N; Jaeger, E F; Hosea, J C; Phillips, C K; Berry, L; Bonoli, P T; Gerhardt, S P; Green, D; LeBlanc, B; Perkins, R J; Ryan, P M; Taylor, G; Valeo, E J; Wilso, J R; Wright, J C
2014-07-01
Fast waves at harmonics of the ion cyclotron frequency, which have been used successfully on National Spherical Torus Experiment (NSTX), will also play an important role in ITER and are a promising candidate for the Fusion Nuclear Science Facility (FNSF) designs based on spherical torus (ST). Experimental studies of high harmonic fast waves (HHFW) heating on the NSTX have demonstrated that substantial HHFW power loss occurs along the open field lines in the scrape-off layer (SOL), but the mechanism behind the loss is not yet understood. The full wave RF code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain, is applied to specific NSTX discharges in order to predict the effects and possible causes of this power loss. In the studies discussed here, a collisional damping parameter has been implemented in AORSA as a proxy to represent the real, and most likely nonlinear, damping processes. A prediction for the NSTX Upgrade (NSTX-U) experiment, that will begin operation next year, is also presented, indicating a favorable condition for the experiment due to a wider evanescent region in edge density.*Research supported by the U.S. DOE under Contract No. DE-AC02-09CH11466 with Princeton University.
Psikal, J.; Klimo, O.; Weber, S.; Margarone, D.
2014-07-15
The influence of laser frequency on laser-driven ion acceleration is investigated by means of two-dimensional particle-in-cell simulations. When ultrashort intense laser pulse at higher harmonic frequency irradiates a thin solid foil, the target may become re lativistically transparent for significantly lower laser pulse intensity compared with irradiation at fundamental laser frequency. The relativistically induced transparency results in an enhanced heating of hot electrons as well as increased maximum energies of accelerated ions and their numbers. Our simulation results have shown the increase in maximum proton energy and increase in the number of high-energy protons by a factor of 2 after the interaction of an ultrashort laser pulse of maximum intensity 7â€‰Ã—â€‰10{sup 21â€‰}W/cm{sup 2} with a fully ionized plastic foil of realistic density and of optimal thickness between 100â€‰nm and 200â€‰nm when switching from the fundamental frequency to the third harmonics.
Flux harmonics in large SFR cores in relation with core characteristics such as power peaks
Rimpault, G.; Buiron, L.; Fontaine, B.; Sciora, P.; Tommasi, J.
2013-07-01
Designing future Sodium Fast Reactors (SFR) requires enhancing their operational performance and reducing the probability to go into core disruption. As a consequence of these constraints, these novel reactors exhibit rather unusual features compared to past designs. The cores are much larger with rather flat shape. The consequences of that shape on the core characteristics deserve to be studied. The approach taken in this paper is to calculate the eigenvalue associated to the first harmonic and its associated flux. It is demonstrated that these values are linked to some core features, in particular, those sensitive to spatial effects such as power peaks induced by the movement of control rods. The uncertainty associated to these characteristics is being tentatively studied and guidelines for further studied are being identified. In the development strategy of these new SFR designs, a first demonstration plant of limited installed power (around 1500 MWth) will have to be built first. Identifying the possibility of going later to higher power plants (around 3600 MWth) without facing new challenges is an important criterion for designing such a plant. That strategy is being studied, in this paper, focusing on some rather frequent initiator such as the inadvertent control rod withdrawal for different core sizes with the help of the perturbation theory and the flux harmonics. (authors)
A Proof-of-Principle Echo-enabled Harmonic Generation Free Electron Laser Experiment at SLAC
Pernet, Pierre-Louis
2010-06-24
With the advent of X-ray Free Electron Lasers (FELs), new methods have been developed to extend capabilities at short wavelengths beyond Self-Amplified Spontaneous Emission (SASE). In particular, seeding of a FEL allows for temporal control of the radiation pulse and increases the peak brightness by orders of magnitude. Most recently, Gennady Stupakov and colleagues at SLAC proposed a new technique: Echo-Enabled Harmonic Generation (EEHG). Here a laser microbunches the beam in an undulator and the beam is sheared in a chicane. This process is repeated with a second laser, undulator and chicane. The interplay between these allows a seeding of the X-ray laser up to the 100th harmonic of the first laser. After introducing the physics of FELs and the EEHG seeding technique, we describe contributions to the experimental effort. We will present detailed studies of the experiment including the choice of parameters and their optimization, the emittance effect, spontaneous emission in the undulators, the second laser phase effect, and measurements of the jitter between RF stations. Finally, the status and preliminary results of the Echo-7 experiment will be outlined.
Harmonic Resonant Kicker Design for the MEIC Electron Circular Cooler Ring
Huang, Yulu; Wang, Haipeng; Rimmer, Robert A.
2015-09-01
Bunched-beam electron cooling of the high-energy ion beam emittance may be a crucial technology for the proposed Medium energy Electron Ion Collider (MEIC) to achieve its design luminosity. A critical component is a fast kicker system in the Circular Ring (CR) that periodically switches electron bunches in and out of the ring from and to the driver Energy Recovery Linac (ERL). Compared to a conventional strip-line type kicker, a quarter wave resonator (QWR) based deflecting structure has a much higher shunt impedance and so requires much less RF power. The cavity has been designed to resonate simultaneously at many harmonic modes that are integer multiples of the fundamental mode. In this way the resulting waveform will kick only a subset of the circulating bunches. In this paper, analytical shunt impedance optimization, the electromagnetic simulations of this type of cavity, as well as tuner and coupler concept designs to produce 5 odd and 5 even harmonics of 47.63MHz will be presented, in order to kick every 10th bunch in a 476.3 MHz bunch train.
Singh, Arvinder E-mail: naveens222@rediffmail.com; Gupta, Naveen E-mail: naveens222@rediffmail.com
2015-01-15
This paper presents an investigation of relativistic self-focusing effect of a q-Gaussian laser beam on second harmonic generation in a preformed parabolic plasma channel. An expression has been derived for density perturbation associated with the plasma wave excited by the laser beam. This in turn acts as a source of second harmonic generation. The moment theory approach has been used to derive a differential equation that governs the evolution of spot size of the laser beam with the distance of propagation. The detailed effects of intensity distribution deviation from Gaussian distribution, intensity of laser beam, density, and depth of the channel have been studied on self-focusing as well as on second harmonic generation.
Interaction between O{sub 2} and ZnO films probed by time-dependent second-harmonic generation
Andersen, S. V.; Vandalon, V.; Bosch, R. H. E. C.; Loo, B. W. H. van de; Kessels, W. M. M.; Pedersen, K.
2014-02-03
The interaction between O{sub 2} and ZnO thin films prepared by atomic layer deposition has been investigated by time-dependent second-harmonic generation, by probing the electric field induced by adsorbed oxygen molecules on the surface. The second-harmonic generated signal decays upon laser exposure due to two-photon assisted desorption of O{sub 2}. Blocking and unblocking the laser beam for different time intervals reveals the adsorption rate of O{sub 2} onto ZnO. The results demonstrate that electric field induced second-harmonic generation provides a versatile non-contact probe of the adsorption kinetics of molecules on ZnO thin films.
Emelin, M Yu; Ryabikin, M Yu
2013-03-31
The influence of the magnetic field of a laser pulse and the depletion of bound levels of working-medium atoms on the generation of high harmonics of mid-IR laser radiation in gases is investigated using numerical quantum-mechanical calculations. The maximum attainable spectral widths of high harmonics are estimated for model atoms with different ionisation potentials taking into account the aforementioned limiting effects. It is shown (within a two-dimensional model) that high harmonics with wavelengths to several angstroms can be generated by irradiating helium atoms with high-power femtosecond pulses of a laser [5] with a centre wavelength of 3.9 {mu}m. The possibility of observing experimentally relativistic effects using modern desktop mid-IR laser sources is demonstrated. (extreme light fields and their applications)
Heger, Matthias; Suhm, Martin A.; Mata, Ricardo A.
2014-09-14
The discrepancy between experimental and harmonically predicted shifts of the OH stretching fundamental of methanol upon hydrogen bonding to a second methanol unit is too large to be blamed mostly on diagonal and off-diagonal anharmonicity corrections. It is shown that a decisive contribution comes from post-MP2 electron correlation effects, which appear not to be captured by any of the popular density functionals. We also identify that the major deficiency is in the description of the donor OH bond. Together with estimates for the electronic and harmonically zero-point corrected dimer binding energies, this work provides essential constraints for a quantitative description of this simple hydrogen bond. The spectroscopic dissociation energy is predicted to be larger than 18 kJ/mol and the harmonic OH-stretching fundamental shifts by about ?121 cm{sup ?1} upon dimerization, somewhat more than in the anharmonic experiment (?111 cm{sup ?1})
Burkhardt, J. J.; Heath, G.; Cohen, E.
2012-04-01
In reviewing life cycle assessment (LCA) literature of utility-scale concentrating solar power (CSP) systems, this analysis focuses on reducing variability and clarifying the central tendency of published estimates of life cycle greenhouse gas (GHG) emissions through a meta-analytical process called harmonization. From 125 references reviewed, 10 produced 36 independent GHG emissions estimates passing screens for quality and relevance: 19 for parabolic trough (trough) technology and 17 for power tower (tower) technology. The interquartile range (IQR) of published estimates for troughs and towers were 83 and 20 grams of carbon dioxide equivalent per kilowatt-hour (g CO2-eq/kWh),1 respectively; median estimates were 26 and 38 g CO2-eq/kWh for trough and tower, respectively. Two levels of harmonization were applied. Light harmonization reduced variability in published estimates by using consistent values for key parameters pertaining to plant design and performance. The IQR and median were reduced by 87% and 17%, respectively, for troughs. For towers, the IQR and median decreased by 33% and 38%, respectively. Next, five trough LCAs reporting detailed life cycle inventories were identified. The variability and central tendency of their estimates are reduced by 91% and 81%, respectively, after light harmonization. By harmonizing these five estimates to consistent values for global warming intensities of materials and expanding system boundaries to consistently include electricity and auxiliary natural gas combustion, variability is reduced by an additional 32% while central tendency increases by 8%. These harmonized values provide useful starting points for policy makers in evaluating life cycle GHG emissions from CSP projects without the requirement to conduct a full LCA for each new project.
Chen, M.-C.; Arpin, P.; Popmintchev, T.; Gerrity, M.; Zhang, B.; Seaberg, M.; Popmintchev, D.; Murnane, M. M.; Kapteyn, H. C.
2010-10-22
We demonstrate fully phase-matched high harmonic emission spanning the water window spectral region important for nano- and bioimaging and a breadth of materials and molecular dynamics studies. We also generate the broadest bright coherent bandwidth ({approx_equal}300 eV) to date from any light source, small or large, that is consistent with a single subfemtosecond burst. The harmonic photon flux at 0.5 keV is 10{sup 3} higher than demonstrated previously. This work extends bright, spatially coherent, attosecond pulses into the soft x-ray region for the first time.
Observation of spectral gain narrowing in a high-order harmonic seeded soft-x-ray amplifier
Tissandier, F.; Sebban, S.; Ribiere, M.; Gautier, J.; Zeitoun, Ph.; Lambert, G.; Barszczak Sardinha, A.; Goddet, J.-Ph.; Burgy, F.; Lefrou, T.; Valentin, C.; Rousse, A.; Guilbaud, O.; Klisnick, A.; Nejdl, J.; Mocek, T.; Maynard, G.
2010-06-15
We report an observation of spectral gain narrowing of a high-order harmonic amplified by a soft-x-ray optical-field-ionized plasma. The temporal coherence and spectral linewidth of both the seeded and unseeded soft-x-ray lasers were experimentally measured using a varying-path-difference interferometer. The results showed that the high-order harmonic is subject to a strong spectral narrowing during its propagation in the plasma amplifier without rebroadening at saturation. This is in good agreement with a radiative transfer calculation including gain narrowing and saturation rebroadening.
A Perpendicular Biased 2nd Harmonic Cavity for the Fermilab Booster
Tan, C. Y.; Dey, J.; Madrak, R. L.; Pellico, W.; Romanov, G.; Sun, D.; Terechkine, I.
2015-07-13
A perpendicular biased 2nd harmonic cavity is currently being designed for the Fermilab Booster. Its purpose cavity is to flatten the bucket at injection and thus change the longitudinal beam distribution so that space charge effects are decreased. It can also with transition crossing. The reason for the choice of perpendicular biasing over parallel biasing is that the Q of the cavity is much higher and thus allows the accelerating voltage to be a factor of two higher than a similar parallel biased cavity. This cavity will also provide a higher accelerating voltage per meter than the present folded transmission line cavity. However, this type of cavity presents technical challenges that need to be addressed. The two major issues are cooling of the garnet material from the effects of the RF and the cavity itself from eddy current heating because of the 15 Hz bias field ramp. This paper will address the technical challenge of preventing the garnet from overheating.
Chen, Bao-Qin; Zhang, Chao; Liu, Rong-Juan; Li, Zhi-Yuan
2014-10-13
We have designed and fabricated a lithium niobate (LN) nonlinear photonic crystal (NPC) with a two-dimensional (2D) ellipse structure of inverse poling domains. The structure can offer continuously varying reciprocal lattice vectors in different directions to compensate the phase-mismatching during the second harmonic generation (SHG) for diverse pump wavelengths. We consider three propagation directions with large effective nonlinear susceptibility and measure the nonlinear conversion efficiency of SHG. The experimental data are in good agreement with the quantitative calculation results using the effective susceptibility model with pump depletion. With high-efficiency SHG in multiple propagation direction, the 2D ellipse structure of LN NPC has the potential to realize various broadband nonlinear frequency conversion processes in different propagation direction with a single crystal.
Heteroclinic tangle phenomena in nanomagnets subject to time-harmonic excitations
Serpico, C.; Quercia, A.; Perna, S.; Bertotti, G.; Ansalone, P.; D'Aquino, M.; Mayergoyz, I.
2015-05-07
Magnetization dynamics in uniformly magnetized nanomagnets excited by time-harmonic (AC) external fields or spin-polarized injected currents is considered. The analysis is focused on the behaviour of the AC-excited dynamics near saddle equilibria. It turns out that this dynamics has a chaotic character at moderately low power level. This chaotic and fractal nature is due to the phenomenon of heteroclinic tangle which is produced by the combined effect of AC-excitations and saddle type dynamics. By using the perturbation technique based on Melnikov function, analytical formulas for the threshold AC excitation amplitudes necessary to create the heteroclinic tangle are derived. Both the cases of AC applied fields and AC spin-polarized injected currents are treated. Then, by means of numerical simulations, we show how heteroclinic tangle is accompanied by the erosion of the safe basin around the stable regimes.
Modeling of high harmonic fast wave current drive on EAST tokamak
Li, J. C.; Gong, X. Y. Li, F. Y.; Dong, J. Q.; Gao, Q. D.; Zhang, N.
2015-10-15
High harmonic fast waves (HHFW) are among the candidates for non-inductive current drive (CD), which is essential for long-pulse or steady-state operation of tokamaks. Current driven with HHFW in EAST tokamak plasmas is numerically studied. The HHFW CD efficiency is found to increase non-monotonically with the wave frequency, and this phenomenon is attributed to the multi-pass absorption of HHFW. The sensitivity of CD efficiency to the value of the parallel refraction index of the launched wave is confirmed. The quasilinear effects, assessed as significant in HHFW current drive with the GENRAY/CQL3D package, cause a significant increase in CD efficiency as RF power is increased, which is very different from helicon current drive. Simulations for a range of toroidal dc electric fields, in combination with a range of fast wave powers, are also presented and indicate that the presence of the DC field can also enhance the CD efficiency.
Nakai, Hiromi; Ishikawa, Atsushi
2014-11-07
We propose a novel quantum chemical method, called the harmonic solvation model (HSM), for calculating thermochemical parameters in the condensed phase, particularly in the liquid phase. The HSM represents translational and rotational motions of a solute as vibrations interacting with a cavity wall of solvent molecules. As examples, the HSM and the ideal-gas model (IGM) were used for the standard formation reaction of liquid water, combustion reactions of liquid formic acid, methanol, and ethanol, vaporâ€“liquid equilibration of water and ethanol, and dissolution of gaseous CO{sub 2} in water. The numerical results confirmed the reliability and applicability of the HSM. In particular, the temperature dependence of the Gibbs energy of liquid molecules was accurately reproduced by the HSM; for example, the boiling point of water was reasonably determined using the HSM, whereas the conventional IGM treatment failed to obtain a crossing of the two Gibbs energy curves for gaseous and liquid water.
Electro-optic harmonic conversion to switch a laser beam out of a cavity
Haas, R.A.; Henesian, M.A.
1984-10-19
The present invention relates to switching laser beams out of laser cavities, and more particularly, it relates to the use of generating harmonics of the laser beam to accomplish the switching. When laser light is generatd in a laser cavity the problem arises of how to switch the laser light out of the cavity in order to make use of the resulting laser beam in a well known multitude of ways. These uses include range finding, communication, remote sensing, medical surgery, laser fusion applications and many more. The switch-out problem becomes more difficult as the size of the laser aperture grows such as in laser fusion applications. The final amplifier stages of the Nova and Novette lasers at Lawrence Livermore National Laboratory are 46 centimeters with the laser beam expanded to 74 centimeters thereafter. Larger aperture lasers are planned.
Cari, C. Suparmi, A.
2014-09-30
Dirac equation of 3D harmonics oscillator plus trigonometric Scarf non-central potential for spin symmetric case is solved using supersymmetric quantum mechanics approach. The Dirac equation for exact spin symmetry reduces to Schrodinger like equation. The relativistic energy and wave function for spin symmetric case are simply obtained using SUSY quantum mechanics method and idea of shape invariance.