skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs–Xe mixture. Part I: Review of the method and its fundamentals

Abstract

The first part of the review is presented which is dedicated to the time-resolved method of imaging and measuring the spatial distribution of the intensity of millimeter waves by using visible continuum (VC) emitted by the positive column (PC) of a dc discharge in a mixture of cesium vapor with xenon. The review focuses on the operating principles, fundamentals, and applications of this new technique. The design of the discharge tube and experimental setup used to create a wide homogeneous plasma slab with the help of the Cs–Xe discharge at a gas pressure of 45 Torr are described. The millimeter-wave effects on the plasma slab are studied experimentally. The mechanism of microwave-induced variations in the VC brightness and the causes of violation of the local relation between the VC brightness and the intensity of millimeter waves are discussed. Experiments on the imaging of the field patterns of horn antennas and quasi-optical beams demonstrate that this technique can be used for good-quality imaging of millimeter-wave beams in the entire millimeter-wavelength band. The method has a microsecond temporal resolution and a spatial resolution of about 2 mm. Energy sensitivities of about 10 μJ/cm{sup 2} in the Ka-band and about 200 μJ/cm{sup 2}more » in the D-band have been demonstrated.« less

Authors:
 [1]
  1. Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)
Publication Date:
OSTI Identifier:
22614037
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plasma Physics Reports; Journal Volume: 43; Journal Issue: 2; Other Information: Copyright (c) 2017 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ANTENNAS; BRIGHTNESS; CESIUM; GAS DISCHARGE TUBES; HOMOGENEOUS PLASMA; MICROWAVE RADIATION; PHOTON EMISSION; POSITIVE COLUMN; REVIEWS; SLABS; SPATIAL DISTRIBUTION; SPATIAL RESOLUTION; TIME RESOLUTION; VISIBLE SPECTRA; WAVELENGTHS; XENON

Citation Formats

Gitlin, M. S., E-mail: gitlin@appl.sci-nnov.ru. Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs–Xe mixture. Part I: Review of the method and its fundamentals. United States: N. p., 2017. Web. doi:10.1134/S1063780X17020040.
Gitlin, M. S., E-mail: gitlin@appl.sci-nnov.ru. Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs–Xe mixture. Part I: Review of the method and its fundamentals. United States. doi:10.1134/S1063780X17020040.
Gitlin, M. S., E-mail: gitlin@appl.sci-nnov.ru. Wed . "Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs–Xe mixture. Part I: Review of the method and its fundamentals". United States. doi:10.1134/S1063780X17020040.
@article{osti_22614037,
title = {Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs–Xe mixture. Part I: Review of the method and its fundamentals},
author = {Gitlin, M. S., E-mail: gitlin@appl.sci-nnov.ru},
abstractNote = {The first part of the review is presented which is dedicated to the time-resolved method of imaging and measuring the spatial distribution of the intensity of millimeter waves by using visible continuum (VC) emitted by the positive column (PC) of a dc discharge in a mixture of cesium vapor with xenon. The review focuses on the operating principles, fundamentals, and applications of this new technique. The design of the discharge tube and experimental setup used to create a wide homogeneous plasma slab with the help of the Cs–Xe discharge at a gas pressure of 45 Torr are described. The millimeter-wave effects on the plasma slab are studied experimentally. The mechanism of microwave-induced variations in the VC brightness and the causes of violation of the local relation between the VC brightness and the intensity of millimeter waves are discussed. Experiments on the imaging of the field patterns of horn antennas and quasi-optical beams demonstrate that this technique can be used for good-quality imaging of millimeter-wave beams in the entire millimeter-wavelength band. The method has a microsecond temporal resolution and a spatial resolution of about 2 mm. Energy sensitivities of about 10 μJ/cm{sup 2} in the Ka-band and about 200 μJ/cm{sup 2} in the D-band have been demonstrated.},
doi = {10.1134/S1063780X17020040},
journal = {Plasma Physics Reports},
number = 2,
volume = 43,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}
  • We present a high-sensitivity technique for time-resolved imaging of millimeter waves (MMWs) using the visible continuum (VC) from the positive column (PC) of a medium-pressure Cs-Xe dc discharge. For the MMW imaging application, a uniform plasma slab of the PC of a Cs-Xe discharge with 10x8 cm{sup 2} aperture and 2 cm in thickness was generated for 45 Torr xenon. The imaging technique is based on the fact that the intensity of the e-Xe bremsstrahlung continuum from the PC increases in the visible region when the electrons in the plasma are heated by MMWs. It is shown that in themore » MMW intensity range from zero to the threshold of the microwave-induced plasma breakdown, the intensity of the VC from the PC of a Cs-Xe discharge increases approximately as a second-order polynomial function of the MMW intensity. The obtained experimental data agree well with our calculations of the dependence of the VC intensity on electron temperature. The Ka-band MMW field patterns at the output of conical horn antennas and in the quasioptical beam were imaged using the discharge technique. It is shown that the technique can be used for time-resolved measurement of the profiles of watt- and subwatt-level MMWs. An energy flux sensitivity of the technique of about 10 {mu}J/cm{sup 2} in the Ka-band was demonstrated. The temporal resolution of the technique is about 0.8 {mu}s. Our modeling of the transient behavior of the electron temperature in the PC shows that the time history of the electron temperature variation coincides well with the measured time history of the VC intensity variation.« less
  • A precise absolute intensity calibration of a flat-field space-resolved extreme ultraviolet (EUV) spectrometer working in wavelength range of 60-400 A is carried out using a new calibration technique based on radial profile measurement of the bremsstrahlung continuum in Large Helical Device. A peaked vertical profile of the EUV bremsstrahlung continuum has been successfully observed in high-density plasmas (n{sub e}{>=} 10{sup 14} cm{sup -3}) with hydrogen ice pellet injection. The absolute calibration can be done by comparing the EUV bremsstrahlung profile with the visible bremsstrahlung profile of which the absolute value has been already calibrated using a standard lamp. The line-integratedmore » profile of measured visible bremsstrahlung continuum is firstly converted into the local emissivity profile by considering a magnetic surface distortion due to the plasma pressure, and the local emissivity profile of EUV bremsstrahlung is secondly calculated by taking into account the electron temperature profile and free-free gaunt factor. The line-integrated profile of the EUV bremsstrahlung continuum is finally calculated from the local emissivity profile in order to compare with measured EUV bremsstrahlung profile. The absolute intensity calibration can be done by comparing measured and calculated EUV bremsstrahlung profiles. The calibration factor is thus obtained as a function of wavelength with excellent accuracy. It is also found in the profile analysis that the grating reflectivity of EUV emissions is constant along the direction perpendicular to the wavelength dispersion. Uncertainties on the calibration factor determined with the present method are discussed including charge-coupled device operation modes.« less
  • The present understanding of critical heat flux (CHF) in subcooled flow boiling with water is reviewed and fusion reactor component high-heat flux (HHF) requirements are outlined. This survey (Parts I and II), which contains a representative coverage of the literature over the last 30 years, is concerned only with CHF in the subcooled flow boiling regime. CHF data base parameter ranges are also given as an aid for fusion component designers in locating the appropriate data for an application. Because of the relatively HHF levels and long pulse durations in the next generation reactors, fusion components must be actively cooled.more » All fusion components are heated nonuniformly over their surface and their surface area ranges from 0.1 to 1000 m/sup 2/. Although most components are subjected to fluxes from about 0.005 kW/cm/sup 2/ (first wall) to near 1 kW/cm/sup 2/ (limiters and divertors), some components are subjected to fluxes from 2 kW/cm/sup 2/ (first wall in compact reactors) to 8 kW/cm/sup 2/ (beam dumps). Subcooled flow boiling has the greatest potential of accommodating the steady-state HHF levels encountered by fusion reactor components. Although the available heat flux data base brackets those for most fusion components, the existing data are sparse or nonexistent for the length-to-diameter ratios (e.g., >200 for limiters and >50 for beam dumps) necessary for future HHF fusion components. There are more than 20 parameters that influence subcooled flow boiling CHF and many other tested techniques that enhance heat transfer by a factor of >2. The engineering implementation and design of fusion components cannot be optimized until the physical relationships between the maximum CHF and both the flow parameters and thermophysical properties have been determined. This can be accomplished only if improvements are made in the understanding of the fundamental mechanisms controlling the heat transfer and CHF in the subcooled flow boiling regime.« less
  • We present experimental results on measuring the emittance of short-pulsed (≤100 μs) high-current (80–100 mA) ion beams of heavy gases (Nitrogen, Argon) formed from a dense plasma of an ECR source of multiply charged ions (MCI) with quasi-gas-dynamic mode of plasma confinement in a magnetic trap of simple mirror configuration. The discharge was created by a high-power (90 kW) pulsed radiation of a 37.5-GHz gyrotron. The normalized emittance of generated ion beams of 100 mA current was (1.2–1.3) π mm mrad (70% of ions in the beams). Comparing these results with those obtained using a cusp magnetic trap, it was concluded thatmore » the structure of the trap magnetic field lines does not exert a decisive influence on the emittance of ion beams in the gas-dynamic ECR source of MCI.« less
  • Interconnected ground systems with hundreds of even thousands of circuit elements are relatively frequent in the electrical industry. If used the common matricial representation of the complete ground circuit, the quality of the solution decreases with the size of the circuit, due to the propagation of the relative error of each circuit element. For very large circuits, all digits of a solution can become non-significant. This paper presents the ''Decoupled Method'' (1), (2), (7), (8), which is a set of procedures allowing the determination of an equivalent circuit generally 10-60 times smaller than the original one. The flow-chart of themore » corresponding computer program is also presented. The reduced size of this equivalent circuit avoids the error propagation and allows even huge ground systems to be studied using microcomputers. A companion paper presents the theoretical justification of some techniques used in this paper, and also shows how the ''Decoupled Method'' was used for studying and detailing important ground facilities of the 1300 MW Itaipu Generation Complex (including four large nearby substations interconnected through ACSR ground-wires of several 500 kV and 220 kV transmission lines). It is shown that field measurements bear out the computed values.« less