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

Title: A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator

Abstract

High power microwave sources at X-Band, delivering 400 to 500 of megawatts for about 400 ns, have been recently developed. These sources can power a microwave undulator with short period and large gap, and can be used in short wavelength FELs reaching the nm region at a beam energy of about 1 GeV. We present here an experiment designed to demonstrate that microwave undulators have the field quality needed for high gain FELs.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
877508
Report Number(s):
SLAC-PUB-11379
TRN: US0601454
DOE Contract Number:
AC02-76SF00515
Resource Type:
Conference
Resource Relation:
Conference: Prepared for 27th International Free Electron Laser Conference (FEL 2005), Stanford, California, 21-26 Aug 2005
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BACKSCATTERING; FREE ELECTRON LASERS; WAVELENGTHS; WIGGLER MAGNETS; Accelerators,ACCPHY, XFEL

Citation Formats

Tantawi, S., Dolgashev, V., Nantista, C., /SLAC, Pellegrini, C., Rosenzweig, J., Travish, G., and /UCLA. A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator. United States: N. p., 2005. Web.
Tantawi, S., Dolgashev, V., Nantista, C., /SLAC, Pellegrini, C., Rosenzweig, J., Travish, G., & /UCLA. A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator. United States.
Tantawi, S., Dolgashev, V., Nantista, C., /SLAC, Pellegrini, C., Rosenzweig, J., Travish, G., and /UCLA. Wed . "A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator". United States. doi:. https://www.osti.gov/servlets/purl/877508.
@article{osti_877508,
title = {A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator},
author = {Tantawi, S. and Dolgashev, V. and Nantista, C. and /SLAC and Pellegrini, C. and Rosenzweig, J. and Travish, G. and /UCLA},
abstractNote = {High power microwave sources at X-Band, delivering 400 to 500 of megawatts for about 400 ns, have been recently developed. These sources can power a microwave undulator with short period and large gap, and can be used in short wavelength FELs reaching the nm region at a beam energy of about 1 GeV. We present here an experiment designed to demonstrate that microwave undulators have the field quality needed for high gain FELs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Dec 14 00:00:00 EST 2005},
month = {Wed Dec 14 00:00:00 EST 2005}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • The LCLS-II at SLAC will feature a 4 GeV CW superconducting (SC) RF linac [1] that can potentially drive a 5th harmonic X-Ray FEL Oscillator (XFELO) to produce fully coherent, 1 MW photon pulses with a 5 meV bandwidth at 14.4 keV [2]. The XFELO output can serve as the input seed signal for a high-gain FEL amplifier employing fs electron beams from the normal conducting SLAC linac, thereby generating coherent, fs x-ray pulses with TW peak powers using a tapered undulator after saturation [3]. Coherent, intense output at several tens of keV will also be feasible if one considersmore » a harmonic generation scheme. Thus, one can potentially reach the 42 keV photon energy required for the MaRIE project [4] by beginning with an XFELO operating at the 3rd harmonic to produce 14.0 keV photons using a 12 GeV SCRF linac, and then subsequently using the high-gain harmonic generation scheme to generate and amplify the 3th harmonic at 42 keV [5]. We report extensive GINGER simulations that determine an optimized parameter set for the combined system.« less
  • The high-gain amplifiers for short wavelength free electron lasers (FELs) such as the LCLS project require a long undulator. The construction of the undulator as well as the FEL operation would become easier if the undulator could be interrupted with drift sections every few gain lengths. We have investigated the influence of such interruption on the FEL performances. Three effects are considered: (i) the diffraction loss, (ii) the phase mismatch and, (iii) the phase smearing due to velocity spread and to dispersion errors. The effect (i) is the loss during the process in which the optical mode in a sectionmore » of the undulator leaves the undulator, propagates through the free space and then re-enters and re-adjusts in the next section. The effect (ii) is the fact that the phase of the optical beam is displaced with respect to the electrons density modulation for optical FEL interaction due to the slippage of the electron beam in the interruption region. The effect (iii) is the fact that electrons velocity spread, emittance, and dispersion due to misalignment of the quadrupoles used for additional focusing lead to a reduction of the bunching factor. We present an approximate analysis of these effects. When applied to the LCLS parameters, we find that the effect (i) is negligible, the effect (ii) gives a condition on the length of the drift section, and the effects (iii) are small, but could be non-negligible if there are sufficient number of interruptions.« less
  • We present measurements and a theoretical analysis of a new method of generating harmonic radiation in a free-electron laser oscillator with a two section undulator in a single optical cavity. To produce coherent harmonic radiation the undulator is arranged so that the downstream undulator section resonance frequency matches a harmonic of the upstream undulator. Both the fundamental and the harmonic optical fields evolve in the same optical cavity and are coupled out with different extraction fractions using a hole in one of the cavity mirrors. We present measurements that show that the optical power at the second and third harmonicmore » can be enhanced by more than an order of magnitude in this fundamental/harmonic configuration. We compare the production of harmonic radiation of a two sectioned fundamental/harmonic undulator with that produced from a FEL operating at its highest efficiency with a step-tapered undulator, where the bunching at the end of the first section is very large. We examine, the dependence of the harmonic power on the intracavity power by adjusting the optical cavity desynchronism, {delta}L. We also examine the evolution of the fundamental and harmonic powers as a function of cavity roundtrip number to evaluate the importance of the small signal gain at the harmonic. We compare our measurements with predictions of a multi-electron numerical model that follows the evolution of fundamental and harmonic power to saturation. This fundamental/harmonic mode, of operation of the FEL may have useful applications in the production of coherent X-ray and VUV radiation, a spectral range where high reflectivity optical cavity mirrors are difficult or impossible to manufacture.« less
  • The Electron Laser Facility (ELF) at LLNL has been used to generate high peak-powers at 140 GHz, extending the operating range of the device from previous experiments at 35 GHz. With 30 watts of input signal, an exponential gain of 21 dB/m and a saturated output power of over 50 MW were measured. Numerical tapering studies indicate that space charge effects were sufficiently large to affect trapping efficiency. Broadband spontaneous emission was observed over a wide range of wiggler fields at frequencies corresponding to FEL resonance. Over 150 MW of spontaneous power was measured near 94 GHz. The results aremore » in good agreement with particle simulation codes. 4 refs., 9 figs.« less