Power and spectral evolution of a Free Electron Laser oscillator with electron beam energy ramping

Marks, H.S. and Borodin, D. and Lurie, Y. (2021) Power and spectral evolution of a Free Electron Laser oscillator with electron beam energy ramping. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1004: 165376. ISSN 0168-9002

[thumbnail of NIMA EA-FELo___06_04_2021]

Text (NIMA EA-FELo___06_04_2021)
NIMA_EA_FELo_06_04_2021.pdf - Accepted Version
Available under License Creative Commons Attribution Non-commercial No Derivatives.
Download (1MB)

Abstract

This work is focused on experiments showing enhancements in power extraction efficiency and spectral control of a W-band Free Electron Laser oscillator (FELo) using ramping of the electron beam energy. The FELo operates at 1.4 MeV with electron beam currents of 1–2 A with pulse duration 10–20 μs. Changing the beam energy post-laser-saturation of the initially unbunched continuous electron beam changes the phase-space oscillation trajectory between the beam energy and trapping ponderomotive wave. This enables very significant increases in output power with just 2% changes in beam energy, cases of 39%, and 100% are presented. Unlike in previous work a variable delay has been introduced between the start of the electron beam and the ramp in electron beam energy such that the effect can be observed unambiguously despite significant system jitter from shot-to-shot. In addition to increasing radiative efficiency, where desirable this could be used to rapidly modulate the power without a need to modify parameters such as the beam current or resonator out-coupling. This effect is shown to pull the locked longitudinal modes up or down depending on the direction of the ramp allowing fine frequency control and influence over mode-competition and mode-hops. To complement the experiments simulations were run to map the full range of beam-energy-ramping against resonator out-coupling and beam current for the experimental system.

Item Type:

Journal Article

Journal or Publication Title:

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Additional Information:

This is the author’s version of a work that was accepted for publication in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ?-?, ?, 2021 DOI: 10.1016/j.nima.2021.165376

Uncontrolled Keywords:

/dk/atira/pure/subjectarea/asjc/3100/3105

Subjects:

?? electron beam energy rampingfel oscillatorlasing optimizationregenerative amplifierelectron beamselectronsoptimizationphase space methodsresonatorselectron beam energyelectron-beamfree-electron laserslaser oscillatorspowerregenerativer amplifiersfree elec ??

Departments:

Faculty of Science and Technology > Engineering

ID Code:

156841

Deposited By:

ep_importer_pure

Deposited On:

12 Jul 2021 13:45

Refereed?:

Yes

Published?:

Published