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Measurements and simulation of the radiation build-up process in a prebunched free-electron maser oscillator

Conference ·
OSTI ID:238712
; ;  [1]
  1. Tel-Aviv Univ. (Israel); and others
Numerical studies of the radiation buildup process in a prebunched free-electron maser oscillator (FEM), were carried out at Tel-Aviv University (TAU) and at the University of Maryland (UMD), and compared to the experimental measurements taken on the prebunched beam FEM experiments in TAU. We present measurements of the temporal evolution of radiation excited from noise until a steady-state operation is established. The evolution of the spectral characteristics of the radiation was investigated using the data collected by a fast digitizing scope, which recorded the IF signal obtained from heterodyning the laser radiation with a stable local oscillator. The mode competition process was observed. The experimental results were compared to analytical calculations of the spontaneous emission power and small-signal gain. Nonlinear {open_quote}amplifier{close_quote} simulation codes were employed for calculation of the extraction efficiency and saturation power. Multi-frequency simulations of the mode competition process were carried out using simulation (MALT ID) code, which is based on a space-time one-dimensional model of a free-electron laser oscillator. Conditions for establishment of single-(longitudinal) mode operation were identified and compared to the experimental measurements. Prebunching of the e-beam current permits external interference in the mode competition and coherence build-up process. We found experimentally and confirmed numerically that prebunching can determine the frequency of oscillation if the e-beam is injected with a sufficient bunching power, and shortens the oscillation buildup and coherence establishment time.
Research Organization:
Brookhaven National Lab., Upton, NY (United States)
OSTI ID:
238712
Report Number(s):
BNL--61982-Absts.; CONF-9508156--Absts.; ON: DE96002729
Country of Publication:
United States
Language:
English

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