Wa. Gillespie et al., ELECTRON-ENERGY SPECTRAL MEASUREMENTS IN THE LARGE-SLIPPAGE REGIME, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 358(1-3), 1995, pp. 232-235
Time resolved electron spectra have been measured at FELIX while lasin
g in the 8-30 mu m range. Over this wavelength range the slippage, giv
en by the longitudinal coupling parameter, mu(c) = N lambda/sigma(c),
varies considerably (0.5 < mu(c) < 3). Limit-cycle behaviour, previous
ly observed in optical spectra [1], is also evident in the electron sp
ectra. Efficiencies of up to 1.6% have been measured. In these cases t
he output electron energy distribution has a total width of more than
14%! Also presented are measurements of the electron and optical spect
ra in the case when the electron energy is swept at a rate of 0.3%/mu
s while lasing at 30 mu m.