First operation of the Los Angeles free-electron laser oscillator

An FEL oscillator has been operated at wavelengths between 9 and 11 (MU)m with a peak intracavity power of about 20 MW and an average output power of 1 kW in 70- (MU)s pulses. The design parameters and operating characteristics are presented. Measurements of spontaneous emission, start-up of oscillations, and signal growth through approx. 9 orders of magnitude to saturation are also presented. The dependence of gain and saturation on cavity length, alignment, beam parameters, and other critical variables are discussed and compared with theory.