Temporal and spectral evolution of the high power Terahertz FEL radiation

We report the temporal and spectral evolution of the optical pulse in the high power Terahertz FEL at ISIR, Osaka University. Autocorrelation of the FEL pulses were measured with a Michelson type interferometer and Si bolometers, and the wavelength spectra of the FEL were obtained by Fourier transform of the interferogram. The temporal and spectral distribution of the FEL optical pulse during the exponential amplification were measured by shortening of the macro-pulse duration of the electron beam. (author)