HIGH-POWER SELF-SIMILAR RADIATION PULSE IN A FREE-ELECTRON LASER

Using 1D short wavelength (8 mu m) Compton free electron laser (FEL) e quations with slippage, we explore propagation of a high power pulse d own a tapered undulator FEL travelling wave amplifier. For an appropri ate taper, a short pulse (similar to 300 fs FWHM) with regular feature s will propagate self-similarly as it grows in power, slipping through a much longer electron pulse. The power spectrum of the pulse is near ly Gaussian with no sidebands. The electron energy is depressed by sim ilar to 33%, but slippage causes the peak pulse intensity to be about the same as the electron beam power density, similar to 10 TW/cm(2).