NUMERICAL-SIMULATION TO UV COHERENT HARMONIC RADIATION ON HEFEI STORAGE-RING FEL

It is a prospective technical route to generate UV coherent radiation using external high-power laser to pre-bunch ultra-relativistic electr on beam provided by storage ring and then amplifying its harmonic comp onents with the super-radiation method. In this paper, based on the pr imary parameters of Hefei Storage Ring (NSRL) FEL system, firstly we m ade the simulation to the electron beam energy modulation process in a n optical klystron, the simulation parameters include: gamma = 1000, t he relativistic factor of the electron beam; the wavelength and power of the injected external laser are, lambda(s) = 0.353 mu m and 100 MW; the period number and wavelength of the undulators are N-u = 20, and lambda(u) = 7.2 cm (we have the same structure for the modulator and r adiator); and the normalized amplitude of the magnetic held is K = 4.2 . An effective energy modulation can be achieved when the rms energy s pread for the electron beam is less than 10(-4), i.e., sigma(gamma)/ga mma less than or equal to 10(-4). Then density modulation for the ener gy-modulated electron beam in the dispersive section is also simulated . Under the above-mentioned conditions when the dispersive parameter N -d congruent to 76, a good density modulation results can be obtained. Finally, we also give the harmonic super radiation output power compo nents P-3, P-5, P-7 in the radiator section. (C) 1998 Elsevier Science B.V. All rights reserved.