• C.H. Chen, K.Y. Huang, Y.-C. Huang
  NTHU, Hsinchu
• W.K. Lau, A.P. Lee
  NSRRC, Hsinchu

A THz-pulse-train photoinjector is under construction at the High-energy OPtics and Electronics (HOPE) Lab. at National Tsinghua University, Taiwan. This photoinjector is believed to be useful for generating high-power THz radiation, as well as for driving or loading a plasma-wave accelerator. A THz laser beat wave with full tunability in its beat frequency is employed to induce the emission of the THz electron pulses from the photoinjector. We show in our study that such a photoinjector is capable of generating periodically bunched MeV electrons with a bunching factor larger than 0.1 at THz frequencies for a total amount of 1nC charges in a 10-ps time duration. We will also present a driver laser technology that can tune the electron bunch frequency with ease and help the growth of the high harmonics in the bunching spectrum of accelerated electrons. Experimental progress on this photoinjector will be reported in the conference. The authors gratefully acknowledge funding supports from National Scienc Council under Contract NSC 97-2112-M-007-018 -MY2, National Synchrotron Radiation Research Center under Project 955LRF01N, and National Tsinghua University under Project 98N2534·10¹.

• W.K. Lau, J.H. Chen, J.-Y. Hwang, A.P. Lee, C.C. Liang, T.H. Wu
  NSRRC, Hsinchu
• W.C. Cheng
  National Chiao Tung University, Hsinchu
• N.Y. Huang
  NTHU, Hsinchu

A 25-30 MeV S-band linac system that equipped with thermionic cathode rf gun is being constructed at NSRRC for generation of ultrashort relativistitic electron beam. According to simulation studies, high quality GHz repetition rate electron pulses of about 50 pC as short as few tens fsec can be produced. This injector system will be used as the driver for experiments on fsec head-on inverse Compton scattering X-ray source and high power wake field microwave sources. The progress of our construction work will be presented.