Study of the 100 fs 10 kA X-band linac

Design and numerical analysis of an X-band femtosecond electron linear accelerator (linac) is presented. We aim to generate a 100 fs (full width at half maxium: FWHM) electron single bunch with more than 1 nC at the X-band femtosecond linac. The simulation of electron dynamics including magnetic pulse compression is carried out by using PARMELA and SUPERFISH. It is found that the 700 ps (tail-to-tail) electron emission from a 150 kV thermionic gun can be bunched and compressed to 100 fs (FWHM) electron single bunch with the charge of 1 nC which gives 10 kA. We plan to use one high power X-band klystron which can supply 60 MW with more than 200 ns pulse duration. The flatness of plateau of the RF pulse should be 0.2% for stable ultrashort bunch generation. The influence of the klystron voltage fluctuation on the accelerating voltage is quantitatively evaluated and the vacuum design is also done. We have confirmed the feasibility of the linac from viewpoints of state-of the-art technologies.