Development of a low jitter synchronization between an ultrashort electron bunch linac and a laser plasma electron accelerator

Research is being conducted for the practical application of laser plasma electron acceleration. We are developing a linear accelerator for producing ultrashort electron bunches as an electron injector to the plasma wave in order to investigate the characteristics of the acceleration scheme. Extremely precise timing control is required for synchronization between electron bunch injection and plasma wave excitation because a typical plasma wavelength is about 10 to 100 fs. An RF master oscillator that generates reference signals has been developed and its noise level has reached -100dB/c at a sideband 10Hz point of the output frequency 5712MHz. We are currently designing an ultrafast laser oscillator based on fiber laser technology. By modulating the cavity length and pump power of the laser oscillator, the optical pulse train is locked in phase with an RF master oscillator within a synchronization accuracy of 10fs or less. The output of the laser oscillator is wavelength-converted and amplified, and then supplied as seed lights for a plasma wave excitation laser and a photocathode drive laser, and hence, the electron generation, electron injection, and plasma wave excitation are precisely synchronized. (author)