Timing control of a high voltage pulse deflector to stabilize EUV laser light at the SCSS test accelerator

A high-voltage pulse deflector cuts out a single bunch beam of 1 ns from a long beam pulse of more than 2 μs generated with a single crystal thermionic gun at the SCSS test accelerator. In order to realize a stable EUV laser, we should precisely control the deflector gate timing, which determines a beam arrival time at a 238-MHz pre-buncher cavity. Unfortunately, the deflector timing system was not enough for our requirement in an early stage, because the gate timing drifted due to a temperature change of a timing module. In addition, machine operators of the accelerator often manually had to tune the gate timing for the stable machine operation. To ameliorate this situation, we improved the timing monitor system of the high-voltage pulse passing through the deflector strip line. The detail of the improvements were exchanging an IC in a level converter module to improve a temperature coefficient and replacing a manual delay line with a remote control one. We also introduced a PID control system using the remote control delay line to automatically stabilize the timing. At the result, the stability of the EUV laser is not affected by the deflector gate timing anymore. (author)