A 2.5-MV subnanosecond pulser with laser-triggered spark gap for the generation of high-brightness electron bunches

Generation of ultra-short high-brightness electron bunches, suitable for injection into single-pass free electron lasers or laser wakefield accelerators, requires accelerating fields >1GV/m. To generate such fields, a 2.5-MV subnanosecond pulser was built and tested. The pulser is based on a Tesla transformer with an output voltage of up to 2.5 MV. The output pulse is transferred through a laser-triggered spark gap to a pulse-forming line. The spark gap is triggered using a 5-ns (frequency doubled Nd:Yag) laser pulse, resulting in a jitter of 5 ns at the end of the line. The pulse-forming line after the Tesla transformer was tuned to allow accurate shaping of the pulse. The output pulse of the system has a duration of 1 ns and a risetime of approximately 150ps. The output voltage can be varied and a maximum pulse height of 2.4 MV was achieved.