Fiber-optic controlled high voltage trigger generator for a ten-stage linear transformer driver module.

Synchronously triggering is one of the challenges in building large-scale linear transformer drivers (LTD). To obtain multiple high voltage trigger pulses with short rise time and low jitter, a compact trigger generator combining DC bias avalanche photoconductive semiconductor switch (PCSS) and spark gap switch is developed by utilizing only one pulse compression stage. A fiber-optic controlled three-electrode field distortion spark gap switch is used as the output switch of the trigger generator, and the PCSS is in parallel with one of the spark gaps. The PCSS has a dark-state resistance of ∼1.8 GΩ, and its jitter is <1 ns with no self-excitation under a bias of 35 kV DC voltage. The tests show that the fiber-optic controlled trigger generator outputs a pulse voltage of ∼100 kV with a 10%-90% rise time of ∼20 ns when it is connected to five 75 Ω coaxial output cables. The total jitter of the trigger generators is <3 ns. Two generators are used to trigger a fast LTD module with ten cavities in series, realizing synchronous discharge of the 230 pieces of spark gap switches in the LTD module.