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A 22-stage 4 MV laser-triggered multistage multi-channel switch (LTS) was designed according to the hypothesis that the well-proportioned electrical field distribution is helpful in reducing the jitter of delay. Field distribution in the switch section is regulated by a metal field regulation ring and several gradient rings. In order to reduce the jitter further, a SF6/N2 mixture is chosen as the switching medium. The generalized standard deviation of the self-breakdown voltage and the deviation of the average value from the prediction is less than 4.4% and 13% respectively. Linearity of the self-breakdown voltage is better than 0.95. Triggered by a laser pulse of 35 mJ/3 ns, the delay is about 26 ns at a working voltage of 85%±3% USB (Self-breakdown Voltage). Maximum deviation of delay is less than ±2.5 ns. Jitter is less than 1.5 ns. The delay and jitter decrease with the increase in the working ratio (the ratio of working voltage to USB), pressure or voltage.

A high precision laser trigger system is built up in the single test module of Primary Test Stand (PTS) facility. A fourth harmonic, with a wavelength λ of 266 nm, Q-switched Nd:YAG laser was used to trigger the 5 MV multi-gap multi-channel gas switch which was filled with high pressure SF6-N2 mixture gas. The maximum deviation and the standard deviation in the jitter time of the trigger system is ± 0.7 ns and 0.3 ns respectively. The maximum deviation and the standard deviation in the jitter time for the multi-gap multi-channel laser triggering switch is ± 2.4 ns and 1.5 ns respectively. The curve of switch delay-time versus laser energy is obtained, which is helpful for the choice of fitting laser energy. The successful test with two lasers indicated that the design of using twenty-four lasers to trigger twenty-four switches respectively is feasible in ``PTS''.

A new type of surface flashover switch, suitable for multiplex pulse generation, is studied. The switch is composed of several parallel rail gaps (PRGs). Each multistage PRG is composed of several serial subgroup gaps (SSG) formed by intermediate electrodes. The trigger electrode of the switch is a common electrode isolated from the main discharge circuit and located parallel to the central line of PRGs. The multistage scheme of PRG is helpful to multi-channel discharge. The switch has some advantages, such as a low jitter, low conduct inductance and short switching time. These advantages and the multiplex scheme make the switch suitable for short frontal rising time pulse formation and accurate synchronization for a multi-module parallel operation device. In a primary test, the jitter of the switch is about 3.3 ns. It has been applied in a linear transformer device successfully.