A compact coaxial gas filled switch

Summary form only given. As we know, the risetime of the output voltage of a pulse power generator is mainly determined by the performance of the main discharge switch. Recently, to calibrate nanosecond pulse voltage dividers, A nanosecond pulse generator with an output voltage of 2–10 kV was constructed. The generator was composed of a DC charging source, a 50 Ohm coaxial cable as a pulse forming line (PFL), a self-breakdown coaxial gas filled switch, a 50 Ohm coaxial cable as pulse transmission line (PTL), and a matched load. The gas filled switch with two plate electrodes was made as compact as possible to reduce the switch inductance. The gap distance of the switch is fixed to be ∼0.5mm and filled with pressurized nitrogen gas. Extensive tests were made to measure the risetime of the output voltage as the filled gas pressure changed from 0.1MPa ∼0.6Mpa. the averaged risetime of the output voltage is ∼14 ns as the switch gas pressure is set to be 0.1MPa, while the risetime is ∼1.5 ns as the gas pressure increased to 0.6MPa. A CCD camera was used to take pictures of the discharge arc between the main electrodes. As the gas pressre is ∼0.1Mpa, only one single discharge channel was observed. While the gas pressure is above 0.5Mpa, the switch usually breaks down in multi-channel mode, which would result in a low switch inductance and a faster risetime of the output voltage.