A compact, low cost Marx bank for generating capillary discharge plasmas

We describe in detail a low power Compact Marx Bank (CMB) circuit that canprovide 20 kV, 500A pulses of approximately 100–200 ns duration. One applicationis the generation of capillary discharge plasmas of density ≈ 1018 cm3 used in laserplasma accelerators. The CMB is tiggered with a high speed solid state switch andgives a HV output pulse with a ns scale rise time into a 50Ω load (coaxial cable)with < 4 ns voltage jitter. Its small size (10 cm × 25 cm × 5 cm) means that it canbe placed right next to the capillary discharge in the target chamber so avoiding theneed to impedance match. The electrical energy required per discharge is < 1 J andthe CMB can be run at shot repetition rates of >∼ 1 Hz. This low power requirementmeans the circuit can easily be powered by a small lead acid battery and so thereforecan be floated relative to laboratory earth. The CMB is readily scalable and pulses> 45 kV are demonstrated in air discharges