Two gas switches with low inductance applying to a compact fast Marx generator

Abstract

Firstly, the design and experiments of three-electrode field distortion gas switch and two-electrode gas switch are presented. The switches diameter is 90 mm. The length of three-electrode switch is 75 mm, and the length of two-electrode switch is 62 mm. The effect of variations in the gas pressure, gap, and gas component on self-breakdown voltage of the switches has been experimentally studied. The results showed the relation between self-breakdown voltages and gas pressure (0∼0.3 MPa) was linear. The breakdown voltage of two-electrode rail-gap switch is up to 190 kV. The linear extrapolation self-breakdown voltage will be up to 210 kV with 11.9mm gap and 0.3 MPa SF6 gas. Working voltages of three-electrode switch can be controlled between 90 kV and 200 kV by adjusting gas pressure (relative) from 0 to 0.3 MPa. The testing of the switches inductance by short circuit discharge showed the inductance of two-electrode switch was about 20 nH, and the one of three-electrode switch was about 22 nH. Secondly, on the basis of the switches developed, a six stages compact Marx generator pulsed power source is introduced. Single pulse capacitor's capacitance is 40 nF, and its rated voltage is 100 kV. The Marx generator is charged synchronously with positive and negative current. There are three switches. The first one is triggered gas switch; others are self-breakdown gas switches. The insulation inside the pulsed power source uses SF 6 gas of 0.3 MPa. The pulsed power source's cross section is approximately 0.1 m2, and its length is about 0.5 m. According to circuit simulation results, when charging voltage of capacitors is 95 kV, the output pulse power will be about 10 GW on a 16 Ω load with the pulse width of more than 150 ns and rising time of less than 40 ns.