Investigation Of Spark Gap Switch Multi-pulse Operating In The Self-breakdown Mode

Repetitive operation is one of the primary developmental directions of pulse power technology. Water dielectric pulse power modulator has been widely applied because of its merits of high energy storage density, compactness, and capability to drive low impedance high power microwave sources. Research for multi-pulse operation of high power spark gap switch with high current and comprehending its physical properties are the basis to study multi-pulse operation or repetitive operation of water dielectric pulse power modulator. In the thesis, the insulation recovery properties of spark gap switch are investigated through theoretic analyses and numerical calculation, and the influence of gas flow on the insulation recovery of switch is studied experimentally. The results provide a theoretic basis to research the multi-pulse operation of high power spark gap.As the breakdown mechanism is concerned, the influence of rough electrode on the V/p (switch breakdown voltage/gas pressure) curve is analyzed originally using breakdown possibility. The requirements of flat V/p curve are presented, which provides a theoretical basis for controlling and utilizing the curve. With respect to the gas status recovery in the spark gap, the conduction and convection of hot gas are simulated numerically. The decay of residual charge particles is analyzed and simulated also. The main factors affecting the insulation recovery velocity of gas are analyzed and discussed. All analysis and simulations results indicate several methods improving the insulation recovery of spark gap switch: (1) using the gas with good thermal conductivity, such as H2 and SF6; (2) using the gas flow; (3) utilizing the V/p cure; (4) modifying the geometry and size of the electrode; (5) using the gas with good electronegativity, such as SF6.Some experiments on the multi-pulse operation of high power spark gap switch are carried out. The insulation recoveries of switch without and with gas flow are both investigated. A series of multi-pulse experiments are performed at breakdown voltage up to 400kV, peak current up to 30kA with an interval of 5ms, which shows spark gap switch could be obtained good insulation recovery in several milliseconds under the condition of water dielectric pulse power modulator with low load.Finally, the design and the test experiment of a high power matching load are introduced. The load has a steady resistance of 5.82? and a low inductance of 190nH, which is in good agreement with the theory.