Breakdown characteristics study of glycerol medium in coaxial pulse forming line

As the glycerol medium has important applications in the pulse forming line, its breakdown characteristics are studied experimentally in a scaled coaxial specimen under different conditions, including electrode surface, magnetic field, bubbles and so on. A thyristor controlled air-core pulse transformer with a maximum output voltage of 500 kV and the rising time of 26 s is built. A coaxial breakdown specimen immersed in pulsed magnetic field with the maximum magnetic field of 1 T is designed. Through the control of thyristors, the breakdown can be limited in the quasi stationary magnetic field. Four coaxial electrodes with the same shape but different surface disposed measures including sanding, wool polishing, metal electroplating and nonmetal electroplating are manufactured. The experimental results show that the breakdown of the glycerol has no polarity; the magnetic field of 1 T has no effect on the breakdown characteristics of the glycerin; different electrodes have significantly different microcosmic morphologies, resulting in the differences between breakdown characteristics of the glycerol, indicating that some kind of electronical process on the electrode surface has much influence on the breakdown; the probability of breakdown in glycerol can be reduced by evacuating the bubbles with large diameters, and the generated tiny bubbles after the breakdown reduce the average breakdown strength of the glycerol.