Tesla transformer for charging water-dielectric pulse forming line

Pulse forming network (PFN) and spiral pulse forming line (PFL) are two effective methods to achieve long pulse. The high power pulse transformer is a very important part in the two methods. This article presents two wildly used types of high voltage pulse transformer, which are air-core pulse transformer and Tesla high power pulse transformer for oil-PFL charging. Neither of them is suitable for water-PFL charging. In order to charge the water-PFL quickly and efficiently, a Tesla pulse transformer with coupling coefficient 0.75 is designed and experimentally investigated. The designed transformer consists of primary windings, secondary windings, inside and outside magnetic cores and so on. The primary windings is made from copper strip fastened by supporting case and the secondary windings is made from copper line, which is wound along a spiral groove on a tapered nylon stick. The formulas for calculating the primary and secondary inductances of the Tesla transformer with open magnetic core are deduced, with which the main parameters of the transformer are calculated theoretically. In addition, the process of the Tesla transformer charging the PFL is simulated through the PSpice software. The transformer is employed to charge spiral water-PFL in a high current electron beam accelerator. When the primary voltage is 50 kV, the transformer can charge the water-PFL to 720 kV with an energy conversion efficiency of 36%. The theoretical and simulated results agree well with the experimental results. The transformer is featured by its compactness, stability and reliability.