Insulation Improvement Of An All-Solid Pulse Forming Line With Film Dielectric

A pulse forming line (PFL) cascaded in the radial direction by multistage rolled strip line units is put forward. With this method, the dielectric thickness of the rolled strip line unit is decreased. So, the reliability of the PFL under a high voltage will increase. At the same time, the difficulty for rolling the PFL will decrease. The factors affecting the pulse lifetime of the rolled PFL are analyzed by theory and simulation, and two improvement methods are put forward. First, the electric field enhance at the edges of the electrodes of the rolled PFL is so large that corona discharge occurs at these positions. The improvement method is to use the combination dielectric layer combined by corona-resistant polyimide (PI) films and polypropylene (PP) films as the dielectric of the rolled strip line unit. With this method, the normal electric field of the electrode edges is decreased. Besides, the corona resistance of the dielectric layer is much improved because the PI film has a good performance under corona discharge. Second, the positions where the output foils are located are the insulation weakness of the PFL because these positions are discontinuous. The improvement method is to increase the insulation thickness of these positions. A rolled PFL is cascaded by 3 stages of rolled strip lines, which has a charging voltage of 90 kV. According to the lifetime test, the pulse lifetime of the rolled PFL reaches 300 000 pulses, which is 100 times larger than the pulse lifetime of a rolled PFL without the improvement method. Published under license by AIP Publishing.