High-voltage pulser development

This paper highlights the development of a pulse generator that utilizes a single, midplane, triggered spark gap (TSG) to discharge a p ulse-forming network (PFN) into a CS2laser cavity load. The PFN is a four-section line pulser. When charged to 116 kV, it can discharge 300 J in 700 ns, full width half maximum (FWHM). The system operates at 0 to 50 pps. In designing the PFN inductors, the pulse rise time was kept long enough to avoid excessive ringing in the output cables. Such ringing can cause arcing in the cavity or damage to the cables themselves. The PFN capacitors were potted into a coaxial configuration to minimize inductance. As the pulse repetition rate increases or the charge duration decreases, special consideration must be given to design of the midplane TSG voltage grading network to ensure the trigger electrode always stays at some set fraction of the PFN voltage during charge. This paper describes a circuit that makes operation of the grading network independent of frequency and charge duration, within certain limits. Tests were run in synthetic air and in nitrogen to evaluate operating voltage and the amount of jitter and misfire as a function of pressure.