In this article a novel way of synchronizing two parallel connected sparkgap switches with accuracies of 1–5 ns for high frequency pulsed power applications is described. The circuit design of a synchronized sparkgap switch circuit is discussed. The circuit uses a combination of one master sparkgap and a set of inductor and capacitors to synchronize two sparkgaps and can be controlled via an IGBT switch. Critical issues for circuit design are presented together with analytical calculations and simulations. Experimental verification of the novel topology is carried out in a prototype experimental setup. Results showing nanosecond level of accuracy in synchronization are reported in this paper along with simulations and analysis.

Novel synchronization technique for two parallel connected sparkgap switches.

We report the design and implementation of a reversible, square-pulse generator for triggering spark gaps. It employs coaxial cables for charge-storage and pulse formation, and a thyratron as the switch. The generator has a nominal output voltage 5–30 kV, and a pulse length governed by the cable’s physical length. Two variants are presented: 1) single-stage one consisting of one charged cable that is discharged with a thyratron, 2) two-stage having an inverting circuit that uses a second coaxial cable to reverse the polarity of the pulse produced by the first one. Since the cables employed were wound solenoid-like special insulation was devised to avoid breakdown between adjacent coils in the winding when the pulses propagate along the shields of the cables. The rise-time obtained is mostly dictated by the switching time of the thyratron; with the one we used in the tests, rise-times in the range 30–40 ns were obtained. We present the results obtained in the application of the generator to triggering a Marx generator and a plasma focus.

High voltage trigger-pulse generator for marxes and plasma foci

A design is presented for a reversible, square-pulse generator that employs coaxial cables for charge storage and pulse formation and a thyratron as the switch. The generator has a nominal output voltage of 5-30 kV and a pulse duration determined by the cable's physical length. Two variations are presented: (1) a single-stage one consisting of cable that is charged via its shield on one end and discharged with a thyratron on the opposite end and (2) a two-stage one having an inverting circuit that uses a coaxial cable to reverse the polarity of the pulse. The generator operates with "flying shields," i.e., high-voltage pulses also propagate on the outside of the cables; this calls for a dedicated insulation that avoids breakdown between sections of the cable's shield. The rise time obtained is mostly dictated by the switching time of the thyratron; with the one we used in the tests, rise times in the range of 30-40 ns were obtained. We present the results obtained in the implementation of the generators as well as its application to fire a large Marx generator.

E. Guzman

Papers

Reversible, high-voltage square-wave pulse generator for triggering spark gaps

High voltage trigger-pulse generator for marxes and plasma foci