Abstract :
A series of fast-acting and repetitively operable bimodal gas discharge switches capable of both the initiation and the interruption of high pulse currents at high-voltage levels has been designed, built, and tested. Based on hydrogen thyratron technology, these switches retain most of the characteristics of thyratrons when switching from the open to the closed state. In addition, the interruption of high currents against high source voltages is achieved when an externally generated, pulsed magnetic field is transversely applied to the current by means of a plasma-field interaction region built into the device. The interruption process is rapid (typically requiring less than 10 μs), complete (current is reduced to zero), and permanent (the current in the device does not restrike even when the field pulse terminates). In general, operation at lower voltages allows the interruption of higher currents for a given magnetic field energy. Typical data are the interruption of 1000 A against 15 kV with a field energy of 8 J, and 100 A against 50 kV with a field energy of 33 J. The theory, design, and construction of such switches are described, and the results of various parametric studies are discussed. It is shown that the voltage level of the interruption is the dominant factor affecting both the conduction and interruption characteristics of the device. A unique interaction region geometry that markedly reduces magnetic field energy requirements is described. It is shown that with proper interaction region design, the voltage drop across the switch during conduction is only about 2 percent of the applied voltage for a switch capable of opening against 50 kV. The device is scalable to various voltage and current levels, and has an inherent repetition rate capability of the order of 10 kHz.
