Current Limitations In The Magnetically Delayed Vacuum Switch

The magnetically delayed vacuum switch (MDVS) represents a significant improvement--in terms of closure rate, jitter, lifetime, recovery rate, and repetition rate (10 kHz operation lias been demonstrated)--over conventional triggered vacuum gap switches. The maximum current carrying capacity of the MDVS is a function both of injected trigger plasma density and of electrode material selection. Insufficient initial trigger plasma injection results in a transient current interruption shortly after commutation, and transition to a high-loss mode of operation. The power loss associated with this mode results in anode erosion, degradation of switch performance, and a decrease in switch lifetime. High speed imaging techniques have been used to investigate processes associated with current conduction in the MDVS. Results of these studies the high-loss mode is erosion of the plasma density in suggest that the mechanism causing the transition to the mid-gap region. During the transition to the high loss mode, the MDVS appears to exhibit behavior similar to the initial opening phase of a plasma erosion opening switch.