Design of a command-triggered plasma opening switch for terawatt applications

Inductive energy storage systems can have high-energy density, leading to smaller, less-expensive systems. The crucial element of an inductive energy storage system is the opening switch. This switch must conduct current while energy is stored in an inductor, then open quickly to transfer this energy to a load. Plasma can perform this function. The plasma opening switch (POS) has been studied for more than two decades. Though advances have been made, success with the conventional plasma opening switch has been limited. The plasma opening switch concept described here has the potential to increase the power achieved with inductive energy storage pulsed-power systems. This system is also command-triggered. Major improvements in performance and command-triggering both require control of the plasma conductor. This paper shows the design of a system that uses magnetic fields to control the plasma. An externally applied magnetic field clears plasma from the transmission line, For maximum power, efficiency, and accurate pulse shaping, the plasma must be cleared from most of the transmission line conductor spacing. The goal of the system described here is to clear more than 60% of the gap. This is much more than present performance levels. This paper discusses the operation of plasma opening switches, and the ways this switch design overcomes some of the limitations. Because of the importance of magnetic field penetration into the plasma, a model for field penetration is presented. The design of a terawatt-level system is shown, and the mechanism to reduce the trigger power is described. Particle-in-cell simulations of the triggered opening are shown.