Pressure and Gas Type Effects on the Plasma Limiter Operation at the S-band

The gas discharge for a plasma limiter is simulated at the S-band (2.86 GHz) microwave with 500 kW peak power in three-dimensions. We employed a standard rectangular waveguide WR284 along with metal pins. In this paper, the influence of radius and gap size of pins and also gas type and pressure on the plasma parameters and the limiter operational characteristics are investigated by the finite element method. The wave equation, electron drift–diffusion equation, and particle transfer equation in plasma are used to characterize the interaction between electromagnetic wave and plasma. The optimization parameters include plasma thickness, S 21 parameter, response time, insertion loss, and flat leakage. Based on these analyses, the plasma limiter operation is optimized with respect to the pin dimensions, gas type, and pressure. The results show that the optimized parameters for the plasma limiter at S-band are 1 mm pin radius and 4 mm gap between pins. Furthermore, Xe gas at pressure 35 torr has best operation for these pins structure. For these parameters, the plasma limiter is able to switch with a fast response time about 1 ns, to the cutoff operation regime. The proposed plasma limiter could cause a sharp drop in the field amplitude of the incident microwave and reduce the transmitted peak power to 2mW, providing proper protection of the radar system electronic equipment against high power microwave (HPM) threats.