Experimental Investigations on the Pulsed Power Switch of a HIRA based UWB System

Abstract

The ultrawideband (UWB) system has been a subject of research in the last few decades due to its utility in various highpower electromagnetic applications. Effectiveness of the UWB system, for the targeted performance, is expressed mainly in terms of the intensity and the frequency spectrum of the radiated field. If the system is simultaneously meant for high-energy output with good pulse repetition rate and jitter then the performance of the source of the UWB system, i.e., the pulsed power system, and in particular, the switch becomes extremely important. This paper presents the work carried out on such a UWB system with focus on the experimental investigations performed on a 50 kV pulsed power system. The switch of the pulsed power system is designed to use various dielectric gases, such as dry Air, N 2 , SF 6 , and a mixture of these gases as the switching media at varying pressures which are above and below atmospheric pressure levels. For gas pressures above the atmospheric pressure level, the relationship between the switch breakdown voltage and the gas pressure as well as between the rise time and the gas pressure have been studied. Rise time performances of the switch for various pure gaseous media have been estimated. Jitter and shot life performance of the switch for N 2 and SF 6 as the switching media have also been studied. Effect of shot life on the switch jitter has been evaluated for N 2 filled switch for a shot life of 10.8 × 10 6 shots. In case of switch filled with subatmospheric pressure SF 6 gas, the rise time as a function of pressure has been characterized up to a voltage level of 45 kV. The Paschen's curve for the subatmospheric pressure levels is also derived from the results.Index Terms-High-power electromagnetics (HPEM), pulsed power system, switch, ultrawideband (UWB).