Advanced semiconductor switches for EM launchers

Electric launchers of many types for various applications may be energized by switching pulses of variable magnitude and time from a pulsed alternator or a pulse forming network. In order to achieve the desired muzzle energy, the switches must withstand the action of the current pulse: the square of current integrated over time. Because of this requirement, high pressure s park gap switches and vacuum switches of various architectures have been ut ilized in most of the launcher development programs, Recent advances in sem iconductor technology hold a promise of replacing these large and bulky swi tches with solid state switches which may become leading candidates for fut ure combat systems applications. The U.S. Army Research Laboratory has been testing and evaluating solid state snitches of various types for several d ifferent applications. One type of semiconductor switch that was tested and evaluated is a thyrist or that is 125 mm in diameter made by Silicon Power Corporation (SPCO), Whe n a thyristor with this large diameter is turned on, it is necessary. to de velop and spread plasma uniformly and quickly across the wafer. This will e nsure that the current from the anode to the cathode is uniformly distribut ed, and not concentrated in local hot spots where an excessive current dens ity. could cause over heating and damage. This plasma spread can be control led by the design of the gate structure and the triggering technique. These devices had internal gate drivers. Thyristors with different gate structur es were tested and compared, The experimental findings of the turn-on chara cteristics and the maximum current capabilities for each design will be pre sented, The status of futuristic wide band gap semiconductor switch technol ogy will also be reviewed.