Overview of the electric launch activities at the French-German Research Institute of Saint-Louis (ISL)

An overview of the Research Institute of Saint-Louis (ISL) activities and program on electric guns is presented. Experimental and/or numerical results for the railgun, electrothermal-chemical (ETC) guns, and pulse-forming networks (PFNs) are reported. The ISL railguns are supplied by fast-discharge capacitors and use projectiles provided with metallic brush armatures. Velocities up to about 2000 m/s are reached without any arcing. The 10-MJ distributed energy storage railgun facility PEGASUS has proved to have an overall efficiency over 30%. Velocities of 2300 m/s have been achieved with this facility, the projectile masses ranging from 350 to 650 g. The energy storage of the facility consists of 200 PFN units of 50 kJ equipped with semiconductor switches. The objective of the ETC program is to ignite a high-loading-density solid propellant (SP) with small electrical energy and power. Some recent ISL studies have determined the minimum energy and power levels needed to ignite the powder of a 20-mm, a 60-mm, and a 120-mm gun by means of a plasma. Tests with a 20-mm gun allowed the ignition of an SP with a loading density of 1.3 g/cm/sup 3/. The studies of high-power semiconductor switches have led to the development and construction of a thyristor with a blocking voltage of 11 kV and a crowbar diode with a blocking voltage of 12 kV. A fast semiconductor switch developed by ISL and Asea Brown Bovery Semiconductor Company with a highly interdigitated gate has an excellent turn-on capability with current rates dI/dt>15 kA//spl mu/s. First studies on solid-state opening switches demonstrated the possibility of switching off a current of about 20 kA. A steerable electromagnetic launcher based on pancake coils is studied as an active armor system. The launcher is fed by capacitor modules characterized by peak currents of 120 kA and current rates of about 2.5 kA//spl mu/s. Experimental tests have demonstrated that the trajectory can be selected in the range of /spl plusmn/- 5/spl deg/ with an angle error less than /spl plusmn/0.5/spl deg/. Protection elements are ejected at a velocity of about 245 m/s with an overall efficiency of 25%.