Rail Heating in a Rapid-Fire Multirail Launcher Powered by a Pulsed MHD Generator

The operation of electromagnetic multirail launchers of solids in the mode of rapid-fire sequential launching of several projectiles has been studied by a combined 2-D and 3-D nonstationary numerical simulation. A Sakhalin type pulsed magnetohydrodynamic generator is used in the calculations as a power supply for the launchers. Launchers with three or five pairs of parallel rails connected into a series electrical circuit are considered. The acceleration of different numbers of projectiles in a burst and for different masses of projectiles is simulated. It has been found that the heating of the rails is a major factor that limits the operation of the launchers in these modes. An essential feature that determines the rate of rail heating is the nonuniform current density distribution over the rail cross section due to the nonstationary diffusion of the magnetic field into the rails. The calculations taking into account the nonstationary distribution of currents in the rails of a multirail launcher have shown that an appropriate choice of the mass of projectiles, their number in a bursts on the order of five projectiles with a firing frequency on the order of 200 Hz, it is possible to accelerate projectiles weighing up to 800 g to velocities 1.8-2.5 km/s without the rails melting.