ELECTROTHERMAL PLASMA GUN AS A PELLET INJECTOR

The NCSU electrothermal plasma gun SIRENS has been used to accelerate plastic (Lexan polycarbonate) pellets, to determine the feasibility of the use of electrothermal guns as pellet injectors. The use of an ele ctrothermal gun to inject frozen hydrogenic pellets requires a mechani sm to provide protective shells (sabots) for shielding the pellet from ablation during acceleration into and through the barrel of the gun. The gun has been modified to accommodate acceleration of the plastic p ellets using special acceleration barrels equipped with diagnostics fo r velocity and position of the pellet, and targets to absorb the pelle t's energy on impact. The length of the acceleration path could be var ied between 15 and 45 cm. The discharge energy of the electrothermal g un ranged from 2 to 6 kJ. The pellet velocities have been measured via a set of break wires. Pellet masses were varied between 0.5 and 1.0 g rams. Preliminary results on 0.5 and 1.0 g pellets show that the exit velocity reaches 0.9 km/s at 6 kJ input energy to the source. Higher v elocities of 1.5 and 2.7 km/s have been achieved using 0.5 and 1.0 gm pellets in 30 cm long barrel, without cleaning the barrel between the shots.