Dense Hypervelocity Plasma Jets

High velocity dense plasma jets are under continued experimental development for a variety of fusion applications including refueling, disruption mitigation, rotation drive, and magnetized target fusion. The technical goal is to accelerate plasma slugs of density $>10^{17} cm^{-3}$ and total mass $>100$ micrograms to velocities $>200$ km/s. The approach utilizes symmetrical injection of very high density plasma into a coaxial EM accelerator having a tailored cross-section geometry to prevent formation of the blow-by instability. Injected plasma is generated by electrothermal capillary discharges using either cylindrical capillaries or a newer toroidal spark gap arrangement that has worked at pressures as low as $3.5 \times 10^{-6}$ Torr in bench tests. Experimental plasma data will be presented for a complete 32 injector accelerator system recently built for driving rotation in the Maryland MCX experiment which utilizes the cylindrical capillaries, and also for a 50 spark gap test unit currently under construction.