Experimental investigation of a small bore plasma armature rail launcher at high current densities

This paper presents experimental results obtained with a small bore (/spl phi/6 mm) plasma armature rail launcher with electrothermal preacceleration. Special attention is focused on rail and insulator ablation for high rail line current densities (up to 100 kA/mm). The measurements indicate that most of the ablated rail material enters the plasma armature in liquid state. Secondary arcing occurred during all experiments and was identified to be the most substantial loss mechanism. Typically the momentum efficiency of the propulsive arcs was in the range of 80%, showing that viscous and ablation drag, which are often stated to be severe velocity limiting effects, may be neglected in the velocity range up to 5 km/s.>