Design and operation of the electrogun, an electrothermal gun for producing metal and carbon plasma jets

摘要

The electrogun is a type of electrothermal gun especially modified to produce metal and carbon plasma jets. These jets are capable of deep penetration into room temperature, atmospheric-pressure gases, so that the plasma composing the jet is vigorously mixed into an excess of cold gas. Reaction products are rapidly quenched and form a room-temperature gas suspension of nanoparticles which gradually settles to the reactor door. These unusual and extreme conditions are ideal for the production of novel materials, especially novel nanostructured materials. An electrogun with a prestressed ceramic barrel has been tested and found to work well if certain simple rules are followed. Seal failure wastes material and precipitates destructive internal short circuits, so particular care must he paid to seal design. Seams to be sealed must be preloaded tightly together to prevent seam separation. The operating characteristics of titanium, aluminum, and carbon plasma have been measured. Operating with carbon plasma presents special difficulties. Graphite cathodes tend to fracture if overheated. Carbon plasma is prone to contamination by vaporized metal and by vaporized ceramic extracted from the bore.