Electrothermal-Chemical Plasma Ignition of Gun-Propelling Charges: The Effect of Pulse Length

An experimental investigation was conducted on the effect of plasma pulse length on gun-charge ignition. The investigation began with visualization of open-air, capillary-generated plasma jet flows and concluded with plasma interaction with a JA2 propelling charge in a 25-mm gun chamber. The plasma energy utilized by the capillary was about 1.1 kJ. With plasma pulse lengths of 0.3 and 1 ms, the resultant flow fields observed were profoundly different in several areas of importance. Typically, the longer pulse length produced a narrower flow field with a greater penetration into the air. The luminosity in the flow region also remained much longer, although at lower intensity. In a JA2-packed chamber, the overall luminosity was higher with the 0.3-ms pulse length during the early time; however, ignition/combustion of the propellant was not sustained. With the 1-ms pulse length, at the same level of energy input from the capillary, sustained ignition/combustion was achieved. Results conclude that plasma pulse length is of importance in optimizing a plasma ignition system for effective ignition of a charge system using a minimum amount of plasma energy. The original document contains color images.