Electrothermal tapered capillary hyper jet focused-injection plasma source concept

Tapered capillaries operating in the confined controlled arc regime have the advantage of producing focused hyper plasma jets useful for ignition of electrothermal-chemical ETC systems, at peak kinetic temperatures in the range of 14,000-21,000K (∼1.2-1.8eV) and considerable jet pressures of 10-70MPa for input discharge current of 20-30kA over a short pulse length 100-150μs. A tapered geometry made of Lexan polycarbonate with 16.8mm inlet and 8.8mm outlet radii produces a plasma jet with a plasma temperature of 14,253K (1.23eV) at a peak bulk velocity of 4.027km/s with a 10.38MPa exit pressure, and a total ablated mass of 10.56mg. Reducing the tapering to 12.6mm inlet and 6.6mm outlet radii produces a plasma jet with 16,382K (1.411eV) at a bulk velocity of 4.34 km/s with 23.27mg ablated mass. Further reduction in the tapering to 8.4mm inlet and 4.4mm outlet radii produces a plasma jet with 20,954K (1.8eV) at a bulk velocity of 4.89km/s with 70.78MPa exit pressure, and total ablated mass of 15.09mg. The preliminary study shows that the narrow tapering angle produces higher pressure, temperature, velocity and more ablated mass. Radiant heat flux at the taper exit varies from 2.2GW/m² at the wider tapers to 6.24GW/m² for the narrower taper.