Hyper Jet Focused-Injection Tapered Capillary Plasma Source Concept

The concept of tapered capillary is introduced as a method of injecting focused plasma jet into the breach of bulk-loaded electrothermal-chemical (ETC) launcher. Tapered capillaries will operate in the confined controlled arc regime, and they can provide the advantage of producing focused hyper plasma jets useful for ignition of ETC systems at controlled plasma temperatures and pressures. The concept is also useful for focused implantation of plasma ions on substrates with desired patterns. Such tapered capillaries can inject plasmas at peak kinetic temperatures in the range of 14000-21000 K (~1.2-1.8 eV) and considerable jet pressures of 10-70 MPa for an input discharge current of 20-30 kA over a short pulselength of 100-150 μs. A tapered geometry made of Lexan polycarbonate with 16.8-mm inlet and 8.8-mm outlet radii produces a plasma jet with a plasma temperature of 14253 K (1.23 eV) at a peak bulk velocity of 4.027 km/s with a 10.38-MPa exit pressure, and a total ablated mass of 10.56 mg. Reducing the tapering to 12.6-mm inlet and 6.6-mm outlet radii produces a plasma jet with a plasma temperature of 16382-K (1.411 eV) at a bulk velocity of 4.34 km/s and a total of 23.27-mg ablated mass. Further reduction in the tapering to 8.4-mm inlet and 4.4-mm outlet radii produces a plasma jet with a plasma temperature of 20954 K (1.8 eV) at a bulk velocity of 4.89 km/s with a 70.78-MPa exit pressure, and a total ablated mass of 15.09 mg. 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 2.2 GW/m² for the wider tapers to 6.24 GW/m² for the narrower ones.