15 KW Induction-Coupled Plasma Minitorch
The Minitorch is a high enthalpy facility generating a vertical jet of plasma in a 0.3 m diameter, 1.2 m long test chamber, where pressure can be varied from 30 mbar to atmospheric. The plasma is generated by electrical induction inside a 3 cm diameter uncooled quartz tube. The two-turn inductor is supplied by a high frequency, high voltage, vacuum tube generator (27.12 MHz, 15 kW, 6kV) via a capacitive 4x voltage multiplier and impedance match. A recirculating water system is used to protect the test chamber from plasma heating, as well as to cool the gas extracted from the test chamber by a 190 m3/h vacuum pump. The facility operates normally in the subsonic regime, but by addition of a cooled Laval nozzle a supersonic plasma jet at Mach 2.2 can be obtained. Argon, nitrogen, carbon dioxide, air or other gas mixtures can be used to generate the plasma.
Available instrumentation includes cooled pressure and heat flux probes, Langmuir probes, and a laser Doppler velocimeter that uses a special seeder for plasma velocity measurements. Also the Plasmatron instrumentation (emission spectrometer and two-color pyrometer) can be used in the Minitorch.
The facility is used for instrumentation studies and training, for inductively coupled plasma torch optimization studies, and for comparisons with numerical simulations of inductively coupled plasma flows. Finally, thermal protection material testing, including catalycity determination, can be performed in the Minitorch at lower heat flux levels than in the Plasmatron.