MEASUREMENTS OF PLASMA-FLOW VELOCITY IN DC PLASMA JETS USING PERPENDICULAR AND PARALLEL MACH PROBES

A rotating electric probe system has been developed to measure the par ameters of spray plasma jets from a de plasma torch at atmospheric pre ssure. Four different types of unmagnetized single probes have been us ed for the diagnostics of high power-flux plasma-two probes are mutual ly perpendicular ('perpendicular mach probe') and the remaining two ar e oppositely directed to each other ('parallel mach probe')-to measure the plasma flow velocity and density along the axial and radial direc tions of the plasma flame. Near the nozzle exit of a 15 kW plasma torc h, plasma flow velocity, density and electron temperature are measured as similar to 910 m/s, 4 x 10(13) cm(-3) and 4.7 eV, respectively.