Generation of Supersonic Plasma Flow by an Ion Extraction Electrode

Abstract

A concept of ion extraction has been adopted to generate and analyze supersonic plasma flow (M-infinity > 1) in steady state condition. A capacitively coupled plasma (CCP) with weakly magnetic intensity (B = 100 G) was used as a plasma source along the axial direction and a cylindrical electrode was installed to generate negative potential within plasma by depleting ions. Characteristics of ion velocity distribution have been analyzed by equation of energy conservation from depletion ratio of ions within an ion extraction electrode. The normalized velocity (M-infinity = v(i)/C-s) of flowing plasmas was deduced by using a Mach probe (MP) of parallel type using an exponential formula of the ratio of upstream and downstream ion saturation current densities. The first result on the measurement of ion velocity distribution with supersonic plasma flow (M-infinity = similar to 1.1-1.2) is obtained.