Production of sheet plasma using a TP-D plasma source

This is a report on a method of sheet plasma production using a TP-D plasma source, which includes a detailed description of the machine. A sheet plasma is a magnetized plasma whose thickness is approximately equal to the mean ion cyclotron diameter. By this method it is possible to produce a steady-state sheet plasma characterized by its large density, high degree of ionization, and high spatial uniformity. The major conditions required for ensuring the proper operation for the machine are (1) to keep the working gas pressure high so far as circumstances permit, (2) to confine the discharge to extending only over the path between the cathode and the rim of the anode slit, (3) to prevent ions attracted to the cathode from concentrating in a limited area of the cathode, and (4) to accumplish coincidence of the central axis of the discharge path through the anode and floating-electrode system and the axis of the magnetic field. In an argon sheet plasma produced by this method, we obtained an electron temperature of about 10 eV and an electron density of the order of 10 12 cm −3 for discharge currents in the range of 5 to 20 A. It has been confirmed that the sheet plasma can be regarded as a very thin boundary-like plasma, in which the plasma space potential is far lower around the midplane of the plasma than on the boundary and a sharp potential well is formed.