Action of a static magnetic field on an argon discharge produced by a traveling wave

Abstract

This paper deals with a low-pressure argon microwave discharge (5–100 mTorr), created and sustained by a traveling wave (390 MHz), in the presence of an axial static magnetic field (up to 550 G). First, the propagation characteristics of the wave (wave number, wave collisional damping, radial distribution of the electromagnetic energy) have been computed from the numerical resolution of the dispersion equation. It has been emphasized that the plasma is sustained either by a surface wave, or by a volume wave, according to the electron density and magnetic field values. Second, the electron density, the effective electron-neutral collision frequency ν for momentum transfer, the mean power θ required to maintain an electron in the discharge, and the effective electric field Eeff for the discharge maintaining have been experimentally determined, versus the pressure and the magnetic field. At a fixed pressure, the power required to maintain the discharge decreases as the magnetic field increases. It has been shown that this experimental result is consistent with simple theoretical modeling, describing the decrease of the electron loss by diffusion and recombination on the discharge tube walls.