Pressure Sensitivity of Emission Intensities and Plasma Voltage for a Planar Magnetron Glow Discharge

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Abstract
A glow discharge device is described which uses a curved magnetic field passing through the surface of a planar cathode in order to trap electrons near the cathode surface and thus obtain stable operation at unusually low pressures. The magnetic field is obtained from a ring-shaped ceramic magnet and a coaxial Co-Sm rare-earth magnet located directly behind the cathode. In Ar, the device operates over the pressure range 6 × 10−4 Torr to over 2.5 Torr with plasma voltage under 420 V. Plasma voltage vs. pressure data for Cu and Al cathodes suggest that several modes of operation occur over this pressure range. Emission intensity vs. pressure data are presented for Ar, Ar+, Cu, Al, continuum background, and some residual-gas band systems.