Radial Emission Profiles for a Hollow Cathode Glow Discharge in an Axial Magnetic Field

Abstract

Spatially resolved emission measurements are used to characterize the changes in plasma structure resulting from the application of an external magnetic field to an Ar hollow cathode plasma. The field is generated by ring-shaped permanent magnets which are coaxial with the cathode. The magnetic field is normal to the cathode surface and thus forms electron traps which reduce the rate of electron transport normal to the cathode surface. At lower lamp pressure, the magnetic field dramatically changes the spatial distribution of the continuum background and Ar ion radiation. Radiation from neutral-atom cathode material also is affected by the field. The magnetic field has less influence at higher pressure where collisional effects are larger.