Radial variation of excited atom densities in an argon plasma column produced by a microwave surface wave

The radial variations of radiative and metastable atom densities in an argon plasma column produced by a microwave surface wave are obtained. A large variety of radial profiles is observed as a function of wave frequency (300–1000 MHz), gas pressure (50–200 mTorr), tube diameter (17.5–34 mm) and axial magnetic field. The results differ significantly from those reported for the dc positive column, where the radial distributions keep approximately the same J0 Bessel-like profile.