DEPENDENCE OF THE EMISSION CHARACTERISTICS OF MAGNETIZED SURFACE-WAVEPLASMAS ON THE AZIMUTHAL CONFIGURATION OF THE WAVE-FIELD

A 1D plasma-wave model initially developed for describing a plasma sus tained by a surface wave in the azimuthally symmetric configuration (m =0) was modified for simulating surface waves in the dipolar mode (m = 1). Using this model, it is shown that the maintenance limit for unma gnetized plasmas in the symmetric mode, which, as was previously deter mined, requires that the product of the wave frequency and the plasma radius be smaller than 2 GHz cm, is no longer valid for magnetized pla smas. Comparison of calculated and measured radial distributions of ar gon atoms in a radiative excited state shows that changes observed in this distribution when varying some of the operating conditions can be explained by a switching of the discharge from one mode to the other. Conditions for selection of the mode are derived from considerations on wave propagation and power dissipation along the plasma column. (C) 1997 American Institute of Physics. [S0021-8979(97)03421-X].