Upper limit to the monotonic increasing dependence of the plasma density on the magnetic field in helicon discharges

The line integrated electron density and the ion saturation current are measured for a wide range of the magnetic field including the lower hybrid resonance region in helicon plasmas and the results are compared with the calculated ones based on the particle and power balance. The linear dependence of the magnetic field on the plasma density is not preserved when the magnetic field is higher than its value corresponding to the lower hybrid resonance (B-LH), deviating from the monotonic increasing dependence, as the calculated antenna loading resistance is sharply decreased across B-LH. It has been also observed that oscillations in the ion saturation current sharply increases as B crosses B-LH. (C) 2000 Elsevier Science B.V. All rights reserved.