Plasma Production by m=0 Standing Helicon Waves

Abstract

m=0 standing helicon waves (SHWs) are used to produce high-density Ar plasmas, of the order of 1013 cm-3, in a bounded cylindrical plasma column. Axial mode number N=1, 3, and 5 (N is the number of half-wavelengths in the plasma column) SHWs are strongly excited for plasma length L=10–26 cm with the rf power Prf≤3.5 kW and external static magnetic field B0=237 G. Hollow and parabolic density profiles that depend on the axial mode of SHW are observed. The standing wave ratio decreases with L, and travelling helicon waves dominate the plasma production for L>26 cm. The measured results are compared with a two-dimensional wave calculation.