Wave mode conversion and mode transition in very high radio frequency helicon plasma

Abstract

In a very high radio frequency helicon plasma, experimental evidences for a wave mode conversion between the helicon mode and the Trivelpiece-Gould mode (TG mode) are presented. The helicon mode generation was detected when omega <omega(ce)/2 was satisfied, and the helicon mode was converted to the TG mode at the plasma periphery below 140 G. As no more mode conversion to the TG mode occurs above 140 G, the plasma was directly heated by the helicon mode and a subsequent abrupt mode transition occurred. (c) 2006 American Institute of Physics.