The formation mechanism of the density profile of helicon discharge, which has been a dispute for a long time, is investigated by using a careful self-consistent model. A detailed investigation of the local balance between the source and the loss fluxes reveals how the centrally peaked density profile is generated, despite the strong surface power absorption by the mode-converted Trivelpiece-Gould (TG) wave from the helicon wave, without any assumption of anomalous diffusion. Our results suggest that the flux transport toward the wall balances out the surface source flux by the TG wave, while the plasma core grows by the power of helicon wave deposition, resulting in the centrally peaked density profile. It is also found that the density profile can be controlled successfully to produce centrally peaked, flat, or hollow profiles by adjusting the contribution of the higher axial mode number of the TG wave.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics