Full-wave simulations of the O-X-B mode conversion scenario in the RFX-mode reversed field pinch device

The possibility of coupling electron Bernstein waves (EBW) to the overdense plasma in RFX-mod has been explored. A frequency of 28 GHz has been chosen due to the plasma parameters and the commercial availability of this frequency. A two dimensional full-wave code has been used to model the O-X-B mode conversion process in which an incident O-mode is first converted to an X-mode and then to an EBW. Parameter studies have been carried out to optimise the mode-conversion efficiency. The maximum conversion efficiency for optimal launching conditions amounts to 56% for a single pass. The vacuum vessel has been included in the full-wave calculations to address the effects of multiple reflections between the vessel wall and the plasma boundary. A significant increase in conversion efficiency is observed as a result.