Overdense plasma heating in Wendelstein 7-X(W7-X) stellarator

Abstract

High yield nuclear fusion operating in tokamak and stellarator need to heat plasma up to the required temperatures. As the confined plasma is overdensed, the electron cyclotron resonance heating (ECRH) is inefficient due to cut-off layer. A double mode conversion O-SX and finally electron Bernstein waves (EBW) O-SXB, offer an attractive possibility for plasma heating. In this article, a two-step mode conversion process, OXB has been used to examine the influence of critical parameters such as fluctuation amplitude Δnn, ECH frequency (f), poloidal correlation length (λy), magnetic field (B), on the modified transmission function and ultimately increase plasma power for the Wendelstein 7-X(W7-X) stellarator, is studied. Keywords: Overdense plasma, Wendelstein 7-X stellarator, Electron cyclotron resonance heating, O-SX mode conversion, Modified transmission coefficient