Study on resonant electron cyclotron heating by OSXB double mode conversion at the W7-X stellarator

Study Electron Cyclotron Double Mode Conversion in Overdense Plasma

“…We have also presented the same curves for the W7-X parameters in Ref. [7]. Here, we show, for the first time, the normalized resonance EBW frequencies for ω = 10 ω ce harmonics, although in practice higher harmonics may not be used because of technical problems.…”

“…In the resonance layer, the particles are trapped in the potential well of the incident wave field, and the particle wave function is a Gaussian shape, as described by the dispersion relation. Since in the resonance layer the particles absorb energy from the incident wave, one can perceive that the incident wave and the particle wave function have to couple to a Gaussian profile [7].…”

“…Here, the mode conversion efficiency depends on many parameters including the density gradient L n , magnetic field source B 0 , optimum launching angle θ [6]. Moreover, the launching incident EM wave should be rescannable at high harmonics, i.e., at lower harmonics, the process of Landau damping or cold plasma dispersion will happen, but at medium and high harmonics the ECRH heating will occur [7]. Therefore, for optimum heating efficiency, not only we have to use an optimum incident angle but also we have to optimize the harmonics of incident EM waves.…”