In a study of the structure of propagation and absorption of waves in the ion cyclotron range of frequencies (ICRF) in stellarator/heliotron devices, the full Ma.xwell equation, formulated as a stationary boundary-value problem, is solved numerically in a straight helical configuration. A cold plasma approximation is employed to obtain the conductivity tensor. The shapes of plasma boundary, vessel wall and antenna can be chosen arbitrarily by using a finite-element method. Two-ion hybrid resonance heating by the fast wave is studied. The wave field solution shows tunnelling across the evanescent layer, formation of the cavity resonance and absorption near the hybrid resonance surface. The dependence of the loading resistance on the axial wave number shows a shift due to the helical pitch. The dependence of the loading resistance and the deposition profile on the plasma parameters is also studied. In Heliotron-E-grade plasmas, the fast wave can propagate into the central region of the plasma and the antenna loading resistance is as large as it is in tokamaks. A model of the modular torsatron ATF is studied and good coupling of the fast wave to the plasma is also predicted in this device.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Condensed Matter Physics