Fast Wave Current Drive In Tokamak Plasmas

Theoretical and experimental investigations on advanced tokamak are the main topics for nowadays controlled fusion research. Investigation on fast wave current drive is of great significance for the steady-state operation of the future nuclear fusion reactors and the high-performance operation of the plasmas. In this paper, the propagation of fast waves in the ion-cyclotron range of frequencies, the current drive and the power deposition in plasmas are investigated, some important results are as follows.With respect to the propagation of fast waves, the propagation of fast waves in plasmas is studied by using the geometrical optics approximation, and the ray trajectories are obtained by numerically resolving the ray equations with the hot plasmas dispersion relation under some parameters, Fast waves are launched from the low-field-side with the different launch positions, the different initial parallel wave numbers and the differential launch wave frequencies. It shows that, with the appropriate parameters, fast wave can easily propagate in the plasmas and reach the center position of the plasmas and be reflected near the plasmas edge if the width of the cut-off layer is enough, the wave energy can also be absorbed many times. The wave frequencies and the initial parallel wave numbers are important for the propagation of fast waves, and the position of the cut-off layer and the resonant layer are determined by the wave frequencies and the initial parallel wave numbers. The ranges of fast wave frequencies which can be used to drive the plasmas current is especially narrow, may be between 20 MHz and 120 MHz. the launch positions are also important for the first pass absorption for fast waves. The initial parallel wave numbers may be adjusted if the ray trajectories are departed from the center position of the plasmas.With respect to current drive and power deposition, the relativistic bounce-averaged quasi-linear Fokker-Planck equation including the trapped particles effects and the relativistic effects of the electrons is incorporated into ray-tracing code, by using this equation, the values of the current and the deposited power on the ray trajectories are calculated, the codes have been programmed, and are debugging now, and may be completed for a short time.