Full-wave Numerical Simulation Of High-frequency Wave Heating In Tokamaks

The method of electromagnetic wave heating magnetic plasma has been widelyused,as an auxiliary, in tokamak type fusion device. The advantage of this method is notonly can continuous heating the plasma without significantly affect the shape but alsoimproving the plasma constraint. While the wave travel through inhomogeneous plasma, itwill encounter the cut off and resonance region. And thus, the electromagnetic wave can’tpropagate to the high density region. Generally, multiple electromagnetic wave mode willexist at the same zone. Thus, when the incident wave in plasma encounters cutoff andresonance, it will convert into another type of wave through mode conversion. Thepresence of the conversion process provides a feasible way for the heating of high-densityplasma region.Under normal circumstances, using the method of full-wave or ray tracing tosimulate the propagation of wave in the plasma. The ray tracing method can’t give thespatial and temporal distribution of electromagnetic wave field while Full wave methodperform better. However, the calculation amount will become very large such as multiplewave couple parametric instability. And thus，make it difficult to be applied in such case.After the expansion of the kinetic wave dielectric tensor through finite Larmor radius，wewill found that the zero-order expression of dielectric tensor of kinetic wave is equal tothe cold plasma approximation’s. Therefore, under the condition of energy conservation inthe direction of perpendicular to the magnetic field, we can add the first-order of kineticwave’s dielectric tensor in FLR approximate to the cold plasma approximation model as acorrection term. It not only can avoid the problem of large amount of calculation of kineticmethod, but also can simulate the phenomenon of kinetic.The main content of this article:1）Expanding the kinetic dielectric tensor to the first order with finite Larmor radius.And adding the he first-order differential operator to the cold plasma model in current ofx-direction under the condition of energy conservation.2）The computational domain is a one-dimensional slab, with PML as it absorbing boundary. Using the FDTD method for solving electromagnetic wave equation and finitedifference algorithm for solving the momentum equation.3）The paper gives the simulation result of perpendicular incidence waves under lowerhybrid frequency and electron circular frequency. And the results were compared with thedispersion relation’s spatial distribution.It was found that the phenomenon of mode conversion is appear after the kineticcorrection which is not generated in the cold plasma approximation.