Linear gyrokinetic theory for kinetic magnetohydrodynamic eigenmodes in tokamak plasmas

A two-dimensional (2D) numerical solution method is developed for the recen tly derived linear gyrokinetic system which describes arbitrary wavelength electromagnetic perturbations in tokamak plasmas. The system consists of th e gyrokinetic equation, the gyrokinetic Poisson equation, and the gyrokinet ic moment equation. Since familiar magnetohydrodynamic (MHD) results can be recovered entirely from this gyrokinetic model, and all interesting kineti c effects are intrinsically included, this gyrokinetic system offers an app roach for kinetic MHD phenomena which is more rigorous, self-consistent, an d comprehensive than the previous hybrid models. Meanwhile, drift type micr oinstabilities can be also investigated systematically in this theoretical framework. The linear gyrokinetic equation is solved for the distribution f unction in terms of the perturbed fields by integrating along unperturbed p article orbits. The solution is substituted back into the gyrokinetic momen t equation and the gyrokinetic Poisson equation. When the boundary conditio ns are incorporated, an eigenvalue problem is formed. The resulting numeric al code, KIN-2DEM, is applied to kinetic ballooning modes, internal kink mo des, and toroidal Alfven eigenmodes (TAEs). The numerical results are bench marked against the well-established FULL code [G. Rewoldt, W. M. Tang, and M. S. Chance, Phys. Fluids 25, 480 (1982)], the PEST code [J. Manickam, Nuc l. Fusion 24, 595 (1984)], and the NOVA-K code [C. Z. Cheng, Phys. Rep. 211 , No. 1 (1992)]. More importantly, kinetic effects on MHD modes can be inve stigated nonperturbatively. In particular, the kinetic effects of the backg round plasma on internal kink modes and the hot particle destabilization of TAEs are studied numerically. (C) 1999 American Institute of Physics. [S10 70-664X(99)03806-9].