Plasma wave simulation based on a versatile FEM solver on Alcator C-Mod

A new efficient full wave simulation code of the lower hybrid (LH) wave was developed using the finite element method (FEM). A dielectric tensor consisting of the cold plasma contribution and the electron Landau damping (ELD) was used. The non-trivial problem of introducing non-local hot plasma effects into an FEM solver was addressed by iteratively solving the coupled problem of the Maxwell's equations with the convolution integral. With this approach, the EM problem is numerically sparse, and the computational requirements are reduced significantly compared to spectral domain solvers [1]. The simulation of an Alcator C-Mod scale plasma has been done on a desktop computer, suggesting the possibility of an ITER scale plasma simulation. The algorithm was implemented using a general purpose FEM software, COMSOL Multiphysics, and the simulation results of a Maxwellian tokamak plasma showed good agreement with ray tracing calculations in the strong single pass absorption regime. Integration of a Fokker-Planck calculation for a more realistic non-Maxwellian plasma is underway and initial results show reasonable shift of the power absorption towards the plasma edge [2]. Importantly, the FEM approach allows seamless handling of the core, SOL, and antenna regions. This flexibility has been exploited to address issues of antenna-plasma coupling in the LH and ICRF frequency ranges. Techniques to use the FEM package for this purpose were validated by solving the LH grill antenna coupling problem whose analytic solution is known. The code has been applied to a new Alcator C-Mod ICRF antenna to assess the antenna near field pattern [3]. \\[4pt] [1] J. C. Wright, et. al., Comput. Phys. 4, 545 (2008) \\[0pt] [2] O. Meneghini, et. al., this conference \\[0pt] [3] M. Garrett, et. al., this conference