All-orders spectral calculation of radio-frequency heating in two-dimensional toroidal plasmas

Spectral calculations of radio-frequency (rf) heating in tokamak plasmas ar e extended to two dimensions (2-D) by taking advantage of new computational tools for distributed memory, parallel computers. The integral form of the wave equation is solved in 2-D without any assumption regarding the smalln ess of the ion Larmor radius (rho) relative to the perpendicular wavelength (lambda (perpendicular to)). Results are therefore applicable to all order s in k(perpendicular to)rho, where k(perpendicular to)=2 pi/lambda (perpend icular to). Previous calculations of rf wave propagation and heating in 2-D magnetized plasmas have relied on finite Larmor radius expansions (k(perpe ndicular to)rho <1) and are thus limited to relatively long wavelengths. In this paper, no such assumption is made, and we consider short wavelength p rocesses such as the excitation and absorption of ion Bernstein waves in 2- D with k(perpendicular to)rho >1. Results show that this phenomenon is far more complex than simple one-dimensional plasma models would suggest. Other applications include fully self-consistent 2-D solutions for high-harmonic fast-wave heating in spherical tokamaks. These calculations require the st orage and inversion of a very large, dense matrix, but numerical convergenc e can be improved by writing the plasma current in the laboratory frame of reference. To accurately represent the wave spectrum in this frame, the loc al plasma conductivity is corrected to first order in rho /L, where L is th e equilibrium scale length. This correction is necessary to ensure accuracy in calculating the wave spectrum and hence the fraction of power absorbed by ions and electrons. (C) 2001 American Institute of Physics.