Full wave simulations of fast wave mode conversion and lower hybrid wave propagation in tokamaks

Publication Type:

Journal Article

Source:

Physics of Plasmas, Volume 11, Issue 5, p.2473 (2004)

Abstract:

Fast wave (FW) studies of mode conversion (MC) processes at the ion-ion
hybrid layer in toroidal plasmas must capture the disparate scales
of the FW and mode converted ion Bernstein and ion cyclotron waves.
Correct modeling of the MC layer requires resolving wavelengths on
the order of $k_\perp \rho_i$ which leads to a scaling of the maximum
poloidal mode number, Mmax , proportional to $1/\rho^* (\rho^* =\rho_i
/L)$. The computational resources needed scale with the number of
radial (Nr), poloidal (Nm), and toroidal (Nphi) elements as Nr*Nm*Nphi.
Two full wave codes, a massively-parallel-processor (MPP) version
of the TORIC-2D finite Larmor radius code [M. Brambilla, Plasma Phys.
Controlled Fusion 41, 1 (1999)] and also an all orders spectral code
AORSA2D [E. F. Jaeger et al., Phys. Plasmas 9, 1873 (2002)], have
been developed which for the first time are capable of achieving
the resolution and speed necessary to address mode conversion phenomena
in full two-dimensional (2-D) toroidal geometry. These codes have
been used in conjunction with theory and experimental data from the
Alcator C-Mod [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]
to gain new understanding into the nature of FWMC in tokamaks. The
massively-parallel-processor version of TORIC is also now capable
of running with sufficient resolution to model planned lower hybrid
range of frequencies experiments in the Alcator C-Mod.