Monte Carlo orbit/full wave simulation of ion cyclotron resonance frequency wave damping on resonant ions in tokamaks

Abstract

To investigate the experimentally observed interaction between beam ion species and fast Alfv́n wave (FW), a Monte Carlo code, ORBIT-RF [V. S. Chan, S. C. Chiu, and Y. A. Omelchenko, Phys. Plasmas 9, 501 (2002)], which solves the time-dependent Hamiltonian guiding center drift equations, has been upgraded to incorporate a steady-state neutral beam ion slowing-down distribution, a quasilinear high harmonic radio frequency diffusion operator and the wave fields from the two-dimensional ion cyclotron resonance frequency full wave code (TORIC4) [M. Brambilla, Plasma Phys. Controlled Fusion 41, 1 (1999)]. Comparison of ORBIT-RF simulation of power absorption with fixed amplitudes of FW fields from TORIC4 power absorption calculation, which assumes Maxwellian plasma distributions, attains agreement within a factor of two. The experimentally measured enhanced neutron rate is reproduced to within 30% from ORBIT-RF simulation using a single dominant toroidal and poloidal wave number. © 2005 American Institute of Physics