Effects of nonresonant hot ions with large orbits on Alfvén cascades and on magnetohydrodynamic instabilities in tokamaks

Effects of nonresonant hot ions with large orbits on Alfvén cascades and on magnetohydrodynamic instabilities in tokamaks

Effects of nonresonant hot ions with large orbits on Alfvén cascades and on magnetohydrodynamic instabilities in tokamaks 150 150 Mathew

Effects of nonresonant hot ions with large orbits on Alfvén cascades and on magnetohydrodynamic instabilities in tokamaks

The effects of nonresonating hot ions on the spectrum of magnetohydrodynamic (MHD) waves and instabilities in tokamaks are studied in the limit when the width of the hot ion drift orbits is much larger than the radial scale length of the MHD perturbations. Due to the large magnetic drift velocities the hot ions cannot contribute to the MHD perturbations directly, but two main effects of the hot ions, the hot-ion density-dependent effect and the hot-ion pressure-dependent effect, influence the MHD perturbations indirectly. The physics of both effects is elucidated and it is shown that both these effects can be described in MHD approach. A new code, MISHKA-H (MISHKA including the hot-ion indirect effects), is developed as an extension of the ideal MHD code MISHKA-D [Huysmans et al. , Phys. Plasmas 8 , 4292 (2002)]. Analytical benchmarks for this code are given. Results of the MISHKA-H code on Alfven spectrum in a shear-reversed discharges with ion-cyclotron resonance frequency (ICRF) heating are presented. Modeling of Alfven cascades and their transition into toroidal Alfven eigenmodes in shear-reversed tokamak equilibrium is considered.

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01/05/2004