[Table of Contents]

Plasma and Fusion Research

Volume 9, 3403068 (2014)

Regular Articles


Large-Scale Simulation of Energetic Particle Driven Magnetohydrodynamic Instabilities in ITER Plasmas
Yasushi TODO1,2) and Andreas BIERWAGE3)
1)
National Institute for Fusion Science, Toki 509-5292, Japan
2)
The Graduate University for Advanced Studies (SOKENDAI), Toki 509-5292, Japan
3)
Japan Atomic Energy Agency, Rokkasho 039-3212, Japan
(Received 10 December 2013 / Accepted 13 March 2014 / Published 10 June 2014)

Abstract

Magnetohydrodynamic (MHD) instabilities driven by energetic alpha particles and beam deuterium particles are investigated for ITER operation scenarios using a hybrid simulation code for energetic particles interacting with an MHD fluid. The particle simulation method with finite Larmor radius effects is applied to both alpha and beam deuterium particles. For the steady-state scenario with 9 MA plasma current, beta-induced Alfvén eigenmodes (BAE modes) with low toroidal mode number (n = 3, 5) were found to become dominant in the nonlinear phase although many toroidal Alfvén eigenmodes (TAE modes) with n ∼ 15 are most unstable in the linear phase. The redistribution of energetic particles with δβα ∼ δβbeam ∼ 0.07%, which respectively correspond to 6% and 8% of the central values, occurs in the nonlinear phase. When the toroidal mode number of the fluctuations is restricted to n ≤ 8, the redistribution is substantially reduced, thus, suggesting that the resonance overlap between the n ∼ 15 TAE and low-n BAE modes enhances the energetic particle transport in the run with full toroidal mode numbers. For the ITER scenario with 15 MA plasma current, an MHD instability with n = 3 that peaks around the q = 1 (q is the safety factor) magnetic surfaces is driven by bulk plasma current and bulk pressure, and results in significant redistribution of alpha particles with δβα ∼ 0.3%. For the equilibrium profile with the safety factor profile uniformly raised by 0.1 to remove the q = 1 surfaces, only a benign MHD instability occurs and the energetic particle transport is negligible.


Keywords

ITER, Alfvén eigenmode, MHD instability, alpha particle, beam ion

DOI: 10.1585/pfr.9.3403068


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This paper may be cited as follows:

Yasushi TODO and Andreas BIERWAGE, Plasma Fusion Res. 9, 3403068 (2014).