Presentation Self-consistent long-time simulation of chirping energetic particle modes and abrupt large events in beam-driven JT-60U tokamak plasmas

ビアワーゲ, アンドレアス

Recurring bursts of chirping Alfven modes as well as so-called Abrupt Large Events (ALE) that were observed in JT-60U tokamak plasmas driven by negative-ion-based neutral beams (N-NB) are reproduced in first-principle simulations performed with an extended version of the hybrid code MEGA. This code simulates the interactions between gyrokinetic fast ions and magnetohydrodynamic (MHD) modes in the presence of a realistic fast ion source and collisions, so that it self-consistently captures dynamics across a wide range of time scales (0.01--100 ms). Detailed comparisons with experimental measurements are performed. On the long time scale (10--100 ms) the simulation reproduces ALEs with the associated avalanche-like transport of fast ions. ALEs are shown to occur when multiple modes with toroidal mode numbers n = 1, 2, 3 are excited to large amplitudes. On the meso time scale (1--10 ms), bursts of chirping modes are reproduced, which are shown to be n = 1 energetic particle modes (EPM). On the short time scale (0.01--0.1 ms), pulsations and phase jumps are reproduced, which we interpret as the result of beating between multiple resonant wave packets.
58th Annual Meeting of the American Physical Society Division of Plasma Physics

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