Recent progress in TAE stability analysis in tokamak plasmas
- Princeton Plasma Physics Lab., NJ (United States); and others
A critical issue for tokamak reactors is whether the fusion alpha particles can excite MHD instabilities, such as the Toroidal Alfven Eigenmodes (TAE). Substantial progress has been made recently in understanding the stability of TAE driven by energetic particles in tokamak plasmas. In this work, we present results of stability calculations using the kinetic-MHD NOVA-K code for several tokamak experiments, including TFTR DT experiments, JT-60 ICRF experiments, and DIII-D NBI experiments. Work is in progress to assess the damping mechanisms in JET antenna-driven TAE experiments. Our physics model includes the finite orbit width effects of energetic particles, the electron and ion Landau damping, the collisional damping, and the radiative damping. The main results are: (a) In TFTR DT experiments, TAE modes axe calculated to be stable, consistent with the experimental observations. The main damping mechanisms are the beam ion Landau damping and the radiative damping. The core localized TAE modes are predicted to be driven unstable by alpha particles for weakly reversed shear profiles; (b) In JT-60U ICRF experiments, TAE modes are destabilized by fast minority ions powered by the ICRF heating. The stability of TAE modes are strongly dependent on the mode location. This results in sequential excitation of high-n TAE modes as the central q drops in time. The effects of finite banana width of fast ions are essential. The radiative damping is found to be the dominating stabilizing mechanism. The calculated threshold is somewhat lower than the estimated experimental value. This indicates that the continuum damping might play a role. (c) In DIII-D NBI experiments, TAE modes are destabilized by energetic beam ions. The main damping mechanism comes from the radiative damping. The calculated stability threshold agrees reasonably well with the experimental observations. The implications of these results for ITER will be discussed.
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 489518
- Report Number(s):
- CONF-960354--
- Country of Publication:
- United States
- Language:
- English
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