English

Linear stability of the ITER 15 MA scenario against the alpha fishbone

Plasma Physics 2020-08-26 v1

Abstract

The stability of the n=m=1n=m=1 alpha-fishbone kinetic-MHD mode on the ITER 15 MA baseline scenario \cite{ITERB} is analyzed using the nonlinear hybrid Kinetic-MHD code XTOR-K. Quantitative agreement is found between the complex frequencies ω+iγ\omega + i\gamma computed with the linear model in \cite{Brochard2018} and XTOR-K's linear simulations. Identical precessional resonance positions in phase space are also found between the linear model and XTOR-K. Linear hybrid simulations performed with XTOR-K on the ITER 15 MA scenario reveal that this configuration is likely to be unstable against the alpha fishbone mode. The fishbone thresholds for kinetic-MHD equilibria with flat q profiles with on-axis safety factor just below unity lies between βα,thres/βtot=610%\beta_{\alpha,thres}/\beta_{tot} = 6-10\%, whereas the expected beta ratio on ITER is βα/βtot=1520%\beta_{\alpha}/\beta_{tot} = 15-20\% \cite{ITERB}.

Keywords

Cite

@article{arxiv.2002.02191,
  title  = {Linear stability of the ITER 15 MA scenario against the alpha fishbone},
  author = {G. Brochard and R. Dumont and H. Lütjens and X. Garbet},
  journal= {arXiv preprint arXiv:2002.02191},
  year   = {2020}
}

Comments

22 pages, 12 figures, submitted to Nuclear Fusion