Study of MHD response of high-beta tokamak plasmas

高ベータトカマクプラズマにおける電磁流体的応答解析

Bierwage, A.; Lauber, P.*

Bierwage, A.; Lauber, P.*

The structure of the continuous spectra of shear Alfven continua and ion sound waves in a high-beta JT-60U tokamak plasma is studied with a linear gyrokinetic code (LIGKA). It is found that increasing the electron temperature relative to that of the ions has a destabilizing effect on ion sound waves at low frequencies (below BAE), but a stabilizing effect at high frequencies (above BAE). Moreover, it is found that the inclusion of (Maxwellian) fast ions gives rise to "hot sound" continua, which have a significant influence on the structure of shear Alfven continua. Implications for a recently proposed Alfven-acoustic self-heating channel for burning tokamak plasmas are discussed. The present linear study lays foundations for nonlinear analyses, that will contribute to a better understanding of energy flows in high-beta fusion experiments (such as JT-60SA) and burning plasmas (DEMO).