The effects of anisotropic pressure on plasma displacement and its deviation from flux surfaces

Abstract

Abstract A significant impact of pressure anisotropy on the plasma displacement associated with ideal Magnetohydrodynamic (MHD) stability is found. A heliotron plasma, such as a large helical device plasma, is analyzed. Simulations are performed using the equilibrium solver Anisotropic Neumann Inverse Moments Equilibrium Code and the ideal MHD stability code TERPSICHORE. Both codes provide a treatment of the pressure anisotropy by the bi-Maxwellian model. The ratio of hot particle pressure to total pressure < β h > / < β > has been scanned over. Other simulation parameters have been chosen such that the simulations represent an experimentally relevant condition with an external, off-axis heating scheme. The radial location of the peak of the plasma displacement of the n = 1, m = 2 mode number has been compared to the radial location of the ι = 0.5 resonant surface. This comparison shows that this difference in location increases monotonically for increasing < β h > / < β > . These results provide insight on the effect of external heating schemes on MHD stability.