Influence of plasma finite pressure effects on stability of small-scale MHD-modes in a two-turn torsatron

Equilibrium and stability of finite pressure plasma in a two-turn torsatron are numerically and analytically investigated. Using two-dimensional MHD-code the ultimate plasma pressure value in designed ''Uragan-2M'' torsatron is determined. It is shown that under off-current operation the magnetic ''well'' hollow due to finite pressure effects results in stability of ideal small-scale MHD-modes. In this case the maximal β-bar parameter value is defined by plasma filament equilibrium condition and attains 3%. Under conditions of ideal mode stabilization plasma stability relatively to dissipative perturbations build-up, in particular, gravitational-dissipative mode (g-mode) is investigated. A determining role in g-mode destabilization is stated to belong to cubic by plasma pressure components