Drift-Ideal MHD Simulations of Flow-Stabilized Z-Pinch Plasmas*

A number of experimental and theoretical studies suggest that the presence of a modest radial shear in the axial plasma flow velocity can provide stabilization of Z-pinch plasmas against the most destructive ideal MHD instabilities (sausage and kink), thereby making the flow stabilized Z-pinch (FSZP) configuration attractive for magnetic fusion energy applications [1]. While radial variations in the plasma flow velocity that occur on the pinch-size scale a can stabilize these large-scale (k~1/a) MHD modes, weaker short-scale drift-wave instabilities that occur on the much smaller gyro-Bohm scale (k~Cs/Wi) are less affected and can act over time to reduce the velocity shear and degrade the confinement. The effects of these drift-type modes as well as standard ideal modes on the stability of the shear-flowed Z-pinch configuration are studied in this work via the numerical simulation of the drift-ideal MHD equations [2] in 2D. The drift-ideal MHD model is an extension of ideal MHD to include finite ion-inertial length/gyrofrequency effects.