Tearing Mode Stability of Model Plasmas in NCSX

Predictive simulations of target plasmas for the National Compact Stellarator Experiment (NCSX) were performed as part of the design effort. The resistive stability of these simulated target plasmas was studied using a quasi-cylindrical ' stability code, as has been done with some success for W7-AS plasmas. The plasmas were found to be classically unstable to an m = 2, n = 1 tearing mode during the start-up, but the 2/1 saturated island size in the target equilibrium was small, <2%. Inclusion of neoclassical effects resulted in negligible island sizes throughout.