Heuristic closures for numerical simulations of neoclassical tearing modes

Heuristic closures are presented for use in simulations of neoclassical modifications to magnetohydrodynamic phenomenon in tokamaks. The closures capture the dominant physics expected from linear and quasilinear neoclassical instability theory and are computationally easy to implement. Numerical results from the NIMROD [A. H. Glasser, C. R. Sovinec, R. A. Nebel et al., Plasma Phys. Controlled Fusion 41, A747 (1999)] code are shown which demonstrate poloidal flow damping, growth rate reduction due to the neoclassical enhancement of the polarization current, and generation of perturbed bootstrap currents and subsequent generation of a neoclassical tearing mode.