High-beta Extended MHD Simulations of Stellarators with Finite Parallel Transport

The nonlinear, extended MHD code NIMROD is employed to simulate high beta stellarator physics. This work concentrates on the dependency of the resulting MHD equilibrium configuration on finite parallel transport processes. In particular, the numerical simulations show that anisotropic heat conduction has a significant effect on the pressure profile in regions with stochastic magnetic fields. As a consequence, the attained stored energy is sensitive to the size of the anisotropy in this region, underscoring that equilibrium beta limits are sensitive to anisotropic transport properties.

The configuration under investigation is an l=2, M=10 torsatron with vacuum rotational transform near unity. Finite-beta plasmas are created using a volumetric heating source and temperature dependent resistivity. Extended MHD simulations are performed to generate steady state solutions that represent 3D equilibria. Due to the presence of finite parallel heat conduction, pressure profiles can exist in regions of magnetic stochasticity. Here, we present results of varying the parallel and perpendicular thermal anisotropy. Preliminary studies with temperature dependent Braginskii conduction closures are also presented.