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P: Fachverband Plasmaphysik

P 7: Helmholtz Graduate School III

P 7.2: Vortrag

Mittwoch, 1. September 2021, 14:25–14:50, H4

First results for stellarator simulations with JOREK — •Nikita Nikulsin¹, Rohan Ramasamy¹, Matthias Hoelzl¹, Alessandro Zocco², Karl Lackner¹, and Sibylle Guenter¹ — ¹Max Planck Institute for Plasma Physics, 85748 Garching, Germany — ²Max Planck Institute for Plasma Physics, 17491 Greifswald, Germany

The JOREK code has recently been extended to allow nonlinear fully 3D stellarator simulations. This is made possible by generalizing the JOREK reduced MHD model to support stellarator geometries, and by allowing the grid to be non-axisymmetric, so that it can be aligned to the flux surfaces in a stellarator.

The models differ mainly in that the magnetic field can be represented as any curl-free field plus a perturbation in the stellarator model, whereas in the tokamak model it is a toroidal field plus a perturbation. We implement the curl-free field as a gradient of a Dommaschk potential, which in turn is calculated from the vacuum magnetic field as given by the EXTENDER code. In order to run a stellarator simulation, we must initialize the reduced MHD variables using the data from the GVEC equilibrium code.

Finally, we present the very first stellarator simulation results. While force balance is not satisfied exactly in stellarator reduced MHD, we show the error to be small. For stable plasmas, a barely noticeable shift is seen, after which equilibrium is restored and persists for thousands of Alfvén times. We also simulate unstable plasmas and benchmark the growth rates against the linear MHD code CASTOR3D.