Extended magnetohydrodynamic simulations of toroidal fusion plasmas

Project Description

Fusion reactors are prone to harmful instabilities known as neoclassical tearing modes (NTMs), which degrade reactor confinement and frequently give rise to damaging, rapid expulsion of superheated plasma into the reactor wall. Such disruptive events can be particularly damaging and costly in large devices (e.g. ITER, the international fusion facility presently under construction in France). The development of efficient, reliable, and well-understood methods of NTM suppression is thus of great importance. Experimentally, injection of carefully tailored radiofrequency (RF) waves resonant with electron cyclotron motion in the reactor has been shown to drive localized plasma currents which suppress the NTM. However, the requirements for alignment of these currents within the plasma are strict; misaligned current may have no effect on or even destabilize the NTM. The proposed research supports ongoing efforts over the last five years to (a) expand NIMROD’s ability to efficiently simulate experimentally relevant NTM physics, (b) explore the physics imparted to the plasma by RF injection, and (c) develop optimal NTM stabilization strategies through the use of active feedback-controlled RF. Though much progress has been made on each of these fronts, a number of logical “next steps” in the research require greater computational resources than are presently available to us. We believe that our plan to perform a few high-resolution physics studies while exploring methods to improve code performance lays good groundwork for continued progress, and expect that our continued efforts will ultimately enable us to carry out predictive modeling and optimization studies for the ITER device.