ITER TOKAMAK AND PLANT SYSTEMS, 2016 Credit © ITER Organization,

Tokamak Fusion Theory Program

The Tibbar Plasma Technologies program supported by the DOE Office of Fusion Energy Sciences is a theoretical and computational program related to resistive MHD (magnetohydrodynamic) instabilities in tokamaks in the presence of a resistive wall and feedback control. Control of these instabilities is of vital importance to the operation of ITER because it is known that these instabilities can lead to major disruptions, which can be severely damaging to the device.

The issues currently under study include: (a) Tearing layer effects such as favorable average field line curvature, which can influence the linear stability of the mode and the possibility of real frequencies. Such effects can also effect an important nonlinear phenomenon, the locking to an error field or to the resistive wall, specifically causing the locking to occur to a finite plasma rotation rate; (b) The effect of shaping of the plasma on the resistive plasma – resistive wall modes, and in particular the effect of stabilizability by external control; (c) The self-consistent nonlinear response including the possibility of locking to a finite velocity but also including the effects of stabilization by nonlinear flattening of the current density profile and destabilization by flattening the pressure profile, leading to removing of the stabilizing influences of the favorable average curvature in the tearing mode layers; and (d) the effect of energetic particles on resistive wall tearing modes.

Papers and Presentations

APS Presentation November 2016: “Real frequency tearing modes with parallel dynamics and their effect on locking and resistive wall modes”
Physics of Plasmas January 2018: “Shaping effects on the rotational stabilizability of magnetohydrodynamic modes in the presence of plasma and wall resistivity”
Physics of Plasmas April 2018: “Degenerate variational integrators for magnetic field line flow and guiding center trajectories”
Submitted to “Real frequency tearing layers with parallel dynamics and their effect on locking and resistive wall modes”