2024 – Shaping dependence of n=2 stability limits and control in FPP-relevant plasmas

Shaping dependence of n=2 stability limits and control in FPP-relevant plasmas

2024 Research Campaign, Steady State and Pulsed Fusion Core

Purpose of Experiment

This experiment will test several hypotheses related to n=2 plasma response and stability in a high beta, advanced tokamak regime: (a) n=2 external kink beta limits have analogous shape dependences to n=1 limits, ie increasing with triangularity while decreasing with squareness, (b) I-coil fields have significantly better coupling to the n=2 plasma kink mode than C-coil fields, (c) passive kinetic stabilization above the no-wall limit works for n=2 modes (as previously shown).

Experimental Approach

We will test these hypotheses by performing controlled plasma shape variations, measuring the plasma response to n=2 I-coil perturbations, and applying n=2 I-coil mode control in high beta, advanced tokamak, FPP-relevant DIII-D discharges. n=1), (d) uncorrected n=2 error field response contributes to rotation braking that weakens both n=1 and n=2 stability, and (e) operational beta limits can be increased with combined C-coil n=1 and I-coil n=2 mode control. Experimental Approach: We will test these hypotheses by performing controlled plasma shape variations, measuring the plasma response to n=2 I-coil perturbations, and applying n=2 I-coil mode control in high beta, advanced tokamak, FPP-relevant DIII-D discharges.