Suppression of Tearing Modes by RF Current Condensation

Abstract

Currents driven by rf (radio frequency) waves in the interior of magnetic islands can stabilize deleterious tearing modes in tokamaks. Present analyses of stabilization assume that the local electron acceleration is unaffected by the presence of the island. However, the power deposition and electron acceleration are sensitive to the perturbation of the temperature. The nonlinear feedback on the power deposition in the island increases the temperature perturbation, and can lead to a bifurcation of the solution to the steady-state heat diffusion equation. The combination of the nonlinearly enhanced temperature perturbation with the rf current drive sensitivity to the temperature leads to an rf current condensation effect, which can increase the efficiency of rf current drive stabilization and reduce its sensitivity to radial misalignment of the ray trajectories. The threshold for the effect is in a regime that has been encountered in experiments, and will likely be encountered in ITER.

arXiv comment6 pages, 2 figures

References in corpus (5)

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Cited by in corpus (14)

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• RF current condensation in magnetic islands and associated hysteresis phenomena
• On the stabilisation of locked tearing modes in ITER and other large tokamaks
• RF current condensation in the presence of turbulent enhanced transport
• Generation of Localized Lower-Hybrid Current Drive By Temperature Perturbations
• Disruption Avoidance via RF Current Condensation in Magnetic Islands Produced by Off-Normal Events
• Spectral broadening from turbulence in multiscale lower hybrid current drive simulations
• Two-fluid model of rf current condensation in magnetic islands
• Advanced fuel fusion, phase space engineering, and structure-preserving geometric algorithms
• On the merit of hot ion mode for tearing mode stabilization
• Coupled heat pulse propagation in two fluid plasmas
• Calculating RF current condensation with self-consistent ray-tracing