Flattening of the tokamak current profile by a fast magnetic reconnection with implications for the solar corona

Abstract

During tokamak disruptions the profile of the net parallel current is observed to flatten on a time scale that is so fast that it must be due to a fast magnetic reconnection. After a fast magnetic reconnection has broken magnetic surfaces, a single magnetic field line covers an entire volume and not just a magnetic surface. The current profile, given by $K\equiv {\mu }_0{j}_{||}/B$, relaxes to a constant within that volume by Alfvén waves propagating along the chaotic magnetic field lines. The time scale for this relaxation determines the commonly observed disruption phenomena of a current spike and a sudden drop in the plasma internal inductance. An efficient method for studying this relaxation is derived, which allows a better understanding of the information encoded in the current spike and the associated sudden drop in the plasma internal inductance. Implications for coronal heating are also discussed.

arXiv comment4 pages, no figures

References in corpus (4)

• Runaway dynamics in the DT phase of ITER operations in the presence of massive material injection
• Runaway Electron Seed Formation at Reactor-Relevant Temperature
• Particle acceleration and fast magnetic reconnection
• Fast magnetic reconnection and the ideal evolution of a magnetic field

Cited by in corpus (7)

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• Radio Emission of Pulsars. I. Slow Tearing of a Quantizing Magnetic Field
• The rapid destruction of toroidal magnetic surfaces
• Example of exponentially enhanced magnetic reconnection driven by a spatially-bounded and laminar ideal flow
• Magnetic field evolution and reconnection in low resistivity plasmas
• The interaction of the ITER first wall with magnetic perturbations
• Local analysis of fast magnetic reconnection