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

Allen H Boozer

doi:10.1063/5.0014107

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arXiv · 2005.02285

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

Allen H Boozer

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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 $K\equiv\mu_0j_{||}/B$, relaxes to a constant within that volume by Alfv\'en 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.

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Allen H Boozer. 2020-05-05. Flattening of the tokamak current profile by a fast magnetic reconnection with implications for the solar corona. https://doi.org/10.1063/5.0014107

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