A current-driven resistive instability and its nonlinear effects in simulations of coaxial helicity injection in a tokamak

Hooper, E. B.; Sovinec, C. R.

doi:10.1063/1.4964292

Title: A current-driven resistive instability and its nonlinear effects in simulations of coaxial helicity injection in a tokamak

Journal Article · Sat Oct 01 00:00:00 EDT 2016 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4964292· OSTI ID:1328138

Hooper, E. B.; Sovinec, C. R.

An instability observed in whole-device, resistive magnetohydrodynamic simulations of the driven phase of coaxial helicity injection in the National Spherical Torus eXperiment is identified as a current-driven resistive mode in an unusual geometry that transiently generates a current sheet. The mode consists of plasma flow velocity and magnetic field eddies in a tube aligned with the magnetic field at the surface of the injected magnetic flux. At low plasma temperatures (~10–20 eV), the mode is benign, but at high temperatures (~100 eV) its amplitude undergoes relaxation oscillations, broadening the layer of injected current and flow at the surface of the injected toroidal flux and background plasma. The poloidal-field structure is affected and the magnetic surface closure is generally prevented while the mode undergoes relaxation oscillations during injection. Furthermore, this study describes the mode and uses linearized numerical computations and an analytic slab model to identify the unstable mode.

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Research Organization:: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Organization:: USDOE

Grant/Contract Number:: AC02-05CH11231; AC52-07NA27344; FC02-05ER54813

OSTI ID:: 1328138

Alternate ID(s):: OSTI ID: 1343838; OSTI ID: 1421100

Report Number(s):: LLNL-JRNL-698022

Journal Information:: Physics of Plasmas, Journal Name: Physics of Plasmas Vol. 23 Journal Issue: 10; ISSN 1070-664X

Publisher:: American Institute of PhysicsCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 4 works

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Cited By (3)

Three-dimensional plasmoid-mediated reconnection and the effect of toroidal guide field in simulations of coaxial helicity injection Ebrahimi, F. Physics of Plasmas, Vol. 26, Issue 9 https://doi.org/10.1063/1.5098482	journal	September 2019
Nonlinear reconnecting edge localized modes in current-carrying plasmas Ebrahimi, F. Physics of Plasmas, Vol. 24, Issue 5 https://doi.org/10.1063/1.4983631	journal	May 2017
Plasma density injection and flow during coaxial helicity injection in a tokamak Hooper, E. B. Physics of Plasmas, Vol. 25, Issue 2 https://doi.org/10.1063/1.5018196	journal	February 2018

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