Magnetic Turbulence and Current Drive during Local Helicity Injection

Richner, N. J.; Bodner, G. M.; Bongard, M. W.; Fonck, R. J.; Nornberg, M. D.; Reusch, J. A.

doi:10.1103/PhysRevLett.128.105001

Title: Magnetic Turbulence and Current Drive during Local Helicity Injection

Journal Article · Mon Mar 07 00:00:00 EST 2022 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.128.105001· OSTI ID:1847964

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Magnetic measurements during dc helicity injection tokamak startup indicate Alfvénic turbulence in the injected current streams mediates magnetic relaxation and results in macroscopic plasma current drive. Localization of such activity to the injected current streams, a bias voltage dependence to its onset, and higher-order spectral analysis indicate super-Alfvénic electrons excite instabilities that drive the observed turbulence. Measured fluctuation helicity is consistent with an α-dynamo electromotive force driving net current comparable to the macroscopic equilibrium current density. These results imply new constraints for scaling local helicity injection to larger devices.

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Research Organization:: Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: SC0020402; SC0019008

OSTI ID:: 1847964

Alternate ID(s):: OSTI ID: 1847925

Journal Information:: Physical Review Letters, Journal Name: Physical Review Letters Vol. 128 Journal Issue: 10; ISSN 0031-9007

Publisher:: American Physical SocietyCopyright Statement

Country of Publication:: United States

Language:: English

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