Magnetic and velocity fluctuations from nonlinearly coupled tearing modes in the reversed field pinch with and without the reversal surface

Craig, D.; Martin, D.; Den Hartog, D. J.; Nornberg, M. D.; Reusch, J. A.

doi:10.1063/1.4996907

Title: Magnetic and velocity fluctuations from nonlinearly coupled tearing modes in the reversed field pinch with and without the reversal surface

Journal Article · Tue Aug 01 00:00:00 EDT 2017 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4996907· OSTI ID:1474288

Craig, D. ^[1]; Martin, D. ^[1]; Den Hartog, D. J. ^[2];

^[2];

^[2]

Wheaton College, Wheaton, IL (United States)
Univ. of Wisconsin - Madison, Madison, WI (United States)

Here, we investigate the role of poloidal mode number m = 0 fluctuations on m = 1 velocity and magnetic field fluctuations in the Reversed Field Pinch (RFP). Removing the m = 0 resonant surface in the Madison Symmetric Torus (MST), results in suppressed m = 0 activity without a reduction in m = 1 magnetic activity. However, the m = 1 velocity fluctuations and fluctuation-induced mean emf are reduced as m = 0 modes are suppressed. Velocity fluctuations are measured directly using fast Doppler spectroscopy. Similar results are seen in visco-resistive MHD simulation with the DEBS code. An artificial line-averaged velocity diagnostic is developed for DEBS simulations to facilitate direct comparisons with experimental measurements. The sensitivity of the m = 1 velocity fluctuations and corresponding emf to changes in m = 0 mode activity is a feature of tearing modes in the nonlinear regime with a spectrum of interacting modes. These results have implications for RFP sustainment strategies and inform our understanding of the role of magnetic turbulence in astrophysical contexts

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

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

Grant/Contract Number:: FC02-05ER54814

OSTI ID:: 1474288

Alternate ID(s):: OSTI ID: 1373445

Journal Information:: Physics of Plasmas, Vol. 24, Issue 8; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 4 works

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References (18)

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Cited By (1)

Role of resistivity and viscosity in the excitation of stable m = 0 modes during the RFP sawtooth crash Futch, A. M.; Craig, D.; Hesse, R. Physics of Plasmas, Vol. 25, Issue 11 https://doi.org/10.1063/1.5054578	journal	November 2018

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