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

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
Authors:
 [1] ;  [1] ;  [2] ; ORCiD logo [2] ; ORCiD logo [2]
  1. Wheaton College, Wheaton, IL (United States)
  2. Univ. of Wisconsin - Madison, Madison, WI (United States)
Publication Date:
Grant/Contract Number:
FC02-05ER54814
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 8; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Wisconsin - Madison, Madison, WI (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1474288
Alternate Identifier(s):
OSTI ID: 1373445

Craig, D., Martin, D., Den Hartog, D. J., Nornberg, M. D., and Reusch, J. A.. Magnetic and velocity fluctuations from nonlinearly coupled tearing modes in the reversed field pinch with and without the reversal surface. United States: N. p., Web. doi:10.1063/1.4996907.
Craig, D., Martin, D., Den Hartog, D. J., Nornberg, M. D., & Reusch, J. A.. Magnetic and velocity fluctuations from nonlinearly coupled tearing modes in the reversed field pinch with and without the reversal surface. United States. doi:10.1063/1.4996907.
Craig, D., Martin, D., Den Hartog, D. J., Nornberg, M. D., and Reusch, J. A.. 2017. "Magnetic and velocity fluctuations from nonlinearly coupled tearing modes in the reversed field pinch with and without the reversal surface". United States. doi:10.1063/1.4996907. https://www.osti.gov/servlets/purl/1474288.
@article{osti_1474288,
title = {Magnetic and velocity fluctuations from nonlinearly coupled tearing modes in the reversed field pinch with and without the reversal surface},
author = {Craig, D. and Martin, D. and Den Hartog, D. J. and Nornberg, M. D. and Reusch, J. A.},
abstractNote = {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},
doi = {10.1063/1.4996907},
journal = {Physics of Plasmas},
number = 8,
volume = 24,
place = {United States},
year = {2017},
month = {8}
}