Direct measurements of the 3D plasma velocity in single-helical-axis RFP plasmas
Abstract
The first local velocity measurements of helical equilibrium plasmas in the Reversed Field Pinch (RFP) Single Helical Axis (SHAx) state using a Charge Exchange Recombination Spectroscopy (CHERS) diagnostic are presented. Measurements show strong axisymmetric and non-axisymmetric flow, with n = 5 components of flow related to the (m,n)=(1,5) dominant magnetic mode on the order of the axisymmetric flow in certain regions of the plasma, as well as significant n > 5 flow. Flow measurements are compared with NIMROD simulations of visco-resistive, single-fluid MHD in toroidal and cylindrical geometries with limited axial periodicity. Both measurements and the simulation with toroidal geometry show stronger inboard flows relative to the outboard flows, which is attributed to the toroidal geometry of the device. In the experiment, the n = 5 component of flow is phase shifted from the reconnection-like flow pattern observed in the single-fluid simulations, possibly due to decoupling of the ion and electron fluids over much of the plasma. Finally, the strength of the helical angular flow shear relative to the critical shear necessary to disrupt nonlinear coupling between tearing modes is calculated around the helical magnetic axis. The shear in the measured flow is on the order of the theoretical critical threshold needed to nonlinearly decouple modes,more »
- Authors:
-
- Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics
- Univ. of Wisconsin, Madison, WI (United States). Dept. of Engineering Physics
- Department of Physics, University of Wisconsin–Madison, Madison, Wisconsin 53706, USA
- Wheaton College, Wheaton, IL (United States). Dept. of Physics
- Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Univ. of Wisconsin, Madison, WI (United States). Dept. of Engineering Physics
- Publication Date:
- Research Org.:
- Univ. of Wisconsin, Madison, WI (United States); Univ. of California, Oakland, CA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- OSTI Identifier:
- 1849043
- Alternate Identifier(s):
- OSTI ID: 1761250
- Grant/Contract Number:
- FC02-05ER54814; FG02-85ER53212; SC0018266; AC02-05CH11231; FC02- 05ER54814
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Physics of Plasmas
- Additional Journal Information:
- Journal Volume: 28; Journal Issue: 1; Journal ID: ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Physics; Plasma confinement; Plasma devices; Charge exchange recombination spectroscopy; Plasma flows; Plasma instabilities; Plasma discharges; Magnetohydrodynamics
Citation Formats
Boguski, J., Nornberg, M. D., Gupta, U., McCollam, K. J., Almagri, A. F., Chapman, B. E., Craig, D., Nishizawa, T., Sarff, J. S., Sovinec, C. R., Terry, P. W., and Xing, Z. A. Direct measurements of the 3D plasma velocity in single-helical-axis RFP plasmas. United States: N. p., 2021.
Web. doi:10.1063/5.0025696.
Boguski, J., Nornberg, M. D., Gupta, U., McCollam, K. J., Almagri, A. F., Chapman, B. E., Craig, D., Nishizawa, T., Sarff, J. S., Sovinec, C. R., Terry, P. W., & Xing, Z. A. Direct measurements of the 3D plasma velocity in single-helical-axis RFP plasmas. United States. https://doi.org/10.1063/5.0025696
Boguski, J., Nornberg, M. D., Gupta, U., McCollam, K. J., Almagri, A. F., Chapman, B. E., Craig, D., Nishizawa, T., Sarff, J. S., Sovinec, C. R., Terry, P. W., and Xing, Z. A. Thu .
"Direct measurements of the 3D plasma velocity in single-helical-axis RFP plasmas". United States. https://doi.org/10.1063/5.0025696. https://www.osti.gov/servlets/purl/1849043.
@article{osti_1849043,
title = {Direct measurements of the 3D plasma velocity in single-helical-axis RFP plasmas},
author = {Boguski, J. and Nornberg, M. D. and Gupta, U. and McCollam, K. J. and Almagri, A. F. and Chapman, B. E. and Craig, D. and Nishizawa, T. and Sarff, J. S. and Sovinec, C. R. and Terry, P. W. and Xing, Z. A.},
abstractNote = {The first local velocity measurements of helical equilibrium plasmas in the Reversed Field Pinch (RFP) Single Helical Axis (SHAx) state using a Charge Exchange Recombination Spectroscopy (CHERS) diagnostic are presented. Measurements show strong axisymmetric and non-axisymmetric flow, with n = 5 components of flow related to the (m,n)=(1,5) dominant magnetic mode on the order of the axisymmetric flow in certain regions of the plasma, as well as significant n > 5 flow. Flow measurements are compared with NIMROD simulations of visco-resistive, single-fluid MHD in toroidal and cylindrical geometries with limited axial periodicity. Both measurements and the simulation with toroidal geometry show stronger inboard flows relative to the outboard flows, which is attributed to the toroidal geometry of the device. In the experiment, the n = 5 component of flow is phase shifted from the reconnection-like flow pattern observed in the single-fluid simulations, possibly due to decoupling of the ion and electron fluids over much of the plasma. Finally, the strength of the helical angular flow shear relative to the critical shear necessary to disrupt nonlinear coupling between tearing modes is calculated around the helical magnetic axis. The shear in the measured flow is on the order of the theoretical critical threshold needed to nonlinearly decouple modes, but the measurement uncertainty in the gradient of the flow is large.},
doi = {10.1063/5.0025696},
journal = {Physics of Plasmas},
number = 1,
volume = 28,
place = {United States},
year = {Thu Jan 21 00:00:00 EST 2021},
month = {Thu Jan 21 00:00:00 EST 2021}
}
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