skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Mode rotation control in a tokamak with a feedback-driven biased electrode

Abstract

Rotation of the plasma and MHD modes in tokamaks has been shown to stabilize resistive wall and tearing modes as well as improve confinement through suppression of edge turbulence. In this work, we control mode rotation with a biased electrode inserted into the plasma of the High Beta Tokamak-Extended Pulse’s facility in conjunction with its active GPU (Graphical Processing Unit) feedback system. We first characterize a negative linear relationship between the electrode voltage and mode rotation. Using this relationship, we design, simulate, and implement a proof-of-concept, GPU-based active-control system, which shows consistent success in controlling mode rotation in both feedforward and feedback operation. Controllability is limited by operating conditions, the electrode’s voltage range, and by the electrode’s proximity to the vessel’s walls. The final control system has a 15 μs cycle time, but the addition of various signal filters results in a full cycle latency of 200 μs.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Columbia Univ., New York, NY (United States)
  2. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1512695
Grant/Contract Number:  
FG02-86ER53222; SC0014664
Resource Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 90; Journal Issue: 2; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Brooks, J. W., Stewart, I. G., Boyer, M. D., Levesque, J. P., Mauel, M. E., and Navratil, G. A. Mode rotation control in a tokamak with a feedback-driven biased electrode. United States: N. p., 2019. Web. doi:10.1063/1.5062271.
Brooks, J. W., Stewart, I. G., Boyer, M. D., Levesque, J. P., Mauel, M. E., & Navratil, G. A. Mode rotation control in a tokamak with a feedback-driven biased electrode. United States. doi:10.1063/1.5062271.
Brooks, J. W., Stewart, I. G., Boyer, M. D., Levesque, J. P., Mauel, M. E., and Navratil, G. A. Fri . "Mode rotation control in a tokamak with a feedback-driven biased electrode". United States. doi:10.1063/1.5062271. https://www.osti.gov/servlets/purl/1512695.
@article{osti_1512695,
title = {Mode rotation control in a tokamak with a feedback-driven biased electrode},
author = {Brooks, J. W. and Stewart, I. G. and Boyer, M. D. and Levesque, J. P. and Mauel, M. E. and Navratil, G. A.},
abstractNote = {Rotation of the plasma and MHD modes in tokamaks has been shown to stabilize resistive wall and tearing modes as well as improve confinement through suppression of edge turbulence. In this work, we control mode rotation with a biased electrode inserted into the plasma of the High Beta Tokamak-Extended Pulse’s facility in conjunction with its active GPU (Graphical Processing Unit) feedback system. We first characterize a negative linear relationship between the electrode voltage and mode rotation. Using this relationship, we design, simulate, and implement a proof-of-concept, GPU-based active-control system, which shows consistent success in controlling mode rotation in both feedforward and feedback operation. Controllability is limited by operating conditions, the electrode’s voltage range, and by the electrode’s proximity to the vessel’s walls. The final control system has a 15 μs cycle time, but the addition of various signal filters results in a full cycle latency of 200 μs.},
doi = {10.1063/1.5062271},
journal = {Review of Scientific Instruments},
number = 2,
volume = 90,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share:

Works referenced in this record:

Simultaneous feedback control of plasma rotation and stored energy on the DIII-D tokamak
journal, October 2007


Effect of magnetic islands on the local plasma behavior in a tokamak experiment
journal, September 2002

  • Taylor, E. D.; Cates, C.; Mauel, M. E.
  • Physics of Plasmas, Vol. 9, Issue 9
  • DOI: 10.1063/1.1499715

Improved feedback control of wall stabilized kink modes with different plasma–wall couplings and mode rotation
journal, January 2016


Nondestructive synchronous beam current monitor
journal, December 2014

  • Covo, Michel Kireeff
  • Review of Scientific Instruments, Vol. 85, Issue 12
  • DOI: 10.1063/1.4902903

Controlled Fusion and Plasma Physics
journal, June 2007


Effect of toroidal plasma flow and flow shear on global magnetohydrodynamic MHD modes
journal, June 1995

  • Chu, M. S.; Greene, J. M.; Jensen, T. H.
  • Physics of Plasmas, Vol. 2, Issue 6
  • DOI: 10.1063/1.871247

Modeling and control of plasma rotation for NSTX using neoclassical toroidal viscosity and neutral beam injection
journal, February 2016


A novel approach for mitigating disruptions using biased electrode in Aditya tokamak
journal, June 2014


The high beta tokamak-extended pulse magnetohydrodynamic mode control research program
journal, May 2011


Adaptive control of rotating magnetic perturbations in HBT-EP using GPU processing
journal, June 2013


Dynamics of MHD instabilities near a ferromagnetic wall
journal, September 2018


Tokamak edge plasma rotation in the presence of the biased electrode
journal, February 2013


The interaction between plasma rotation, stochastic fields and tearing mode excitation by external perturbation fields
journal, January 2008


The Experimental Results of MHD Instability Suppression with Electrode Biasing in the HT-7 Tokamak
journal, January 2015


MHD-mode locking by controlled halo-current in the T-10 tokamak
journal, July 2003


Application of benchmarked kinetic resistive wall mode stability codes to ITER, including additional physics
journal, November 2017

  • Berkery, J. W.; Wang, Z. R.; Sabbagh, S. A.
  • Physics of Plasmas, Vol. 24, Issue 11
  • DOI: 10.1063/1.4989503

Understanding Langmuir probe current-voltage characteristics
journal, December 2007

  • Merlino, Robert L.
  • American Journal of Physics, Vol. 75, Issue 12
  • DOI: 10.1119/1.2772282

Real-time measurement and feedback control of ion temperature profile and toroidal rotation using fast CXRS system in JT-60U
journal, December 2009


Effect of electrode biasing on m / n   =  2/1 tearing modes in J-TEXT experiments
journal, September 2016