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Title: A Reduced Resistive Wall Mode Kinetic Stability Model for Disruption Forecasting

Abstract

Kinetic modification of ideal stability theory from stabilizing resonances of mode-particle interaction has had success in explaining resistive wall mode (RWM) stability limits in tokamaks. With the goal of real-time stability forecasting, a reduced kinetic stability model has been implemented in the new Disruption Event Characterization and Forecasting (DECAF) code, which has been written to analyze disruptions in tokamaks. The reduced model incorporates parameterized models for ideal limits on beta, a ratio of plasma pressure to magnetic pressure, which are shown to be in good agreement with DCON code calculations. Increased beta between these ideal limits causes a shift in the unstable region of delta W_K space, where delta W_K is the change in potential energy due to kinetic effects that is solved for by the reduced model, such that it is possible for plasmas to be unstable at intermediate beta but stable at higher beta. Gaussian functions for delta W_K are defined as functions of E cross B frequency and collisionality, with parameters reflecting the experience of the National Spherical Torus Experiment (NSTX). The reduced model was tested on a database of discharges from NSTX and experimentally stable and unstable discharges were separated noticeably on a stability map inmore » E cross B frequency, collisionality space. The reduced model only failed to predict an unstable RWM in 15.6% of cases with an experimentally unstable RWM and performed well on predicting stability for experimentally stable discharges as well.« less

Authors:
; ; ORCiD logo ; ORCiD logo ; ORCiD logo
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
DOE Contract Number:  
AC02-09CH11466
Product Type:
Dataset
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1367870
DOI:
10.11578/1367870

Citation Formats

Berkery, J.W., Sabbagh, S.A., Bell, R.E., Gerhardt, S.P., and LeBlanc, B.P. A Reduced Resistive Wall Mode Kinetic Stability Model for Disruption Forecasting. United States: N. p., 2017. Web. doi:10.11578/1367870.
Berkery, J.W., Sabbagh, S.A., Bell, R.E., Gerhardt, S.P., & LeBlanc, B.P. A Reduced Resistive Wall Mode Kinetic Stability Model for Disruption Forecasting. United States. doi:10.11578/1367870.
Berkery, J.W., Sabbagh, S.A., Bell, R.E., Gerhardt, S.P., and LeBlanc, B.P. 2017. "A Reduced Resistive Wall Mode Kinetic Stability Model for Disruption Forecasting". United States. doi:10.11578/1367870. https://www.osti.gov/servlets/purl/1367870. Pub date:Mon May 01 00:00:00 EDT 2017
@article{osti_1367870,
title = {A Reduced Resistive Wall Mode Kinetic Stability Model for Disruption Forecasting},
author = {Berkery, J.W. and Sabbagh, S.A. and Bell, R.E. and Gerhardt, S.P. and LeBlanc, B.P.},
abstractNote = {Kinetic modification of ideal stability theory from stabilizing resonances of mode-particle interaction has had success in explaining resistive wall mode (RWM) stability limits in tokamaks. With the goal of real-time stability forecasting, a reduced kinetic stability model has been implemented in the new Disruption Event Characterization and Forecasting (DECAF) code, which has been written to analyze disruptions in tokamaks. The reduced model incorporates parameterized models for ideal limits on beta, a ratio of plasma pressure to magnetic pressure, which are shown to be in good agreement with DCON code calculations. Increased beta between these ideal limits causes a shift in the unstable region of delta W_K space, where delta W_K is the change in potential energy due to kinetic effects that is solved for by the reduced model, such that it is possible for plasmas to be unstable at intermediate beta but stable at higher beta. Gaussian functions for delta W_K are defined as functions of E cross B frequency and collisionality, with parameters reflecting the experience of the National Spherical Torus Experiment (NSTX). The reduced model was tested on a database of discharges from NSTX and experimentally stable and unstable discharges were separated noticeably on a stability map in E cross B frequency, collisionality space. The reduced model only failed to predict an unstable RWM in 15.6% of cases with an experimentally unstable RWM and performed well on predicting stability for experimentally stable discharges as well.},
doi = {10.11578/1367870},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2017},
month = {5}
}

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Works referenced in this record:

Simultaneous feedback control of plasma rotation and stored energy on NSTX-U using neoclassical toroidal viscosity and neutral beam injection
journal, May 2017

  • Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.
  • Physics of Plasmas, Vol. 24, Issue 5
  • DOI: 10.1063/1.4976853

    Works referencing / citing this record:

    Simultaneous feedback control of plasma rotation and stored energy on NSTX-U using neoclassical toroidal viscosity and neutral beam injection
    journal, May 2017

    • Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.
    • Physics of Plasmas, Vol. 24, Issue 5
    • DOI: 10.1063/1.4976853