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Title: Analysis of Alfven eigenmode destabilization in DIII-D high poloidal β discharges using a Landau closure model

Journal Article · · Nuclear Fusion
ORCiD logo [1]; ORCiD logo [1];  [2];  [3];  [1]; ORCiD logo [4];  [3];  [5];  [4];  [4];  [4];  [3];  [6];  [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ.Carlos III de Madrid, Madrid (Spain)
  3. Chinese Academy of Sciences (CAS), Hefei (China). Inst. of Plasma Physics
  4. General Atomics, San Diego, CA (United States)
  5. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  6. Oak Ridge Associated Univ., Oak Ridge, TN (United States)

Alfvén Eigenmodes are destabilized at the DIII-D pedestal during transient beta drops in high poloidal β discharges with internal transport barriers (ITBs), driven by n = 1 external kink modes, leading to energetic particle losses. There are two different scenarios in the thermal β recovery phase: with bifurcation (two instability branches with different frequencies) or without bifurcation (single instability branch). Here, we use the reduced MHD equations in a full 3D system, coupled with equations of density and parallel velocity moments for the energetic particles as well as the geodesic acoustic wave dynamics, to study the properties of the instabilities observed in the DIII-D high poloidal β discharges and identify the conditions to trigger the bifurcation. The simulations suggest that instabilities with lower frequency in the bifurcation case are ballooning modes driven at the plasma pedestal, while the instability branch with higher frequencies are low n (n < 4) Toroidal Alfvén Eigenmodes nearby the pedestal. The reverse shear region between the middle and plasma periphery in the non-bifurcated case avoids the excitation of ballooning modes at the pedestal, although Toroidal Alfvén Eigenmodes and Reverse Shear Alfvén Eigenmodes are unstable in the reverse shear region. The n = 1 and n = 2 Alfvén Eigenmode activity can be suppressed or minimized if the neutral beam injector (NBI) intensity is lower than the experimental value (βf < 0:03). Finally, in addition, if the beam energy or neutral beam injector voltage is lower than in the experiment (Vth,f/VA0 < 0.2), the resonance between beam and thermal plasma is weaker. The n = 3, 4, 5 and 6 AE activity can't be fully suppressed, although the growth rate and frequency is smaller for an optimized neutral beam injector operation regime. In conclusion, AE activity in high poloidal β discharges can be minimized for optimized NBI operation regimes.

Research Organization:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); General Atomics, San Diego, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Nuclear Energy (NE)
Grant/Contract Number:
AC52-07NA27344; FC02-04ER54698; AC05-00OR22725
OSTI ID:
1502036
Alternate ID(s):
OSTI ID: 1460970; OSTI ID: 1474709
Report Number(s):
LLNL-JRNL-752149; 899851
Journal Information:
Nuclear Fusion, Vol. 58, Issue 7; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 12 works
Citation information provided by
Web of Science

References (59)

Cross-Field Transport by Instabilities and Blobs in a Magnetized Toroidal Plasma journal July 2008
Ellipticity induced Alfvén eigenmodes journal August 1991
MHD instabilities and their effects on plasma confinement in Large Helical Device plasmas journal January 2004
Measurements, modelling and electron cyclotron heating modification of Alfvén eigenmode activity in DIII-D journal April 2009
Gyrokinetic simulation of global and local Alfvén eigenmodes driven by energetic particles in a DIII-D discharge journal January 2013
Excitation of Internal Kink Modes by Trapped Energetic Beam Ions journal March 1984
Effect of magnetic configuration on frequency of NBI-driven Alfvén modes in TJ-II journal October 2014
Mode coupling in a toroidal sharp-boundary plasma. I. Weak-coupling limit journal December 1980
Numerical calculations using the full MHD equations in toroidal geometry journal March 1986
Low-n shear Alfvén spectra in axisymmetric toroidal plasmas journal January 1986
Excitation of Alfvén eigenmodes by low energy beam ions in the DIII-D and JET tokamaks journal May 2008
Steepest-descent moment method for three-dimensional magnetohydrodynamic equilibria journal January 1983
Basic physics of Alfvén instabilities driven by energetic particles in toroidally confined plasmas journal May 2008
Properties of toroidal Alfvén eigenmode in DIII-D plasma journal February 2015
Confinement improvement in the high poloidal beta regime on DIII-D and application to steady-state H-mode on EAST journal May 2017
Alfvén eigenmode and energetic particle research in JT-60U journal September 1998
The effect of the fast-ion profile on Alfvén eigenmode stability journal August 2013
Linearized gyrofluid model of the alpha‐destabilized toroidal Alfvén eigenmode with continuum damping effects journal October 1992
Alpha‐Alfvén local dispersion relation and solutions journal December 1992
Progress towards steady-state operation and real-time control of internal transport barriers in JET journal June 2003
Global Alfvén modes: Theory and experiment* journal July 1993
Measurements and modeling of Alfvén eigenmode induced fast ion transport and loss in DIII-D and ASDEX Upgrade journal May 2011
Alfvén eigenmode stability and fast ion loss in DIII-D and ITER reversed magnetic shear plasmas journal September 2012
Steady state tokamak reactor based on the bootstrap current journal February 1990
Low‐ n stability calculations for three‐dimensional stellarator configurations journal September 1990
Alfvén eigenmode properties and dynamics in the TJ-II stellarator journal November 2012
Kinetic theory of low-frequency Alfvén modes in tokamaks journal November 1996
Development of high poloidal beta, steady-state scenario with ITER-like tungsten divertor on EAST journal June 2017
An investigation of beam driven Alfvén instabilities in the DIII-D tokamak journal September 1991
Progress toward steady-state tokamak operation exploiting the high bootstrap current fraction regime journal June 2016
Stability of Alfvén gap modes in burning plasmas journal June 1992
Establishment of magnetic coordinates for a given magnetic field journal January 1982
Gyrokinetic particle simulations of reversed shear Alfvén eigenmode excited by antenna and fast ions journal November 2010
Recent progress of Alfvén eigenmode experiments using N-NB in JT-60U tokamak journal August 2002
Compatibility of internal transport barrier with steady-state operation in the high bootstrap fraction regime on DIII-D journal November 2015
Compressible linear and nonlinear resistive MHD calculations in toroidal geometry journal February 1990
Stability of alpha particle driven Alfvén eigenmodes in high performance JET DT plasmas journal March 1999
Experimental studies of energetic-ion-driven MHD instabilities in Large Helical Device plasmas journal April 2005
Simulation of Alfvén frequency cascade modes in reversed shear-discharges using a Landau-closure model journal April 2013
Operation at the tokamak equilibrium poloidal beta-limit in TFTR journal August 1992
Reaching High Poloidal Beta at Greenwald Density with Internal Transport Barrier Close to Full Noninductive Current Drive journal August 2001
Excitation of toroidal Alfvén eigenmodes in TFTR journal April 1991
Loss of energetic beam ions during TAE instabilities journal May 1993
Characteristics of Alfvén eigenmodes, burst modes and chirping modes in the Alfvén frequency range driven by negative ion based neutral beam injection in JT-60U journal November 1999
Theoretical Model of Fishbone Oscillations in Magnetically Confined Plasmas journal November 1986
Unified theory of resonant excitation of kinetic ballooning modes by energetic ions and alpha particles in tokamaks journal December 1991
New Alfvén Continuum Gaps and Global Modes Induced by Toroidal Flow journal March 2000
Radial Structure of Alfvén Eigenmodes in the DIII-D Tokamak through Electron-Cyclotron-Emission Measurements journal September 2006
The shear Alfvén continuous spectrum of axisymmetric toroidal equilibria in the large aspect ratio limit journal December 1982
Direct Observation of the Structure of Global Alfvén Eigenmodes in a Tokamak Plasma journal October 1984
Noncircular Triangularity and Ellipticity-Induced Alfvén Eigenmodes Observed in JT-60U journal March 1998
Stability of neutral beam driven TAE modes in DIII-D journal December 1993
Observation of beta-induced Alfvén eigenmodes in the DIII-D tokamak journal August 1993
Internal Alfvén eigenmode observations on DIII-D journal September 2006
Energetic Ion Experiments in DIII-D journal October 2005
Fluid moment models for Landau damping with application to the ion-temperature-gradient instability journal June 1990
Experimental observations of enhanced radial transport of energetic particles with Alfvén eigenmode on the LHD journal September 2006
Stability of alpha particle driven Alfvén eigenmodes in high performance JET DT plasmas journal May 1999
Reaching High Poloidal Beta at Greenwald Density with Internal Transport Barrier Close to Full Noninductive Current Drive text January 2001

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