DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Hybrid simulations of sub-cyclotron compressional and global Alfvén eigenmode stability in spherical tokamaks

Abstract

A comprehensive numerical study has been conducted in order to investigate the stability of beam-driven, sub-cyclotron-frequency compressional Alfvén eigenmodes (CAEs) and global Alfvén eigenmodes (GAEs) in low-aspect-ratio plasmas for a wide range of beam parameters. The presence of CAEs and GAEs has previously been linked to anomalous electron temperature profile flattening at high beam powers in NSTX experiments, prompting a further examination of the conditions necessary for their excitation. Linear simulations have been performed with the hybrid MHD–kinetic initial value code HYM in order to capture the general Doppler-shifted cyclotron resonance that drives the modes. Additionally, three distinct types of modes were found in the simulations—co-CAEs, cntr-GAEs, and co-GAEs—with differing spectral and stability properties. The simulations revealed that unstable GAEs are more ubiquitous than unstable CAEs, which is consistent with experimental observations, as they are excited at lower beam energies and generally have larger growth rates. Local analytic theory is used to explain key features of the simulation results, including the preferential excitation of different modes based on beam injection geometry and the growth rate dependence on the beam injection velocity, critical velocity, and degree of velocity space anisotropy. The background damping rate is inferred from the simulations and analyticallymore » estimated for relevant sources absent from the simulation model, indicating that co-CAEs are closer to marginal stability than modes driven by the cyclotron resonances.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2]
  1. Univ. of California, Irvine, CA (United States); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1808310
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 61; Journal Issue: 8; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Lestz, J. B., Belova, E. V., and Gorelenkov, N. N. Hybrid simulations of sub-cyclotron compressional and global Alfvén eigenmode stability in spherical tokamaks. United States: N. p., 2021. Web. doi:10.1088/1741-4326/abf028.
Lestz, J. B., Belova, E. V., & Gorelenkov, N. N. Hybrid simulations of sub-cyclotron compressional and global Alfvén eigenmode stability in spherical tokamaks. United States. https://doi.org/10.1088/1741-4326/abf028
Lestz, J. B., Belova, E. V., and Gorelenkov, N. N. Tue . "Hybrid simulations of sub-cyclotron compressional and global Alfvén eigenmode stability in spherical tokamaks". United States. https://doi.org/10.1088/1741-4326/abf028. https://www.osti.gov/servlets/purl/1808310.
@article{osti_1808310,
title = {Hybrid simulations of sub-cyclotron compressional and global Alfvén eigenmode stability in spherical tokamaks},
author = {Lestz, J. B. and Belova, E. V. and Gorelenkov, N. N.},
abstractNote = {A comprehensive numerical study has been conducted in order to investigate the stability of beam-driven, sub-cyclotron-frequency compressional Alfvén eigenmodes (CAEs) and global Alfvén eigenmodes (GAEs) in low-aspect-ratio plasmas for a wide range of beam parameters. The presence of CAEs and GAEs has previously been linked to anomalous electron temperature profile flattening at high beam powers in NSTX experiments, prompting a further examination of the conditions necessary for their excitation. Linear simulations have been performed with the hybrid MHD–kinetic initial value code HYM in order to capture the general Doppler-shifted cyclotron resonance that drives the modes. Additionally, three distinct types of modes were found in the simulations—co-CAEs, cntr-GAEs, and co-GAEs—with differing spectral and stability properties. The simulations revealed that unstable GAEs are more ubiquitous than unstable CAEs, which is consistent with experimental observations, as they are excited at lower beam energies and generally have larger growth rates. Local analytic theory is used to explain key features of the simulation results, including the preferential excitation of different modes based on beam injection geometry and the growth rate dependence on the beam injection velocity, critical velocity, and degree of velocity space anisotropy. The background damping rate is inferred from the simulations and analytically estimated for relevant sources absent from the simulation model, indicating that co-CAEs are closer to marginal stability than modes driven by the cyclotron resonances.},
doi = {10.1088/1741-4326/abf028},
journal = {Nuclear Fusion},
number = 8,
volume = 61,
place = {United States},
year = {Tue Jul 20 00:00:00 EDT 2021},
month = {Tue Jul 20 00:00:00 EDT 2021}
}

Works referenced in this record:

Stability of the global Alfvén eigenmode in the presence of fusion alpha particles in an ignited tokamak plasma
journal, December 1989

  • Fu, G. Y.; Van Dam, J. W.
  • Physics of Fluids B: Plasma Physics, Vol. 1, Issue 12
  • DOI: 10.1063/1.859175

Localized fast magnetoacoustic eigenmodes in tokamak plasmas
journal, December 1998


Destabilization of counter-propagating Alfvénic instabilities by tangential, co-current neutral beam injection
journal, June 2018


Discrete Alfvén eigenmode spectrum in magnetohydrodynamics
journal, January 1983


Hybrid Simulations of the Effects of Energetic Particles on Low-Frequency MHD Waves
journal, September 1997

  • Belova, E. V.; Denton, R. E.; Chan, A. A.
  • Journal of Computational Physics, Vol. 136, Issue 2
  • DOI: 10.1006/jcph.1997.5738

Localization of compressional Alfvén eigenmodes in spherical tori
journal, May 2003

  • Smith, H.; Fülöp, T.; Lisak, M.
  • Physics of Plasmas, Vol. 10, Issue 5
  • DOI: 10.1063/1.1566441

Anomalous electron transport due to multiple high frequency beam ion driven Alfvén eigenmodes
journal, July 2010


Wave dissipation by electron Landau damping in low aspect ratio tokamaks with elliptic magnetic surfaces
journal, September 2002

  • Grishanov, N. I.; Ludwig, G. O.; de Azevedo, C. A.
  • Physics of Plasmas, Vol. 9, Issue 9
  • DOI: 10.1063/1.1499953

Internal amplitude, structure and identification of compressional and global Alfvén eigenmodes in NSTX
journal, March 2013


Observation of compressional Alfvén eigenmodes (CAE) in a conventional tokamak
journal, January 2006


Quasilinear Diffusion of an Axisymmetric Toroidal Plasma
journal, January 1972


Numerical simulations of global Alfvén eigenmodes excitation and stabilization in NSTX-U
journal, September 2019

  • Belova, E. V.; Fredrickson, E. D.; Lestz, J. B.
  • Physics of Plasmas, Vol. 26, Issue 9
  • DOI: 10.1063/1.5116357

Compressional Alfvén eigenmode dispersion in low aspect ratio plasmas
journal, August 2002

  • Gorelenkov, N. N.; Cheng, C. Z.; Fredrickson, E.
  • Physics of Plasmas, Vol. 9, Issue 8
  • DOI: 10.1063/1.1492803

Theory and observations of high frequency Alfv n eigenmodes in low aspect ratio plasmas
journal, March 2003


Destabilization of TAE modes by particle anisotropy
journal, January 1999


Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks
journal, May 2018

  • Austin, M. E.; Bardoczi, L.; Collins, C. S.
  • Physics of Plasmas, Vol. 25, Issue 5
  • DOI: 10.1063/1.5016160

Excitation of global eigenmodes of the Alfven wave in Tokamaks
journal, September 1982


Kinetic description of Alfvén wave heating
journal, January 1982


NSTX/NSTX-U theory, modeling and analysis results
journal, June 2019


Suppression of Alfvén Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection
journal, June 2017


High-frequency shear Alfvén instability driven by circulating energetic ions in NSTX
journal, December 2006

  • Kolesnichenko, Ya. I.; White, R. B.; Yakovenko, Yu. V.
  • Physics of Plasmas, Vol. 13, Issue 12
  • DOI: 10.1063/1.2402129

Non-linear modulation of short wavelength compressional Alfvén eigenmodes
journal, April 2013

  • Fredrickson, E. D.; Gorelenkov, N. N.; Podesta, M.
  • Physics of Plasmas, Vol. 20, Issue 4
  • DOI: 10.1063/1.4801663

Channeling of the Energy and Momentum during Energetic-Ion-Driven Instabilities in Fusion Plasmas
journal, February 2010


Global Alfvén eigenmode scaling and suppression: experiment and theory
journal, June 2018


Magnetosonic eigenmodes near the magnetic field well in a spherical torus
journal, November 1998

  • Gorelenkova, M. V.; Gorelenkov, N. N.
  • Physics of Plasmas, Vol. 5, Issue 11
  • DOI: 10.1063/1.873133

Correlation between Electron Transport and Shear Alfvén Activity in the National Spherical Torus Experiment
journal, March 2009


Fast-wave heating of a two-component plasma
journal, October 1975


Excitation of Alfvén cyclotron instability by charged fusion products in tokamaks
journal, June 1995

  • Gorelenkov, N. N.; Cheng, C. Z.
  • Physics of Plasmas, Vol. 2, Issue 6
  • DOI: 10.1063/1.871281

Properties of toroidal Alfvén eigenmode in DIII-D plasma
journal, February 2015

  • Wang, Zhixuan; Lin, Zhihong; Deng, Wenjun
  • Physics of Plasmas, Vol. 22, Issue 2
  • DOI: 10.1063/1.4908274

The tokamak Monte Carlo fast ion module NUBEAM in the National Transport Code Collaboration library
journal, June 2004

  • Pankin, Alexei; McCune, Douglas; Andre, Robert
  • Computer Physics Communications, Vol. 159, Issue 3
  • DOI: 10.1016/j.cpc.2003.11.002

Observation of global Alfvén eigenmode avalanche events on the National Spherical Torus Experiment
journal, March 2012


Exploration of the equilibrium operating space for NSTX-Upgrade
journal, August 2012


Self-consistent equilibrium model of low aspect-ratio toroidal plasma with energetic beam ions
journal, August 2003

  • Belova, E. V.; Gorelenkov, N. N.; Cheng, C. Z.
  • Physics of Plasmas, Vol. 10, Issue 8
  • DOI: 10.1063/1.1592155

Analytic stability boundaries for compressional and global Alfvén eigenmodes driven by fast ions. II. Interaction via Landau resonance
journal, February 2020

  • Lestz, J. B.; Gorelenkov, N. N.; Belova, E. V.
  • Physics of Plasmas, Vol. 27, Issue 2
  • DOI: 10.1063/1.5127552

Compressional Alfvén eigenmode structure in spherical tokamaks
journal, May 2009


Phenomenology of compressional Alfvén eigenmodes
journal, July 2004

  • Fredrickson, E. D.; Gorelenkov, N. N.; Menard, J.
  • Physics of Plasmas, Vol. 11, Issue 7
  • DOI: 10.1063/1.1760094

Compressional Alfvén eigenmodes in rotating spherical tokamak plasmas
journal, February 2017


Stabilization of Alfvén Eigenmodes in DIII-D via Controlled Energetic Ion Density Ramp and Validation of Theory and Simulations
journal, April 2021


Fast Ion Induced Shearing of 2D Alfvén Eigenmodes Measured by Electron Cyclotron Emission Imaging
journal, February 2011


On the collisional damping of TAE-modes on trapped electrons in tokamaks
journal, February 1992


Radio-frequency wave dissipation by electron Landau damping in a low aspect ratio D-shaped tokamak
journal, August 2003

  • Grishanov, N. I.; Loula, A. F. D.; Azevedo, C. A. de
  • Plasma Physics and Controlled Fusion, Vol. 45, Issue 9
  • DOI: 10.1088/0741-3335/45/9/315

Alfven wave coupling experiments of the TCA Tokamak
journal, August 1982


Energetic-particle-modified global Alfvén eigenmodes
journal, April 2018

  • Lestz, J. B.; Belova, E. V.; Gorelenkov, N. N.
  • Physics of Plasmas, Vol. 25, Issue 4
  • DOI: 10.1063/1.4998602

Dielectric characteristics of axisymmetric low aspect ratio tokamak plasmas
journal, June 2001

  • Grishanov, N. I.; Azevedo, C. A. de; Neto, J. P.
  • Plasma Physics and Controlled Fusion, Vol. 43, Issue 8
  • DOI: 10.1088/0741-3335/43/8/301

Discrete compressional Alfvén eigenmode spectrum in tokamaks
journal, September 2006


Bi-directional Alfvén cyclotron instabilities in the mega-amp spherical tokamak
journal, August 2014

  • Sharapov, S. E.; Lilley, M. K.; Akers, R.
  • Physics of Plasmas, Vol. 21, Issue 8
  • DOI: 10.1063/1.4891322

Compressional Alfvén Eigenmodes on MAST
journal, October 2008


High-energy components and collective modes in thermonuclear plasmas
journal, January 1986

  • Coppi, B.; Cowley, S.; Kulsrud, R.
  • Physics of Fluids, Vol. 29, Issue 12
  • DOI: 10.1063/1.865749

Observation of Compressional Alfvén Modes During Neutral-Beam Heating on the National Spherical Torus Experiment
journal, September 2001


Recent progress in understanding electron thermal transport in NSTX
journal, March 2017


Nonlinear simulations of beam-driven compressional Alfvén eigenmodes in NSTX
journal, April 2017

  • Belova, E. V.; Gorelenkov, N. N.; Crocker, N. A.
  • Physics of Plasmas, Vol. 24, Issue 4
  • DOI: 10.1063/1.4979278

Thermonuclear Instability of Global-Type Shear Alfvén Modes
journal, November 1990

  • van Dam, James W.; Fu, Guo-Yong; Cheng, C. Z.
  • Fusion Technology, Vol. 18, Issue 3
  • DOI: 10.13182/FST90-A29282

High spatial sampling global mode structure measurements via multichannel reflectometry in NSTX
journal, August 2011


Coupling of Neutral-Beam-Driven Compressional Alfvén Eigenmodes to Kinetic Alfvén Waves in NSTX Tokamak and Energy Channeling
journal, June 2015


Compressional Alfvén eigenmode instability in NSTX
journal, August 2002