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Title: Alfvén eigenmodes and fast ion transport in negative triangularity DIII-D plasmas

Abstract

The first energetic particle experiments in negative triangularity tokamak plasmas have been carried out on DIII-D. Alfvén eigenmode (AE) activity and associated fast ion transport comparable to that in positive triangularity is observed during the current ramp portion of all plasmas with early beam heating indicating negative triangularity does not confer a special advantage with respect to AE induced transport. In these discharges, a range of mode activity driven by the sub-Alfvénic (Vbeam=VA < 0:5) 80 kV neutral beams is found including Beta induced Alfvén Acoustic Eigenmodes (BAAEs), Beta induced Alfvén Eigenmodes (BAEs), Reversed Shear Alfvén Eigenmodes (RSAEs) and Toroidicity induced Alfvén Eigenmodes (TAEs). Mode intermittency and possibly chirping appears to be more common than comparable positive triangularity and/or oval discharges but overall, the unstable spectra and mode amplitudes observed on magnetics, CO2 interferometry, and ECE in a set of matched positive and negative triangularity cases at moderate beam power is similar. Large levels of Alfvén eigenmode induced fast ion transport are found in both positive and negative triangularity with up to 70% central fast ion pressure deficits relative to classical predictions early during the current ramp phase for discharges with 3 MW injected 80 kV neutral beam power. Themore » deficit in both cases is reduced toward zero as the current penetrates and eventually reaches classical levels during current flattop with q_min≈1. Fast ion transport in negative triangularity plasmas measured using a beam modulation technique show very similar levels to those measured in oval plasmas over the range of tested beam powers (P_beam≈2-7 MW). This similarity is found despite quite different unstable spectra in the highest beam power case where a mixture of coherent and quasi-coherent modes in the TAE frequency range are observed in negative triangularity and a spectrum of more typical narrowband TAEs and RSAEs is observed for the oval plasmas.« less

Authors:
ORCiD logo [1];  [1]; ORCiD logo [2];  [3];  [1]; ORCiD logo [4];  [1]; ORCiD logo [4];  [4]; ORCiD logo [4];  [2];  [5];  [6];  [1]; ORCiD logo [1];  [7]; ORCiD logo [1];  [1];  [2]
  1. General Atomics, San Diego, CA (United States)
  2. Univ. of California at Irvine, Irvine, CA (United States)
  3. Univ. of Texas at Austin, Austin, TX (United States)
  4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  5. MIT Plasma Science & Fusion Center, Cambridge, MA (United States)
  6. Univ. of Wisconsin at Madison, Madison, WI (United States)
  7. Univ. of California Los Angeles, Los Angeles, CA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); U.S. Dept. of Energy, Washington D.C. (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1559015
Alternate Identifier(s):
OSTI ID: 1562531
Grant/Contract Number:  
FC02-04ER54698; SC-G903402; AC02-09CH11466; AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 59; 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; magnetohydrodynamic waves; tokamaks; fusion products effects; plasma heating by particle beams; MHD stability; Alfven waves

Citation Formats

Van Zeeland, M. A., Collins, C. S., Heidbrink, W. W., Austin, M. E., Du, X. D., Duarte, V. N., Hyatt, A., Kramer, G., Gorelenkov, N., Grierson, B., Lin, D., Marinoni, A., McKee, G., Muscatello, C., Petty, C., Sung, C., Thome, K. E., Walker, M., and Zhu, Y. B. Alfvén eigenmodes and fast ion transport in negative triangularity DIII-D plasmas. United States: N. p., 2019. Web. doi:10.1088/1741-4326/ab2488.
Van Zeeland, M. A., Collins, C. S., Heidbrink, W. W., Austin, M. E., Du, X. D., Duarte, V. N., Hyatt, A., Kramer, G., Gorelenkov, N., Grierson, B., Lin, D., Marinoni, A., McKee, G., Muscatello, C., Petty, C., Sung, C., Thome, K. E., Walker, M., & Zhu, Y. B. Alfvén eigenmodes and fast ion transport in negative triangularity DIII-D plasmas. United States. https://doi.org/10.1088/1741-4326/ab2488
Van Zeeland, M. A., Collins, C. S., Heidbrink, W. W., Austin, M. E., Du, X. D., Duarte, V. N., Hyatt, A., Kramer, G., Gorelenkov, N., Grierson, B., Lin, D., Marinoni, A., McKee, G., Muscatello, C., Petty, C., Sung, C., Thome, K. E., Walker, M., and Zhu, Y. B. Thu . "Alfvén eigenmodes and fast ion transport in negative triangularity DIII-D plasmas". United States. https://doi.org/10.1088/1741-4326/ab2488. https://www.osti.gov/servlets/purl/1559015.
@article{osti_1559015,
title = {Alfvén eigenmodes and fast ion transport in negative triangularity DIII-D plasmas},
author = {Van Zeeland, M. A. and Collins, C. S. and Heidbrink, W. W. and Austin, M. E. and Du, X. D. and Duarte, V. N. and Hyatt, A. and Kramer, G. and Gorelenkov, N. and Grierson, B. and Lin, D. and Marinoni, A. and McKee, G. and Muscatello, C. and Petty, C. and Sung, C. and Thome, K. E. and Walker, M. and Zhu, Y. B.},
abstractNote = {The first energetic particle experiments in negative triangularity tokamak plasmas have been carried out on DIII-D. Alfvén eigenmode (AE) activity and associated fast ion transport comparable to that in positive triangularity is observed during the current ramp portion of all plasmas with early beam heating indicating negative triangularity does not confer a special advantage with respect to AE induced transport. In these discharges, a range of mode activity driven by the sub-Alfvénic (Vbeam=VA < 0:5) 80 kV neutral beams is found including Beta induced Alfvén Acoustic Eigenmodes (BAAEs), Beta induced Alfvén Eigenmodes (BAEs), Reversed Shear Alfvén Eigenmodes (RSAEs) and Toroidicity induced Alfvén Eigenmodes (TAEs). Mode intermittency and possibly chirping appears to be more common than comparable positive triangularity and/or oval discharges but overall, the unstable spectra and mode amplitudes observed on magnetics, CO2 interferometry, and ECE in a set of matched positive and negative triangularity cases at moderate beam power is similar. Large levels of Alfvén eigenmode induced fast ion transport are found in both positive and negative triangularity with up to 70% central fast ion pressure deficits relative to classical predictions early during the current ramp phase for discharges with 3 MW injected 80 kV neutral beam power. The deficit in both cases is reduced toward zero as the current penetrates and eventually reaches classical levels during current flattop with q_min≈1. Fast ion transport in negative triangularity plasmas measured using a beam modulation technique show very similar levels to those measured in oval plasmas over the range of tested beam powers (P_beam≈2-7 MW). This similarity is found despite quite different unstable spectra in the highest beam power case where a mixture of coherent and quasi-coherent modes in the TAE frequency range are observed in negative triangularity and a spectrum of more typical narrowband TAEs and RSAEs is observed for the oval plasmas.},
doi = {10.1088/1741-4326/ab2488},
url = {https://www.osti.gov/biblio/1559015}, journal = {Nuclear Fusion},
issn = {0029-5515},
number = 8,
volume = 59,
place = {United States},
year = {2019},
month = {6}
}

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Works referenced in this record:

Predictions and observations of global beta-induced Alfvén—acoustic modes in JET and NSTX
journal, November 2007


The effect of plasma triangularity on turbulent transport: modeling TCV experiments by linear and non-linear gyrokinetic simulations
journal, March 2009


Improving fast-ion confinement in high-performance discharges by suppressing Alfvén eigenmodes
journal, March 2017


Consideration of neutral beam prompt loss in the design of a tokamak helicon antenna
journal, November 2016


Electron cyclotron emission radiometer upgrade on the DIII-D tokamak
journal, March 2003


Prediction of nonlinear evolution character of energetic-particle-driven instabilities
journal, March 2017


Global Alfvén modes: Theory and experiment*
journal, July 1993


Achievement of Reactor-Relevant Performance in Negative Triangularity Shape in the DIII-D Tokamak
journal, March 2019


Measurements and modeling of Alfvén eigenmode induced fast ion transport and loss in DIII-D and ASDEX Upgrade
journal, May 2011


Toroidal Alfvén eigenmode‐induced ripple trapping
journal, August 1995


Modulation of prompt fast-ion loss by applied n = 2 fields in the DIII-D tokamak
journal, December 2013


Fast-ion transport by Alfvén eigenmodes above a critical gradient threshold
journal, May 2017


Fast ion transport during applied 3D magnetic perturbations on DIII-D
journal, June 2015


Access to a New Plasma Edge State with High Density and Pressures using the Quiescent H Mode
journal, September 2014


Phase-space dependent critical gradient behavior of fast-ion transport due to Alfvén eigenmodes
journal, June 2017


Measurements, modelling and electron cyclotron heating modification of Alfvén eigenmode activity in DIII-D
journal, April 2009


Coupling of global toroidal Alfvén eigenmodes and reversed shear Alfvén eigenmodes in DIII-D
journal, May 2007


An upgrade of the magnetic diagnostic system of the DIII-D tokamak for non-axisymmetric measurements
journal, August 2014


Frequencies of the geodesic acoustic mode and Alfvén gap modes in high-q2β plasmas with non-circular cross section
journal, December 2013


Effect of triangular and elongated plasma shape on the sawtooth stability
journal, May 2000


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


Magnetic diagnostic system of the DIII-D tokamak
journal, February 2006


Theoretical Interpretation of Alfvén Cascades in Tokamaks with Nonmonotonic q Profiles
journal, October 2001


Anomalous Flattening of the Fast-Ion Profile during Alfvén-Eigenmode Activity
journal, December 2007


Radial Structure of Alfvén Eigenmodes in the DIII-D Tokamak through Electron-Cyclotron-Emission Measurements
journal, September 2006


Beta-induced Alfvén-acoustic eigenmodes in National Spherical Torus Experiment and DIII-D driven by beam ions
journal, May 2009


Alfvén eigenmode observations on DIII-D via two-colour CO 2 interferometry
journal, August 2005


Observation of Critical-Gradient Behavior in Alfvén-Eigenmode-Induced Fast-Ion Transport
journal, February 2016


Loss of energetic beam ions during TAE instabilities
journal, May 1993


Beam distribution modification by Alfvén modes
journal, May 2010


Fast-ion transport in qmin>2, high- β steady-state scenarios on DIII-Da)
journal, May 2015


Multi-phase simulation of fast ion profile flattening due to Alfvén eigenmodes in a DIII-D experiment
journal, October 2014


Plasma pressure effect on Alfvén cascade eigenmodes
journal, November 2005


    Works referencing / citing this record:

    Analytical solutions for nonlinear plasma waves with time-varying complex frequency
    journal, November 2019