Density perturbation mode structure of high frequency compressional and global Alfvén eigenmodes in the National Spherical Torus Experiment using a novel reflectometer analysis technique
Abstract
Reflectometry measurements of compressional (CAE) and global (GAE) Alfvén eigenmodes are analyzed to obtain the amplitude and spatial structure of the density perturbations associated with the modes. A novel analysis technique developed for this purpose is presented. The analysis also naturally yields the amplitude and spatial structure of the density contour radial displacement, which is found to be 2–4 times larger than the value estimated directly from the reflectometer measurements using the much simpler 'mirror approximation'. The modes were driven by beam ions in a high power (6 MW) neutral beam heated H-mode discharge (#141398) in the National Spherical Torus Experiment. The results of the analysis are used to assess the contribution of the modes to core energy transport and ion heating. Here, the total displacement amplitude of the modes, which is shown to be larger than previously estimated, is compared to the predicted threshold for the anomalously high heat diffusion inferred from transport modeling in similar NSTX discharges. The results of the analysis also have strong implications for the energy transport via coupling of CAEs to kinetic Alfvén waves seen in simulations with the Hybrid MHD code. Lastly, the amplitudes of the observed CAEs fall well below the thresholdmore »
- Authors:
- Publication Date:
- Research Org.:
- Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- OSTI Identifier:
- 1437750
- Alternate Identifier(s):
- OSTI ID: 1464645
- Grant/Contract Number:
- AC02-09CH11466; FG02-99ER54527; SC0011810
- Resource Type:
- Published Article
- Journal Name:
- Nuclear Fusion
- Additional Journal Information:
- Journal Name: Nuclear Fusion Journal Volume: 58 Journal Issue: 1; Journal ID: ISSN 0029-5515
- Publisher:
- IOP Publishing
- Country of Publication:
- IAEA
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Alfvén; eigenmodes; energetic ions; plasma heating; plasma transport; wave-particle interactions; reflectometry
Citation Formats
Crocker, N. A., Kubota, S., Peebles, W. A., Rhodes, T. L., Fredrickson, E. D., Belova, E., Diallo, A., LeBlanc, B. P., and Sabbagh, S. A. Density perturbation mode structure of high frequency compressional and global Alfvén eigenmodes in the National Spherical Torus Experiment using a novel reflectometer analysis technique. IAEA: N. p., 2017.
Web. doi:10.1088/1741-4326/aa953e.
Crocker, N. A., Kubota, S., Peebles, W. A., Rhodes, T. L., Fredrickson, E. D., Belova, E., Diallo, A., LeBlanc, B. P., & Sabbagh, S. A. Density perturbation mode structure of high frequency compressional and global Alfvén eigenmodes in the National Spherical Torus Experiment using a novel reflectometer analysis technique. IAEA. https://doi.org/10.1088/1741-4326/aa953e
Crocker, N. A., Kubota, S., Peebles, W. A., Rhodes, T. L., Fredrickson, E. D., Belova, E., Diallo, A., LeBlanc, B. P., and Sabbagh, S. A. Tue .
"Density perturbation mode structure of high frequency compressional and global Alfvén eigenmodes in the National Spherical Torus Experiment using a novel reflectometer analysis technique". IAEA. https://doi.org/10.1088/1741-4326/aa953e.
@article{osti_1437750,
title = {Density perturbation mode structure of high frequency compressional and global Alfvén eigenmodes in the National Spherical Torus Experiment using a novel reflectometer analysis technique},
author = {Crocker, N. A. and Kubota, S. and Peebles, W. A. and Rhodes, T. L. and Fredrickson, E. D. and Belova, E. and Diallo, A. and LeBlanc, B. P. and Sabbagh, S. A.},
abstractNote = {Reflectometry measurements of compressional (CAE) and global (GAE) Alfvén eigenmodes are analyzed to obtain the amplitude and spatial structure of the density perturbations associated with the modes. A novel analysis technique developed for this purpose is presented. The analysis also naturally yields the amplitude and spatial structure of the density contour radial displacement, which is found to be 2–4 times larger than the value estimated directly from the reflectometer measurements using the much simpler 'mirror approximation'. The modes were driven by beam ions in a high power (6 MW) neutral beam heated H-mode discharge (#141398) in the National Spherical Torus Experiment. The results of the analysis are used to assess the contribution of the modes to core energy transport and ion heating. Here, the total displacement amplitude of the modes, which is shown to be larger than previously estimated, is compared to the predicted threshold for the anomalously high heat diffusion inferred from transport modeling in similar NSTX discharges. The results of the analysis also have strong implications for the energy transport via coupling of CAEs to kinetic Alfvén waves seen in simulations with the Hybrid MHD code. Lastly, the amplitudes of the observed CAEs fall well below the threshold for causing significant ion heating by stochastic velocity space diffusion.},
doi = {10.1088/1741-4326/aa953e},
journal = {Nuclear Fusion},
number = 1,
volume = 58,
place = {IAEA},
year = {Tue Dec 12 00:00:00 EST 2017},
month = {Tue Dec 12 00:00:00 EST 2017}
}
https://doi.org/10.1088/1741-4326/aa953e
Web of Science
Works referenced in this record:
Measurement of poloidal velocity on the National Spherical Torus Experiment (invited)
journal, October 2010
- Bell, Ronald E.; Feder, Russell
- Review of Scientific Instruments, Vol. 81, Issue 10
Observation of density fluctuations associated with the resonant q = 2 surface in the Wendelstein VII-AS stellarator
journal, November 1990
- Sanz, J. Sanchez; Hartfuss, H. J.; Anabitarte, E.
- Nuclear Fusion, Vol. 30, Issue 11
Reconstruction of current profile parameters and plasma shapes in tokamaks
journal, November 1985
- Lao, L. L.; St. John, H.; Stambaugh, R. D.
- Nuclear Fusion, Vol. 25, Issue 11
A tutorial on the basic principles of microwave reflectometry applied to fluctuation measurements in fusion plasmas
journal, May 2001
- Nazikian, R.; Kramer, G. J.; Valeo, E.
- Physics of Plasmas, Vol. 8, Issue 5
Coupling of Neutral-Beam-Driven Compressional Alfvén Eigenmodes to Kinetic Alfvén Waves in NSTX Tokamak and Energy Channeling
journal, June 2015
- Belova, E. V.; Gorelenkov, N. N.; Fredrickson, E. D.
- Physical Review Letters, Vol. 115, Issue 1
Phenomenology of compressional Alfvén eigenmodes
journal, July 2004
- Fredrickson, E. D.; Gorelenkov, N. N.; Menard, J.
- Physics of Plasmas, Vol. 11, Issue 7
Radial resolution enhancement of the NSTX Thomson scattering diagnostic
journal, October 2012
- LeBlanc, B. P.; Diallo, A.; Labik, G.
- Review of Scientific Instruments, Vol. 83, Issue 10
Vectorized adaptive quadrature in MATLAB
journal, February 2008
- Shampine, L. F.
- Journal of Computational and Applied Mathematics, Vol. 211, Issue 2
Study of chirping toroidicity-induced Alfvén eigenmodes in the National Spherical Torus Experiment
journal, September 2012
- Podestà, M.; Bell, R. E.; Bortolon, A.
- Nuclear Fusion, Vol. 52, Issue 9
Ion Heating by Fast-Particle-Induced Alfvén Turbulence
journal, October 2001
- Gates, D. A.; Gorelenkov, N. N.; White, R. B.
- Physical Review Letters, Vol. 87, Issue 20
Anomalous electron transport due to multiple high frequency beam ion driven Alfvén eigenmodes
journal, July 2010
- Gorelenkov, N. N.; Stutman, D.; Tritz, K.
- Nuclear Fusion, Vol. 50, Issue 8
Exploration of spherical torus physics in the NSTX device
journal, March 2000
- Ono, M.; Kaye, S. M.; Peng, Y. -K. M.
- Nuclear Fusion, Vol. 40, Issue 3Y
Channeling of the Energy and Momentum during Energetic-Ion-Driven Instabilities in Fusion Plasmas
journal, February 2010
- Kolesnichenko, Ya. I.; Yakovenko, Yu. V.; Lutsenko, V. V.
- Physical Review Letters, Vol. 104, Issue 7
Correlation between Electron Transport and Shear Alfvén Activity in the National Spherical Torus Experiment
journal, March 2009
- Stutman, D.; Delgado-Aparicio, L.; Gorelenkov, N.
- Physical Review Letters, Vol. 102, Issue 11
Internal amplitude, structure and identification of compressional and global Alfvén eigenmodes in NSTX
journal, March 2013
- Crocker, N. A.; Fredrickson, E. D.; Gorelenkov, N. N.
- Nuclear Fusion, Vol. 53, Issue 4
Observation of compressional Alfvén eigenmodes (CAE) in a conventional tokamak
journal, January 2006
- Heidbrink, W. W.; Fredrickson, E. D.; Gorelenkov, N. N.
- Nuclear Fusion, Vol. 46, Issue 2
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
Electron density fluctuation in JET measured with multichannel reflectometry
journal, December 1993
- Kramer, G. I.; Sips, A. C. C.; Cardozo, N. J. Lopes
- Plasma Physics and Controlled Fusion, Vol. 35, Issue 12
Resistive wall stabilized operation in rotating high beta NSTX plasmas
journal, April 2006
- Sabbagh, S. A.; Sontag, A. C.; Bialek, J. M.
- Nuclear Fusion, Vol. 46, Issue 5
Beta-limiting instabilities and global mode stabilization in the National Spherical Torus Experiment
journal, May 2002
- Sabbagh, S. A.; Bell, R. E.; Bell, M. G.
- Physics of Plasmas, Vol. 9, Issue 5
Geodesic Acoustic Waves in Hydromagnetic Systems
journal, January 1968
- Winsor, Niels
- Physics of Fluids, Vol. 11, Issue 11
New Interpretation of Alpha-Particle-Driven Instabilities in Deuterium-Tritium Experiments on the Tokamak Fusion Test Reactor
journal, September 2003
- Nazikian, R.; Kramer, G. J.; Cheng, C. Z.
- Physical Review Letters, Vol. 91, Issue 12