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Title: Multitude of Core-Localized Shear Alfven Waves in a High-Temperature Fusion Plasma

Abstract

Evidence is presented for a multitude of discrete frequency Alfven waves in the core of magnetically confined high-temperature fusion plasmas. Multiple diagnostic instruments confirm wave excitation over a wide spatial range from the device size at the longest wavelengths down to the thermal ion Larmor radius. At the shortest scales, the poloidal wavelengths are comparable to the scale length of electrostatic drift wave turbulence. Theoretical analysis confirms a dominant interaction of the modes with particles in the thermal ion distribution traveling well below the Alfven velocity.

Authors:
; ; ; ;  [1];  [2]; ; ;  [3]; ; ; ;  [4]; ;  [5]; ; ;  [6];  [7]
  1. Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)
  2. University of Texas at Austin, Austin, Texas 78712 (United States)
  3. General Atomics, San Diego, California 92186-5608 (United States)
  4. University of California at Los Angeles, Los Angeles, California 90095 (United States)
  5. University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
  6. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
  7. Oak Ridge Institute for Science Education, Oak Ridge, Tennessee 37831 (United States)
Publication Date:
OSTI Identifier:
20777091
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 96; Journal Issue: 10; Other Information: DOI: 10.1103/PhysRevLett.96.105006; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALFVEN WAVES; EXCITATION; LARMOR RADIUS; PLASMA; PLASMA CONFINEMENT; PLASMA DIAGNOSTICS; PLASMA DRIFT; PLASMA WAVES; TOKAMAK DEVICES; TURBULENCE; WAVELENGTHS

Citation Formats

Nazikian, R., Budny, R.V., Gorelenkov, N.N., Kramer, G.J., Solomon, W.M., Berk, H.L., Burrell, K.H., La Haye, R.J., Strait, E.J., Doyle, E.J., Peebles, W.A., Rhodes, T.L., Zeng, L., Fonck, R.J., McKee, G.R., Holcomb, C., Jayakumar, R.J., Makowski, M.A., and VanZeeland, M.A. Multitude of Core-Localized Shear Alfven Waves in a High-Temperature Fusion Plasma. United States: N. p., 2006. Web. doi:10.1103/PhysRevLett.96.105006.
Nazikian, R., Budny, R.V., Gorelenkov, N.N., Kramer, G.J., Solomon, W.M., Berk, H.L., Burrell, K.H., La Haye, R.J., Strait, E.J., Doyle, E.J., Peebles, W.A., Rhodes, T.L., Zeng, L., Fonck, R.J., McKee, G.R., Holcomb, C., Jayakumar, R.J., Makowski, M.A., & VanZeeland, M.A. Multitude of Core-Localized Shear Alfven Waves in a High-Temperature Fusion Plasma. United States. doi:10.1103/PhysRevLett.96.105006.
Nazikian, R., Budny, R.V., Gorelenkov, N.N., Kramer, G.J., Solomon, W.M., Berk, H.L., Burrell, K.H., La Haye, R.J., Strait, E.J., Doyle, E.J., Peebles, W.A., Rhodes, T.L., Zeng, L., Fonck, R.J., McKee, G.R., Holcomb, C., Jayakumar, R.J., Makowski, M.A., and VanZeeland, M.A. Fri . "Multitude of Core-Localized Shear Alfven Waves in a High-Temperature Fusion Plasma". United States. doi:10.1103/PhysRevLett.96.105006.
@article{osti_20777091,
title = {Multitude of Core-Localized Shear Alfven Waves in a High-Temperature Fusion Plasma},
author = {Nazikian, R. and Budny, R.V. and Gorelenkov, N.N. and Kramer, G.J. and Solomon, W.M. and Berk, H.L. and Burrell, K.H. and La Haye, R.J. and Strait, E.J. and Doyle, E.J. and Peebles, W.A. and Rhodes, T.L. and Zeng, L. and Fonck, R.J. and McKee, G.R. and Holcomb, C. and Jayakumar, R.J. and Makowski, M.A. and VanZeeland, M.A.},
abstractNote = {Evidence is presented for a multitude of discrete frequency Alfven waves in the core of magnetically confined high-temperature fusion plasmas. Multiple diagnostic instruments confirm wave excitation over a wide spatial range from the device size at the longest wavelengths down to the thermal ion Larmor radius. At the shortest scales, the poloidal wavelengths are comparable to the scale length of electrostatic drift wave turbulence. Theoretical analysis confirms a dominant interaction of the modes with particles in the thermal ion distribution traveling well below the Alfven velocity.},
doi = {10.1103/PhysRevLett.96.105006},
journal = {Physical Review Letters},
number = 10,
volume = 96,
place = {United States},
year = {Fri Mar 17 00:00:00 EST 2006},
month = {Fri Mar 17 00:00:00 EST 2006}
}
  • Evidence is provided for a multitude of discrete frequency Alfvén waves in the core of magnetically confined high-temperature fusion plasmas. Multiple diagnostic instruments verify wave excitation over a wide spatial range from the device size at the longest wavelengths down to the thermal ion Larmor radius. At the shortest scales, the poloidal wavelengths are like the scale length of electrostatic drift wave turbulence. Theoretical analysis verifies a dominant interaction of the modes with particles in the thermal ion distribution traveling well below the Alfvén velocity.
  • An instability of Alfven waves driven by parallel velocity shear has been derived for a high ..beta.. collisionless plasma. The unstable waves propagate in a narrow cone around the magnetic field.
  • Reversed shear Alfven eigenmodes (RSAE) that were observed in the Joint European Torus (JET) [P. H. Rebut and B. E. Keen, Fusion Technol.11, 13 (1987)] and DIII-D [J. L. Luxon, Nucl. Fusion42, 614 (2002)] are studied with the ideal magnetohydrodynamic code NOVA-K [C. Z. Cheng, Phys. Rep.211, 1 (1992)]. It was found that the frequency behavior of the RSAEs can be described accurately by the NOVA-K code when plasma compressibility effects and toroidal plasma rotation are taken into account. For the mode activity on JET, the calculated drive exceeds the mode damping rate, consistent with experimental observations, while on DIII-Dmore » the growth rate from neutral beam ions for modes with high toroidal mode numbers is insufficient to account for the excitation of the modes and a major part of the drive comes from the background plasma.« less
  • Low frequency electrostatic and electromagnetic waves in a dense magnetoplasma are studied. The dispersive contribution of electron quantum effects in an electron-ion plasma in the presence of positively or negatively charged dust particles in the background is emphasized. By employing the quantum hydrodynamic model, a linear dispersion relation is derived which shows coupling of electrostatic and shear Alfven modes which shows influence of electron quantum effects and dust density.
  • Using two-dimensional particle-in-cell simulations, we study generation of turbulence consisting of transversely small-scale dispersive Alfven and electrostatic waves when plasma is driven by a large-scale standing shear Alfven wave (LS-SAW). The standing wave is set up by reflecting a propagating LS-SAW. The ponderomotive force of the standing wave generates transversely large-scale density modifications consisting of density cavities and enhancements. The drifts of the charged particles driven by the ponderomotive force and those directly caused by the fields of the standing LS-SAW generate non-thermal features in the plasma. Parametric instabilities driven by the inherent plasma nonlinearities associated with the LS-SAW inmore » combination with the non-thermal features generate small-scale electromagnetic and electrostatic waves, yielding a broad frequency spectrum ranging from below the source frequency of the LS-SAW to ion cyclotron and lower hybrid frequencies and beyond. The power spectrum of the turbulence has peaks at distinct perpendicular wave numbers (k{sub Up-Tack }) lying in the range d{sub e}{sup -1}-6d{sub e}{sup -1}, d{sub e} being the electron inertial length, suggesting non-local parametric decay from small to large k{sub Up-Tack }. The turbulence spectrum encompassing both electromagnetic and electrostatic fluctuations is also broadband in parallel wave number (k{sub ||}). In a standing-wave supported density cavity, the ratio of the perpendicular electric to magnetic field amplitude is R(k{sub Up-Tack }) = |E{sub Up-Tack }(k{sub Up-Tack })/|B{sub Up-Tack }(k{sub Up-Tack })| Much-Less-Than V{sub A} for k{sub Up-Tack }d{sub e} < 0.5, where V{sub A} is the Alfven velocity. The characteristic features of the broadband plasma turbulence are compared with those available from satellite observations in space plasmas.« less