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Title: Development of core ion temperature gradients and edge sheared flows in a helicon plasma device investigated by laser induced fluorescence measurements

Abstract

We report experimental observation of ion heating and subsequent development of a prominent ion temperature gradient in the core of a linear magnetized plasma device, and the controlled shear de-correlation experiment. Simultaneously, we also observe the development of strong sheared flows at the edge of the device. Both the ion temperature and the azimuthal velocity profiles are quite flat at low magnetic fields. As the magnetic field is increased, the core ion temperature increases, producing centrally peaked ion temperature profiles and therefore strong radial gradients in the ion temperature. Similarly, we observe the development of large azimuthal flows at the edge, with increasing magnetic field, leading to strong radially sheared plasma flows. The ion velocities and temperatures are derived from laser induced fluorescence measurements of Doppler resolved velocity distribution functions of argon ions. These features are consistent with the previous observations of simultaneously existing radially separated multiple plasma instabilities that exhibit complex plasma dynamics in a very simple plasma system. The ion temperature gradients in the core and the radially sheared azimuthal velocities at the edge point to mechanisms that can drive the multiple plasma instabilities, that were reported earlier.

Authors:
;  [1];  [2];  [3]; ; ;  [4]
  1. Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego, California 92093 (United States)
  2. (United States)
  3. Center for Energy Research, University of California at San Diego, San Diego, California 92093 (United States)
  4. Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506 (United States)
Publication Date:
OSTI Identifier:
22599907
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ARGON; ARGON IONS; DISTRIBUTION FUNCTIONS; DOPPLER EFFECT; FLUORESCENCE; HEATING; ION TEMPERATURE; LASERS; MAGNETIC FIELDS; PLASMA; PLASMA INSTABILITY; SHEAR; TEMPERATURE GRADIENTS; VELOCITY

Citation Formats

Thakur, S. C., Tynan, G. R., Center for Energy Research, University of California at San Diego, San Diego, California 92093, Gosselin, J. J., McKee, J., Scime, E. E., and Sears, S. H. Development of core ion temperature gradients and edge sheared flows in a helicon plasma device investigated by laser induced fluorescence measurements. United States: N. p., 2016. Web. doi:10.1063/1.4960824.
Thakur, S. C., Tynan, G. R., Center for Energy Research, University of California at San Diego, San Diego, California 92093, Gosselin, J. J., McKee, J., Scime, E. E., & Sears, S. H. Development of core ion temperature gradients and edge sheared flows in a helicon plasma device investigated by laser induced fluorescence measurements. United States. doi:10.1063/1.4960824.
Thakur, S. C., Tynan, G. R., Center for Energy Research, University of California at San Diego, San Diego, California 92093, Gosselin, J. J., McKee, J., Scime, E. E., and Sears, S. H. Mon . "Development of core ion temperature gradients and edge sheared flows in a helicon plasma device investigated by laser induced fluorescence measurements". United States. doi:10.1063/1.4960824.
@article{osti_22599907,
title = {Development of core ion temperature gradients and edge sheared flows in a helicon plasma device investigated by laser induced fluorescence measurements},
author = {Thakur, S. C. and Tynan, G. R. and Center for Energy Research, University of California at San Diego, San Diego, California 92093 and Gosselin, J. J. and McKee, J. and Scime, E. E. and Sears, S. H.},
abstractNote = {We report experimental observation of ion heating and subsequent development of a prominent ion temperature gradient in the core of a linear magnetized plasma device, and the controlled shear de-correlation experiment. Simultaneously, we also observe the development of strong sheared flows at the edge of the device. Both the ion temperature and the azimuthal velocity profiles are quite flat at low magnetic fields. As the magnetic field is increased, the core ion temperature increases, producing centrally peaked ion temperature profiles and therefore strong radial gradients in the ion temperature. Similarly, we observe the development of large azimuthal flows at the edge, with increasing magnetic field, leading to strong radially sheared plasma flows. The ion velocities and temperatures are derived from laser induced fluorescence measurements of Doppler resolved velocity distribution functions of argon ions. These features are consistent with the previous observations of simultaneously existing radially separated multiple plasma instabilities that exhibit complex plasma dynamics in a very simple plasma system. The ion temperature gradients in the core and the radially sheared azimuthal velocities at the edge point to mechanisms that can drive the multiple plasma instabilities, that were reported earlier.},
doi = {10.1063/1.4960824},
journal = {Physics of Plasmas},
number = 8,
volume = 23,
place = {United States},
year = {Mon Aug 15 00:00:00 EDT 2016},
month = {Mon Aug 15 00:00:00 EDT 2016}
}