Subcyclotron Instability of Alfven Eigenmodes due to Energetic Ions in Low Aspect Ratio Plasmas

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High-frequency modes with frequencies below the fundamental cyclotron frequency of thermal ions were observed in the National Spherical Torus Experiment (NSTX). Based on the measured spectrum of high-frequency modes they are identified as Compressional Alfven Eigenmodes (CAEs) and Global Alfven Eigenmodes (GAEs). CAEs have similar time evolution as plasma parameters change, while GAEs may intersect due to q-profile relaxation. A theory has been developed to study the properties of these modes. Both types of instabilities are driven by the tangential neutral-beam injection in NSTX. Beam ions excite CAEs/GAEs through the Doppler-shifted cyclotron resonance. The main source for the drive is ... continued below

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740 Kilobytes pages

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Gorelenko, N.N.; Fredrickson, E.; Belova, E.; Cheng, C.Z.; Gates, D. & White, R. August 21, 2003.

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High-frequency modes with frequencies below the fundamental cyclotron frequency of thermal ions were observed in the National Spherical Torus Experiment (NSTX). Based on the measured spectrum of high-frequency modes they are identified as Compressional Alfven Eigenmodes (CAEs) and Global Alfven Eigenmodes (GAEs). CAEs have similar time evolution as plasma parameters change, while GAEs may intersect due to q-profile relaxation. A theory has been developed to study the properties of these modes. Both types of instabilities are driven by the tangential neutral-beam injection in NSTX. Beam ions excite CAEs/GAEs through the Doppler-shifted cyclotron resonance. The main source for the drive is the velocity space anisotropy of the beam ion distribution function. Simulations of the effect CAEs/GAEs may have on plasma ions indicate that these modes may provide a channel for efficient energy transfer from fast ions directly to thermal ions.

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740 Kilobytes pages

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INIS; OSTI as DE00814748

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  • Other Information: PBD: 21 Aug 2003

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  • Report No.: PPPL-3857
  • Grant Number: AC02-76CH03073
  • DOI: 10.2172/814748 | External Link
  • Office of Scientific & Technical Information Report Number: 814748
  • Archival Resource Key: ark:/67531/metadc738358

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  • August 21, 2003

Added to The UNT Digital Library

  • Oct. 18, 2015, 6:40 p.m.

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  • April 15, 2016, 9:55 p.m.

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Gorelenko, N.N.; Fredrickson, E.; Belova, E.; Cheng, C.Z.; Gates, D. & White, R. Subcyclotron Instability of Alfven Eigenmodes due to Energetic Ions in Low Aspect Ratio Plasmas, report, August 21, 2003; Princeton, New Jersey. (digital.library.unt.edu/ark:/67531/metadc738358/: accessed July 15, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.