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Bidirectional tornado modes on the Joint European Torus

Patrik Sandquist (Institutionen för radio- och rymdvetenskap, Icke-linjär elektrodynamik) ; S. E. Sharapov ; Mietek Lisak (Institutionen för radio- och rymdvetenskap) ; Thomas Johnson
PHYSICS OF PLASMAS Vol. 14 (2007), 12, p. 122506.
[Artikel, refereegranskad vetenskaplig]

In discharges on the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] with safety factor q(0)<1 and high-power ion cyclotron resonance heating (ICRH), monster sawtooth crashes are preceded by frequency sweeping “tornado modes” in the toroidal Alfvén eigenmode frequency range. A suite of equilibrium and spectral magnetohydrodynamical codes is used for explaining the observed evolution of the tornado mode frequency and for identifying temporal evolution of the safety factor inside the q=1 radius just before sawtooth crashes. In some cases, the tornado modes are observed simultaneously with both positive and negative toroidal mode numbers. Hence, a free energy source other than the radial gradient of the energetic ion pressure exciting these modes is sought. The distribution function of the ICRH-accelerated ions is assessed with the SELFO code [J. Hedin et al., Nucl. Fusion 42, 527 (2002)] and energetic particle drive due to the velocity space anisotropy of ICRH-accelerated ions is considered analytically as the possible source for excitation of bidirectional tornado modes. © 2007 American Institute of Physics.

Nyckelord: fusionsplasmafysik, våginstabiliteter, tokamaker



Denna post skapades 2008-01-17.
CPL Pubid: 67265

 

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Institutioner (Chalmers)

Institutionen för radio- och rymdvetenskap, Icke-linjär elektrodynamik (2005-2010)
Institutionen för radio- och rymdvetenskap (2005-2010)

Ämnesområden

Fysik

Chalmers infrastruktur