Spontaneous transition of core radial electric field driven by magnetic islands in the H-1NF heliac

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Nuclear Fusion

DOI:https://doi.org/10.1088/0029-5515/51/8/083003· OSTI ID:1036687

Kumar, S T. A. ^[1]; Blackwell, B D ^[2]; Howard, J ^[2]; Harris, J H ^[3]

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1. University of Wisconsin, Madison
2. Australian National University, Canberra, Australia
3. Oak Ridge National Laboratory (ORNL)

This paper reports an experimental observation of spontaneous transition of the core radial electric field to a large positive value (E(r) similar to 5 kV m(-1)), with a strong electric-field shear (similar to 700 kV m(-2)) in a low temperature (T(e) similar to 10 eV) radio frequency generated argon plasma in the H-1NF heliac stellarator. The transition, which seems to be driven by a spontaneous excitation of m = 2 magnetic islands near the core, is associated with a localized increase in the plasma density and excitation of coherent low frequency (similar to 3 kHz) oscillations possibly due to unstable E(r) shear driven modes. Evidence suggests development of the core electron-root scenario, which previously has been observed only at high temperature electron cyclotron heated plasmas.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1036687
• Journal Information: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 8 Vol. 51; ISSN 0029-5515
• Country of Publication: United States
• Language: English

Related Subjects

CONFIGURATION
CONFINEMENT BIFURCATIONS
GENERATION
INTERNAL TRANSPORT BARRIER
MODE
PLASMA
SHEAR
STELLARATOR
TJ-II
TOKAMAK