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Electrostatic Driftwave Instabilities in Field Reversed Configurations

Author: Calvin K Lau
Requested Type: Poster Only
Submitted: 2015-01-18 11:50:39

Co-authors: D.Fulton, I.Holod, Z.Lin, S.Dettrick, T.Tajima, L.Schmitz

Contact Info:
University of California, Irvine
4129 Frederick Reines Hall
Irvine, California   92697
USA

Abstract Text:
Drastic improvement of the plasma stability in the field-reversed configuration (FRC) has recently produced stable plasmas for transport study [1]. Microscopic turbulence has been identified to correlate with the confinement properties of the high performance C2 FRC experiment at Tri Alpha Energy, Inc. (TAE). To identify the sources of the fluctuations and the mechanisms of the transport, we have upgraded the global gyrokinetic toroidal code (GTC) for the first gyrokinetic simulations of driftwave instabilities in the core and the scrape-off layer (SOL) regions of C2.

Using experimentally realistic parameters, we find that the C2 core is stable to the long wavelength ion temperature gradient instabilities, but unstable to shorter wavelength modes (between ion and electron gyroradius) with a flute-like mode structure. In the scrape-off layer, we observe a class of instabilities with longer wavelength and universal-instability-like mode structure. Simulations show that collisional effects significantly affect the instabilities. These simulation results are consistent with fluctuation measurements in C2, and provide a theoretical framework to understand turbulent transport in FRC. We will also report upgraded simulation capabilities for studying the coupling between the core and SOL regions, and the effects of large ion cyclotron orbits.

[1] Tuszewski, M., et al. "Field Reversed Configuration Confinement Enhancement through Edge Biasing and Neutral Beam Injection." Physical review letters 108.25 (2012): 255008.

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