Non-linear saturation mechanism of electron temperature gradient modes

Journal Article · Mon Oct 15 04:00:00 EDT 2012 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4759009· OSTI ID:22068810

Tokluoglu, E K; Sokolov, V; Sen, A K ^[1]

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1. Plasma Physics Laboratory, Columbia University, New York, New York 10027 (United States)

The electron temperature gradient (ETG) mode is a very plausible candidate to explain the large electron particle transport and thermal conduction. Production and identification of slab ETG modes and measurement electron transport have been already reported [X. Wei, V. Sokolov, and A. K. Sen, Phys. Plasmas 17, 042108 (2010); V. Sokolov and A. K. Sen, Phys. Rev. Lett. (2011)]. Now, we develop a theoretical model of non-linear saturation mechanism of ETG mode based on the three wave coupling of an unstable high frequency ETG mode with a damped ETG radial harmonic and a damped ion acoustic (IA) mode. Bicoherence analysis of Columbia linear machine (CLM) data show coupling between ETG modes ({approx}2.4 MHz) and a low frequency mode ({approx}50 kHz). The large damping drive of the ETG radial harmonic accompanied by the smaller but finite damping of the IA mode presents an energy sink for the unstable ETG mode, thus causing saturation. This model predicts a saturation level of {approx}10% and agrees with the observed levels of ETG modes in the CLM.

• OSTI ID: 22068810
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 10 Vol. 19; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHARGED-PARTICLE TRANSPORT
COUPLING
DAMPING
ELECTRON TEMPERATURE
ION ACOUSTIC WAVES
KHZ RANGE
MHZ RANGE
NONLINEAR PROBLEMS
SATURATION
TEMPERATURE GRADIENTS
TEMPERATURE MEASUREMENT
THERMAL CONDUCTION