Nonlinear saturation of collisionless trapped electron mode turbulence: Zonal flows and zonal density

Journal Article · Thu May 15 04:00:00 EDT 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2884036· OSTI ID:21120351

Jianying, Lang; Parker, Scott E; Yang, Chen ^[1]

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1. Center for Integrated Plasma Studies, Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309 (United States)

Gyrokinetic {delta}f particle simulation is used to investigate the nonlinear saturation mechanisms in collisionless trapped electron mode (CTEM) turbulence. It is found that the importance of zonal flow is parameter-sensitive and is well characterized by the shearing rate formula. The effect of zonal flow is empirically found to be sensitive to temperature ratio, magnetic shear, and electron temperature gradient. For parameters where zonal flow is found to be unimportant, zonal density (purely radial density perturbations) is generated and expected to be the dominant saturation mechanism. A toroidal mode-coupling theory is presented that agrees with simulation in the initial nonlinear saturation phase. The mode-coupling theory predicts the nonlinear generation of the zonal density and the feedback and saturation of the linearly most unstable mode. Inverse energy cascade is also observed in CTEM turbulence simulations and is reported here.

• OSTI ID: 21120351
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DISTURBANCES
ELECTRON TEMPERATURE
FEEDBACK
NONLINEAR PROBLEMS
PARTICLES
PERTURBATION THEORY
PLASMA
PLASMA DENSITY
SIMULATION
TEMPERATURE GRADIENTS
TRAPPED ELECTRONS
TURBULENCE