Nonlinear gyrokinetic turbulence simulations of ExB shear quenching of transport
- Lehigh University, Bethlehem, Pennsylvania 18015 (United States)
The effects of ExB velocity shear have been investigated in nonliner gyrokinetic turbulence simulations with and without kinetic electrons. The impact of ExB shear stabilization in electrostatic flux-tube simulations is well modeled by a simple quench rule with the turbulent diffusivity scaling like 1-{alpha}{sub E}{gamma}{sub E}/{gamma}{sub max}, where {gamma}{sub E} is the ExB shear rate, {gamma}{sub max} is maximum linear growth rate without ExB shear, and {alpha}{sub E} is a multiplier. The quench rule was originally deduced from adiabatic electron ion temperature gradient (ITG) simulations where it was found that {alpha}{sub E}{approx_equal}1. The results presented in this paper show that the quench rule also applies in the presence of kinetic electrons for long-wavelength transport down to the ion gyroradius scale. Without parallel velocity shear, the electron and ion transport is quenched near {gamma}{sub E}/{gamma}{sub max}{approx_equal}2 ({alpha}{sub E}{approx_equal}1/2). When the destabilizing effect of parallel velocity shear is included in the simulations, consistent with purely toroidal rotation, the transport may not be completely quenched by any level of ExB shear because the Kelvin-Helmholtz drive increases {gamma}{sub max} faster than {gamma}{sub E} increases. Both ITG turbulence with added trapped electron drive and electron-directed and curvature-driven trapped electron mode turbulence are considered.
- OSTI ID:
- 20764301
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 6 Vol. 12; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
Similar Records
The effect of plasma shaping on turbulent transport and ExB shear quenching in nonlinear gyrokinetic simulations
Coupled ion temperature gradient and trapped electron mode to electron temperature gradient mode gyrokinetic simulations