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Liao, X.

Publications and source records attributed to Liao, X..

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Microturbulence in DIII-D tokamak pedestal. III. Effects of collisions

Gyrokinetic simulations of the H-mode pedestal in DIII-D discharge 145701 find that the kinetic ballooning mode (KBM) is the most unstable mode for low toroidal numbers (n ≤ 25) and that the trapped electron mode (TEM) dominates over the KBM at higher toroidal mode numbers for realistic pressure gradients in the pedestal. Collisions reduce the TEM growth rate but have little effects on the KBM. KBM has the conventional ballooning mode structure peaking at the outer mid-plane, while TEM has an unconventional mode structure peaking at the top and bottom of the poloidal plane.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Microturbulence in DIII-D tokamak pedestal. IV. Electrostatic turbulent transport

Gyrokinetic simulations of electrostatic microturbulence in the edge plasmas of DIII-D shot 131997 find that the geodesic acoustic mode (GAM) is generated after nonlinear saturation both at the pedestal top and in the peak gradient region, and in turn, regulates the turbulence in both regions. Collisions significantly reduce the GAM amplitude and the associated GAM modulation of the turbulence in both regions. Collisions have little effects on the ion temperature gradient turbulent transport level at the pedestal top. Finally, on the other hand, collisional damping of the TEM significantly reduces the turbulent transport level in the peak gradient region.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Magnetic curvature effects on plasma interchange turbulence

The magnetic curvature effects on plasma interchange turbulence and transport in the Z-pinch and dipole-like systems are explored with two-fluid global simulations. By comparing the transport levels in the systems with a different magnetic curvature, we show that the interchange-mode driven transport strongly depends on the magnetic geometry. For the system with large magnetic curvature, the pressure and density profiles are strongly peaked in a marginally stable state and the nonlinear evolution of interchange modes produces the global convective cells in the azimuthal direction, which lead to the low level of turbulent convective transport.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗