Gyrokinetic Simulation of Electromagnetic Turbulence and Transport in Tokamaks
Yang Chen
The GyrokineticElectroMagnetic (GEM) code developed at CIPS in the past few years has
been extended to include arbitrary number of minority ions and a beam ion species.
The code is currently applied to spherical tokamak plasmas. An important question is
whether micro-tearing modes can cause significant electron transport in such devices.
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Hybrid Simulation of MHD Waves
Yang Chen
Long wave length MagnetoHydroDynamics (MHD) waves are difficult to simulate using kinetic electrons. Kinetic effects of the ions, such as the finite Larmor radius effect and the orbit width effect, are important. For such phenomena, an alternative to kinetic electron simulation is to treat the electrons as massless fluid. In order to recover MHD waves such as the toroidicity-induced-Alfvén-eigenmodes, developing a hybrid kinetic ion fluid electron model that shows explicitly the MHD limit is crucial.
Effects of Magnetic Perturbation on Turbulent Transport in Shaped Plasmas
Yang Chen, Scott Parker
In order for the fusion reaction to take place in a tokamak in a self-sustained manner,
Ìýthe plasma must be heated and maintained at a certain level of density and temperature. However, instabilities tend to develop in such plasmas which either terminate the plasma or lead to saturated turbulence and enhanced particle and energy transport. The study of such instabilities and turbulence can be carried out using the GEM code. The GEM code can handle arbitrary equilibrium profiles and flux-surface shapes. Full electron dynamics and magnetic perturbation are included. GEM simulations indicate that both elongation and Shafranov shift tend to shift the instabilities toward higher toroidal mode numbers. Effect of magnetic perturbation is generally weaker than has been observed in flux-tube simulations.