| 2 (2007) | |||||||||||||
Abstract | |||||||||||||
| Much progress has been made in simulating tokamak turbulent transport using both gyrofluid and gyrokinetic particle techniques. Recent simulations have focused on Ion Temperature Gradient (ITG) driven electrostatic turbulence, a potential candidate for explaining turbulence in some parameter regimes, and have explored experimentally-relevant physics issues such as the long-wavelength peak in measured spectra, the important role of sheared flows in turbulence, and the scaling of the transport with normalized gyroradius ae i =a and other parameters. This paper presents the first nonlinear gyrofluid simulations which simultaneously include trapped-electron effects (for arbitrary collisionality) as well as the ion temperature gradient drives, in 3-D toroidal simulations capable of high resolution. This enables more realistic comparisons with experiments, and provides the full transport matrix (of electron and ion heat and particle fluxes), so that such issues as particle pinches or convection multipliers can be investigated. A relatively sophisticated trapped-electron model is used which retains pitch-angle dependence throughout. This is potentially important for advanced tokamak regimes (negative shear, second stability) where a major fraction of the trapped particles have favorable drift. We also present initial linear results including the passing electron fluid equations needed to get fully electro-magnetic fluctuations (i.e., "finite fi " effects which introduce coupling between drift-like and MHD-like modes) to look for a possible fi dependence of the transport. 1. | |||||||||||||
Details der Publikation | |||||||||||||
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