(TH/P8-27) Quasilinear Transport Fluxes Driven by Microinstabilities in Tokamaks

T. Fülöp1), I. Pusztai1), P. Helander2)
 
1) Chalmers University of Technology and Euratom-VR Association, Gothenburg, Sweden
2) Max-Planck-Institut für Plasmaphysik, Greifswald, Germany

Abstract.  Quasilinear transport fluxes driven by electrostatic microinstabilites in weakly-collisional tokamak plasmas are calculated by a semi-analytical approach based on a solution of the gyrokinetic equation, where collisions are modelled by a Lorentz operator. Scalings with collisionality, magnetic drift frequency, diamagnetic frequency and ratio of the density and temperature scale lengths have been determined. The particle transport due to ion temperature gradient (ITG) modes can be reversed from inward to outward as electron collisions are introduced, if the plasma is far from marginal stability. However, if the plasma is close to marginal stability, collisions may even enhance the inward transport. Comparison with transport fluxes calculated when collisions are modelled by an energy-dependent Krook operator shows that the sign and the magnitude of the fluxes are very sensitive to the form of the collision operator.

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