ANOMALOUS PERTURBATIVE TRANSPORT IN TOKAMAKS DUE TO DRIFT-WAVE TURBULENCE

A new method for calculating the anomalous transport in tokamak plasmas is presented. The renormalized nonlinear plasma response function is derived using the direct-interaction approximation (DIA). A complete calculation for the case of electrostatic drift-wave turbulence is presented. Explicit expressions for all coefficients of the anomalous transport matrix relating particle and heat fluxes to density and temperature gradients in the plasma are obtained. The anomalous transport matrix calculated using the DIA does not have the Onsager symmetry. As an example of application, the parameters of the Texas Experimental Tokamak (TEXT) [Nucl. Technol. Fusion 1, 479 (1981)] are used to evaluate all transport coefficients numerically, as well as the spectrum modulation. The relation between the theoretical results and the experimental data is discussed. Although this paper focuses on electron transport for simplicity, the method can also be used to calculate anomalous transport due to ion instabilities, such as the ion-temperature-gradient instability

On Solving the Coronal Heating Problem

This article assesses the current state of understanding of coronal heating, outlines the key elements of a comprehensive strategy for solving the problem, and warns of obstacles that must be overcome along the way.Comment: Accepted by Solar Physics; Published by Solar Physic

ANOMALOUS ELECTRON HEAT-TRANSPORT DRIVEN BY LOW-FREQUENCY ELECTROMAGNETIC TURBULENCE

We consider the anomalous electron and heat transport in a tokamak plasma. The electrons are described by the nonlinear drift-kinetic equation. We analyze transport through the averaged response function in the presence of drift-Alfvén wave turbulence. In contrast to recent findings by Terry, Diamond, and Hahm, we conclude that magnetic fluctuations lead to a substantial transport of both parallel and perpendicular energies. The latter, previously neglected, is found to be significant and of the order of the test-particle diffusion

ANOMALOUS PERTURBATIVE TRANSPORT IN TOKAMAKS DUE TO DRIFT-ALVEN-WAVE TURBULENCE

The method developed in Thoul, Similon, and Sudan [Phys. Plasmas 1, 579 (1994)] is used to calculate the transport due to drift-Alfven-wave turbulence, in which electromagnetic effects such as the fluttering of the magnetic field lines are important. Explicit expressions are obtained for all coefficients of the anomalous transport matrix relating particle and heat fluxes to density and temperature gradients in the plasma. Although the magnetic terms leave the transport by trapped electrons unaffected, they are important for the transport by circulating electrons