The scope of this paper is to present and benchmark the first version of a quasilinear calculation, QuaLiKiz, based on a fast linear gyrokinetic code, Kinezero [C. Bourdelle, X. Garbet, G. T. Hoang, J. Ongena, and R. V. Budny, Nucl. Fusion 42, 892 (2002)] accounting for all unstable modes and summing over a wave-number spectrum. The fluctuating electrostatic potential frequency and wave-number spectra are chosen based on turbulence measurements and nonlinear simulations results. A peculiar focus on particle transport is developed. The directions of compressibility and thermodiffusion convections of ions and electrons are analytically derived for passing and trapped particles in both ion and electron turbulence. Also, the charge and mass dependence of trace heavy impurity convection is analytically estimated. These results are compared with quasilinear simulations done by QuaLiKiz. Finally, the impact of accounting for all unstable modes and of summing over the wave-number spectrum is shown to reverse in some cases the direction of particle fluxes.

The entropy production rate is calculated for an interchange driven turbulence both in fluid and kinetic regimes. This calculation provides a rigorous way to define thermodynamical forces and fluxes. It is found that the forces are the gradients of density and temperature normalized to their “canonical” values, which are Lagrangian invariants of the flow. This formulation is equivalent to expressing the fluxes in terms of “curvature pinches,” where the curvature pinches are proportional to the logarithmic gradient of canonical profiles. Off diagonal terms in the transport matrix are found, which correspond to thermodiffusion and its Onsager symmetrical contribution to the heat flux. Hence, if thermodiffusion is significant, a heat pinch due to the density gradient also exists. The entropy production rate is found to be minimum when the profiles are equal to their canonical values. This property yields a generalized form of profile stiffness. However, a state where all profiles match their canonical values is not attainable because it is linearly stable.

This paper presents recent efforts to better understand and quantify charged particle transport in Hall effect thrusters (HETs). Particle-in-cell (PIC) models, hybrid models, laser induced fluorescence (LIF) measurements and collective scattering (CS) experiments are combined to get a better insight into anomalous electron transport in HETs and to increase the predictive capabilities of simulation codes.PIC models have demonstrated that plasma turbulence associated with the development of a high frequency, short wavelength azimuthal instability can be responsible for anomalous transport. Scaling laws for anomalous electron mobility have not yet been derived and hybrid models, which are more practical than PIC models for parametric studies, must use empirical, adjustable transport coefficients that can be inferred from PIC results or LIF measurements of the ion velocity distribution function. CS experiments are aimed at validating the PIC model predictions of the azimuthal instability. The CS results show the first direct experimental evidence of the azimuthal instability predicted by the PIC code. The paper illustrates the synergy between experiments and models toward a complete and quantitative understanding of the physics of HETs.