Impurity transport in trapped electron mode driven turbulence

Abstract

Trapped electron mode turbulence is studied by gyrokinetic simulations with the GYRO code and an analytical model including the effect of a poloidally varying electrostatic potential. Its impact on radial transport of high-Z trace impurities close to the core is thoroughly investigated and the dependence of the zero-flux impurity density gradient (peaking factor) on local plasma parameters is presented. Parameters such as ion-to-electron temperature ratio, electron temperature gradient and main species density gradient mainly affect the impurity peaking through their impact on mode characteristics. The poloidal asymmetry, the safety factor and magnetic shear have the strongest effect on impurity peaking, and it is shown that under certain scenarios where trapped electron modes are dominant, core accumulation of high-Z impurities can be avoided. We demonstrate that accounting for the momentum conservation property of the impurity-impurity collision operator can be important for an accurate evaluation of the impurity peaking factor.

30 pages, 10 figures

References in corpus (3)

• Impurity transport in temperature gradient driven turbulence
• Possible mechanism responsible for observed impurity outward flow under radio frequency heating
• Particle transport in density gradient driven TE mode turbulence

Cited by in corpus (6)

• Isotopic dependence of impurity transport driven by ion temperature gradient turbulence
• Effects of the equilibrium model on impurity transport in tokamaks
• Impact of impurities on zonal flow driven by trapped electron mode turbulence
• Impurity transport in Alcator C-Mod in the presence of poloidal density variation induced by ion cyclotron resonance heating
• Argon, neon, and nitrogen impurity transport in the edge and SOL regions of a Tokamak
• Radio frequency induced and neoclassical asymmetries and their effects on turbulent impurity transport in a tokamak