Impurity transport in magnetically confined fusion plasmas
Doctoral thesis, 2015

Nuclear fusion is foreseen as one of the options for future energy production. In establishing the physics basis of future magnetic fusion reactors it is necessary to find scenarios where the impurity content in the core can be kept low. High concentration of impurities leads to dilution and radiative energy losses and is detrimental for fusion reactivity. Therefore the understanding and control of impurity transport is of critical importance for the success of fusion. Impurity transport in fusion plasmas is often dominated by turbulent fluctuations, but in certain scenarios, and in particular for 3D magnetic configurations, the collisional contribution can be significant. This thesis addresses the effect of poloidal asymmetries on turbulent impurity transport in axisymmetric devices (tokamaks), and collisional impurity transport in 3D configurations (stellarators). In tokamaks, transport driven by ion temperature gradient mode and trapped electron mode turbulence is studied through gyrokinetic modelling. It is shown that poloidal asymmetries can significantly affect radial transport, and could contribute in reducing the impurity core content. The theoretical predictions are compared to experimental data from the Alcator C-Mod tokamak, where poloidal asymmetries are induced by radiofrequency heating. Furthermore, we show that collisional transport in stellarators can cause very strong impurity accumulation, highlighting this as one of the major concerns for 3D devices as a reactor concept. We also investigate how the bootstrap current is affected by the presence of impurities.

fusion plasma physics

transport

turbulence

tokamak

gyrokinetic

impurity

stellarator

drift-kinetic

poloidal asymmetry

PJ-salen, Fysikgården 1, Chalmers University of Technology
Opponent: Dr. Olivier Sauter, Center for Research in Plasma Physics, École Polytechnique Fédérale de Lausanne, Switzerland

Author

Albert Mollén

Chalmers, Applied Physics, Nuclear Engineering

Turbulent transport of impurities and their effect on energy confinement

Plasma Physics and Controlled Fusion,; Vol. 55(2013)p. 074012-

Journal article

On collisional impurity transport in nonaxisymmetric plasmas

Journal of Physics: Conference Series,; Vol. 561(2014)p. 012012-

Paper in proceedings

Impurity transport in Alcator C-Mod in the presence of poloidal density variation induced by ion cyclotron resonance heating

Plasma Physics and Controlled Fusion,; Vol. 2014(2014)p. 124005-

Journal article

Effect of poloidal asymmetries on impurity peaking in tokamaks

Physics of Plasmas,; Vol. 19(2012)p. 052307-

Journal article

Impurity transport in trapped electron mode driven turbulence

Physics of Plasmas,; Vol. 20(2013)

Journal article

Driving Forces

Sustainable development

Subject Categories

Physical Sciences

Fusion, Plasma and Space Physics

Areas of Advance

Energy

Roots

Basic sciences

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

ISBN

978-91-7597-192-6

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3873

PJ-salen, Fysikgården 1, Chalmers University of Technology

Opponent: Dr. Olivier Sauter, Center for Research in Plasma Physics, École Polytechnique Fédérale de Lausanne, Switzerland

More information

Created

10/7/2017