Turbulence and transport in multi ion species fusion plasmas

SNIC 2018/3-33


SNAC Medium

Principal Investigator:

Pär Strand


Chalmers tekniska högskola

Start Date:


End Date:


Primary Classification:

10303: Fusion, Plasma and Space Physics




Fusion energy research is entering into a new phase with the advent of the ITER device which is currently being constructed in Southern France. In parallel to the construction of the device an increased effort on the physics understanding and modelling with the aim of achieving an improved predictive capacity is undertaken. In this context we study aspects of turbulent heat and particle transport using both the nonlinear gyrokinetic code GENE and a reduced physics but highly efficient drift wave based fluid model. The study of multiple ion species plasmas is motivated by the JET DT campaign, planned for 2019-20. In this context, interpretative and predictive fluid simulations which retain up to at least four or five active particle species will be carried out, including also the He-ash, preparing the way for future turbulence studies of ITER DT plasmas with Q>10. Another JET experiment of interest in this regard is the particle transport studies in D, H and T plasmas planned for 2018-2019 where the isotope effect on the diffusive and convective velocity will be compared to theoretical predictions. The analysis of the results obtained in H and D plasmas has already started. Additionally, a basic understanding of plasma stability and confinement in the presence of energetic alpha particles is needed in order to design plasma scenarios for ITER that are compatible with the strong self-heating that defines the burning plasma regime. Accordingly, understanding the plasma stability and transport properties of the burning plasma regime requires a self-consistent multiple species treatment of the plasma and its interaction with the energetic particles. Another relevant topic of research is the interaction between neoclassical and the dominant turbulent transport. In the modelling of heat transport in tokamaks turbulent and neoclassical effects are usually treated separately, also by use of specialized codes for higher efficiency. This is justified in the flux-tube limit, where the perpendicular length scales of the two effects are assumed to be completely separate. For small machines or regions with steep gradients (typically transport barriers), however, it is necessary to consider the global density and temperature profiles and the radially varying geometry to capture nonlocal effects. In this case interactions between the neoclassical background and the turbulent fluctuations are expected. The resources of this project would support a larger ongoing effort studying this phenomenon.