## Plasma Physics and Fusion Research

The goal of this project:

To study of the properties of the characteristic properties of plasma turbulence that lead to non-diffusive nature of the particle tracer transport in those plasmas.

Methodology

Using quantitative measures of the topological properties of the turbulent flow to connect these properties with the properties of the distribution function of the particle tracers in these turbulent flows. For this we will make use of Computational Homology. An important tool will be the software developed by the Computational Homology Project (CHomP), which, in particular, computes some topological invariants (the Betti numbers) of three-dimensional spaces. We will investigate the possibility of developing or using other tools, which allow improving the numerical resolution of the calculations. The Spanish Ministry of Science and Innovation funds this project through the grant ENE2009-07247. Main collaborators: Irene Llerena, Universidad de Barcelona, Barcelona, Spain. Luis Garcia, Universidad Carlos III, Madrid, Spain, Iván Calvo, Laboratorio Nacional de Fusión, Asociación EURATOM-CIEMAT, Madrid, Spain.

Initial results

The continuous time random walk approach allows us the construction of transport models based on the waiting times and particle flights distributions. It has been shown the connection between the distribution of particle flights and the distribution of radial extends of the connected components of the flow [1] and the connection between the large-scale cycles of the flow structure and the trapping times is explored. It is shown that the distribution of trapping times of the tracers is given by the distribution of lifetimes of the large scales cycles in the flow structure. This distribution has a power tail, which is the result of the dynamics of avalanche transport. [2]

[1] Phys. Rev.E 80, 046410 (2009)

[2] To be published in Plasma Physics and Control Fusion.