ISSI Team 132


Comparative study of turbulence and anomalous transport

in space and fusion plasmas


The intent of the proposed Team is to perform a comparative study of space and fusion plasma turbulence in view of applications to the anomalous transport problem. The Team purpose is the interpretation of data in the broader context of sharing data from multi-point space missions and from fusion devices, applying various approaches and methods developed in space plasma and fusion research in order to reach a level of quantitative estimates of the turbulent transport in plasma boundary layers. The desired outcomes are the improvement of the predictive power of turbulent cascade models, providing credible experiment interpretation, and building a bridge between the measurable statistical properties of different plasmas and theoretical derivations of the transport scaling.

Plasma fluctuations observed in the turbulent plasma boundary layers at Earth's magnetopause and in fusion devices exhibit self-similar behavior, suggesting that the properties of plasma boundary turbulence are universal. In the magnetopause boundary layer, fluctuations of magnetic field and ion flux recorded by the Interball-1 spacecraft unraveled scale-invariance and intermittency of the turbulence, similar to measurements in fusion devices like tokamaks, stellarators and linear plasma machines. The Team intends to compare data from these fusion devices with data from Cluster and Interball-1 in the magnetopause boundary layer. This comparison has the advantage of exploiting the experimental and theoretical experience of the fusion community for space purposes. Order-of-magnitude estimates [Savin et al., 2005] demonstrate that classical diffusion in the turbulent cusp-boundary layer is capable of populating the dayside magnetosphere. Application of software developed for the fusion plasma [Budaev et al., 2006] to a characteristic Interball-1 sample interval exhibited features of super-diffusion and multifractality that is very similar to that found in fusion boundary layers. Moreover, in space we can make excellent in situ observations at small scales, whereas in fusions plasmas one can better control the larger scales and structures along with the integrated plasma losses. We would also address the role of coherent structures, in particular, it would use the spatial Cluster resolution.

The Team is complementary to International meetings. These deal with the general comparison of space and laboratory plasmas. In contrast, the Team concentrates solely on the statistical properties of boundary layer turbulence. The interdisciplinary orientation of ISSI provides the unique opportunity for specialists from both fields, space and fusion plasmas, to join in common data analyses and interpretations. Starting from one selected Interball case we will proceed to Cluster observations, which are unique for studying the spatial dependence of fluctuations. Applying algorithms for statistical analysis of fusion plasma fluctuations we expect to obtain quantitative estimates of the super-diffusive mass flux in the magnetopause and cusps. These estimates will be compared with predictions from computer simulations and theory of turbulence.

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