The series of international workshops on “Stochasticity in Fusion Plasmas” – in short “SFP” – was initiated by Forschungszentrum Jülich in 2003. From March 2 – 4, Chairman Bernhard Unterberg and scientific secretary Oliver Schmitz welcomed more than 50 scientists from all over the world to Jülich for the fourth SFP workshop to discuss the recent progress in the understanding of stochastic processes in nuclear fusion. Or in plain English one would say, the experts were exploring the chaotic processes within the plasma. These have been found to be quite useful when it comes to influencing or even avoiding turbulences (see the article on the Transport Topical Group in this issue).

Uncontrolled instabilities in the plasma edge, such as, Edge Localised Modes (ELMs) release huge amounts of energy very suddenly. In high-energy machines, like ITER, they will limit the wall and divertor lifetime and may cause the degradation of the plasma performance by increased impurity release. Hence, ELMs and the ways to mitigate them by generating a stochastic magnetic field layer in the plasma edge have been of utmost interest at the workshop this year. With this method one could demonstrate complete supression of ELMs at DIII-D tokamak in San Diego and ELM mitigation at JET. The Dynamic Ergodic Divertor (DED) is a supporting experiment in this context which elucidates the basic physics aspects of stochastic magnetic edge layers. It is a subsystem of Jülich’s TEXTOR tokamak, comprising special coils, the magnetic field of which perturbs the tokamak field at the plasma edge. In 2007, the ITER Design Review added ELM control coils to the ITER Design.

The SFP workshop series has traditionally brought together experts from universities working on basic mechanisms and those developing control schemes on present day fusion devices and also specialists planning for future devices such as ITER. The presentations at SFP 2009 have demonstrated, in a very lively way, that ITER has stimulated intense experimental and theoretical work in this challenging field of non-linear physics.

Contributions to the workshop will be published in a special issue of Nuclear Fusion. More information can be found at

For more detailed version of this article please follow the link:

Ralph P. Schorn and Bernhard Unterberg
Forschungszentrum Jülich