The European Atomic Energy Community, Association EURATOM - University of Latvia (AEUL),  FP7   
"Stochastization of magnetic fields and magnetic reconnection"

Dates: 01.01.2010.-31.12.2010.
Responsible person: O.Dumbrajs
Tel. 67187480 


An important goal of fusion research with magnetically confined plasmas is to maximize the achievable plasma pressure. In a tokamak, neoclassical tearing modes (NTMs), i.e. magnetic islands with poloidal and toroidal  mode numbers driven unstable by the loss of bootstrap current inside the island, are of major concern as they are considered to be the most severe limitation to the maximum achievable plasma pressure. Developing of such magnetic islands requires resistive reconnection of the magnetic field lines. The resistive reconnection assumes a resistive diffusion of the magnetic field through the plasma which is a rather slow process. It was found in the ASDEX Upgrade that some MHD processes involving these tearing modes have much faster time scales compared with the resistive diffusion time. These processes involve the interaction of several modes and can be explained by stochastization of the magnetic field lines. Stochastization means that for the trajectory of an object time averaging and spatial averaging can be exchanged. This means also that the trajectory of an object starting from any point in a stochastic area comes infinitely close to any other point in this volume.
The main objective of the proposed project is development of tools for studying the role of stochastization in fast MHD phenomena in ASDEX Upgrade.