MONTE-CARLO MODELING OF THE TRANSPORT IN THE STELLARATOR PERIPHERY WITH MAGNETIC ISLANDS

Two Monte Carlo methods have been developed to model the transport phe nomena of impurities in the edge plasma of stellarators taking into ac count the complex magnetic field topology in the stellarator periphery : (i) a new version of the ERO code, where the sputtered impurity atom s are followed through successive states of ionization and recombinati on during their 3D motion in the whole plasma volume; (ii) a self-cons istent set of hydrodynamic equations describing the dynamics of the pl asma and the impurities, supplemented by a kinetic equation for the de scription of the neutral particles dynamics, is solved using Monte Car lo techniques. The magnetic island structure is described by the Chiri kov-Taylor map technique, The corresponding effects are studied for di fferent cross diffusion coefficients and impurity injection positions. The results show that the existence of magnetic islands significantly influences the transport in the stellarator periphery and that the in jection of impurities into the magnetic island region leads to effecti ve plasma cooling and lowering of the energy flux to the target.