Measured and simulated poloidal asymmetries of the FTU SOL in the toroidallimiter configuration

The scrape-off layer (SOL) of FTU in the magnetic configuration generated b y a TZM (Molybdenum) toroidal limiter has been studied by an array of recip rocating Langmuir probes extended over a large part of the poloidal angle, and the results have been compared with the 2-dimensional multifluid SOL co de EPIT. A comparison with the previous poloidal limiter configuration with the same main plasma conditions, showed at the last closed magnetic surfac e (LCMS) longer and more poloidally uniform connection lengths, and a corre sponding better uniformity of SOL plasma parameters. Asymmetry of electron density is observed, which can be associated with the recycling of plasma n ear the toroidal limiter plates in a configuration with long connection len gths. Electron temperature appears to be less dependent of power entering t he SOL than in the old poloidal limiter configuration. Experimentally obser ved dependence of the edge plasma condition on L-con has been confirmed by the results of the 2D code EPIT. (C) 1999 Elsevier Science B.V. All rights reserved.