Hydrogen H(alpha) shift is measured in a plasma characterized by a noticeable coupling due to a high electron density (N(e)>/=2x10(18) cm(-3)) and a relatively low temperature (T=8900 K). The plasma is produced by a single laser breakdown in an underwater medium, creating a stable and radially homogeneous plasma. The results cannot be explained by the known contributions to the shift, which predict shifts by a factor of 2 greater than the experimental shifts. A contribution called dipole ionic-electronic shift (DIES) is introduced. The data presented in this work constitute the experimental discovery of this phenomenon. Indeed, the total theoretical shifts obtained taking into account the DIES are in excellent agreement with our experimental values.

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Fuel retention, a crucial issue for next step devices, is assessed in present tokamaks using two methods : particle balance performed during shots and post mortem analysis carried out during shutdowns between experimental campaigns. Post mortem analysis generally gives lower estimates of fuel retention than particle balance. In order to understand the discrepancy between these two methods, a dedicated experimental campaign has been performed in Tore Supra to load the vessel walls with deuterium (D) and monitor the trapped D inventory through particle balance. The campaign was followed by an extensive post mortem analysis phase. This paper presents the status of the analysis phase, in particular the assessment of the D content in gap deposits. Indeed, using combined surface analysis techniques, it was possible to derive the relative contributions of different zones of interest on the Tore Supra limiter (erosion, thick deposits, thin deposits), showing that the post mortem inventory is mainly due to codeposition (90% of the total), in particular due to gap deposits. At the present stage of analysis, 50% of the inventory deduced from particle balance has been found through post mortem analysis, a significant progress with respect to previous studies (factor 8-10 discrepancy).