Edge plasma and fluctuations in TFTR

Edge fluctuations and their associated transport have been measured in TFTR with a fast reciprocating drive shaft fitted with a Langmuir probe array specially designed to withstand high power density and to provide spatial resolution required for fluctuation measurements. Simultaneous measurements of plasma potential, electron temperature and density in the scrape-off layer (SOL) and in the edge region just inside the last-closed flux surface (LCFS) were obtained to characterize the edge fluctuations in ohmic discharges. Significant changes in the properties of the fluctuations in the SOL were observed in both Supershot and H-mode plasmas.