Fluctuation measurements using a five-pin triple probe in the Joint European Torus boundary plasma

A multi-probe system has been developed to investigate the importance of electron temperature fluctuations turbulent transport in the Joint European Torus boundary plasma. The compact five-pin triple probe has been designed to reduce the phase delay of fluctuations due to the finite pin separation in the standard triple probe technique, while still avoiding the effects of probe shadowing. This probe has been found to have advantages over the standard triple probe in the region close to the separatrix (r-rsep<0.01 m), where the fluctuation wavelength is large. Importantly, results obtained with the probe support the standard estimation of cross-field particle flux, which ignores temperature fluctuations. They cannot be ignored, however, in the estimation of energy losses since measurements show that the conducted energy may be as large as the convected component