EFDA-JET-CP(04)01/08

Fluctuation Measurements Using a 5-Pin Triple Probe in the JET Boundary Plasma

A new multi-probe system has been developed to investigate the importance of electron temperature fluctuations on turbulent transport in the JET boundary plasma. The compact 5-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 new 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 new 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.
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EFDC040108 1.04 Mb