15th Topical Conference on High Temperature Plasma Diagnostics, 19 a 22 de Abril de 2004, San Diego, USA

	Fluctuations Measurements Using a 5-pin Triple Probe in the JET Boundary Plasma
	C. Silva, C. Hidalgo, B. Gonçalves, K. Erents, G. Matthews, M.A. Pedrosa e R. Pitts
	Resumo
	Temperature fluctuations are difficult to measure and therefore often ignored when estimating the fluctuations induced transport. The aim of this work is to use a compact probe to study fluctuations and to evaluate the importance of temperature fluctuations, in turbulent transport. The main disadvantage of the triple probe method is that measurements are not local. To partially compensate for this problem a 5-pin probe has been installed and operated at JET. The electron temperature has been evaluated using a modified triple probe method where one tip was operated at a fixed applied voltage (Vap ) and the remaining two tips measured the floating potential, Vf , and the ion saturation current, Isart . Vf and Isart were measured at two poloidally symmetric positions in relation to the pin operated at Vap , compensating therefore for fluctuations with wavelengths larger than the distance between pins. The poloidal dimension of the probe array, ~5 mm, allows the measurement of the plasma parameters in a dimension smaller than the typical correlation length of fluctuations.