Divertor Langmuir Probe Measurements in JET

In this paper, results from the array of fixed Langmuir probes in the JET Mark I divertor are presented. During low density discharges there is good agreement between single and triple probes. At higher density, near the onset of divertor detachment, very low values of the electron to ion saturation current (even < 1) are observed which results in an overestimation of the electron temperature, particularly by the triple probe. Alternative methods of probe interpretation are applied and comparisons carried out with independent measurements. The consistency of probe measurements during H-mode discharges are also briefly discussed.