EFDA-JET-PR(09)41

Inboard and Outboard Electron Temperature Pedestal Profiles at JET Measured with ECE Diagnostics

In this paper a novel use of the heterodyne radiometer in JET is presented. The operation of the diagnostic has been extended to allow measuring simultaneously the pedestal temperature profile at the inboard and outboard midplane with high spatial and temporal resolution. The radiometer in JET consists of 96 closely spaced channels distributed in 4 bands that can be set up to measure either first harmonic ordinary mode or second harmonic extraordinary mode electron cyclotron emission. Access to the inboard midplane region is obtained by measuring the O-mode polarization (no harmonic overlap) using an antenna located on the low field side of the torus. To assess the potential of the ECE temperature measurements in the inboard pedestal region, a detailed analysis of ECE spectrum will be discussed. The measured electron temperature profile are presented along with the method employed to calibrate the fundamental O-mode emission, including a discussion of the main uncertainties in the analysis. The comparison of inboard and outboard temperature pedestal profiles in a variety of H-mode plasmas shows a reasonable agreement in both shape and magnitude. Plans for the further exploitation of this new experimental data are also discussed.
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EFDP09041 3.14 Mb