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Abstract

High resolution XUV spectra from JET plasmas have been recorded by a Schwob-Fraenkel 2 m radium grating duo multichannel spectrometer (KT4). Located on Octant no.3, the instrument views a midplane horizontal chord at a slight angle (11circ35') to the major radius. The total wavelength range is 10-340 AA with a measured spectral resolution (FWHM) of about 0.2 AA (600 grooves/mm grating). Line peaks can be measured to an accuracy of approximately 0.05 AA in the first grating order, corresponding to an uncertainty of one pixel. Two moveable scanning detectors allow simultaneous observations of two sections of the spectra, each covering 20 to 60 AA depending on the position of the detector carriages on the Rowland circle. One hundred and twenty-seven spectra per detector may be recorded during a JET plasma discharge with a time resolution of 164 ms. Spectra have been systematically investigated under various plasma conditions. Several examples of spectra are presented as well as examples of line time histories chosen in such a way to point out the advantages of the instrument. Doppler shifts and widths of strong spectral lines have been measured. In this case line widths and relative peak positions can be measured with an uncertainty of about 0.1 pixel. These measurements, in combination with impurity transport code calculations, have been used in infer radial profiles of plasma toroidal rotation velocity during neutral beam injection and of impurity ion temperature. For Ni XXVI, ion temperatures approaching 10 keV and toroidal rotation velocities up to 3times105 m/s have been obtained. The intercombination to resonance line intensity ratio of He-like CV has been studied and used to deduce electron temperatures at the radial position of the CV emission shell. Depending upon various plasma conditions and modifications in the plasma edge behaviour, temperatures in the range of 140 to 300 eV have been observed. Cl contamination has been frequently observed and unusual elements such as Fe, Mo, and Cu have been identified in some discharges.

Additional information

Authors: SAOUTIC B, JET JOINT UNDERTAKING, ABINGDON, UK;RAMETTE J, JET JOINT UNDERTAKING, ABINGDON, UK;MATTIOLI M, JET JOINT UNDERTAKING, ABINGDON, UK;DENNE B, JET JOINT UNDERTAKING, ABINGDON, UK;BEHRINGER K, JET JOINT UNDERTAKING, ABINGDON, UK;MAGYAR G, JET JOINT UNDERTAKING, ABINGDON, UK;PEACOCK N, JET JOINT UNDERTAKING, ABINGDON, UK;RAVESTEIN A, JET JOINT UNDERTAKING, ABINGDON, UK;SCHWOB J L JET JOINT UNDERTAKING, ABINGDON, UK, JET JOINT UNDERTAKING, ABINGDON, UK
Bibliographic Reference: REPORT JET-R(87)14, 1987, AVAILABILITY: JET, ABINGDON, UK
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