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Proceedings Paper

High-power ruby and alexandrite lasers for LIDAR-Thomson scattering diagnostics
Author(s): C. Gowers; A. Gadd; Kurt Hirsch; P. Nielsen; H. Salzmann
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Paper Abstract

By combining the time-of-flight or LIDAR principle with a Thomson backscatter diagnostic, spatial profiles of the electron temperature and density can be measured with a single set of detectors for all spatial points. The technique was demonstrated for the first time on the JET tokamak and has been in routine operation since July 1987. Originally a ruby laser (3 J pulse energy, 300 Ps pulse duration, 0.5 Hz repetition rate) was used together with a 700 MHz bandwidth detection and registration system which yielded a spatial resolution of about 12 cm. A large filter spectrometer with 6 spectral channels covering the wavelength range 400 - 800 nm gives a dynamic range for the temperature measurements of 0.2-20 keV. The original system is described, examples of measurements are given and compared with the results of other diagnostics. The system is being upgraded to make measurements at 10 Hz and a major component of the new system is an Alexandrite laser (1-2 J pulse energy, 350+1-50 ps pulse duration, 10 Hz repetition rate) which is currently being constructed. The new laser and other technological improvements being incorporated into the upgraded diagnostic will also be described.

Paper Details

Date Published: 1 August 1990
PDF: 12 pages
Proc. SPIE 1277, High-Power Solid State Lasers and Applications, (1 August 1990); doi: 10.1117/12.20594
Show Author Affiliations
C. Gowers, JET Joint Undertaking (United Kingdom)
A. Gadd, JET Joint Undertaking (United Kingdom)
Kurt Hirsch, Univ. Stuttgart (Germany)
P. Nielsen, JET Joint Undertaking (United Kingdom)
H. Salzmann, Max-Planck-Institut fuer Plasm (Germany)

Published in SPIE Proceedings Vol. 1277:
High-Power Solid State Lasers and Applications
Clive L. M. Ireland, Editor(s)

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