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Abstract

This report describes the design of a LIDAR (Light Detection and Ranging) Thomson scattering system. The time-resolved measurement of the backscattered light from a subnanosecond laser enables spatial resolution via time-of-flight measurements. A spatial resolution of 12 cm is achieved by iodine laser in combination with microchannelplate photomultipliers and 1 GHz oscilloscope. The statistical errors of electron temperature and density measurements are calculated. Several laser input and collection optics for measuring vertical spatial profiles over a 2.5 m chord length are examined and compared. A spatial scanning option is considered; suppression of stray light dealt with and alignment and calibration methods discussed. The feasibility of 1 Hz operation over a sequence of 10 shots is demonstrated successfully. The performance of a high speed MCP photomultiplier is investigated experimentally: with good results. In a full-scale optical set-up using a low energy, frequency doubled iodine laser, it is shown that the stray light constitutes no problem for the Thomson scattering experiments. In summary, the design study shows that the proposed LIDAR Thomson scattering technique is applicable to JET and to future large fusion devices.

Additional information

Authors: BREDERLOW G, MAX-PLANCK-INSTITUT FUR PLASMAPHYSIK, GARCHING BEI MUNCHEN (GERMANY);GRUBER J E, MAX-PLANCK-INSTITUT FUR PLASMAPHYSIK, GARCHING BEI MUNCHEN (GERMANY);HIRSCH K, MAX-PLANCK-INSTITUT FUR PLASMAPHYSIK, GARCHING BEI MUNCHEN (GERMANY);ROEHR H, MAX-PLANCK-INSTITUT FUR PLASMAPHYSIK, GARCHING BEI MUNCHEN (GERMANY);SALZMANN H, MAX-PLANCK-INSTITUT FUR PLASMAPHYSIK, GARCHING BEI MUNCHEN (GERMANY);WITTE K J MAX-PLANCK-INSTITUT FUR PLASMAPHYSIK, GARCHING BEI MUNCHEN (GERMANY), MAX-PLANCK-INSTITUT FUR PLASMAPHYSIK, GARCHING BEI MUNCHEN (GERMANY)
Bibliographic Reference: WRITE TO MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, 8046 GARCHING BEI MUNCHEN (GERMANY), MENTIONING REPORT IPP 1/299, 1984
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