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Proceedings Paper

Window materials for high power gyrotron
Author(s): Mohammed Nurul Afsar
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Paper Abstract

At room temperature the absorption coefficient of crystalline sapphire specimen increases almost linearly with increasing frequency in the millimeter wavelength region. At cryogenic temperature the absorption coefficient value increases to about 90 GHz then decreases and shows a minimum at about 180 GHz before increasing again. The minimum around 180 GHz can be seen for 6.5 K, 30 K and 77 K The most suitable frequency for window application of sapphire at cryogenic temperature is therefore 180 GHz. Beyond 200 GHz other materials such as extra high resistivity silicon or extra high resistivity silicon coated with diamond film would certainly make a better candidate in the future. A single crystal synthetic diamond window would be the next choice. However the synthetic diamond film growth technology is in its infant state at this time. A delay of about one or two years is expected in order to reduce the graphite concentration in such a material for effective application. as a window material.

Paper Details

Date Published: 14 December 1992
PDF: 2 pages
Proc. SPIE 1929, 17th International Conference on Infrared and Millimeter Waves, 192929 (14 December 1992); doi: 10.1117/12.2298198
Show Author Affiliations
Mohammed Nurul Afsar, Tufts Univ. (United States)

Published in SPIE Proceedings Vol. 1929:
17th International Conference on Infrared and Millimeter Waves
Richard J. Temkin, Editor(s)

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