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Development of Short-Wavelength Far-Infrared Lasers and Optical Elements for Plasma Diagnostics

Kazuya NAKAYAMA, Masahiro TOMIMOTO, Shigeki OKAJIMA, Kazuo KAWAHATA¹⁾, Kenji TANAKA¹⁾, Tokihiko TOKUZAWA¹⁾, Tsuyoshi AKIYAMA¹⁾ and Yasuhiko ITO¹⁾

Chubu University, Kasugai, Aichi 487-8501, Japan

1)

National Institute for Fusion Science, Toki, Gifu 509-5259, Japan

(Received 10 December 2006 / Accepted 11 March 2007 / Published 20 November 2007)

Abstract

Powerful 48- and 57-μm CH₃OD lasers pumped by a 9R(8) CO₂ laser have been developed to establish a new two-color FIR laser interferometer system for high density and large volume plasma diagnostics. To design the collimated beams for the interferometer, the beam profiles and the divergence angles have been measured for the 48- and 57-μm CH₃OD lasers oscillated simultaneously. Water vapor absorptions for the laser wavelengths have been measured at 22 °C C to realize an efficient transmission line. Optical constants and transmittance and reflectance of crystal quartz, silicon, CVD-diamond, polyethylene sheet, Mylar film, TPX plate, metal mesh and wire grid have been measured to design the optical components (observation windows and beam splitters) in the 48- and 57-μm laser interferometer system.

Copyright (c) 2007 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

far-infrared (FIR) laser, water vapor absorption of FIR laser beam, refractivie index and absorption coefficient for FIR region, FIR laser interferometer, plasma diagnostics

DOI: 10.1585/pfr.2.S1114

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References

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This paper may be cited as follows:

Kazuya NAKAYAMA, Masahiro TOMIMOTO, Shigeki OKAJIMA, Kazuo KAWAHATA, Kenji TANAKA, Tokihiko TOKUZAWA, Tsuyoshi AKIYAMA and Yasuhiko ITO, Plasma Fusion Res. 2, S1114 (2007).