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Gamma-ray irradiation effects on optical coatings and polarizers for edge Thomson scattering system in ITER
- Source :
- Fusion Engineering and Design. 160:111846
- Publication Year :
- 2020
- Publisher :
- Elsevier BV, 2020.
-
Abstract
- This paper reports the gamma-ray irradiation effects on optical coatings and polarizers to be used in the ITER edge Thomson scattering system (ETS). Outside a diagnostic port-plug, in the Interspace, a total dose of the order of 1 MGy is expected through 20 years of ITER operation. In this study, gamma-ray irradiation experiments were performed up to 10 MGy. A high peak power laser beam, i.e. a pulse energy of 5 J and a pulse duration of ∼4 ns, is needed for a Thomson scattering measurement in ITER. Laser-induced damage threshold (LIDT) of anti-reflection (AR) and high-reflection (HR) coatings at the laser wavelengths after gamma-ray irradiation were investigated. LIDT of AR coating for 0° injections was more likely higher for the irradiated samples at a wavelength of 1064 nm. Regarding HR coatings, LIDT was not noticeably degraded by gamma-ray irradiation. Regarding polarizers, no degradation of transmission and extinction ratio was observed at visible and near infrared wavelength ranges when a wire-grid polarizer substrate is made of fused silica. Since a signal of ETS is almost linearly polarized, a wire-grid polarizer enables to improve signal to noise ratio of electron temperature and density measurements by Thomson scattering in ITER.
- Subjects :
- Materials science
Extinction ratio
Thomson scattering
business.industry
Mechanical Engineering
Pulse duration
Polarizer
Laser
01 natural sciences
010305 fluids & plasmas
law.invention
Anti-reflective coating
Optics
Optical coating
Nuclear Energy and Engineering
law
0103 physical sciences
General Materials Science
Irradiation
010306 general physics
business
Civil and Structural Engineering
Subjects
Details
- ISSN :
- 09203796
- Volume :
- 160
- Database :
- OpenAIRE
- Journal :
- Fusion Engineering and Design
- Accession number :
- edsair.doi...........0fc814baf4417ef9cc595b6f1b90bcfe