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Gamma-ray irradiation effects on optical coatings and polarizers for edge Thomson scattering system in ITER
- Publication Year :
- 2020
-
Abstract
- This paper reports the gamma-ray irradiation effects on optical coatings and polarizers to be used in the ITERedge Thomson scattering system (ETS). Outside a diagnostic port-plug, in the Interspace, a total dose of the orderof 1 MGy is expected through 20 years of ITER operation. In this study, gamma-ray irradiation experiments wereperformed 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-re-flection (AR) and high-reflection (HR) coatings at the laser wavelengths after gamma-ray irradiation were in-vestigated. LIDT of AR coating for 0° injections was more likely higher for the irradiated samples at a wavelengthof 1064 nm. Regarding HR coatings, LIDT was not noticeably degraded by gamma-ray irradiation. Regardingpolarizers, no degradation of transmission and extinction ratio was observed at visible and near infrared wa-velength ranges when a wire-grid polarizer substrate is made of fused silica. Since a signal of ETS is almostlinearly polarized, a wire-grid polarizer enables to improve signal to noise ratio of electron temperature anddensity measurements by Thomson scattering in ITER.
Details
- Database :
- OAIster
- Notes :
- English
- Publication Type :
- Electronic Resource
- Accession number :
- edsoai.on1375203312
- Document Type :
- Electronic Resource