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Title: Development of a laser cleaning method for the first mirror surface of the charge exchange recombination spectroscopy diagnostics on ITER

A set of optical diagnostics is expected for measuring the plasma characteristics in ITER. Optical elements located inside discharge chambers are exposed to an intense radiation load, sputtering due to collisions with energetic atoms formed in the charge transfer processes, and contamination due to recondensation of materials sputtered from different parts of the construction of the chamber. Removing the films of the sputtered materials from the mirrors with the aid of pulsed laser radiation is an efficient cleaning method enabling recovery of the optical properties of the mirrors. In this work, we studied the efficiency of removal of metal oxide films by pulsed radiation of a fiber laser. Optimization of the laser cleaning conditions was carried out on samples representing metal substrates polished with optical quality with deposition of films on them imitating the chemical composition and conditions expected in ITER. It is shown that, by a proper selection of modes of radiation exposure to the surface with a deposited film, it is feasible to restore the original high reflection characteristics of optical elements.
Authors:
 [1] ;  [2] ; ; ; ;  [1] ;  [2]
  1. National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation)
  2. State Research Center Troitsk Institute for Innovation and Fusion Research (TRINITI) (Russian Federation)
Publication Date:
OSTI Identifier:
22471866
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Atomic Nuclei; Journal Volume: 78; Journal Issue: 14; Other Information: Copyright (c) 2015 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CLEANING; CONTAMINATION; DEPOSITION; FIBERS; FILMS; ITER TOKAMAK; LASER RADIATION; LASERS; METALS; MIRRORS; OPTICAL PROPERTIES; OXIDES; PLASMA; PLASMA DIAGNOSTICS; PULSED IRRADIATION; REFLECTION; REMOVAL; SPUTTERING