Laser damage thresholds of ITER mirror materials and first results on in situ laser cleaning of stainless steel mirrors

M. Wisse, L. Marot, Baran Eren, R. Steiner, D. Mathys, E. Meyer

Research output: Contribution to journalArticlepeer-review

Abstract

A laser ablation system has been constructed and used to determine the damage threshold of stainless steel, rhodium and single-, poly- and nanocrystalline molybdenum in vacuum, at a number of wavelengths between 220 nm and 1064 nm using 5 ns pulses. All materials show an increase of the damage threshold with decreasing wavelength below 400 nm. Tests in a nitrogen atmosphere showed a decrease of the damage threshold by a factor of 2-3. Cleaning tests have been performed in vacuum on stainless steel samples after applying mixed Al/W/C/D coatings using magnetron sputtering. In situ XPS analysis during the cleaning process as well ex situ reflectivity measurements demonstrate near complete removal of the coating and a substantial recovery of the reflectivity. The first results also show that the reflectivity obtained through cleaning at 532 nm may be further increased by additional exposure to UV light, in this case 230 nm, an effect which is attributed to the removal of tungsten dust from the surface.

Original languageEnglish
Pages (from-to)388-399
Number of pages12
JournalFusion Engineering and Design
Volume88
Issue number5
DOIs
StatePublished - Jun 2013

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering
  • General Materials Science
  • Nuclear Energy and Engineering
  • Civil and Structural Engineering

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