| Autor: |
N. I. Velichko, N.N. Agashkova, L. Bohne, V.V. Abraimov, A.M. Markus, F. Lura, A. V. Krevsun, L. A. Mirzoeva |
| Rok vydání: |
1996 |
| Předmět: |
|
| Zdroj: |
A Cryogenic Engineering Conference Publication ISBN: 9781461380221 |
| DOI: |
10.1007/978-1-4613-0373-2_148 |
| Popis: |
Effects of space factors such as proton and electron radiation (E=160 keV), extra-atmospheric solar (and VUV) radiation at λ = 5 – 2500 nm upon the reflectivity of mirrors in scale model IR instruments are investigated experimentally. The phenomena of blistering and flaking — complex defective structures on the mirror surface after exposure to protons (E=160keV) are described. These are either round craters of 2 – 5 μm in diameter (flaking) or blisters (detachment of the AI and Ag films from the mirror surface) of 10 – 50 μm in size (blistering). Blistering and flaking develop in a jump — like way during short times (δτ=1–2 sec) when the radiation dose becomes critical, Dcr≈6·1015 particles/cm2 at T=340K. The defect density is much dependent on the radiation dose and the temperature of the mirrors. The phenomena are related to the formation of hydrogen in the process of proton-electron recombination (p++e− → H) in the material. Hydrogen accumulates in blisters in a thin surface layer of glass, its thickness being equal to the proton mean free path ep+=2μm. When the hydrogen pressure in the blisters exceeds the ultimate strength aF of the space optics material, brittle failure occurs in the glass covered with mirror and protective coatings (flaking) and the plastic films (AI or Ag) peel off the mirror surface (blistering). This specific “space erosion” of the mirror surface appreciably impairs the reflectivity of mirrors in a wide spectral range. The experimental findings are interpreted within current models of blistering in metallic materials of nuclear reactors due to He+ and D+ ions and are in qualitative agreement with the theory of blistering developed by Yu.V.Martynenko [1,2]. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
