Radiation Effects Of Protons And Electrons On Fused Quartz Glass Based Silver Film Reflector

The parameter selection of space electron and proton irradiation and damage effects of an optical reflector were investigated through ground-base testings and Monte Carlo simulation analysis. The range and energy loss distribution of protons and electrons in the optical reflector were analyzed using SRIM and CASINO software. It is found that the energy deposited in the surface film layers by protons of 0.01～1MeV and electrons of 0.01～0.2MeV is the most. The protons and electrons with in the two energy ranges can make a serious damage to the reflector. It is advised that for the ground simulation tests of space electron and proton irradiation, the radiation damage effect is betlen to be simulated by the 0.01～1MeV protons and 0.01～0.2MeV electrons mainly. Synergisic effect of protons and electrons was found to exist, so that the proton and electron irradiations should be carry out simultaneously. A suggestion on chosing irradiation of the electriferous simulation parameters for the reflector was given out according to the energy spectrum of GEO.The spectral reflectance changes of the quartz glass substrate silver film mirror caused by different energy protons and electrons was studied on the conditions of the single and combined irradiations, using a space combined radiation simulator and a high-energy proton accelerator. The charged particle irradiation first causes a change of spectrum in the UV range, and the reflectance of visible light decreases under larger fluences. The radiation has a little impact to the infrared band almost. The change in spectrum of the exhibits the radiation dose effect, i.e. spectrum descends with increasing irradiation fluence.The absorbed spectrum of the reflector was analyzed, and the result shows that space proton and electron irradiation can introduce color centers in the surface film layers of reflector, including the E' color centers in the SiO2 layer at 225nm and 236nm, and the F series of color centers in the Al2O3 layer at 251nm, 332nm and 510nm, and the Al impurity color centers at 420nm. High radiation fluence may lead to the formation of composite color centers, and causing the absorption band changes within a certain wavelength range. These color centers could absorb photons in the 200～500nm spectral range, leading to the changes in reflective properties.