Design and performance of a vacuum-UV simulator for material testing under space conditions
arXiv:1406.1607 · doi:10.1016/j.asr.2013.08.010
Abstract
This paper describes the construction and performance of a VUV-simulator that has been designed to study degradation of materials under space conditions. It is part of the Complex Irradiation Facility at DLR in Bremen, Germany, that has been built for testing of material under irradiation in the complete UV-range as well as under proton and electron irradiation. Presently available UV-sources used for material tests do not allow the irradiation with wavelengths smaller than about nm where common Deuterium lamps show an intensity cut-off. The VUV-simulator generates radiation by excitation of a gas-flow with an electron beam. The intensity of the radiation can be varied by manipulating the gas-flow and/or the electron beam. The VUV simulator has been calibrated at three different gas-flow settings in the range from nm to nm. The calibration has been made by the Physikalisch-Technische Bundesanstalt (PTB) in Berlin. The measured spectra show total irradiance intensities from to mW (see Table 4.2) in the VUV-range, i.e. for wavelengths smaller than nm. They exhibit a large number of spectral lines generated either by the gas-flow constituents or by metal atoms in the residual gas which come from metals used in the source construction. In the range from nm to nm where Deuterium lamps are not usable, acceleration factors of to Solar Constants are reached depending on the gas-flow setting. The VUV-simulator allows studies of general degradation effects caused by photoionization and photodissociation as well as accelerated degradation tests by use of intensities that are significantly higher compared to that of the Sun at AU.