Space Environment Simulation for Radiation Tests of Materials: Third Version of an International Standard

Abstract

In the framework of the International Organization for Standardization (ISO) activity of 1996 we started development of an international standard series for a space environment simulation of on-ground tests of materials. A draft of the first international standard ‘Space environment simulation for radiation tests of materials’ (first version) was presented at the 7th Int. Symp. on Materials in Space Environment by Briskman et al (1997). The second version of the standard was limited to nonmetallic materials and was presented at the 20th Space Simulation Conf. The Changing Testing Paradigm by Briskman et al (1998). The third version of the standard was discussed at the last ISO TC20/SC14 meeting (Torino, Italy, 1999); in essence it was completely revised.

A new standard orbit for the International Space Station is introduced in the recommended list of such orbits. The values of energy fluences for electrons and protons at all six orbits are calculated just as the absorbed doses on the 1 mg cm⁻² depth in aluminum. Values of the depth distribution criterion of the absorbed dose for two exponents are also calculated for four standard orbits. Now the list of radiation includes the near ultraviolet region. The spectral solar irradiances for far and near ultraviolet radiation based on ASTM E 490 data are introduced into the document. Accordingly, the ‘Radiation sources for simulation’ issue is enlarged and the section ‘Terms and definitions’ is replaced with a new version, the list being enlarged from seven to 32 terms. For the section ‘Requirements for simulation of space radiation’ a fixed procedure is recommended for space environment simulation of the radiation tests. For the section ‘Simulation of radiation dose rate’ extra sections are introduced that correspond to induced factors limiting the conduct of radiation tests conduction: radiation heating, residual atmosphere impact, vacuum requirements and electrical charging. Special attention is focused on dose rate effects in nonmetallic material, irradiated in vacuum.