Effect of Particulate Contamination on a Silicon Pore Optic

The European Space Agency ATHENA mission is an x-ray observatory that will study the formation of galaxy clusters and the growth of black holes within the energy range of 0.5 to 10 keV. Due for launch in early 2030s, ATHENA will use silicon pore optic (SPO) mirror modules to create the x-ray mirror. The first confocal SPO mirror module (MM) was entered into a preliminary environmental test program for the ATHENA mission. The objective of this program was to determine whether particulate contamination causes loss of effective area for silicon pore optics. The confocal MM under test was manufactured by cosine measurement systems and first tested at MPE's PANTER x-ray test facility in July 2019. After this campaign, it was contaminated with a total of 2000 ppm in two 1000-ppm-level contamination periods. After each 1000-ppm contamination step, x-ray measurements were made to determine the effective area. The pre- and post-contamination effective area measurements, and the contamination of the optic, were carried out at the PANTER facility. The paper provides an overview of the contamination testing carried out at PANTER, and the corresponding results for each contamination level. We find no measurable degradation in effective area on a 5% level. We also look into the possibilities and limitations for the determination of the effective area within our facility. In future campaigns we plan to reach a 2% accuracy for the determination of the effective area for similar type optics.