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A key aspect of the thin film coating development for the NewATHENA X–ray optics, is to determine the adhesion efficiency and the residual stress limitation of the coatings on silicon substrates. To do so, we magnetron sputtered different layer thicknesses of chromium layers underneath iridium/carbon bilayer and linear graded multilayer coatings. The samples were characterized using X–ray Reflectometry (XRR) to derive the thickness and micro–roughness. The residual stress was assessed by profilometry using a Dektak 150 stylus profilometer. The curvature of the samples before and after coating, along with the total film thickness derived from XRR, was used to evaluate the residual stress.
The facility is compact (just 8 m x 14 m). Thanks to an innovative optical design based on an asymmetrical-cut crystal associated with a paraboloidal grazing incidence mirror, it can produce an expanded X-ray beam (170 mm x 60 mm) with low divergence (about 2 arcsec measured for the 4.51 keV beamline) at the two monochromatic energies of 4.51 keV and 1.49 keV. This allows us to calibrate each SPO MM's Effective Area and Point Spread Function precisely.
The first beamline, at 4.51 keV photon energy, is already operational, as the commissioning was completed in Q1-2023. The second beamline, at 1.49 keV energy, is being developed. It presents some more challenging aspects from both the design and implementation points of view. The monochromator stage is based on two Quartz (100); two ADP asymmetric-cut crystals (101) will provide the horizontal expansion of the beam. The X-ray source needs to be very brilliant (5 x 1011 - 1012 ph/s/sterad) due to the large fraction of photons rejected by the crystals.
This paper describes the ongoing activities. It will present the results of the 4.51 keV X-ray beamline optimization and the tests performed on a coated MM. It will also describe the progress in implementing the 1.49 keV components and discuss the comparison with other X-ray testing facilities.
We present in this paper the status of the optics production and illustrate not only recent X-ray results but also the progress made on the environmental testing, manufacturing and assembly aspects of SPO based optics.
The Silicon Pore Optics (SPO) enables the NewAthena mission, delivering an unprecedented combination of good angular resolution, large effective area and low mass. The SPO technology builds significantly on spin-in from the semiconductor industry and is designed to allow a cost-effective flight optics implementation, compliant with the programmatic requirements of the mission.
The NewAthena X-ray optics is highly modular, consisting of hundreds of compact mirror modules arranged in concentric circles and mounted on a metallic optical bench. All aspects of the optics are being developed in parallel, from the industrial production of the mirror plates, over the highly efficient assembly into mirror modules, to the alignment of the mirror modules and their fixation on the optical bench. Dedicated facilities are being built to measure the performance of the NewAthena X-ray telescope optics, demonstrating their compatibility with the environmental and scientific requirements.
An overview is provided of the activities preparing the implementation of the NewATHENA optics.
XRR scans provide detailed insights into thin film properties, however, the dependence on accurate a priori knowledge necessitates a robust model for solving the inverse problem. Addressing this limitation, XPS proves invaluable in revealing the chemical composition of thin films, improving the accuracy of the XRR model. Combined characterization through OM and XRR is very useful to find visual insights into surface contamination-induced changes when mirrors are stored for long periods in a clean room environment, as might be the case for some astronomical missions. The synergy among these techniques is pivotal for evaluating coating quality for high-energy astronomical telescopes, with a specific focus on NewAthena and upcoming missions. This research not only advances methodologies in this field but also highlights the collaborative power of XRR, XPS, and OM in providing a comprehensive understanding of thin film coatings, emphasizing the importance of pre-coating mirror quality and mitigating contamination effects throughout the optics production process to ensure optimal performance.
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