After two and a half years of observation, IXPE has detected positive polarization from nearly all classes of celestial sources that emit X-rays. In this report, we describe the IXPE mission, detailing the performance of the scientific instrumentation after 2.5 years of operation. We also present the main astrophysical results and a few examples of scientific performance during flight.
A direct current (DC) magnetron sputtering system has been developed at NASA Marshall Space Flight Center for depositing broadband x-ray optic multilayer coatings. The system has the capability to house up to four, 2-in.-diameter direct-cooled DC magnetron cathodes. The 2-in.-diameter cathodes facilitate low-cost, early stage research and development of various types of optical coatings. Despite the small target diameter, good coating uniformity on 4-in.-diameter substrates is demonstrated. Sources of both systematic and random error in the deposition of depth-graded multilayer coatings were identified and compensated for, resulting in the ability to deposit coating that required ∼7.5 h of total deposition time. Final verification of the system was concluded with the deposition of an NuSTAR W/Si depth-graded multilayer coating design (flight recipe 10).
Simulations show that a substantial improvement in angular resolution is possible with this approach after multiple correction ‘cycles’. To assess this, custom coating systems have been developed and corrections of full-shell optics are underway. To date, a factor of < 2 improvement in the imaging quality of the optics has been demonstrated in x-ray tests after a single stage of correction.
In addition to MSFC's optics fabrication, there are also several areas of research and development to create the high resolution light weight optics which are required by future x-ray telescopes. Differential deposition is one technique which aims to improve the angular resolution of lightweight optics through depositing a filler material to smooth out fabrication imperfections. Following on from proof of concept studies, two new purpose built coating chambers are being assembled to apply this deposition technique to astronomical x-ray optics. Furthermore, MSFC aims to broaden its optics fabrication through the recent acquisition of a Zeeko IRP 600 robotic polishing machine. This paper will provide a summary of the current missions and research and development being undertaken at NASA's MSFC.
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