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.