Advances in the use of plasma spraying for the fabrication of light weight X-ray optics

The next generation of X-ray observatories requires large area optics, with optimal angular resolution, minimal mass, and affordable fabrication techniques. Furthermore, for survey applications, a Ritchey-Chretien or polynomial design is called for, which precludes the use of foil or glass segment cone approximations. In order to meet these requirements, we have been exploring the use of plasma spraying as a replication technology to improve shape control and stiffness with a minimal mass penalty. Our main improvements to the basic concept is the lamination of the sprayed material with electroformed Ni on the outer surface along with the electroformed Ni inner surface of the mirror. We have also used metal-coated ceramic micro-spheres for the sprayed material and controlled the substrate temperature during spraying. These enhancements show the promise of making the technology viable. An up-to-date characterization of the properties of test pieces are presented.