Magnetic smart materials (MSMs) offer an alternative to the typical piezo-electric actuators that are currently being used to control X-ray optics on beam lines. MSMs combined with an overcoating of a magnetic hard material means a deformable mirror whose non-reflecting side is coated with a MSM plus magnetic hard overcoat can work in a power-off mode. The process works by using an electromagnet (EM) to impose a magnetic field in the bilayer of MSM and magnetic hard overcoat. Once the EM is turned off, the mirror settles to a new shape within minutes. The new shape can then remain intact for days. Since the EM is not fixed to the mirror, the exact placement of the magnetic field can be adjusted by relocating the EM. This feature allows for fine-scale adjustments and avoids the “dead pixel” replacement problem common with piezo patches that are attached to the mirror. We will give an overview and a progress report.
Based on the science case for the SMEX ESCAPE mission, a normal incidence EUV mirror mission would be an interesting follow on. Our provisional SmallSat/CubeSat design has a 1 m diameter primary deployable mirror. The mirror would be coated with multilayers for normal incidence EUV reflectivity. The deployable mirror substrate is a shape memory alloy (SMA). The SMA needs to be over coated with a material that can be polished and then smoothed further. The combination that worked well on an aluminum cylinder is a high phosphorous content electroless nickel (eNiP) super-polished and then coated with carbon nitride (CNx). The multilayers were deposited on the eNiP+CNx stack. We report here our progress toward putting in place the pieces for a proof of concept. We discuss a scale up of previous return to shape on sheets of NiTi and the ray tracing results that demonstrate a sufficient return to shape of 1 micron. Furthermore, corrections post deployment are possible if desired.
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