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Correcting and coating thin walled X-ray Optics via a combination of controlled film deposition and magnetic smart materials
Completed
TRL 1 (started at 1, targeting 3)
Description
The project goal is to demonstrate that thin walled (<400 micron thick) X-ray optics can be controllably shaped to produce high quality (~1” or better) X-ray optics at an affordable price. Since the desired surface area for the next generation X-ray telescope is >10x that of Chandra, the >10x requirement is then for >200 m^2 of surface area with a surface finish of better than 0.5 nm. Therefore, replication of some sort is called for. Because no replication technology has been shown to achieve ≤1” angular resolution, post fabrication figure corrections are likely going to be necessary. Some have proposed to do this in orbit and others prelaunch including us. Our prelaunch approach is to apply in-plane stresses to the thin walled mirror shells via a magnetic field. The field will be held in by some magnetically hard material such as NiCo. By use of a so called magnetic smart material (MSM) such as Terfenol-D, we already shown that strong enough stresses can be generated. Preliminary work has also shown that the magnetic field can be held in well enough to apply the figure correcting stresses pre-launch. What we call “set-it and forget-it.” However, what is unique about our approach is that at the cost of complexity and some areal coverage, our concept will also accommodate in-orbit adjustments. Furthermore, to the best of our knowledge ours is one of two known stress modification processes that are bi-axial. Our plan is first to validate set-it and forget-it first on cantilevers and then to expand this to working on 5 cm x 5 cm pieces. We will work both with NiCo and glass or Si coated with Terfenol-D. Except for the NiCo, substrates we will also coat the samples with NiCo in order to have a film that will hold in the magnetic field. As part of the coating process, we will control the stress of the film by varying the voltage bias while coating. The bias stress control can be used to apply films with minimal stress such as Terfenol-D and X-ray reflecting coatings such as Ir. Ir is a highly desirable coating for soft X-ray astronomy mirrors that can have significant built in stress unless some technique like our is used to apply the coating. An alternative use for the bias stress control coating process is to improve the initially fabricated mirror by applying spatially dependent stresses with a Cr film. We will also expand upon the work we have done that shows this method has promise to reduce the amount of corrections needed by the MSM plus the magnetic field process.
Benefits
The Astrophysics Research and Analysis program (APRA) supports suborbital and suborbital-class investigations, development of detectors and supporting technology, laboratory astrophysics, and limited ground-based observing. Basic research proposals in these areas are solicited for investigations that are relevant to NASA's programs in astronomy and astrophysics, including the entire range of photons, gravitational waves, and particle astrophysics. The emphasis of this solicitation is on technologies and investigations that advance NASA astrophysics missions and goals.
Details
| Technology area | Sensors and Instruments > Observatories > Mirror Systems |
| Program | Astrophysics Research and Analysis (APRA) |
| Lead organization | Northwestern University, Evanston, IL |
| Start date | 2017-01-01 |
| End date | 2019-12-31 |
Project contacts
Listed on TechPort itself — the most direct way to ask about this specific project.
- Melville P Ulmer
- Jian Cao
- Joshua J Richards
- Lahsen Assoufid
- Qiang Zeng
- Semyon Vaynman
- Yip-wah Chung
How to get involved
This is early/mid-stage (TRL 1) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.
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