Paper TF-ThM10
First Steps Towards Accessing Aluminum’s Far UV Reflectance for Space-based Telescopes

Thursday, December 15, 2016, 11:00 am, Room Makai

We report on our progress on vacuum removal of protective layers on aluminum mirror surfaces using hydrogen plasmas and/or heating. One of NASA’s flagship astrophysical missions of the 2020’s or 30’s will likely be a LUVOIR (large, UV-optical-IR) telescope. This space-based observatory will employ the largest mirrors ever flown. The reflective coating will almost certainly be aluminum since such telescopes would profit from truly broad-band mirrors. The top surface of such aluminum mirrors, however, need to be bare without the oxide layers that naturally form in air. (The local space environment for the observatory should be sufficiently oxygen-free that a pristine surface should remain bare for decades.) We will discuss our research into protecting as-deposited aluminum mirrors before atmosphere exposure with a robust, protective layer, or layers, that could be deposited to coat the aluminum immediately after its deposition, before it comes in contact with air, and cleanly and relatively easily removed once the mirror is in space. This removal must be gentle enough to not roughen the mirror surface nor redepositing material removed from the protec­tive layer on the mirror or other spacecraft components. Thus our choice of hydrogen plasmas. We will specifically discuss the deposition and removal of organic and inorganic (Cd-containing and Zn) films that were evaporated onto the aluminum immediately after its deposition. This could open up the 11-15eV band for space-based astrophys­ics without sacrificing IR, visible and UV reflectance.