I guess this is getting off into the weeds a bit, but is the quartz layer doped with cerium in the mass? Or is the cerium diffused into the surface by immersion in a molten cerium compound?
------- Original Message ------- On Tuesday, December 20th, 2022 at 2:26 AM, Andrew Meulenberg <mules...@gmail.com> wrote: > Robin, > > The whole deal is a set of tradeoffs that depends on the environment to be > encountered. At some altitudes, the Van Allen Belts have too much penetrating > radiation to allow solar cells to be used for long-term missions. > > Addition of coverslides makes the solarcell assembly vulnerable to solar > ultra-violet radiation. It is necessary to use high-purity fused silica for > the coverslides to prevent themselves from being damaged by the UV. But these > coverslides allow the UV to damage the adhesive that holds them to the solar > cells. Thus, it is necessary to put a UV filter on these coverslides. The UV > filters can be damaged by the trapped-proton environment if there is a > manufacturing error. Cerium-doped microsheet (CMS) is generally used for > coverslides because it does not transmit the UV that can damage the special > adhesives (flexible conformal coatings) that can function through the thermal > excursions experienced when the spacecraft enters and exits the Earth's > shadow. However, the CMS cutting out the damaging UV also lowers the starting > efficiency of the solar arrays that can derive energy from the UV. > > It is a tradeoff that must even recognize the possibility of solar flares > that, when extreme and aimed at the earth, can cause more damage (in days) > than all of the other sources of degradation over the rest of the mission. > The tradeoff is further complicated by the variety of cells and materials > (filters and coverslides) available. There is also the mission variables that > are sometimes of greatest concern. Sometimes it is more important to have max > power at the beginning of a mission; sometimes at the end. > > It was a portion of my job for nearly 30 years. > > Andrew > _ _ _ > On Mon, Dec 19, 2022 at 12:41 PM Robin <mixent...@aussiebroadband.com.au> > wrote > >> In reply to Andrew Meulenberg's message of Mon, 19 Dec 2022 00:25:20 -0600: >> Hi Andrew, >> >> I'm sure it does, however the high energy particles from other sources are >> also present, so it seems to be fairly >> effective against them too? Otherwise surely it would have been noticed that >> cells in space deteriorate rapidly? >> >>>Robin, >>> >>>This thickness of coverslide stops the low-energy trapped protons of the >>>Van Allen belts that would cut the cell efficiency by ~30% in not too many >>>months. >>> >>>Andrew >> [snip] >> Cloud storage:- >> >> Unsafe, Slow, Expensive >> >> ...pick any three.
