Andrew Aurigema eosraptor@... [VacuumX] wrote
I believe I have eroded aluminum with plasma. The once shiny aluminum foil
is now dull and pitted and missing in some places after 2 minutes of purple
plasma.
A bud tore apart a microwave oven and rigged me up a high voltage DC supply
fed by a variac. With about 40 vac input to the microwave oven
transformer, the output is about 450 vdc. The little roughing pump is
pulling down to about 5 torr and the electrodes are about 10mm apart.
The magnetron I ginned up is just the circular magnet from the transformer
with a little N35 ( super magnet ) held at its center with an aluminum
plug. I covered the magnets with aluminum foil and put the whole assembly
on a plastic stand in the little degassing chamber. The magnet gets hot
quick so test runs are less than 3 minutes.
This is a long way from making telescope mirrors reflective but it is a
start.
I have been meaning to try something very similar but just keep running out of time.
Are the magnets coupled by a magnetic path such as iron underneath ?
Did you check if Al was being deposited ?
Why choose Al for sputter testing. It is supposedly very slow to sputter so something else should work a lot better ?
I seem to remember that you have an evaporative Al setup so this seems unnecessary for Al coated mirrors.
I have two Hign Vact setups. One will deposit (evaporate) Al on a mirror surface but the vacuum is not clean enough for good adhesion.
I had thiughtg of revamping this to sputtering hoping the plasma will glean as well and promote better adhesion. And a magnetron setup seems a good way to speed things up.
So I now have this oilless setup which I want to experiment with as well. Unfortunately, while I have partly built a chamber with leadins etc it is not finished and I am very bust with other work at the moment. Some of what I want to do is quite small.
Please post anything else you do and hopefully in a few weeks I may have something of my own to add.
Peter Smith
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