See also parts I, II & III
It's been four months since I handed over the new reactor I designed to my Master's student. Now I have the results in hand: "Experimental investigation of new structured radio-frequency plasma electrodes".
For a Master Thesis, R. sure had nice results - but you aren't interested in those, so I'll proceed to present you pretty pictures, photographed by R.:
The small experiment itself - it's the little tower in the middle, sandwiched between two much larger DC arc experiments. R. confessed to occasional feelings of inadequacy when comparing his small plasma box with the huge one meter, 600 amps arcs. "Size doesn't matter," I told him, with a smirk.
Closeup of the plasma box inside the vacuum vessel, before attaching all the diagnostics to it. The pink glow is from a hydrogen plasma.
It is very easy to ignite an argon plasma, but you'll get instabilities (the bright blobs in the middle) faster than you can say "metastables are your uncle". So R. worked mostly in hydrogen, which is closer in behaviour to the silane used in silicon deposition anyway.
This is what it looks like if you drive a plasma box I designed for about 100, 200 Watts max at 600 Watts. Why do it? "To find out what happens," he shrugs. Students: Pushing the limits of technology since the dawn of time. "Urg make fire hotter!" must have been how pottery was invented.
The inescapable results of working on the bleeding edge of plasma physics - or at least of not listening when I mildly suggest that even though your generator is capable of a 1000 Watts output, that does not mean you are obliged to use all of them.
Still, all in all it was quite enjoyable supervising R.'s master thesis, and much less hassle than I thought it would be.
1 week ago