Thanks to those of you who came out for the nitrogen laser build, and my apologies to those of you who I missed when I made a sudden change of plans. I made a quick trip out to the Moon Day event and ran over the time I had.
We tested the vacuum seal on the nitrogen laser and found it wanting. I could tell that we had a good seal, but after several seconds into pumping down the tube, I heard a “pop,” and the tube reached atmospheric pressure. This was after going through three refrigerator compressors, supplied by David Ratcliff, that functioned as the vacuum pump. I’m glad about the seal on the end plates; it’s microscope slides held on by paraffin.
The leak turned out to be near the middle of the tube, where some of the silicone apparently was too thin. I applied more silicone to the area and left it to cure.
One of the consequences of pumping down the tube is that the copper foil electrodes warped out of shape. I expected they would warp, as that’s normal when 1000 lbs of force press down on a foil sheet, but I didn’t know how much they would warp. It turns out that the electrodes warp enough that we wouldn’t be able to use them like that. I’m thinking that I could get around the problem by using thicker copper sheet.
Another idea that crossed my mind is adding a third electrode inside the tube, above and straddling the other two. I’m wondering what kind of beam that would make? I’d have to widen the output coupler windows to do that, though, and they are already about as wide as the microscope slides could cover.
I’m procrastinating on firing up the electrical circuits. I think we have too many unshielded spark gaps. I also don’t like the charging inductor layout.
The UV/IR laser safety goggles arrived, so it looks like we might avoid getting cataracts from operating the laser.