I finally found a way to go though my roughly 3k photos and find some of these, been meaning to put them up here for awhile and comment on the things we've tried, and how well they worked.
So far, it's been a near monotonic rise in "goodness" and I'm going to try to start near where we did and progress to where we are on this thread. Y'all -- add yours too!
I skipped our first nasty looking grid and run that made neutrons, if there's any requests I'll add that one, but it wasn't all that interesting, except perhaps to prove you can make it work "ugly".
This one shows something interesting (this one is in BillF's fusor). Note the stream of ions coming out of the end of the grid, through an insulator with a big length to hole size ratio.
We have, in effect, pressurized the grid center area, and I'm supposing some sort of pressure or Coloumb repulsion is responsible for this. This run was in He gas, not D, which is how we were doing our testing before we got D in a bottle, instead of heavy water we had to deal with. This grid did make neutrons fairly well, it's about 3/4" by 2.5" and will show up in another picture.
Here's one of our early Ti grids. Trying to brute force things turns out not to be either effective or very wise. Making the end of a bit of Ti rod was dumb, it weighed too much. It took almost yellow heat to make this slump. And by the way -- it still works and makes neutrons just fine.
As we learned, I started focusing on, well, focus, and thought that perhaps something that looked more like an electrostatic lens design would help. Well, sort of. But if you are depending on the normal dynamic equilibrium and whatever ion recycling to happen, it hurts. This is an example of something that will work well with AC drives to make things work out right. This is one vane grid inside another. All is Ti metal, except for some fancy spacers and mountings which need more design work so they don't short when Ti gets sputtered onto them. Very do-able, just wasn't done yet. The idea here was going to be to have the outer grid relatively low voltage -- this way, any ions that hit it haven't had a lot of energy invested in them. Just didn't scale some things right for the conditions. Kept these for later use when I get that nice video amp built up to drive it correctly. Probably the most notable thing in this picture is the window it was taken through. I used the lathe to cut an o-ring slot in a flange adapter, and used a window blank from McMaster (cheap) and a couple of clips to hold the window when vacuum isn't doing that job. Super fast and easy way to get in and out of the tank, and the O ring appeases the tempco force monster just fine.
Because owning the lathe made it easy, we tried a spiral grid. This totally stank, and this is the best picture it ever took. Very few neutrons ever came out of this. It also embrittled so badly that I broke it when removing it.
One of the nicer things about the big tank is that all this runs in a sidearm, and I have a lotta windows, so I can get pictures from various angles that show us things I don't see how we'd learn with the spherical geometry. Note the lack of well defined rays. FWIW -- also lack of neutron output.
More in the next post on this thread.