I have too many computers! To easily get this youtube link, I'm posting it here in this thread before I'm really ready to do the rest of the thread, but what I've done is take a sweep of the fusor vs "you name it" and collected some darned good data that shows me some things we all knew already - and some things most of us never had a clue about. This vid just shows my setup, there is a LOT more to come with real data, 4-d plots and movies of me twirling them around, the whole shebang. This should put to rest a bunch of the dumb newbie questions - and yes, when I'm done I'll also post a teaser over on fusor.net.
http://www.youtube.com/watch?v=bLU9AZZroy0
Now for the good stuff. Here's a vid of the resulting data. Volts, milliamps, and Q (x,y,z) vs pressure (color) are shown in a video that lets me twirl the axes so you can see all the features of the data, concatenated from all those runs (I will make the files into a zip so you can download them yourself and use plotdat, already up here someplace, to do it - or you can just look at the text yourself).
This is the setup for this movie:
Now for the cool part:
http://www.youtube.com/watch?v=WJe0YBAXwPw
Note, I mis-spoke in the video, but not in reality. Q is computed here as neutonrs/minute over power, not mere current, as you can see clearly in the setup above. Oops.
More to come - Now that I have all this data, there's more than one very interesting way to show it, this is just one of them.
It's pretty obvious that at higher voltages and lower pressures, Q is highest - I even had a couple of rogue points I edited out when the thing went unlit, then lit back up again, which showed Q's (on this arbitrary scale, not the real deal quite) on the order of 100's - that's because at 1 sample/second, I missed the current the power supply was actually putting out - so I edited out a few points that made me look too good to be true, because, hey, they weren't true. You have to know the limitations of your gear!
I've known most of this all along, but got a lotta crap trying to explain it to the beginners. Here it is now, in a form a child could understand. No kidding - more pressure or more current just don't get you an advantage in Q, and usually not in raw neutron output either. I will take another set of runs at lower pressures using an ion source to keep the fusor "lit" at the lower pressure, where I fully expect to see even higher Q's on my arbitrary scale. But the fact that max Q happens at far less than max output - or input is something no one had mentioned (or measured) so far - so this is "news" or should be to most fusor people. With an ion source, I can sweep more of the space - lower voltages and lower pressures at any voltage, to explore whether gas pressure has an effect (of course it does) and in which direction (collisions with neutrals, space charge limits, and all that stuff). Stay tuned!