if you're looking at the top part, that's from Fredrik Terman's Radio Engineers handbook, which gives speed vs total potential of 5.97e7 * sqrt(E) cm/sec, where E is in volts (real volts like we use on voltmeters).
Seems to check out with transit time effects in radio tubes etc? You can put the charge/mass ratio vs electron in the square root for heavier stuff (1/1831 for proton - according to wikipedia and others, our old familiar numbers have changed a bit over the years)
Maybe you were faked out by my bad GUI design (it just grew, honest) - for the top lines it's 102 volts or thereabouts...there's more than one volts box.
The bottom part I put together from the stuff I linked in the code...it was a pita to be sure. FWIW, it works out to 50kv when I measure time, distance, and put 50kv on the thing.
Which seems high for the volts, as I'd expect various things (scattering) to reduce the effective potential in there. On the other hand, this is really low pressure compared to what we normally ran- fairly deep into molecular flow (billiard balls) everywhere but near the focus.
EMI is just a cap coupled signal from the main grid and is due to the supply having some series impedance (it's a scope probe near the HV to the main grid). Faraday_F is more or less when the ion source goes positive and starts repelling deuterons which hit a wire in the tank nearby. There is some geometric error there, and it probably varies depending on the main grid field. I'm working on that one now. Supposedly, the EMI signal would be "highest" when the deuterons are just entering the outside of the grid? (induction)
I haven't really verified the top line stuff yet, other than it's accurately reversible. It was just a start to working out the time to distance stuff, which is really the main thing I wanted to know what kind of drive speeds and feeds to use on a main grid waveform to bunch the incoming deuterons and then yank the electrons in after them. I hope it's close, as those kinds of speeds and feeds are fairly easy to make compared to DC<>Daylight, though it'll take two stepup transformers to handle the slow and fast ones (over 60x different F
0).
Having the pulsed ion source is what made the measurement possible. Not perfect, but I wanted to get in the right octave before building things and burning them up.
I triggered on the neutrons, and selected for "a burst that overloaded the phototube/ZnS recovery time". The events of creating and then accelerating the ions naturally would occur first since they happen mostly on the other side of the tank from where the neutrons happen. We see some before the main arrival, and some after, but the peak is pretty much when they seem to be hitting the focus - it's that gaussian you mention, once you "get" what was measured. Sure, we get some on the way in, and on the way out but most where they are densest and head-on.
Happy late birthday!
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.