TL;DR - it works darn well. It shows more hysteresis between what it takes to get "lit off" and what it'll hold down to, pressure wise, lighting off around 2.5 or 3 e-2 millibar, and even then only when helped by a few Kv on the main grid. But once lit, it'll stay that way down to e-3 kinds of pressures in the tank, even without help. Instead of "rays" arouund my ion grid, it just makes blobs of very faintly glowing gas (no pics right now, it's really dim and hard to capture). The AC source is around 10Kv peak here...depending. I have a choke in series with the primary of the stepup transformer and am able to run somewhere above it's resonance at the point where its capacitive reactance resonates with the choke and the primary voltage is actually about double what the drive signal (square wave from H bridge) is. FWIW, this draws more current with no load than when "lit" - the choke and step up transformer core get warm...
I took some other data (in a post soon to come) and realized I hadn't decently baselined this thing as to how for example the AC phase seen by my faraday pickups varied under various conditions vs the phase of the transformer drive waveform. So this was taking a step back so I'll be able to interpret the other data. The "EMI" trace in this is just a HV probe hanging near the ion AC HV output, so that's the gospel on what's going into the tank. The trace marked "Neutron" is for the moment, the drive signal on the transformer primary, which looks a lot different from the square wave coming out of the H bridge due to the reactances involved as described. The other two labels are what they are - faraday in the front of the tank, faraday in the back of the tank. Without tearing it down, I'm not even completely sure which one the ion grid is closer to - as the back one is near the tank vertical centerline, as is the main grid (EMI), and the front one is way up top behind the ion grid. It's even hard to get in a picture.
Here's the log text I wrote while doing this with info on what I was doing. The first two (one picture and one plot) were at a lower frequency than the later ones - I adjusted to nearer resonance to get more voltage out and easier light-off at some expense in higher power when not under load. It actually draws fewer watts under load!
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17_08_12_16:15:33.scopedat
17_08_12_16:16:19.scopedat
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Above not lit, different scope gains, changed frequency higher nearer resonance
These lit no DC, but it took 3e-2 and ion DC to light, then took down to 1.9
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17_08_12_16:22:10.scopedat
DC on:
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17_08_12_16:24:48.scopedat
DC wasn't into the higher voltages for good neutron production, more like 10kv or so - current limited at 5ma - I used what we used to use for the ion DC power for this.
It did make some neutrons, just nothing to write home about - around 100k/second.
- At the lower frequency.
- Plotted from scope data (colors and scale different)
If anyone wants raw data to do analysis from, I've got that - I just wrote a grabber program and a plotter program (which for now mainly concentrates on shapes, not labels and pretty stuff).
Gnuplot lets one place a cursor anywhere and then see the XY coordinates of that spot exactly. So one can find out what was when and how loud for basic human mark 1 eyeball analysis and not worry about the camera being tilted. And we know the scope sample rate, so at least we get time exactly right.
After turning up the frequency somewhat, but still no gas, no DC power and no light:
- Slightly higher frequency and amplitude
- Plot. The glitches are where the H bridge switch happens.
I put in a bunch of gas (around 3.5 e-2 mbar) and temporarily turned on main grid DC (about 30kv no load) to get it to light, then took gas back out to around 1.9 e-2 mbar and turned off the DC for now. That resulted in the below. Note that I changed gains etc to get a good picture; part of the reason there is both a screen capture and a plot for each state here - the picture shows all the incidental scope parameters better. Some things, like the coupling from the ion AC source to the faraday probes get a LOT louder when it's lit - which kind of makes some sense. The load changes the primary waveform and now the peak voltage at the output is around one of the zero crossings of the H bridge (see glitch). This is some of the info I need to be able to interpret the rest I'll be putting up later on.
- Note lower volts on primary and vastly different waveform there. Supply for h bridge drawing *less* current in this state(!)
- gnuplot of roughly the same stuff (can't hit two buttons at once, but I try)
...Don't think I'll be running short anytime soon, as I'm using .5 tB for, well, everything else I've collected up till now (I'm not doing pirated movies obviously, but I do have 7k or so CD rips - of my own CDs, multiple virtual machines and you name it else).