25kV AC

The field doesn't "collapse". It decreases fast enough to induce a rapidly increasing voltage across the secondary, and the changing voltage charges the interwinding capacitance of the secondary, which induces a current that largely compensates for the rapid decline of the current through the prima ry.

You can write out the equations for the process - which is a bit more helpf ul than saying that the field "collapses" though it does - initially - go d own pretty fast.

That's not what's going on.

It doesn't "snap" up to a high voltage. It rises rapidly - at a rate set by the self-resonant frequency of the ignition coil. Calling it a "snap up" i s unrealistic, and rather unhelpful.

The 14v sets the current through the primary of the ignition coil, and it s ets the starting point for the voltage rise after the points have opened.

You would see about 140V across the secondary of the ignition coil when the current first started ramping up, but it drops as the current rises and th e resistance of the primary starts limiting the current.

It's irrelevant after the points have opened.

snipped-for-privacy@decadence.org wrote in news:qmvjk3$507$1 @gioia.aioe.org:

errr... IPC

Bill Sloman wrote in news: snipped-for-privacy@googlegroups.com:

Oh it full on collapses. That is how the even gets generated.

A sine wave is too soft to induce more than the standard step up ratio offers. A high slew rate event, however, steps into the realm of infinity because the event is of near zero length. Other physical factors clamp that down, but that is the mechanism. That high slew rate (collapse) is the driving engine.

Do the math.

Win,

Um, AC is the hard way to increase production, unless your in a certain Rus sian non-wovens factory where they run the whole plant off a big transforme r. :-)

Start a Espin jet with the usual DC. Note the voltage where the Taylor co ne ruptures and the jet starts. Note that you can decrease the HV until t he jet starves for current, however they tend to make smaller fibers if yo u decrease the voltage a little Say 5-10% after starting.

Note if you really increase the voltage over the static start voltage, the Taylor cone nearly implodes with the impulse and starts the jet fast, but i t is unstable.

This is where I mention the words "Grounded Grid Shunt Regulator" such as 6 EN4, but I imagine some of the Russian Surplus ceramic RF triodes would wor k just as well, if you cant find a 6EN4.

Basically shunt the jet assembly to not quite ground. Makes a pulsed DC, th at acts like AC.

This idea should be credited to Dominick Galluzzo at Gamma High Voltage who used to sell the fast shunt switch box as a made on demand product. We b ought our HV PSUs from Dom, usually the dual PSU with +30Kv adjustable an d -30KV adjustable, in the same box. As his PSUs have a good protection st age built in, they tended to withstand student and professor abuse such as shorting and arcing and low impedance loads for years.

Basically we used mechanical means to get around this. I used to have a Ba sic Stamp drive a simple servo swinging a fiberglass rod from one PSU pole to the other on the dual PSU as a means of testing reversing of the field. This would let us shoot high speed video of the process your thinking about . When your around 60KV, you like simple, robust, and cheap. You also iso late your measurement and control PCs with long plastic fiber optics, but t hat is another story.

I also tried various Kilovac HV relays and spinning disk DPDT switches.

But it is easier to do things mechanically.

As for increasing production:

You can do things like a spinning cup of polymer with a serrated edge. Cent ripetal force pushes the liquid to the edge, and the edge is fine toothed b andsaw blade. The fluid "climbs up" and launches from the sharp field at t he tooth. You can get a lot of polymer into the air this way, but your col lector drum needs to be above the cup and grossly overcharged.

The other technique I like for multiple jets involves naturally rough, thi n, tungsten wires dipping into the polymer pool. Say six wires 30-60 cm lo ng mounted between two 6 cm spinning disks on the same shaft.

Yet another technique involves one wire wound into a tight helix that dips into and out of a polymer solution pool along its long axis.

Steve

Also we used to use arrays of jets, either pressurized needle, or gravity cone, driven with 1 Gig ballast resistors off the same PSU.

How you get into tens of grams per minute is what I can't discuss.

Steve

One thing I forgot to mention. Shunt regulators can give off low energy X-rays. Low Energy X-rays are not fun, as their tissue adsorption is very high. A 1/8th inch thickness aluminum box was sufficient for our purposes.

Steve

See Also:

Review of Scientific Instruments 79, 093904 (2008);

Review of Scientific Instruments 80, 026106 (2009);

While not related to your problem, it gives a good overview of what happens with closed loop control.

Steve

On a sunny day (Tue, 1 Oct 2019 09:30:28 -0700 (PDT)) it happened snipped-for-privacy@gmail.com wrote in :

Yes, this was also a thing with KTV parallel stabilizers (PD500) at 25 kV

After a while the glass would turn a bluish color from the Xray radiation.

Once had a bunch of these tubes...

Win, it does indeed need to be operated under mineral/transformer oil to prevent corona and tracking damage. If the transformer has been pulled out of the X-ray head and oil for any length of time, it should be fully re-submerged and vacuum degassed to remove entrapped air. Since you only need ~25 kVRMS, a variable autotransformer will allow you to easily reduce primary voltage for the desired output.