Science/Engineering/Technical forums

I am installing an e-beam gun in one of my chambers to do e-beam dep. The guns run at about 5 to 10kv depending on the model and up to an amp. I am not terribly sure on the voltage yet, once I get the gun installed and jerry-rigged to a psu I should know better what voltage it will want to operate at so the beam is in the right spot.

Any ideas on a power supply?

How much main beam current? Usually you'll need some other odd voltages referenced to main power, like focus, filament etc. It really depends on the power. For low power I've been using these little Spellmans (size of a big phone book). They take abuse without problems - and there's always some getting going (the odd arc etc). But they are in the 250 watt range. We see them pretty frequently on ebay, often modified for some customer of Spellman (some have quite a lot more output). Spellman has been good to me about helping me get some of these oddballs going again. They have the "this just works" quality going for them.

Oh, I see you said "an amp" Gheezus, that's a lot. I do have a 4kv power supply that could be doubled, but it's very hard to move - old school, iron and copper. Weighs a few hundred pounds. I *think* it's about 16kw rated, I've never fired it up.
Huge transformer. It might cost more to shop across country than finding something else would.

Jerry,
I am guessing you want a metallic coating so voltage regulation is not that big a deal. How about a rectified pole transformer driven by a variable frequency AC drive?
-Peter

You cant drive a transformer from a VFD, you can use a RPC and there are ways to rewire three phase transformers for single phase. I am just trying to avoid all that.

Doubling works but the caps have to be freeking massive to keep the ripple down to even a decent level, 40-100uf in general. I have a 2400v transformer good for something like 4 or 5 amps.

No, I plan on mostly dielectrics.

Found the specs for my e-beam gun, it was made by Sloan and there is still a company that makes a modern variant of it. I also picked up a 4 pocket unit from a guy in canada, another Sloan.

The units run at 10kv and can handle up to 1.2 amps emission current. I would probably be happy with 300-600ma.

Jerry I’d be shocked if you couldn't configure a motor VFD to drive a step up transformer, both are just steel and copper with the same physics. 30 years ago in university we modeled induction motors as transformers.
Enjoy the journey.
-Peter

From what I see in my fusor with 50kv and 10's of milliamps in regards space-charge beam expansion due to repulsion, I'd think ripple wouldn't be the biggest deal - you're lucky to make a beam of that perveance at all that has anything like a "focus" at a mere 10kv, and good thing you only have to hit the target, which can be a decent size. This isn't electron microscopy, after all. I wouldn't think you need all those kilowatts anyway, since in a vacuum, things heat up pretty easily.

But I agree on the huge caps - they are indeed huge in the 100kv/50ma supply I built - and there's still plenty of ripple even with caps that store more energy than a .308 rifle shell - scary stuff indeed. In my case, I can tolerate some series impedance and sank some ballast resistors into the oil - because an arc across one of those takes it out of the circuit, and 100kv is snakey-flakey stuff. I wound up using maxwell caps, not because I needed the tiny series R and L, but because that's what happened to be on ebay that month - 100kv stuff isn't common! Imagine a few thousand joules dumped in nanoseconds, resulting in a lab full of burning hot oil mist! Not my lab, you don't.

Jerry
Look for a big ion pump psu Varian etc
10kV @ 2 amps is what I have used with 6 600l/s ion pumps
Ok @ 2 amps the supply sags to around 6 kV but--nice and cheap I have seen them on epay

VFDs have really crappy waveform output and do not handle loads like that well. You get all sorts of harmonics and spikes, it is pretty nasty. If you want three phase from single phase that you can do whatever you want with you need a Phase Perfect. They are a bit spendy.

I dont think ripple is too big of a deal, the only "focus" is the acceleration voltage and by varying that the beam will land in a different spot.

Yeah, you do need to start at about 3kw to really do anything. These e-guns I have are rated up to 12kw.

John, a the professor friend I have at PSU said the same thing, big ion pump supply. I will keep an eye out for one of these ion supplies.

Here is the manual for the single pocket gun:

https://drive.google.com/file/d/0B1bUBQ ... sp=sharing