Adventures With Vacuum Deposition Power Supplies

[macona] called this a “fail of the week”, but of course failure is just another part of the hacker adventure. Fail and fail often! He’s been slowly assembling a vacuum deposition system. These systems let you deposit thin films on a substrate. Vacuum deposition systems have all sorts of exciting applications, not only are they used in semiconductor manufacturing, but as [Ben Krasnow] has shown can create conductive transparent coatings. They’re even sometimes used for silvering mirrors.

A common feature of these systems is that they require high voltage, we’re not talking a few hundred volts or even a few thousand volts. But 10 to 20 kilovolts. You need such a high voltage in order to accelerate electrons and ions, which are used to eject atoms from a source and deposit them as a thin film on a substrate.

It was this HV supply [macona] was working on, cobbling the system together from parts found on eBay. Unfortunately he could only reach 9kv unloaded, which we’d expect to drop considerably under load. So [macona] has now found a different solution. But this teardown and write up still makes great reading.

We’re left to pondering on what projects the spare parts could be useful for: “I might be able to series the secondaries and get 30kv at 500ma! That would make one hell of a bug zapper! Actually these transformers scare the hell out of me….” me too Jerry! Me too!

21 thoughts on “Adventures With Vacuum Deposition Power Supplies

      1. Now, I’m beginning to wonder if there is a supplier that sells such a coated polycarbonate, and if it would maintain conductivity after being vacuum formed. It’d make certain things (space suit costumes and the like) much easier to work with; adding vent fans is a pain in the-well, lets say its annoying.

        1. It might conduct some, but from my experience in bending an aluminum coated piece of scintillating plastic is that the result will not be pretty, it might conduct in some places but I am betting it is not going to be very even. The plastic should be coated after forming.

          There are compounds use for the insides of motorcycle visors that work well to keep the fog down, Cat Crap (brand name) is supposed to be good.

  1. I’ve often wondered if you could simply recycle power supplies from the numerous amounts of old CRT’s that people practically give away for free, since essentially it’s the same voltage requirements for similar applicatons. Any ideas as to the feasibility of this?

    1. None. The max power usage of the electron beam gun I am using is 12kw, that’s 1.2 amps at 10000kvdc. A fly back transformer in a typical TV is closer to 30kv in the milliamp range.

      1. I think you put in an extra thousand there… 10000kV*1.2A would be 1.2MW, which is getting into “you can power less than a thousand of these from a full-scale coal plant”.

    1. You can get X-rays off stainless at around the 5-6kv range and copper will emit a little at around 8kv but none of these are very significant and will be stopped by the chamber walls. Since the gun cant operate with the chamber open there are no worries there.

      The chances of me killing myself with x-rays are orders of magnitude than that of me frying myself with the power supply.

  2. CRTs, Tetrodes, TWTs, CFAs etc don’t emit much in the way of x-rays until up around 50kV unless you are working with an actual x-ray tube, but probably not many of those have a working voltage that low anyway. Any shielding at all will pretty much stop them at 10 – 20kV.

    10-20-30kV is pretty easy to get if you have low current requirements, if you need full Amps average, you’re getting into a lot of $$.

    Pulsed with a peak current of 1.2A isn’t as bad if you stick with tried and true tubes as your switching device. It just becomes a balancing act of keeping your output caps charged before you can discharge them to the point of droop.

    1. Not peak 1.2amps, thats the steady state current (max) used by the gun. In reality I will probably be running in the 500-600ma range because I am going to probably have to run this the new power supply off a rotary phase converter. The power supply that I am getting uses a Einac 4cx15000A tetrode for regulation.

    1. At 12.5kv, the highest ocv in the supply, you don’t have a whole lot of leakage issues. Everything just sits on ceramic standoffs and stuff. Nothing special, generic crimp terminals, generic HV wire (GTO-15), etc.

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