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High current power supply for vacuum sputtering deposition - project and questions.

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LAN_403

Hazmatt_(The Underdog)

Sat May 26 2018, 05:53AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Your trying to ballast DC with a high frequency core????????

So for ripple, you could use this HF core with a few turns for noise rejection, OR what you would typically do for DC is use a large iron core ballast with many turns like you are attempting to do here.

at DC is this core going to have the permeability and inductance to be effective... or is it just going to behave as a big lossy resistor? So you'll need to do some calculations to see if this guy is going to work for you.

That is also aside from the fact that a ballast is gapped so it won't saturate, this thing here is for HF inverting .. so its conceptually right..(put a bunch of wire on a core) but the wrong core for the job.

Hopefully you can do some testing with a dummy load and see if this arrangement will be effective or not.

stamasd

Sat May 26 2018, 06:39PM

Registered Member #61903 Joined: Sat Nov 11 2017, 12:04AM
Location:
Posts: 8

Nope, that is the secondary of a HV transformer for a SMPS I'm building. Unrelated project, has to do with the fusor.

radiotech

Sun May 27 2018, 07:46AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

I won't need very high voltages, I figure at most 1500-2000V for ignition of the plasma and probably 500-800V for maintenance of the discharge. I will need high currents though, probably at least 400mA or up to 1A for my purpose. I also want to get this done as cheaply as possible for the reasons above.

Do you know the actual voltage across the discharge ?

Some associated stuff to look at is how sodium vapor lights
work.

They need a high voltage to strike, and then a stable arc at
a voltage related to the wattage of the lamp.

Will your arc run at ~600 watts ?

An iron core choke, with winding resistance, as ballast, to
drop voltage will throw high voltage if you short it, which will
then strike your load.

A MOT primary might work as such a choke, tamed by damping,
by resistance across unused secondaries.

(fact-the bulb socket in a Na vapor fixture looks like a common
type, but may be rated at 5000 volts, so the striker works)

stamasd

Sun May 27 2018, 11:35PM

Registered Member #61903 Joined: Sat Nov 11 2017, 12:04AM
Location:
Posts: 8

radiotech wrote ...

Do you know the actual voltage across the discharge ?

Some associated stuff to look at is how sodium vapor lights
work.

They need a high voltage to strike, and then a stable arc at
a voltage related to the wattage of the lamp.

Will your arc run at ~600 watts ?

An iron core choke, with winding resistance, as ballast, to
drop voltage will throw high voltage if you short it, which will
then strike your load.

A MOT primary might work as such a choke, tamed by damping,
by resistance across unused secondaries.

(fact-the bulb socket in a Na vapor fixture looks like a common
type, but may be rated at 5000 volts, so the striker works)

The actual discharge voltage will vary with many factors. The quality of the vacuum, the gas used, the geometry of the electrodes, the intensity of the magnetic field etc. I expect for the design parameters I used, and assuming that all will go well, to have a sustained plasma voltage anywhere between 300 and 500V; for plasma ignition, probably 1000V or so. I aim for a target current of 20mA/cm2 or more (in stable plasma), i.e. for the small magnetron design 40-50mA. I plan on bigger magnetrons though if this one works. Thus my aiming for higher currents, I prefer to build one power supply that can be reused as my designs evolve.

One alternative design that I've started working on in parallel is to use ion beam sputtering instead of magnetron plasma sputtering. Completely different geometry, and I wouldn't need a high voltage supply for that one. Essentially the work gas would be ionized by high intensity RF instead of an arc, the ion beam focused (well OK I will need some HV for that but not at high current) and directed at the sputtering target. I'll need for that a generator that will produce a few hundred watts of RF power in one of the ISM bands, probably 13.56MHz.

johnf

Mon May 28 2018, 09:40AM

Registered Member #230 Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284

All of this smacks of fairy tales
to get 10's of mA /sqcm you need many tens of kv of beam energy ( read acceleration) otherwise the beam blows up ( defocuses) due to ion repulsion
you want to sputter a film with stickabilty you need the ion's to ariive with 100's of eV of energy, this is usually done with beam on target sputtering not magnetron sputtering as used in PVD systems which tend to deposit layers that can be peeld off with force.

Patrick

Tue May 29 2018, 05:45AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Is the form on that inductor 3D printed ?

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