Arduino in a high vacuum chamber

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jrwst36
 
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Arduino in a high vacuum chamber

Post by jrwst36 »

Hello,

I would like to use an Arduino setup to apply a bias to a transistor while measuring it in a ultra high vacuum chamber (UHV). The measurement is x-ray photoelectron spectroscopy (XPS), and unfortunately, I don't have electrical ports going into the vacuum chamber. So my whole biasing assembly has to be self contained and placed on the sample stage next to the sample. I would like to use the Arduino BT to apply the bias, 0 to 5 V, and a maybe up to a few hundred milliamps. I don't think I can use batteries because they would probably explode under UHV, though I can get some capacitors stacked up.

So my question is, is this a reasonable setup? I have not used an Arduino setup before, so I am new to this. But it seems pretty simply. Simply, wirelessly control a voltage output from 0-5V.

Thanks,
Jesse

madworm_de
 
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Re: Arduino in a high vacuum chamber

Post by madworm_de »

a) Do you really think you'll be happy after putting _plastic_ into you UHV system. All the hydro-carbons evaporating. I don't think you'll get down to 10^-10mbar that way.
b) What about the bake-out procedure. If this is truly a UHV system, you'll surely bake the system at 200°C to get rid of all the adsorbed water. At those temperatures all the electrolytic capacitors will boil and pollute your system.
c) How is the RF signal supposed to get into the chamber? Stainless steel walls...

I suggest you have a look at your favourite vacuum fittings dealer and get a feedthrough that fits to your chamber's ports. Lesker / Hositrad / Varian ... your choice.

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jrwst36
 
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Re: Arduino in a high vacuum chamber

Post by jrwst36 »

These are all good questions.

"a) Do you really think you'll be happy after putting _plastic_ into you UHV system. All the hydro-carbons evaporating. I don't think you'll get down to 10^-10mbar that way."

The vac in our XPS chamber is 10-9 Torr, and we've had plastic in there before (a plastic sample is the calibration standard for the charge neutralizer). We use carbon tape all the time, and we've even had fish scales in there. All the time our vacuum has been fine. Having said that, I don't know if this plastic out gasses more. I would test it by leaving it in the load lock chamber.

"b) What about the bake-out procedure. If this is truly a UHV system, you'll surely bake the system at 200°C to get rid of all the adsorbed water. At those temperatures all the electrolytic capacitors will boil and pollute your system."

The arduino system would sit on the sample stage, which in not present in the chamber during bake out.

"c) How is the RF signal supposed to get into the chamber? Stainless steel walls..."

There are plenty of optical ports present. Clearly they block x-rays, but not light. So I guess the RF signal could pass though... but I'm not certain.

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adafruit_support_bill
 
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Re: Arduino in a high vacuum chamber

Post by adafruit_support_bill »

Not sure if electrolytic caps would survive the vacuum. You could probably build up a minimal boarduino without voltage regulator or caps if you can get a steady 5v to it.

If you have optical ports, you might consider IR communication instead of RF.

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jrwst36
 
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Re: Arduino in a high vacuum chamber

Post by jrwst36 »

Okay, thanks! I'll look into IR.

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westfw
 
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Re: Arduino in a high vacuum chamber

Post by westfw »

Well, and Ardiuno is cheap enough to try a few possible-destructive experiments, right?
I don't think any of the components are vacuum rated, and power is going to be a real problem since I would expect caps to be one of the more serious issues...

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jrwst36
 
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Re: Arduino in a high vacuum chamber

Post by jrwst36 »

Yea, power is an issue. I considered a small but efficient solar panel with a UV light source directed at it. I could get a few watts out of it.

madworm_de
 
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Re: Arduino in a high vacuum chamber

Post by madworm_de »

It is painful to read what efforts are made to avoid getting a decent electrical feedthrough. You can _never_ have enough feedthroughs. Even if you now shy away from paying the 250$+ for a decent multi-pin one, it will pay off in the future multiple times.

Lesker has a decent variety of those for CF and KF flanges. Unless you really absolutely definitely need all present optical ports (windows, AR coated for 800nm?, or CaF for high UV transmittance?), sacrifice one and get a feedthrough.

Don't waste your time with stuff like this. I did in my time in the lab and it didn't do me any good.

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didier
 
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Re: Arduino in a high vacuum chamber

Post by didier »

I found this interesting topic by pure chance, sorry for excavating it.
Yes you can put some "plastic parts" inside a vacuum chamber. 10-9 is real HIVAC and all precautions should be taken in order to avoid desorption. Desorption has not only an impact on pressure measurement, it is also generating million of molecules traveliing freely accross the vacuum chamber and possibly the measuring cell. Condensing these molecules is a nightmare for the analyst.
At first glance, Arduino board is the last thing that I would put inside a HIVAC chamber: too many plastics of unknown composition and a lot of cavities which retain gaseous or condensed molecules: they lengtehn the pumping time a lot...
So that I ould prefer putting a nano or mini instead of a uno inside this HIVAC chamber!
Feedthrough are definetly my favorite too. You may make one of your own, using an used pipe connexion after modifying a KF cap (I did that with success in the past)

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jrwst36
 
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Re: Arduino in a high vacuum chamber

Post by jrwst36 »

Hi didier,
Actually, I ran this experiment years ago. Degassing wasn't my biggest worry; I was thinking that the batteries or the capacitor might explode.

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