DIY Penning gauge controller?

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
Post Reply
User avatar
Nikodem Czechowski
Posts: 16
Joined: Sat Jan 16, 2021 8:56 pm
Real name: Nikodem Czechowski
Location: Poland
Contact:

DIY Penning gauge controller?

Post by Nikodem Czechowski » Fri Jan 29, 2021 10:59 pm

I've recently obtained an Leybold PR35 Penning gauge. Obviously, I have no controller, and I think that it will be close to impossible to obtain one soon, especially in a limited budget.

Do you think it is possible to fabricate a DIY controller? In theory it should be really simple - generate some 1.6 kV and measure the current (that should be extremally low). Is this feasible?

User avatar
Richard Hull
Moderator
Posts: 12923
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: DIY Penning gauge controller?

Post by Richard Hull » Sat Jan 30, 2021 4:46 pm

Yes, it would be an interesting project, but calibration would be the main issue. The electronics would be easy.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Cai Arcos
Posts: 146
Joined: Fri Oct 12, 2018 1:30 pm
Real name: Cai Arcos
Location: Barcelona, Spain.

Re: DIY Penning gauge controller?

Post by Cai Arcos » Sun Jan 31, 2021 1:30 pm

In a spanish forum, they constructed a Penning Gauge from zero. They used a CCFL inverter and measured the current from the low side of the transformer to the ground of the primary, in order to avoid arcing and safety issues. As Richard stated, calibration is a problem which is pretty much impossible to solve without another reliable already known-good gauge. I leave the link in spanish:

http://www.cientificosaficionados.com/f ... 8ef16865b4

Diego Gonzalez
Posts: 4
Joined: Sat Jan 30, 2021 10:07 pm
Real name: Diego González Álvarez

Re: DIY Penning gauge controller?

Post by Diego Gonzalez » Sun Jan 31, 2021 9:55 pm

Hello.

I'm the second person who made that CCG in that forum and I'm satisfied with the result. I haven't calibrated it yet but I use it to know relative pressures.

Best regards

User avatar
Nikodem Czechowski
Posts: 16
Joined: Sat Jan 16, 2021 8:56 pm
Real name: Nikodem Czechowski
Location: Poland
Contact:

Re: DIY Penning gauge controller?

Post by Nikodem Czechowski » Sun Jan 31, 2021 11:10 pm

Calibrating it might not be that bad. It's an Leybold PR35, so someone in the world might be able to measure the current... right? If not, then maybe I will be able to borrow a second gauge, or bring this one to someone.

Regarding the electronics - the HV is not that bad, there are plenty of ways to get a 1.6 kV and even to regulate it to a constant level. But what about the measurement? I have not searched for an in-amp that woul be ok with such high CM voltage, but this troubles me..

User avatar
Maciek Szymanski
Posts: 155
Joined: Wed Nov 20, 2019 7:31 pm
Real name: Maciek Szymański
Location: Warsaw, Poland

Re: DIY Penning gauge controller?

Post by Maciek Szymanski » Mon Feb 01, 2021 7:38 am

Here you are the schematic of the Unima PWN100 vacuum gauge. It is combined gauge with two TC low vacuum sensors (G1 and G2) and cold cathode ionization sensor (GJ). There is also automatic range switching comparator for the low vacuum range, making the circuit a bit more complicated. But the basic circuit for the ionization gauge should be quite obvious. Sorry for the poor quality, but it is from the very old photocopy.

BTW the cold cathode gauges are rather unreliable from my experience. I have used the Unima reversed omegatron type and Leybold’s penning type and both had really annoying histeresis of almost one order of magnitude. The hot cathode gauges are completely different story and precision.
Attachments
C1D47245-5AEB-4F2D-806D-909B14C6210D.jpeg
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland

User avatar
Nikodem Czechowski
Posts: 16
Joined: Sat Jan 16, 2021 8:56 pm
Real name: Nikodem Czechowski
Location: Poland
Contact:

Re: DIY Penning gauge controller?

Post by Nikodem Czechowski » Thu Feb 04, 2021 1:20 pm

Thanks for the schematic!

In the interesting area the penning gauge shoud have almost flat curve, generally speaking:

I = K * p^m

m is generally gas dependent. For nitrogen it is 1.17 and for helium 1.30

So only two parameters are needed, maybe I can calibrate with a low vacuum gauge and extrapolate the calibration?

(see here for the equation sourc: https://indico.cern.ch/event/565314/con ... ten_v2.pdf)

Post Reply

Return to “Vacuum Technology (& FAQs)”