Homemade Diffusion Pump

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Justin Fozzard
Posts: 19
Joined: Thu Aug 24, 2017 11:11 am
Real name: Justin Fozzard
Location: Essex, England

Homemade Diffusion Pump

Post by Justin Fozzard » Fri Aug 25, 2017 8:37 pm

Here is a photo of my attempt at building a diffusion pump as a 14-year old schoolboy.
Homemade Diffusion Pump.jpg
Homemade Diffusion Pump
It was my own design based on a picture in an encyclopedia article. I never got round to testing the pump and don't know if it would have worked.
I was given an old vacuum sputter coater shortly after finishing it and used that for my plasma experiments.
It sat in a damp shed for about twenty years so the central mild steel jet support has rusted and stained the copper and brass parts.

I've recently stripped down a rather lethal looking Kaiser 80kV 50mA power supply that I hope to modify for fusor use:
Kaiser 80kV Power Supply.jpg
Kaiser 80kV Power Supply 1.jpg
Kaiser 80kV Power Supply 2.jpg
The power supply uses a triode in series with the output to regulate the voltage and also has a 240V 80kV isolation transformer.

I have two of these 500kg monsters and stripped this one down because I managed to drop it on its side while unloading it from my truck. The castor and baseplate were damaged and I don't know if the tube has broken. Fortunately the transformers and rectifiers look undamaged.

Regards,
Justin Fozzard

ian_krase
Posts: 512
Joined: Mon Nov 28, 2016 7:48 am
Real name: Ian Krase

Re: Homemade Diffusion Pump

Post by ian_krase » Sat Aug 26, 2017 2:46 am

Nice! How is the jet stack put together m?

Justin Fozzard
Posts: 19
Joined: Thu Aug 24, 2017 11:11 am
Real name: Justin Fozzard
Location: Essex, England

Re: Homemade Diffusion Pump

Post by Justin Fozzard » Sun Aug 27, 2017 9:11 pm

Hello Ian,
The top jet is screwed onto a steel shaft that is in turn screwed into the centre of the brass base casting.
The second jet is sits on a step turned on the outside of the inner copper jet tube.
The jet tubes are silver soldered into annular grooves turned in the base casting.
The lower ring is soldered onto the the second jet tube and has slots filed in it to allow condensed oil to pass back to the heated base of the pump.
The copper tubes are all standard plumbing sizes, 1/2", 1" and 1-1/2" diameter. The brass parts were all cast from scrap at school and were turned on my father's 3-1/2" Myford Super Seven lathe.
Thin copper 1/8" tube used to be wrapped around the top of the outer and side backing pump tube for water cooling, but I took it off for use in a later project.
I had hoped to heat the base casting with a small electric element, but with hindsight, I think it would have taken rather a lot to heat the heavy brass base and tubes.

The pump did eventually get a use: I took it along to my first job interview and I think it helped me get the job when I explained that although the pump only took about 50ml of oil, I would need to buy about 200ml as I was bound to spill some!
Jet Assembly.JPG
Jet Assmbly
Jet Assembly 1.jpeg
Jet Assembly 1
Jet Assembly 2.jpeg
Jet assembly 2
Regards,

Justin Fozzard

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