Skip to main content
shopping_basket Basket 0

SIXTH PROJECT: A high vacuum diffusion pump designed with DSM 5


One of the (cheap) "workhorses" of high vacuum creation in science (10-2 to 10-8 mbar) is the diffusion pump. It uses high-speed jets of vapour to direct gas molecules coming from the top in the pump throat down into the bottom of the pump and out the exhaust. The jets are generated by boiling synthetic oil and directing the vapour through the jet assembly nozzles. The outside of the pump is cooled using either airflow or water lines. As the vapour jet hits the outer cooled shell of the pump, the oil condenses and is recovered and directed back to the boiler at the bottom. The pumped gases continue flowing to the base of the pump at increased pressure, flowing out through the outlet and removed by a secondary mechanical pump. 
The top part is an "astrotorus" cold trap with circulating cold water, that prevents escaping backstreaming hot oil vapours from entering the vacuum chamber, which needs to be super clean.

This is how a diffusion pump looks like from the inside. All parts designed from scratch with DesignSpark Mechanical 5.

Diffusion pump that creates high vacuum, Designed with DSM 5.

I am a physicist, working as a research technician at the Institute of Electronic Structure & Laser of the Foundation for Research & Technology - Hellas, in Heraklion, Crete, Greece. Our institute is a satisfied RS customer. I am specialised in lasers and vacuum technology. I am also a CAD designer with years of experience. DSM is currently my primary CAD software. "ScieRtist"

Related Content


June 16, 2021 14:18

Hello TAH1712!
Most of these are existing equipment, which I transfer into 3d CAD designs so that i can practice on DSM as much as possible, as well as having the designs available when needed. For example there may be the need in the future to modify them somehow, add or remove parts etc.
As for the astrotorus trap and the pump, i used 2d sketches i found from the manufacturing company. There were a lot of complex shapes which i found challenging to make, and learned a ton of new things of the DSM software, which is very powerfull...

0 Votes

June 14, 2021 11:41

Thanks - that's quite interesting. I've seen a few of your articles now. Are these 'designs' actually going to be made or are they for academic interest?
It would be nice to see a close view of the"astrotorus" cold trap. Also, that would look very nice with the enhanced shading in V5.
Thanks again for publishing.

0 Votes
DesignSpark Electrical Logolinkedin