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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.