#1 FAQ - Basic Vacuum System Diagram

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Richard Hull
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#1 FAQ - Basic Vacuum System Diagram

Post by Richard Hull » Wed Apr 02, 2014 4:25 am

Attached, find a very crude basic diagram of just the vacuum system portion of a full fusing fusor.

Little explanation is needed.

The forepump is a standard, preferably, two stage mechanical pump of either a direct or belt drive type.

The foreline needs a vacuum rated valve to isolate the foreline pump from the secondary diffusion pump.
NOTE***** the forline in the diagram is a mile too long and is drawn to show detail. All forelines need to be very short and of large diameter!!!! A 6" long hose is getting to be too long.

The oil diffusion pump is the most often chosen secondary pump to achieve a sub micron vacuum of aleast 10e-4 torr, but preferably a 10e-5 torr final pressure in the fusor prior to admitting deuterium for fusion. Diffusion pumps can be had used for as little as $100.00 or less. NOTE**** A turbomolecular pump is more desirable, but new costs of over $2500.00 makes outright purchase of these, even if used, over $500.00 with controller and cabling a bit prohibitive to the amateur.

A throttle type high vacuum valve is needed between the diffusion or secondary high vacuum pump and the fusor to isolate the fusor from this pump and to control the continuous, operational evacuation rate.

The need for a speical high vacuum gauge reading fusor pressure is an improtant addition.

Plumbing lines: All plumbing, (pipes and hoses) should be as large as possible in diameter and as short as can be tolerated based on mechanical design, which should put all pumps and fusor chamber jammed as close together as possible. Use reason!!! A fore pump with a 1" outlet will not benefit from a 6" diameter hose connecting it to the diffusion or turbo pump. A very short, under 6" long, 1" diameter line is fine. A two inch throat on a diff pump need not have a connection to the fusor larger than 2" in diameter....JUST KEEP IT VERY SHORT!! Note: The foreline in the diagram below is shown way too long only for the sake of clarity.

There are other FAQs in the is forum discussing use, operation and cleaning of both types of pumps.

Richard Hull
Vac system.JPG
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