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Technical Information
Diffusion Pump Description
Diffusion pumps are used where throughput for heavy gas loads is important. The
diffusion pumps begin to work at approximately 10
-3
Torr after a mechanical
backing pump has exhausted most of the air in the system.
Figure 2 HS-20 Diffusion Pump
There are no moving parts in a diffusion pump, the heart of which is the multistage
jet assembly, a group of concentric cylinders that are capped to leave small
openings through which vapor can be deflected down and out toward the pump
walls. A cold cap, mounted on top of the jet assembly helps keep pump fluid vapor
out of the evacuation chamber. The pumps are water-cooled.
The vacuum fluid heater is mounted at the bottom of the pump body. The pumps
also have a fill and drain assembly, and thermal protection switches. The inlet is at
the top, and the exhaust is through the foreline.
High Throughput Diffusion Pumps User Manual
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