Sem/eds Theoretical Stuff
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چکیده
Silicone based oil is heated in the boiler of the diffusion pump and the vaporized oil rises in the central tower and streams out of directional flutes directed downward in the pump throat. This allows air molecules to dissolve in the gaseous oil (gas dissolved in gas). As the oil-air mixture cools (due to water cooling coils wrapped around the pump throat) the oil condenses and returns to liquid, the air molecules come out of the gaseous oil solution and are pulled into the buffer tank vacuum. This removal of air from the top of the diffusion pump causes air from the sample chamber and column to diffuse towards the pump throat to replace the removed air molecules, thus the name “diffusion pump”. The beauty is that there are no moving parts to mechanically wear out. Modern silicone based oils withstand the repeated heating and thus diffusion pumps are very durable.
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