I know that in small laboratory setup's for thermal evaporation, a shield is foreseen around the inlet of the turbomolecular pumps in the vacuum chamber. This way a direct gas suction from the evaporation coil is prevented. But will this protect the pump permanently?
I want to prevent Aluminium vapor depositing on the inside of a turbomolecular pump.
What is the best way to protect the pump?
Aluminum has very good sticking coefficient at room temperature so it is unlikely that Al will get into the pump unless there is direct line of site. So a shield will certainly help. When we make deposition systems we typically put the gate valve and pump on an elbow to make sure that no stray material gets on the gate valve sealing surface or the pump blades.
I agree with James that the best solution would be to use an elbow to prevent deposition to come into the turbo. You will loose some pumping speed but a lot less compared with putting a shield above the turbo.
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