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====== Vacuum System for the E-beam Evaporator ======

{{::ebeamevap_schematic.jpg|}}

More information about the roughing pump is on the [[vacuum_pumps]] page of the wiki.

The labels on this diagram should match the labels on the LabView software which is controlling the ebeam evaporator. 

The LabView program is automated to open and close the various valves during pump down and venting. Please learn how and why the open/close sequence is designed so that you will be better equipped for trouble-shooting if there is a problem.

The cold trap is cooled using liquid nitrogen. It should be cold before opening the Hi-Vac valve. Cold traps are used to prevent back streaming of the vapor from the diffusion pump into the chamber. The cold trap is just above the throat of the diffusion pump so that oil vapors passing this point are condensed and returned to the pump. The chamber will then reach a lower pressure than would otherwise be possible.