This is going to be another long term project with multiple offshoot projects. The first part is to get the chamber and all of the associated hardware working together and create a solid vacuum. The chamber is 21 inches in diameter with an ISO250 main access port, five 2.75″ conflat (CF) ports, two 1.33″ CF ports, 1 MDC viewing window, and one 90 degree flange with a ISO100 opening. If you don’t know what these types of fittings our check out my Vacuum Fittings post about the different types of vacuum ports.
The chamber is pumped down via a Varian rotary vane roughing pump then by a Pfeiffer turbo molecular pump to achieve ultra high vacuum. At the time of writing this all of these pumps need to be fully tested, so far I have only conducted basic checks.
Turbo Molecular pumps work on the principle that a gas molecule can be given momentum in a certain direction by constant collision with a sold surface. In a turbo pump the molecules are hit by a turbine rotor that is designed to direct the molecules down into other blades and eventually out through the roughing pump. Because these pumps can operate at speeds of 60,000 rpms or more the newer units use a magnetic bearing system. These types of bearings allow the shaft to levitate with out contact and prevent bearing issues. The unit I am using uses lubricated ceramic bearings. You can see the oil on the side of the unit through the view port. I will be doing a blog post that will be linked here in the near future describing the math and physics behind how these pumps work, for the purpose of this page I feel that that would be getting into far too much detail.