If they were made by Varian, I would doubt they were on an engine.
Their 'turbos' are vacuum pumps.
Ayup. The principles are the same; get the speed of the Vanes up to a high enough speed so as to direct Molecular Flow. With these Varian Turbopumps, I routinely logged Driver Current and Bearing Temperatures; if there was a sudden sharp rise unrelated to Pressure, the pump was removed for new bearings. They had hundreds of Varian Turbos to keep an eye on.
I've also rebuilt quite a number of Varian and PE Ion Pumps. Instead of simply replacing the Titanium and/or Tantalum Elements, as Varian and PE did at great expense, I literally beat the crap out of them, using a particularly peculiar form of Sandblasting.
But this has little to do with the ongoing discussion, so I shall end it here.