Patent ID: 8764413
Filing Date: 2014-07-01
Classification: F04D,H01J

Abstract:
1. A pumping arrangement for differentially pumping a plurality of chambers comprising: a compound pump comprising a first inlet for receiving fluid from a first chamber, a second inlet for receiving fluid from a second chamber, a first pumping section, a second pumping section downstream from the first pumping section, and a third pumping section downstream from the second pumping section, the third pumping section comprising at least one molecular drag stage, wherein pumping stages of the first, second, and third pumping sections are driven by a first drive shaft and arranged such that fluid entering the compound pump from the first inlet passes through the first, second, and third pumping sections, and fluid entering the compound pump from the second inlet passes through, of the pumping sections, only the second and third pumping sections; a booster pump outside a body of the compound pump, wherein the booster pump comprises at least one molecular drag pumping stage driven by a second drive shaft for rotation independent from the first drive shaft, a first inlet for receiving fluid from a third chamber, and a second inlet for receiving fluid from an exhaust of the compound pump; and a backing pump comprising an inlet for receiving fluid exhaust from the booster pump.