Abstract: A vacuum pump of the scroll type having first and second scroll components each having a scroll structure defined thereon. The scroll components are arranged in the pump such that the respective scroll structures inter-engage with the first scroll component being held stationary and the second scroll component orbiting the first scroll component to trap a volume of gas and urge the volume from one end of the respective scroll structures to the other end. The first and second scroll components define inter-engaging scroll structures having an initial multi-start portion including at least two pump inlets and a subsequent single-start portion including a pump outlet.

Abstract: A hybrid vacuum pump comprising a turbomolecular stage positioned at the inlet end of the pump and comprising a stator formed from an array of stationary blades and a rotor formed from a further array of blades arranged for rotation at high speed between the stator blades. A molecular drag stage is positioned at the outlet (high pressure) end of the pump and comprises at least two discs arranged for rotation within a stator with a minimal clearance between the circumferential edge of the discs and the stator. A flow passageway linking the turbomolecular stage with annular channels is defined between the stator and opposing faces of the discs and projections extending from the stator are provided for deflecting gas being pumped from the annular channels during rotation of the discs.

Abstract: A vacuum pump of the molecular drag type comprising a pump body, a cylindrical element adapted for rotation within the pump body about its longitudinal axis and having a plurality of circumferential slots defined in its surface which are substantially perpendicular to the longitudinal axis, a stator element held stationary with regard to the pump body and having projections extending into the slots substantially to fill the slots in the vicinity of the stator, wherein at least some of the surfaces of the stator projections adjacent the walls of the slots are coated with an abradable material.

Abstract: A vacuum pump of the molecular drag type comprising a pump body, a cylindrical element adapted for rotation within the pump body about its longitudinal axis and having a plurality of circumferential slots defined in its surface which are substantially perpendicular to the longitudinal axis, a stator element held stationary with regard to the pump body and having projections extending into the slots substantially to fill the slots in the vicinity of the stator, wherein the cylindrical element comprises a co-axial assembly of a plurality of individual discs, each disc being spaced apart from its adjacent disc(s), thereby defining the circumferential slots between the discs.