PURPOSE: To permit exhaust in a wide vacuum range, by using an axial flow blade as a first exhaust element, a mixed flow blade as a second exhaust element of a suction stage and a swirl flow blade as a third exhaust element on an exhaust side.
CONSTITUTION: A rotor impeller 4 of an axial flow blade is provided on an outside surface of an upper stage of a rotor 1 and rotor impellers of mixing flow blades comprising a plurality of dynamic blade grooves disposed in a circumferential direction are provided with its exhaust side. A swirl flow blade 9 is provided on an outside circumference of a second rotor 2. With the arrangement, performance of exhaust elements such as an axial flow blade, a mixing flow blade or the like disposed on an outside circumference of a bell-shaped rotor can be effected sufficiently, whereby a single pump can exhaust gas in a range covering an atmospheric pressure to an ultra high vacuum pressure.
MATSUBARA KATSUMI
MASE MASAHIRO
UEDA SHINJIRO
AWATA YOSHIHISA
NAKAMORI KAZUAKI
