at least one stage of a first turbine impeller for discharging the sucked gas in the axial direction, {TAIL ~ the first turbine impeller} being affixed to a suction part side end face of {HEAD ~ the rotating shaft}, and 
at least one stage of a first turbine impeller for discharging the sucked gas in the axial direction , { TAIL ~ the first turbine impeller } being affixed to a suction part side end face of { HEAD ~ the rotating shaft } , and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH