Multi-stage turbomolecular pump

A vacuum pump comprising:

• a turbomolecular stage, a drag stage, a stator and a rotor, wherein the rotor comprises a turbomolecular rotor, a single drag rotor and a spindle of a motor;
• wherein
• the turbomolecular rotor comprises a hub from which a plurality of blades extends, the hub comprising a mounting portion that is mounted to the spindle of the motor and a hollow cylindrical portion, the hollow cylindrical portion extending from the mounting portion towards an outlet end of the turbomolecular stage;
• and
• the drag stage comprises a single cylindrical skirt, and wherein an attachment part extends from the single cylindrical skirt, the attachment part extending within the hollow cylindrical portion of the hub of the turbomolecular rotor and being attached to a point that is closer to the mounting portion than to the outlet end of the turbomolecular stage, the single cylindrical skirt and the attachment part forming the single drag rotor, wherein every drag stage in the vacuum pump is formed in part by the single cylindrical skirt, and wherein, at the outlet end of the turbomolecular stage, the turbomolecular rotor is separated from the single cylindrical skirt by a gap.