A turbomolecular pump is provided. In one arrangement, a stator stack and rotor stack have corresponding conical or frustum shapes that allow for adjusting the clearance between the stator vanes and rotor vanes of the pump to provide adjustable compression ratios and/or to adjust clearances. In another arrangement, the actuator or drive mechanism of the pump is formed from coils attached to the upper stage of rotor vanes which are controlled to interact with a plurality of stationary magnets attached to the housing of the pump to rotate the stator stack. In another arrangement, a control system of the pump utilizes the coils of the rotor drive to dynamically balance the pump during operation.