Patent ID: 8373848

Claim:
A lithographic apparatus comprising: an illumination system configured to condition a radiation beam; a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate; and an actuator configured to produce a force in a first direction between a first and a second part of the apparatus, the actuator comprising a first magnet assembly and a second magnet assembly each attached opposite to each other to the first part of the apparatus, the first magnet assembly comprising a first main magnet system and a first subsidiary magnet system, and the second magnet assembly comprising a second main magnet system and a second subsidiary magnet system, the first and second main magnet system defining a space between them in a second direction substantially perpendicular to the first direction, wherein the first and second magnet assembly are arranged in Halbach configuration to provide a magnetic field of which at least a part is directed substantially in the second direction, an electrically conductive element attached to the second part of the apparatus and arranged at least partially in the space between the first and second main magnet system, so as to produce the force by interaction of an electric current carried by the electrically conductive element and the magnetic field, wherein the distance between at least a part of the first subsidiary magnet system and at least a part of the second subsidiary magnet system is smaller than a minimum distance between the first main magnet system and the second main magnet system.