US Patent 7872244 Lithographic apparatus and device manufacturing method

A source configured to generate radiation for a lithographic apparatus is disclosed. The source includes an anode, and a cathode. The cathode and the anode are configured to create a discharge in a fuel in a discharge space between the anode and the cathode so as to generate a plasma, the cathode and the anode positioned relative to each other so that, in use, current lines extending between the anode and the cathode are substantially curved so as to create a force that substantially radially compresses the plasma only in a region proximate an upper surface of the cathode or of the anode.