High flux, high energy photon source
A high energy photon source for generating EUV radiation comprises a nozzle emitting a supersonic stream of source material, a laser or electrical/magnetic pre-ionization mechanism and a laser or electrical/magnetic excitation mechanism and a skimmer plate between them providing a collimated high density beam of source material for excitation.
1. A high energy photon source comprising:
a source material emitter arranged to emit a stream of source material at supersonic velocity;
an excitation component downstream of said source material emitter which is arranged to create a plasma in the source material for emission of high energy photons;
an apertured stop located between said source material emitter and said excitation component which collimates said stream, wherein said apertured stop is operable to collimate said stream of source material for excitation by said excitation component;
a laser pre-ionization element arranged to pre-ionize said stream of source material prior to excitation by the excitation component and to thereby control at least one of the pre-ionization state, the pre-plasma temperature, the density and the shape of the plasma to be created; and,
wherein said excitation component comprises an electrical or magnetic excitation component.
2. A high energy photon source as defined in claim 1 , wherein said apertured stop comprises:
a skimmer plate.
3. A high energy photon source as defined in claim 1 , wherein said excitation component comprises:
a laser pulse component.
4. A high energy photon source as defined in claim 1 , wherein said source material emitter and said excitation component are provided in separate chambers divided by said apertured stop.
5. A high energy photon source as defined in claim 1 , wherein said laser pre-ionization element pre-ionizes said stream of source material stream at a location upstream of a region adjacent said excitation component excitation.
6. A high energy photon source as defined in claim 1 , wherein said laser pre-ionization element pre-ionizes said stream of source material stream at a point in time prior to its excitation by said excitation component.
7. A high energy photon source as defined in claim 6 , wherein said laser pre-ionization element pre-ionizes said stream of source material at a region adjacent said excitation component excitation.