Patent Number: 
Section: claims

1. An extreme ultraviolet light source apparatus for generatingextreme ultraviolet light by introducing a laser beam and irradiating a target material with the laser beam to turn the target material into plasma, said apparatus comprising: a chamber in which the extreme ultraviolet light is generated;a target supply unit configured to supply the target material toward a plasma emission point within said chamber;a collector mirror configured to collect the extreme ultraviolet light radiated from the plasma;a first magnetic source;a first magnetic material to be magnetized by said first magnetic source, said first magnetic material having a leading end portion projecting from an inner wall of said first magnetic source toward the plasma emission point;a second magnetic source, anda second magnetic material to be magnetized by said second magnetic source, said second magnetic material having a leading end portion projecting from an inner wall of said second magnetic source toward the plasma emission point,wherein the leading end portion of said first magnetic material and the leading end portion of said second magnetic material face each other with the plasma emission point in between. 2. The extreme ultraviolet light source apparatus according to claim 1, further comprising a yoke passing through an opening formed in the first magnetic source,wherein the first magnetic material has one leading end portion connected to a leading end portion of the yoke, and another leading end portion located to face the plasma. 3. The extreme ultraviolet light source apparatus according to claim 1, wherein the first and second magnetic materials are located between a trajectory of the target material and said collector mirror. 4. The extreme ultraviolet light source apparatus according to claim 1, further comprising a target collecting tube configured to collect the target material, wherein:the first magnetic material has a cylinder shape surrounding said target supply unit, andthe second magnetic material has a cylinder shape surrounding said target collecting tube. 5. The extreme ultraviolet light source apparatus according to claim 4, wherein a volume of said first magnetic material is smaller than a volume of said second magnetic material. 6. The extreme ultraviolet light source apparatus according to claim 1, wherein a path configured to circulate a refrigerant is formed within the first magnetic material. 7. The extreme ultraviolet light source apparatus according to claim 1, wherein one of said first and second magnetic materials has a through hole through which the laser beam passes. 8. The extreme ultraviolet light source apparatus according to claim 1, wherein:said first and second magnetic sources are provided outside of said chamber, andeach of said first and second magnetic materials have one leading end portion connected to a respective one of the first and second magnetic sources outside of said chamber, and another leading end portion extending into said chamber. 9. The extreme ultraviolet light source apparatus according to claim 1, further comprising within said chamber:an extreme ultraviolet (EUV) light amount sensor;laser beam focusing optics; anda target location monitor unit,wherein the first magnetic material is located to form a magnetic field between the plasma and at least one of said EUV light amount sensor, said laser beam focusing optics, and said target location monitor unit. 10. The extreme ultraviolet light source apparatus according to claim 1, further comprising:an electrode formed on a rear surface of said collector mirror; anda power supply configured to apply a voltage to said electrode. 11. The extreme ultraviolet light source apparatus according to claim 10, further comprising:a charging unit configured to charge particles radiated from the plasma. 12. The extreme ultraviolet light source apparatus according to claim 1, further comprising:a power supply configured to apply a voltage to the first magnetic material. 13. The extreme ultraviolet light source apparatus according to claim 12, further comprising:a charging unit configured to charge particles radiated from the plasma. 14. The extreme ultraviolet light source apparatus according to claim 1, further comprising:two electrodes facing each other with the plasma in between; anda power supply configured to apply a voltage between said two electrodes. 15. The extreme ultraviolet light source apparatus according to claim 14, wherein one of the two electrodes has a through hole through which the laser beam passes. 16. The extreme ultraviolet light source apparatus according to claim 15, further comprising:a charging unit configured to charge particles radiated from the plasma. 17. The extreme ultraviolet light source apparatus according to claim 14, further comprising:a charging unit configured to charge particles radiated from the plasma. 18. The extreme ultraviolet light source apparatus according to claim 1, wherein the surface of the first magnetic material is coated with a material including one of TiN, Si3N4, BN, Al2O3, TiO2, MgAl2O4, carbon (C), titanium (Ti), and porous titanium. 19. An extreme ultraviolet light source apparatus for generating extreme ultraviolet light by introducing a laser beam and irradiating a target material with the laser beam to turn the target material into plasma, the apparatus comprising:a chamber in which the extreme ultraviolet light is generated;a target supply unit configured to supply the target material toward a plasma emission point within the chamber;a collector mirror configured to collect the extreme ultraviolet light radiated from the plasma;a plurality of electromagnetic coils disposed outside of the chamber;a plurality of magnetic cores which respectively project from an inner wall of said plurality of electromagnetic coils toward the plasma emission point to face each other with the plasma emission point in between; anda yoke configured to connect said plurality of magnetic cores to each other.