Patent Number: 
Section: claims

1. A device comprising:an enclosing structure defining a closed loop flow path, said enclosing structure formed with an inlet and an outlet;a system generating plasma at a plasma site, the site being in fluid communication with said flow path;a gas source connected to said inlet; anda conditioner connected to said outlet to condition gas exiting said enclosing structure. 2. A device as recited in claim 1 wherein the plasma comprises tin and the filter removes a compound selected from the group of compounds comprising tin hydrides, tin oxides and tin bromides. 3. A device as recited in claim 1 wherein said conditioner is selected from the group of conditioners consisting of a gas dilution mechanism, a scrubber or a combination thereof. 4. A device as recited in claim 1 wherein said enclosing structure comprises a vessel in fluid communication with a guideway external to the vessel. 5. A device as recited in claim 1 further comprising a pump forcing said gas through said closed loop flow path. 6. A device as recited in claim 1 further comprising a heat exchanger removing heat from gas flowing in said flow path. 7. A device as recited in claim 1 further comprising a filter removing at least a portion of a target species from gas flowing in said flow path. 8. A device comprising:an enclosing structure defining a closed loop flow path;a system generating plasma from a source material at a plasma site, the site being in fluid communication with said flow path, the source material comprising tin;a gas comprising hydrogen disposed in said enclosing structure;a filter removing at least a portion of a target species from gas flowing in said flow path. 9. A device as recited in claim 8 wherein the plasma comprises tin and the filter removes a compound selected from the group of compounds comprising tin hydrides, tin oxides and tin bromides. 10. A device as recited in claim 9 wherein the filter comprises a cold trap. 11. A device as recited in claim 9 wherein the filter comprises a zeolite filter. 12. A device as recited in claim 9 wherein the filter comprises a chemical absorber. 13. A device as recited in claim 9 wherein the filter comprises a plurality of internally cooled metal plates to condense vapors. 14. A device as recited in claim 9 further comprising a pump forcing said gas through said closed loop flow path. 15. A device as recited in claim 9 further comprising a heat exchanger removing heat from gas flowing in said flow path. 16. A device comprising:an enclosing structure defining a closed loop flow path passing through said through-hole;an EUV reflective optic positioned in said enclosing structure;a temperature control system cooling the optic;a system generating plasma at a plasma site, the site being in fluid communication with said flow path; anda gas disposed in said enclosing structure. 17. A device as recited in claim 16 wherein the optic is a near normal incidence mirror. 18. A device as recited in claim 16 wherein the EUV reflective optic has a substrate and wherein at least one cooling channel is formed in the substrate to pass a heat exchange fluid. 19. A device as recited in claim 16 further comprising a heat exchanger removing heat from gas flowing in said flow path. 20. A device as recited in claim 16 wherein the system generates plasma from a source material comprising tin and the gas comprises hydrogen.