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United States Patent | 3,553,452 |
Tiernan , et al. | January 5, 1971 |
A time-of-flight mass spectrometer for the investigation of ion-molecule reactions at ion source pressures up to about 1 Torr. The ion source is operated with a continuous electron beam and a constant repeller voltage of the minimum value necessary to extract ions from the source. A shaped repeller and low electron trap potential are used to provide an uniform field in the source, resulting in a minimum kinetic energy range for the extracted ions. Focusing takes place in the low-pressure region outside the source bounded by the first and second grids between which the focusing pulse is applied. A concurrent blocking pulse is applied to the first grid to prevent ions entering the focusing region during the focusing operation.
Inventors: | Tiernan; Thomas O. (Centerville, OH), Miller; Carrol D. (Dayton, OH), Futrell; Jean H. (Salt Lake City, UT), Abramson; Fred P. (Arcadia, CA) |
Appl. No.: | 04/799,849 |
Filed: | February 17, 1969 |
Current U.S. Class: | 250/287 ; 250/427 |
Current International Class: | H01J 49/40 (20060101); H01J 49/34 (20060101); H01j 039/34 () |
Field of Search: | 250/41.9(G),41.9(ISB),41.9(1) |
2798162 | July 1957 | Hendee |
3296481 | January 1967 | Peters |