GB1320206A - Mass spectrographs - Google Patents

Abstract

1320206 Mass spectrometers INSTITUT FUR PLASMAPHYSIK GmbH 29 July 1970 [30 July 1969] 36779/70 Heading H1D A double focusing mass spectrograph comprises an ion entrance slit 10, Fig. 1, means 16 and 24 for producing electric and magnetic sector fields operating in the same sense, an energy-limiting stop 20, and an electrostatic lens 22 arranged at a distance f equal to its focal length behind the stop 20, and electrostatic means are provided for forming an image of the entrance slit in the plane of the energy limiting stop. In Fig. 1 the latter comprises a second electrostatic lens 18 arranged at a distance f equal to its focal length in front of the stop 20. The focal lengths of the two lenses may be adjustable electrically either together or separately. Fig. 1 also includes a second aperture stop 14 and the widths of the apertures in one or both stops 14 and 20 may be adjustable. The spectrum is formed at the boundary 26 of the magnetic sector, and a photographic plate may be mounted in this plane. In a modification, (Fig. 3, not shown), the lens 18 is disposed before instead of after the electric sector 16. In another modification (Fig. 4, not shown) this lens is omitted and the focusing is achieved by the electric sector which extends over 90 degrees. With this arrangement the entrance plane of the magnetic sector may be oblique to the ion paths and the image plane is inclined to the boundary of the magnetic sector.