A mass spectrometer, more particularly for simultaneously measuring beams of a number of species of ions, has a special homogeneous magnetic sector field, the exit boundary of said field forming a straight line which extends through the point of intersection between the central ray of the incident object-ray pencil of ions and the straight entrance boundary of the sector field, and at least one of the emergent image-ray pencils of ions undergoing second-order directional focusing. In this spectrometer, the lateral magnification V lies in the range O .ltoreq. V .ltoreq. 1, the angle of deflection .phi. in the sector field is between 70.5.degree. and 131.8.degree., the angle .epsilon..sub.1 between the central ray of the incident object-ray pencil and the perpendicular erected at the point of intersection between the central ray and the entrance boundary is between 0.degree. and 90.degree., the distance 1.sub.1 between the object point of the ion source and the point of intersection between the central ray of the object-ray pencil and the straight entrance boundary of the sector field is between 0 and infinity, and the distance 1.sub.2 between the image point of the ion source and the point of intersection between the central ray of the second-order directionally-focused image-beam pencil and the straight exit boundary of the sector field is between 0.236 and 0.943.
A mass spectrometer comprises a source for generating ions, a means for separating the ions according to mass, and means for detecting the separated ions. The mass spectrometer is characterized by that means for separating ions comprises a sector type homogenous magnetic field, and that the magnetic field has a deflection angle ranging from 110 to 135 degrees, and incident and exit angles ranging from 40 to 60 degrees.
A multiple charged-particle detector system includes a plurality of charged-particle detector assemblies (10-12) which are each made up of a first arm (19-22) and a second arm (24-27) extending at an angle to each other. Charged particles (4-7) enter an aperture (14-18) at the entrance of the first arm (19-22) of each detector assembly (10-12) and strike a dynode (30-33) positioned at the intersection of the two arms causing electrons to be emitted by the dynode (30-33). Some of the electrons pass into the second arms (24-27) of the detector assemblies (10-12) and are detected by a continuous-dynode electron multiplier (35-38). The first arms (19-22) are narrower than the detectors (35-38), and the detector assemblies (10-12) are arranged in such a way that the minimum separation at which charged-particle beams (4-7) can be detected is determined by the widths of the said first arms (19-22) of the detector assemblies (10-12), and not by the widths of the detectors (35-38) themselves.
A scanning mass spectrometer (10) in combination with an electro-optical detector (100) which enable greatly increased speed of mass determinations by detecting a limited range of masses simultaneously, thus reducing the number of discrete magnetic field adjustments required over a large range of masses. The electro-optical detector (100) includes a channel electron multiplier assembly (94) with the surface of an image plate (80) located along the ion focal plane (44) and at an angle to the exit plate (106) of the magnetic sector (26) and a fiberoptic window (134) of a special shape optically coupled between the angled image plate (80) and a photodiode detector array (140). The fiberoptic window (134) is shaped in such a way as to enable the entrance ends (entrance plane) (144) of the fibers to be parallel to the angled image plate (80) and the exit ends of the fibers (exit or second image plane) (146) to be parallel to the exit plane (106) while maintaining the ends of the fibers perpendicular to the fiber axes. The channel electron multiplier assembly (94) is within a vacuum envelope (104) and the photodiode array (140) is outside the vacuum envelope (104).
A magnetic sector for charged particle beam transport that includes a magnetic field profile that achieves a linear dispersion from a collimated beam of charged particles proportional to their mass-energy-to-charge ratio. In one embodiment, the field profile necessary for the linear dispersion is obtained by the use of shaped, highly permeable poles powered by permanent magnets or electromagnetic coils.
