Improvements to reduce the size of a GCMS while improving its performance. A first improvement adjusts the magnet for radii of travel. Another feature removes a portion of the magnet to compensate for the fringe field. Yet another improvement shaves portions off of the yoke near where they meet the pole pieces.
This application is a continuation-in-part of U.S. patent application Ser. No. 08/600,861, entitled Array Detectors for Simultaneous Measurements of Ions in Mass Spectrometry, which was filed Feb. 9, 1996 now U.S. Pat. No. 5,801,380.
A system and method for modeling the effect of a molecular contaminant film on performance of an optical system is disclosed. A mass of material outgassed from materials of the optical system is correlated to spectrum of outgassed products. The spectrum of outgassed products is normalized, and an aggregate molecular contaminant film thickness is predicted from each material. The absorbance spectrum of the aggregate molecular contaminant film is derived, and the derived absorbance spectrum of the aggregate contaminant film is convolved with an optical system instrument function. A plot of at least one transmission band as a function of source temperature is performed to determine the degradation in performance of the optical system.
A mass spectrometer suitable to measure both positive and negative particles, such as ions for example in a vacuum chamber. This spectrometer is provided with a turnable permanent magnet segment, which provides the gap of a yoke with adequate magnetic flux having the appropriate direction to separate the positive or the negative particles. Changing the polarity adjusts the flight path of the ions. Thus, negatively charged ions and positively charged ions will follow similar flight paths under opposite polarities, permitting the use of a single array of detectors. One or more coils may be used in place of or in addition to the turnable permanent magnet segment in order to provide the appropriate magnetic flux to the gap, and/or facilitate the turning process of the turnable magnet segment. The turnable magnet and/or the coils may be inside or outside the vacuum chamber. The detector may comprise at least one detector area, two charge mode amplifiers coupled to the detector area, a first CCD shift register coupled to a first one of the charge mode amplifiers and a second CCD shift register coupled to a second one of the charge mode amplifiers.
A system and method for modeling the effect of a molecular contaminant film on performance of an optical system is disclosed. A mass of material outgassed from materials of the optical system is correlated to spectrum of outgassed products. The spectrum of outgassed products is normalized, and an aggregate molecular contaminant film thickness is predicted from each material. The absorbance spectrum of the aggregate molecular contaminant film is derived, and the derived absorbance spectrum of the aggregate contaminant film is convolved with an optical system instrument function. A plot of at least one transmission band as a function of source temperature is performed to determine the degradation in performance of the optical system.
A charged particle detector and method are disclosed providing for simultaneous detection and measurement of charged particles at one or more levels of particle flux in a measurement cycle. The detector provides multiple and independently selectable levels of integration and/or gain in a fully addressable readout manner.
A focal plane detector assembly of a mass spectrometer includes an ion detector configured to detect ions crossing a focal plane of the spectrometer and an electrically conductive mesh lying in a plane parallel to the focal plane, positioned such that ions exiting a magnet of the mass spectrometer pass through the mesh before contacting the ion detector. The mesh is maintained at a low voltage potential, relative to a circuit ground, which shields ions passing through the magnet from high voltage charges from other devices, such as microchannel plate electron multipliers. The mesh may be mounted directly to the magnet or positioned some distance away. The detector array may include any suitable device, including a faraday cup detector array, a strip charge detector array, or a CCD detector array.
