Improvements relating to mass spectrometers

1,034,641. Mass spectrometers. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Nov. 7, 1962 [Nov. 10, 1961], No. 40354/61. Heading H1D. A mass spectrometer, as shown of the 180-degree type, has a glass envelope 1 with the ion source 2, analysing chamber 3 and ion collector 4 supported within the envelope by a plurality of lead-in conductors. The ion source which is of the electron beam bombardment type comprises a metal box supported by the conductor 10 and attached to the analysing chamber by insulating supports 5, 6. The ion repeller electrode at the bottom of the ion source is supported by conductor 15. The ion collector 4 which is surrounded by a metal shield 24 is separately supported by conductor 25. The glass envelope has flat portions 7, 8 against which the magnet polepieces fit and is coated on the outside with graphite to form an electrostatic screen.