GB876247A - Improvements relating to mass spectrometers - Google Patents

Abstract

876,247. Ion sources. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Jan. 14, 1960 [Jan. 19, 1959], No. 1944/59. Class 39(1). An ion source for a mass spectrometer includes a valve for sealing off the ion source from the main body of the spectrometer and so enabling the specimen material to be readily changed, the valve being actuated in a direction oblique to the axis of the ion beam duct 4. The valve shown 54 is of the ball-andsocket type actuated by plunger 53 and piston 62. The ion source includes a pair of arc electrodes held by clamps 11, an apertured plate 38 held at the potential of one of the electrodes, and an accelerating and focusing electrode 39. The plate 38 is supported by insulators 40 and its central aperture 41 is covered by an apertured removable disc 42. Observation windows are shown at 67, 68. The arc electrode supports extend through bellows and may be adjusted in three dimensions. The ion beam emerging from the duct 4 passes through an electrically controlled shutter comprising two earthed outer plates 44, 46 and a divided central plate 45 one half of which is earthed and the other half connected to a source of high potential through a switch. The end plate 3 of the ion source is attached to the body 1 by means of a rubber ring 71 located in an annular groove 72 or, alternatively, by a soft metal seal.