GB728172A - Mass spectrometer - Google Patents

Abstract

728,172. Heavy ion beam tubes. BENDIX AVIATION CORPORATION. Jan. 13, 1953, No. 1026/53. Class 39 (1). A mass spectrometer comprises an ion source, an ion collector, means for creating a region of extended length between the source and collector and for imparting a substantially uniform acceleration to the ions throughout the region towards the collector, and means for indicating the relative times at which ions of different masses reach the collector. In one embodiment, Fig. 1, electrons from a cathode 10 are accelerated, preferably in pulses, and pass through apertures 28 in an insulating cylinder 26 to ionize the gas introduced into the cylinder from a source 34. The ions are accelerated towards collector electrode 42 by grids 36 arranged within the cylinder 26; preferably the grids are spaced apart by equal distances and voltage pulses of equally decreasing magnitudes are applied to the grids so that the ions are uniformly accelerated through the cylinder 26; the voltage pulses may be, for example, of 120, 90, 60 and 30 volts respectively. The collector electrode 42, which may be connected to an oscilloscope 44, is preferably spaced from the end of the cylinder 26 by a distance twice the distance from the end of the cylinder 26 to the ion source. The cylinder 26 may be provided with a conductive coating on its outside to form an electrostatic screen. In a modification, Fig. 3 (not shown), the grids 36 and cylinder 26 are replaced by a cylinder of resistive material and voltage pulses are applied along the length of the cylinder. Specification 713,993 is referred to.