GB737715A - Mass spectrometer - Google Patents

Abstract

737,715. Heavy-ion-beam tubes. BENDIX AVIATION CORPORATION. June 1, 1953 [June 4, 1952], No. 15236/53. Class 39 (1). [Also in Group XL (c)] In a mass spectrometer of the type in which ions of different masses are separated into groups by first storing them and then withdrawing them as a bunch from an ion source 22 with velocities dependent on their masses, the masses being determined by measuring the times of flight of the different groups to a collector 24, the lengths of the groups are modified so as to be inversely proportional to the masses of the constituent ions. The time required to collect a group of ions is then independent of the mass of the ions in the group. In the ion source 22 an electron beam generated by the filament 26 ionizes gaseous molecules introduced into the space between electrodes 38 and 40. The ions stored in the space between electrodes 38 and 40 are extracted after the electron beam is cut off through the electrodes 40 and 42 by applying an accelerating field between the electrodes 38 and 40. As the ions formed into groups according to their mass pass through the electrode 40 a reverse accelerating field is applied between the electrodes 38 and 40, and ions are retracted from the groups according to the lengths of the groups remaining between electrodes 38 and 40. At the same time the field between electrodes 40 and 42 is reduced or suppressed. The ion collector 24 comprises a receptacle 56 positioned within a grounded shield 58. A screen extends across the open side of the shield. The receptacle is connected to an oscilloscope for indicating the relative times-of-flight of the various ions. Specification 713,993 is referred to.