IONENQUELLE MIT KALTKATHODE UND DAMIT AUSGERUESTETES MASSENSPEKTROMETER

摘要

A plasma discharge ion source for a mass spectrometer, having a magnet forming an axial magnetic field, two cathodes axially spaced in said field and an annular anode between the cathodes. Ions generated by the source emerge via an opening in one cathode and then pass in succession through axially aligned openings in two planar electrodes. The electrode closest said one cathode has a further disc or cone shaped electrode positioned in the opening of that electrode so as to form an annular gap between the peripheries of the disc shaped electrode and opening. Ions from the source opening pass in succession through the annular gap and then through the electrode opening in the electrode furtherest from the source opening. By applying suitable electric potentials to the electrodes ions of an energy above a predetermined level are prevented from passing through the electrodes. A mass spectrometer employing the source is also disclosed this employing an electrostatic ion filter and an ion collector to receive filtered ions from the source via the filter. The collector includes a slow ion deflector arranged to deflect emergent ions from the filter to a collector member of the collector and to which deflector emergent ions of high energy travel directly without such deflection.