A simple diode ion source has been developed for direct observation in a mass spectrometer of the positive ions created in an operating diode. The ionic species accelerated toward the cathode were identified. The shape of the peak displayed in the spectrum is related to the region of the diode in which the ions were formed. Variation of experimental parameters, including the composition of the background gases, indicated that the characteristic shapes of the peaks can be related to space charge in the diode. This is complicated by the tendency of some of the species to fragment and further work is indicated before a complete understanding of the relations is obtained. Alkali and halogen ions were observed when an emission current was drawn. These species are assumed to be present as anode impurities. Heavy bombardment of the cathode by alkali ions is associated with an apparent increase in cathode activity. Heating an oxide cathode to temperatures as high as, or higher than, previous processing temperatures led to a further release of CO2 from the cathode. This additional release was not observed with the conventional mass spectrometer ion source thereby indicating that important observations concerning the state of the cathode may be missed when the ions which are analyzed are not created within the operating diode. © 1974.


Materials Science and Engineering

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Article - Journal

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Publication Date

01 Jan 1974