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Title: The temperature and field dependence of thermionic and photoelectric currents
Author: Fitch, R. K.
ISNI:       0000 0001 3467 7536
Awarding Body: University of Aston in Birmingham
Current Institution: Aston University
Date of Award: 1968
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The object of the work described in this thesis has been to investigate some aspects of thermionic and photoelectric emission from an overall point, of view rather than in one particular and narrow section of the subject. With this in mind it was considered necessary that a, reasonable fraction of this thesis should be devoted to a fairly critical review of the relevant published literature. Chapter (1) is concerned with the interpretation of thermionic measurements, whereas Chapter (3) deals with the existing and new theories of the work function and its temperature dependence. Also included in this Chapter is a review of some of the'most important and reliable measurements that have been reported on the variation of work function with temperature. Chapter (2) gives the results of thermionic emission measurements on oxide coated cathodes. The total emission has been estimated from a detailed study of valve characteristics and this method has been successfully applied to find the relationship between the total emission and the space charge limited current. In Chapter (6) these results have been used to examine the influence of shall changes in applied field on the thermionic currents. Chapters (4) and (5) are concerned with photoelectric emission from clean metals and oxide cathodes, from just above room temperature to nearly liquid helium temperature. The results of. this work have shown that it appears to be necessary to consider the work function in two parts. Firstly there is a bulk effect which is not critically dependent upon the temperature. - or applied field. On the other hand a photoelectric emission has been observed in the long wavelength tail which is both temperature and field dependent. An attempt has been made to explain these results in terms of the new theoretical ideas of the work function recently put forward by Dr. C. S. Bull, in this department. The experimental results do appear to support some of his conclusions, although it has been found necessary to modify his proposed model of the work function.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: Physics