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Proceedings Paper

The Effect Of Electron Evaporation On X-Ray Tube Current
Author(s): Ivan A. Brezovich; Gary T. Barnes
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Paper Abstract

Since only electrons which have relatively high energies can escape from a metal, a thermonic emission current, when initiated, reduces the average energy of the remaining electrons and molecules and hence, if not compensated for, the temperature of the emitter. Investigations of several diagnostic x-ray tubes and generators indicate that there is a noticeable, exponential fall-off of x-ray tube current during an exposure (time constant = 130 msec) attributable to this phenomenon. With three-phase generators the equilibrium values observed were approximately 15% lower than the corresponding values at the beginning of the exposure. Smaller fall-offs were observed with single-phase equipment. Theoretical expressions derived from basic thermodynamic considerations, which are in good agreement with observations for the magnitude of the effect and its time constant, are presented.

Paper Details

Date Published: 27 December 1977
PDF: 5 pages
Proc. SPIE 0127, Application of Optical Instrumentation in Medicine VI, (27 December 1977); doi: 10.1117/12.955934
Show Author Affiliations
Ivan A. Brezovich, Department of Radiation Oncology (United States)
Gary T. Barnes, The University of Alabama in Birmingham (United States)

Published in SPIE Proceedings Vol. 0127:
Application of Optical Instrumentation in Medicine VI
Joel E. Gray; William R. Hendee, Editor(s)

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