The Effect Of Electron Evaporation On X-Ray Tube Current

Ivan A. Brezovich; Gary T. Barnes

doi:10.1117/12.955934

27 December 1977 The Effect Of Electron Evaporation On X-Ray Tube Current

Ivan A. Brezovich, Gary T. Barnes

Proceedings Volume 0127, Application of Optical Instrumentation in Medicine VI; (1977) https://doi.org/10.1117/12.955934
Event: Application of Optical Instrumentation in Medicine VI, 1977, Boston, United States

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.

Citation Download Citation

Ivan A. Brezovich and Gary T. Barnes "The Effect Of Electron Evaporation On X-Ray Tube Current", Proc. SPIE 0127, Application of Optical Instrumentation in Medicine VI, (27 December 1977); https://doi.org/10.1117/12.955934

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