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Proceedings Paper

THERMAL analysis of high-power x-ray target: scaling effects
Author(s): Xi Zhang; Vance S. Robinson; Thomas R. Raber; Mark Frontera
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Paper Abstract

High resolution x-ray imaging systems require small focal spots ranging from 1 μm to 1 mm. In NDE applications, the demand for small spot sizes for high spatial resolution conflicts with the need for increased x-ray flux for faster scan times. In this paper, a finite element model is developed to compute the temperature of a stationary x-ray target exposed to micrometer-sized high power (10’s to 100’s of watts) electron beams. Such extremely high power densities at the focal spot are the limiting factor in both performance and life of many x-ray imaging system. This model is used to demonstrate the effect of focal spot size – diameter, on the heat dissipation capability. As the spot size reduces, a higher power density may be sustained by the target. This effect is explained by increased lateral heat conduction. The peak temperature of a small focal spot also becomes more sensitive to the current density distribution of the incident electron beam. The relationship of the peak power and electron beam profile, volumetric power deposition into the x-ray target and focal spot aspect ratio are discussed. Some experimental data demonstrating such scaling effects is included. General design rules for higher-flux capable targets leveraging these scaling effects are also proposed.

Paper Details

Date Published: 26 August 2015
PDF: 8 pages
Proc. SPIE 9590, Advances in Laboratory-based X-Ray Sources, Optics, and Applications IV, 95900G (26 August 2015); doi: 10.1117/12.2186823
Show Author Affiliations
Xi Zhang, GE Global Research Ctr. (United States)
Vance S. Robinson, GE Global Research Ctr. (United States)
Thomas R. Raber, GE Global Research Ctr. (United States)
Mark Frontera, GE Global Research Ctr. (United States)

Published in SPIE Proceedings Vol. 9590:
Advances in Laboratory-based X-Ray Sources, Optics, and Applications IV
Ali M. Khounsary; Carolyn A. MacDonald, Editor(s)

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