Characterization of electron emitters for miniature X-ray sources

Single tip tungsten emitters, nanocrystalline carbon (NCG) emitters, thoriated tungsten thermionic filament emitters, micromachined polycrystalline silicon thermionic emitters, and gated silicon field emitter arrays have been investigated as potential electron sources for miniature X-ray devices. The emission sources were characterized in a demountable 3 mm diameter tube using a 45/spl deg/ cone angle, 1 mm diameter tungsten anode. X-ray characterization was performed in a custom-built shielded system surrounding the demountable tube. With this system, it is possible to measure lateral, distal, and rotational X-ray spectra. From a power consumption point of view, which is important for cardiac artery treatment to avoid heating of the blood, the thermionic emitters are less desirable.