Development of a flat-panel x-ray source
"A novel flat-panel transmission type X-ray source was developed for both medical and industrial use. Depending on the geometry of the given situation, the flat-panel X-ray source could be used in tomography, radiography or tomosynthesis. Furthermore, the unit could be used as a portable X-ray scanner or an integral part of an existing detection system. The design incorporates a field emission cathode made of ultra-nanocrystalline diamonds (UNCD) doped with nitrogen. These field emitters show good electron output at low power and can be deposited over large areas as is the case with carbon nanotube "forest" (CNT) cathodes. This work presents the first generation of the UNCD based FEA prototype which was manufactured at the Center of Nanoscale Material, within Argonne National Laboratory, with standard microfabrication techniques. The prototype is a 3 x 3 pixel field emission array (FEA), with a pixel size of 225 µm by 225 µm and a pitch of 500 µm. The fabricated cathode was developed using a microfabrication process which allows for individual electrically addressable UNCD gated arrays on-chip which demonstrated monolithic integration of the electron extraction grid. The transmission target consists of tungsten for X-ray generation, which is sputtered directly upon a thin aluminum sheet as an X-ray filter. A low voltage power supply allows for electron extraction between the cathode and the grid; while a high voltage power supply accelerates the electrons towards the anode. A low energy X-ray high purity germanium detector (HPGe) is mounted outside of the vacuum chamber for X-ray detection and measurement"--Abstract, page iii.
Field Emission, MCNPX, Monte Carlo, X-ray source, Nuclear Engineering
Missouri University of Science and Technology
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