Fabrication Process for Carbon Nanotube Based Field Emission X-ray Generator Cathodes
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Eccleston, Gracie A.
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Abstract
Carbon nanotube (CNT) field emission (FE) X-ray generators utilize CNTs to enhance electron generation. CNTs are grown on the cathode in a conical shape with an aspect ratio of 2:1. This shape is necessary for optimal FE. Field emission is a quantum tunnelling process that is achieved by applying a voltage difference between the anode and cathode under high vacuum conditions. Electrons will tunnel from the tip of CNT towards the anode; upon striking the anode, Bremsstrahlung and characteristic x-rays will be produced.
This project includes the design, fabrication, and characterization of various cathode/CNT geometries. CNTs are grown through chemical vapor deposition (CVD) which produces vertically aligned and dense forests of CNTs. Since CNT forests are dense, the CNTs must be grown in a configuration where CNTs are longest in the center and decrease in height as it reaches the perimeter. This configuration allows the CNTs to then be chemically processed to further shape them into sharp tips. All designs tested will be discussed and recommendations for future configurations will be given. The optimization of the cathode will decide the overall performance of the x-ray generator and this project seeks to develop a novel fabrication process for the cathode/CNT geometry.
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2025-05-05
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