Controlling thermal failure of silicon field emitters in a commercial X-ray source

The need for a low-cost, low-dose 3D imaging capability, as an alternative to CT and MRI scanners, has driven the development of a multi-cathode, stationary Digital Tomosynthesis (s-DT) scanner. Demonstration experiments with an array of cold cathodes as electron sources have been reported by multiple groups. We report the operation of a protoype with a different field emitter composition and geometry, at 60kV, to obtain images of a dental phantom, and the subsequent reconstruction of the raw images to obtain 3D slices. Thermal heating of the emitters was found to be the primary factor limiting performance of the device, and several well-established control mechanisms were employed to mitigate this. These include using a ballast resistance, metal coatings, conditioning, and optimizing the duty cycle at operating voltage. We report on the consequent improvement in device flux, lifetime and yield, and present the future outlook of our device.