Analysis of CNT emitter-based miniature x-ray tubes for stable and reliable operation

We analyzed the failure mechanism in miniature x-ray tubes with a gated carbon nanotube (CNT) field emitter. The miniature x-ray tube even with a small leakage current of field emission from the CNT emitters to the gate electrode has some distortion of the electron beam trajectory from the cathode to anode passage, causing a charging at insulating parts. The charging at the insulator spacer would lead to an arcing or coupling of the anode and gate electrodes, resulting in a very unstable operation and finally a fatal failure.