Electrophoretic Deposition of Highly Dispersed Carbon Nanotubes for Improving Uniformity and Stability in an Eight-Beam Field-Emission X-Ray Source

Carbon nanotube (CNT) cathodes offer compact size, rapid response, and simplified thermal management, making them promising for stationary tomosynthesis and computed tomography (CT). In this study, we improved the high-purity production process for small-diameter multi-walled CNTs and developed a novel five-state cathode fabrication process based on electrophoretic deposition. This process increased the field-emission current while enabling the reproducible fabrication of cathodes with high consistency. The resulting multi-beam X-ray source, integrating eight cathodes, operated stably at an anode voltage of 110 kV, a pulse width of 5 ms, and a set cathode current of 40 mA (anode current: 25 mA), with an actual current deviation of less than 0.5% among the cathodes and a gate-control-voltage deviation of less than 3.7%. An eight-angle imaging test and 200 h operation (5.76 × 106 pulses) demonstrated that the tube can provide high-resolution imaging, rapid multi-angle acquisition, and stable long-term operation, thereby demonstrating potential for commercial applications. To the best of our knowledge, this study is the first to demonstrate both highly consistent fabrication of high-current CNT cathodes and sustained high-current operation of a multi-beam X-ray tube, providing a key hardware platform for development on stationary tomosynthesis and CT, and may facilitate further advances in medical imaging technology.