Study on a High-Current CNT Cathode X-Ray Tube

This work aims to achieve both high current emission density and high emission current of carbon nanotube (CNT) cathodes for high-power X-ray generation applications. High-purity small-diameter CNT materials were obtained, and a novel "five-state" electrophoretic deposition method was proposed to fabricate CNT cathodes. For an emission area of 10 mm × 0.45 mm, a high and stable cathode emission current of 350 mA was achieved, corresponding to an emission current density of 7.8 A/cm². An X-ray dose rate of 39.49 mGy/s@50 cm was measured under a tube potential of 120 kV, cathode current of 100 mA, and pulse width of 10 ms. The focal spot size of the X-ray source, measured using a slit camera, was 0.98 mm (width) × 1.05 mm (length) at 15% max intensity, and the pulse width range was 100 µs-100 ms. Through continuous testing at 200 mA emission current, 100 µs pulse width, and 0.3% duty cycle for 400 h, the CNT cathode is estimated to exhibit a lifetime of approximately 5085 h, demonstrating stable and reliable durability. This study, for the first time, simultaneously realizes multi-A/cm²-level emission current density, hundreds-of-milliampere emission current, and hundreds-of-millisecond operating pulse width for CNT cathodes.