Fabrication of a compact ceramics-sealed x-ray tube based on carbon nanotube cold cathode

In this study, a compact ceramic-sealed x-ray tube is fabricated using carbon nanotube cold cathode array as electron emission source. The CNT cold cathode array is prepared by a simple and low-cost screen printing process. By optimizing the slurry formulation, the CNT cathode displays a maximum emission current density of about 300mA/cm2 (at 2.76V/μm). At an initial emission current of 1 mA, the CNT cathode also exhibits excellent emission stability within 480 min. Furthermore, the emission current fluctuation of CNT cathode is significantly reduced using a current stabilization circuit based on field effect transistor. In addition, the electron transmission efficiency of the gate is improved via accurately aligning the CNT cathode array with the gate hole array. By optimizing the geometry of the gate hole, an actual electron transmission efficiency of about 90% is obtained. The fabricated ceramic-sealed x-ray tube shows stable anode current and the ability to produce high-quality x-ray images of the objects. The ceramic-sealed x-ray tube has the potential to serve as a radiation source in next-generation CT/x-ray imaging equipments.