Abstract: Carbon nanotube(CNT) field emission cathode has the advantages of quick start, high resolution, long lifetime, and low power consumption. The CNT cathode can be employed in a variety of vacuum electronic devices and components, including flat panel display, vacuum measurement, and vacuum electronic devices. This article discusses major methods for development of carbon nanotube cathode, and emphasizes on direct growth of CNT emitters on catalytic substrate by chemical vapor deposition and substrate anodization with strong adhesion and advantages for applications in the X -ray tube and other vacuum electronic devices. The field emission properties of CNT cathode grown directly on stainless steel substrate are investigated, with the turn -on electric field of 1.46 V/滋m. The high current emission and stability properties of the direct grown CNT emitters are improved significantly comparing with that of the CNT cathode by conventional synthesis on catalytic metal film. The substrate anodization improves clearly the CNT structure and field emission performance. Advantages of large scale production of up to 2 cm in diameter and high current emission of 500 mA/cm2 are also demonstrated.

Key words: Carbon nanotube, field emission, direct growth, anodization, chemical vapor deposition