Ballasted carbon nanotube array based X-ray tube

Ballast resistor under layer can improve reliability and stability of field emission cathode. But it has not been used in carbon nanotube based field emitters. In this article, we introduce a fabrication process of a low-density vertically aligned CNT array with a ballast resistor layer. Its average emission current is ∼0.9uA /CNT, close to the suggested maximum emission current of safety operation. Furthermore, a diode structure X-ray with this cathode is also demonstrated.