As mentioned in the previous chapters, CNTs as cold cathode emitters have several positive qualities, including high yield production, low production cost, excellent chemical inertness, high field concentration due to their large aspect ratio, and high capacity for conducting current. The capability of CNTs to produce high and stable current densities has been established since very early attempts. Another very peculiar yet very effective feature of CNT emitters is that it can produce very stable emissions at elevated temperatures up to 1600 K. This elevated temperature comes mainly from Joule heating either along the nanotube length or at the contacts. The stable field emission largely depends on the stable heat evacuation mechanism. This opens up numerous commercial applications, which often demand the highest possible currents. The other conventional emitters, mainly metal emitters, are able to achieve high emission current density but fail to maintain stability when the temperature increases.