Prospective field emitters for miniature high voltage electronic devices operating at technical vacuum conditions

摘要

The use of field emitters is promising for the creationof systems for formation of electron flows in many elec-tronic devices, since they do not require heating and areinertialess. Until recently, the field emitters were usedmainly in ultra-high vacuum, low current and low voltagedevices. Meanwhile, miniature, but high voltage electron-ic devices, which it is difficult to use with thermioniccathodes, are attracting more and more interest. Such are,for example, electron-beam microwave devices of shortmillimeter and sub-millimeter wavelengths, as well asminiature X-ray sources, operating at accelerating voltag-es of units - tens kV. Emission currents of several tensmilliamps at current densities of the order of or more than100–150 mA/cm 2 , are required, as a rule in these applica-tions. Not only the difficulty of sufficiently high currentsproducing by field emitters, but also their low durabilityimpedes their use in high voltage devices. Basic mechan-isms of cathodes destruction are associated with an in-tense bombardment of their surface by residual gas ionstypical for such devices, with the impact of ponderomo-tive forces, large in strong electric fields, and/or by thethermal effects at the selection of the large emission cur-rents. Using distributed systems as field emitters allowsto facilitate the current load on the single emission center,minimize the effect of ponderomotive forces and thermaleffects. However usually, ion bombardment restricts theuse of field emitters in high-voltage electronic devices.