Carbon Nanotube Field Emitters for Nanoklystrons and other High Frequency Tube Sources

Abstract—Traditional submillimeter-wave vacuum tube sources (backward wave oscillators), now available only from the former Soviet Union, have been a mainstay for generating modest amounts (mW) of narrow band (phase lockable) tunable CW RF power at frequencies from 50 to 1200 GHz. Recently groups in both Europe and the US have recognized the potential for producing these expensive, hand-assembled sources through monolithic techniques. A major step in this process is the forma-tion of the electron gun – typically a hot cathode operating at high temperature and requiring significant power. We have developed a cold field emission cathode based on multi-walled carbon nanotube bundles. This cathode can be integrated di-rectly onto a silicon circuit (as part of a monolithic process), has demonstrated emission at only a few volts/µm and current den-sities (unfocused) of more than 20A/cm2. This short paper sum-marizes the design, fabrication and applications for these new field emission devices as components in proposed monolithic terahertz vacuum tube sources. I