Theoretical Study of a 0.22 THz Backward Wave Oscillator Based on a Dual-Gridded, Carbon-Nanotube Cold Cathode

Abstract

The carbon nanotube (CNT) cold cathode is an attractive choice for millimeter and terahertz vacuum electronic devices owning to its unique instant switch-on and high emission current density. A novel, dual-gridded, field emission architecture based on a CNT cold cathode is proposed here. CNTs are synthesized directly on the cathode surface. The first separating grid is attached to the CNT cathode surface to shape the CNT cathode array. The second separating grid is responsible for controlled extraction of electrons from the CNT emitters. The cathode surface electric field distribution has been improved drastically compared to conventional planar devices. Furthermore, a high-compression-ratio, dual-gridded, CNT-based electron gun has been designed to further increase the current density, and a 21 kV/50 mA electron beam has been obtained with beam transparency of nearly 100%, along with a compression ratio of 39. A 0.22 THz disk-loaded waveguide backward wave oscillator (BWO) based on this electron gun architecture has been realized theoretically with output power of 32 W. The results indicate that higher output power and higher frequency terahertz BWOs can be made using advanced, nanomaterial-based cold cathodes.

Development of a High-Beam-Transparency Gridded Electron Gun Based on a Carbon Nanotube Cold Cathode

“…Our simulations indicate that when the wire-line of grid is fixed, the mesh-hole dominates the electric field distribution at the cathode surface. The electric field distribution is relatively flat in this structure which has been reported in our previous study [13]. The electric field at the cathode surface reaches a maximum when the mesh-hole is 0.6 mm.…”

“…nanoscale, and every lower production costs [9][10][11][12][13][14][15][16]. However, several integration challenges continue to restrict the development of CNT cold cathode VERS, such as the effective and scalable integration of CNT based electron emitters into macroscopic devices [17][18][19].…”

Vertically Aligned Carbon Nanotubes Production by PECVD

“…The obtained results can be used in the development of technological processes for the creation of ultrafast energy-efficient electronic components based on carbon nanostructures, particularly nanoelectromechanical switches [43,44], flexo-and piezogenerators [45,46], gas sensors [47,48], and highly efficient autoelectronic emitters [49,50].…”

Design and Simulation of a Multi-Sheet Beam Terahertz Radiation Source Based on Carbon-Nanotube Cold Cathode

“…To a large extent, the ability to generate high-emission current densities across large areas from CNT emitters is one of the key factors in solving the physical limitations of VEDs in modern THz applications. Toward this aim, it is vital to choose a suitable electron gun architecture that has the ability to simultaneously generate a high beam emission current and high-emission current density [33][34][35][36]. In designing the CNT cold cathode electron gun, it is important that such design tools take into consideration real, data-supported emission characteristics specific to the material from which the emission will be coming, CNTs in the present case [32].…”