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

Qingyun Chen,  Xuesong Yuan,   Matthew T. Cole, Yu Zhang , Lin Meng,  Yang Yan

Figure 1. Schematic of the dual-gridded field emission structure based on carbon nanotube (CNT) cold cathode. SSG: second separating grid; FSG: first separating grid.

 https://www.mdpi.com/2076-3417/8/12/2462/htm

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.

Abstract-A novel terahertz harmonic gyrotron with dual confocal cavity

Xiaotong Guan, Wenjie Fu, Dun Lu, Tongbin Yang,  Yang Yan

https://ieeexplore.ieee.org/document/8391652/

A novel terahertz harmonic gyrotron with dual confocal cavity has been designed and simulated. The dual confocal waveguide is an improved confocal system to enhance beam-wave interaction efficiency. This terahertz gyrotron is designed to operate in the second harmonic of confocal TE0,11 mode. Particle-In-Cell (PIC) simulation results show that an output power of about 5 kW at 328.93 GHz can be generated when the gyrotron cavity driven by a 40 kV, 2A electron beam with guiding center radius of 1.65 mm and velocity ratio equal to 1.5. The interaction efficiency increases from 1.5% in single focal cavity to 6.2% in dual confocal cavity under the same operation parameters.

Abstract-High harmonic terahertz confocal gyrotron with nonuniform electron beam

Wenjie Fu¹, Xiaotong Guan¹ and Yang Yan¹
http://scitation.aip.org/content/aip/journal/pop/23/1/10.1063/1.4939213
1 THz Research Center, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Phys. Plasmas 23, 013301 (2016); http://dx.doi.org/10.1063/1.4939213

The harmonic confocal gyrotron with nonuniform electron beam is proposed in this paper in order to develop compact and high power terahertz radiation source. A 0.56 THz third harmonicconfocal gyrotron with a dual arc section nonuniform electron beam has been designed and investigated. The studies show that confocal cavity has extremely low mode density, and has great advantage to operate at high harmonic. Nonuniform electron beam is an approach to improve output power and interaction efficiency of confocal gyrotron. A dual arc beam magnetron injection gun for designed confocal gyrotron has been developed and presented in this paper.

Abstract-Study on calculation method of terahertz gyrotron with special cross-section cavity

Xuesong Yuan ; Terahertz S&T Res. Center, Univ. of Electron. Sci. & Technol. of China, Chengdu, China ; Yu Han ; Yang Yan

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=6092205

In order to develop high power terahertz sources, high harmonic terahertz gyrotrons with special cross-section cavity have been proposed. The calculation method of the gyrotrons mentioned above has been investigated based on the three-dimensional electromagnetic simulation software CST and traditional nonlinear theory of gyrotrons in this paper. In this method the analytical solution of the high frequency fields is replaced by inserting the simulation results of CST, the beam-wave interaction efficiency, coupling coefficient and starting current have been obtained. A 0.4THz third harmonic TE33 mode gyrotron with corrugated interaction cavity has been designed by making use of this calculation method.