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

2018 ◽  
Vol 8 (12) ◽  
pp. 2462 ◽  
Author(s):  
Qingyun Chen ◽  
Xuesong Yuan ◽  
Matthew Cole ◽  
Yu Zhang ◽  
Lin Meng ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Output Power ◽  
Current Density ◽  
Compression Ratio ◽  
Cathode Surface ◽  
Electron Gun ◽  
Cold Cathode ◽  
Backward Wave Oscillator ◽  
Wave Oscillator ◽  
Backward Wave

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.

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

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1768 ◽  
Author(s):  
Yifan Zu ◽  
Xuesong Yuan ◽  
Xiaotao Xu ◽  
Matthew T. Cole ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Output Power ◽  
Radiation Source ◽  
Low Voltage ◽  
High Current Density ◽  
Electron Gun ◽  
Mode Competition ◽  
Thz Radiation ◽  
Cold Cathode ◽  
Average Output

Carbon nanotube (CNT) cold cathodes are proving to be compelling candidates for miniaturized terahertz (THz) vacuum electronic devices (VEDs) owning to their superior field-emission (FE) characteristics. Here, we report on the development of a multi-sheet beam CNT cold cathode electron optical system with concurrently high beam current and high current density. The microscopic FE characteristics of the CNT film emitter is captured through the development of an empirically derived macroscopic simulation model which is used to provide representative emission performance. Through parametrically optimized macroscale simulations, a five-sheet-beam triode electron gun has been designed, and has been shown to emit up to 95 mA at 3.2 kV. Through careful engineering of the electron gun geometric parameters, a low-voltage compact THz radiation source operating in high-order TM 5 , 1 mode is investigated to improve output power and suppress mode competition. Particle in cell (PIC) simulations show the average output power is 33 W at 0.1 THz, and the beam–wave interaction efficiency is approximately 10%.

Simulation and design of electron gun and focusing system for THz backward wave oscillator

2016 ◽  
pp. 211-214
Author(s):  
Abhay Shankar ◽  
Krishna Kumar Belwanshi ◽  
A. Roy Choudhury ◽  
R.K. Sharma
Keyword(s):  
Electron Gun ◽  
Backward Wave Oscillator ◽  
Wave Oscillator ◽  
Backward Wave

scholarly journals Simulation Investigations of High Power Overmoded Relativistic Backward Wave Oscillator with Trapezoidal Resonant Reflector

2021 ◽  
Vol 71 (03) ◽  
pp. 346-350
Author(s):  
V. Venkata Reddy ◽  
M.A. Ansari ◽  
M. Thottappan
Keyword(s):  
Output Power ◽  
Slow Wave ◽  
High Power ◽  
Wave Structure ◽  
Slow Wave Structure ◽  
Backward Wave Oscillator ◽  
Particle In Cell ◽  
Resonant Reflector ◽  
Wave Oscillator ◽  
Backward Wave

An S-band high power relativistic backward wave oscillator using a trapezoidal resonant reflector and overmoded slow-wave structure is demonstrated by finite difference time domain based Particle-In-Cell code. The trapezoidal resonant reflector and slow-wave structure are chosen to improve the RBWO power handing capability to gigawatt (GW). The Trapezoidal resonant reflector enhances the pre-modulation during electron beam propagation, thus increasing the generated RF signal overall efficiency and coherency. The particle-in-cell simulation generated an RF output power ~5.4 GW in TM01 mode at ~3.6 GHz in a 2.0 T magnetic field and developed a 13.5 kA current for a 1.2 MV DC cathode voltage. The power conversion efficiency is achieved as ~33 %. Further, the influence of different design parameters on frequency, RF output power, and efficiency are analysed through Particle-In-Cell simulations.

scholarly journals Design of X-band backward wave oscillator with 10 GW output power

2011 ◽  
Vol 60 (10) ◽  
pp. 105201
Author(s):  
Ma Qiao-Sheng ◽  
Jin Xiao ◽  
Xu Ming ◽  
Li Zheng-Hong ◽  
Wu Yang
Keyword(s):  
Output Power ◽  
Backward Wave Oscillator ◽  
Wave Oscillator ◽  
X Band ◽  
Backward Wave

A Gridded High-Compression-Ratio Carbon Nanotube Cold Cathode Electron Gun

2015 ◽  
Vol 36 (4) ◽  
pp. 399-401 ◽  
Author(s):  
Xuesong Yuan ◽  
Yu Zhang ◽  
Huan Yang ◽  
Xiaoyun Li ◽  
Ningsheng Xu ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Compression Ratio ◽  
Electron Gun ◽  
Cold Cathode ◽  
High Compression Ratio ◽  
High Compression

A Carbon Nanotube-Based Hundred Watt-Level Ka-Band Backward Wave Oscillator

2021 ◽  
Vol 68 (5) ◽  
pp. 2467-2472
Author(s):  
Xuesong Yuan ◽  
Qingyun Chen ◽  
Xiaotao Xu ◽  
Matthew T. Cole ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Backward Wave Oscillator ◽  
Ka Band ◽  
Wave Oscillator ◽  
Backward Wave
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