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%.

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.

Study on a High Beam Transparency Gridded X-ray Electron Gun Based on Carbon Nanotube Cold Cathode

2018 ◽  
Vol 13 (9) ◽  
pp. 1265-1270 ◽  
Author(s):  
Qingyun Chen ◽  
Xuesong Yuan ◽  
Yu Zhang ◽  
Hailong Li ◽  
Bin Wang ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Electron Gun ◽  
Cold Cathode ◽  
High Beam ◽  
X Ray

A High-Current-Density Terahertz Electron-Optical System Based on Carbon Nanotube Cold Cathode

2020 ◽  
Vol 67 (12) ◽  
pp. 5760-5765
Author(s):  
Yunlong Gu ◽  
Xuesong Yuan ◽  
Xiaotao Xu ◽  
Matthew Cole ◽  
Qingyun Chen ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Optical System ◽  
Current Density ◽  
High Current Density ◽  
Cold Cathode ◽  
High Current ◽  
Electron Optical System

A low-voltage field-emission column with a Schottky emitter

1984 ◽  
Vol 42 ◽  
pp. 454-457
Author(s):  
D.W. Tuggle ◽  
S.G. Watson
Keyword(s):  
Field Emission ◽  
Low Voltage ◽  
High Current Density ◽  
High Vacuum ◽  
Energy Spread ◽  
Electron Gun ◽  
Emission Current ◽  
High Current ◽  
Field Mode ◽  
Over The Top

The advantages of a room-temperature field emission (FE) cathode for forming a sub-micrometer high current, low voltage electron probe, namely small energy spread, high brightness and a small virtual source diameter are somewhat offset by the high vacuum required in the electron gun and the fluctuations in the emission current. The thermal-field mode of operation, with its relaxed vacuum requirements and relatively stable emission current has the disadvantage of an increased energy spread of emission, which degrades the spatial resolution of a focused beam. A Schottky point emitter, similar in geometry to a field emitter but with a larger radius, can achieve high current density by use of a low work function surface operating at elevated temperature. In the Schottky emission (SE) mode, electron transmission over the top of the potential barrier rather than tunneling through the barrier is the emission mechanism.

A truncated-cone carbon nanotube cold-cathode electron gun

Carbon ◽  
2017 ◽  
Vol 120 ◽  
pp. 374-379 ◽  
Author(s):  
Xuesong Yuan ◽  
Yu Zhang ◽  
Matthew T. Cole ◽  
Yang Yan ◽  
Xiaoyun Li ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Electron Gun ◽  
Cold Cathode ◽  
Truncated Cone

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 Low-Voltage, Premodulation Terahertz Oscillator Based on a Carbon Nanotube Cold Cathode

2020 ◽  
Vol 67 (3) ◽  
pp. 1266-1269 ◽  
Author(s):  
Xiaotao Xu ◽  
Xuesong Yuan ◽  
Qingyun Chen ◽  
Matthew T. Cole ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Low Voltage ◽  
Cold Cathode

Development of a conical anode Fe-gun for low voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 978-979
Author(s):  
T. Miyokawa ◽  
S. Norioka ◽  
S. Goto
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
Irradiation Damage ◽  
Cold Cathode ◽  
Virtual Source ◽  
Source Position ◽  
Electrostatic Lens ◽  
Electrostatic Lenses ◽  
Wide Range

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.

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