scholarly journals Study on Low-Temperature Emission Performance of Scandate Cathode with Micro-Blade-Type Arrays

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 100
Author(s):  
Zhipeng Lu ◽  
Shengyi Yin ◽  
Zhaochuan Zhang ◽  
Feng Ren ◽  
Xinping Lv
Keyword(s):  
Low Temperature ◽  
Electric Field ◽  
Current Density ◽  
Electron Emission ◽  
High Current Density ◽  
Field Enhancement ◽  
Enhancement Effect ◽  
High Electron ◽  
Emission Performance ◽  
Scandate Cathode

In order to meet the requirements of high-frequency vacuum electronic devices with small size, high current density, and low working temperature, a kind of porous tungsten scandate cathode with micro-blade-type arrays was developed. The micro-blade-type arrays were fabricated by laser engraving technology. Subsequently, the cathode was prepared by a vacuum copper removal process and impregnated with active substances at high temperature. Experimental results show that the cathode exhibits excellent low-temperature electron emission performance and that the maximum pulse electron emission current density reaches 81.18 A/cm2 at 800 °C. The cathode also shows apparent combined thermal-field emission characteristics. Further analysis shows that a high electric field strength plays an important role in the electron emission of the scandate cathode. By virtue of the electric field enhancement effect formed by the fabricated micro-blade-type arrays on the cathode surface, the prepared cathode achieves high electron emission capacity.

scholarly journals Low Temperature Synthesis of Lithium-Doped Nanocrystalline Diamond Films with Enhanced Field Electron Emission Properties

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 653 ◽  
Author(s):  
Kamatchi Sankaran ◽  
Kalpataru Panda ◽  
Ping-Yen Hsieh ◽  
Paulius Pobedinskas ◽  
Jeong Park ◽  
...  
Keyword(s):  
Low Temperature ◽  
Electron Emission ◽  
High Current Density ◽  
Field Enhancement ◽  
Life Time ◽  
Field Electron Emission ◽  
Nanocrystalline Diamond ◽  
Large Field ◽  
Temperature Sensitive ◽  
Field Electron

Low temperature (350 °C) grown conductive nanocrystalline diamond (NCD) films were realized by lithium diffusion from Cr-coated lithium niobate substrates (Cr/LNO). The NCD/Cr/LNO films showed a low resistivity of 0.01 Ω·cm and excellent field electron emission characteristics, viz. a low turn-on field of 2.3 V/µm, a high-current density of 11.0 mA/cm2 (at 4.9 V/m), a large field enhancement factor of 1670, and a life-time stability of 445 min (at 3.0 mA/cm2). The low temperature deposition process combined with the excellent electrical characteristics offers a new prospective for applications based on temperature sensitive materials.

A New Carbon Nanotube-Based Field Enhanced Thermionic Cathode

2004 ◽  
Vol 858 ◽  
Author(s):  
Feng Jin ◽  
Christopher Day
Keyword(s):  
Electron Emission ◽  
Field Enhancement ◽  
Oxide Coating ◽  
Enhancement Effect ◽  
High Electron ◽  
Thermionic Cathode ◽  
Emission Properties ◽  
Effective Work ◽  
Effective Work Function ◽  
Thermionic Cathodes

ABSTRACTThe electron emission properties and field enhancement effects of carbon nanotubes (CNTs) have been extensively studied. However, all of these studies focus only on the field emission aspect of the materials and its application in cold cathode electron emitters. So far, we have not seen any studies in the literature that link CNTs with thermionic cathodes, which are an equally important cathode type because of their many applications. We present a study of field enhanced electron emissions from a new type of cathode: the CNT-based field enhanced thermionic cathode. This new cathode consists of a metal substrate with CNTs grown on top of its surface. The CNTs are coated with thermionic emission materials (BaO, SrO, and CaO). This unique cathode structure takes advantage of both the field enhancement effect from CNTs and the high electron emission capability of thermionic materials. The electron emission properties of this new cathode, particularly the field enhancement factor and effective work function, are compared with the conventional thermionic cathodes that are made of same oxide coating.

TiN-nanorod-coated carbon fiber cathode for high-current-density electron emission

Vacuum ◽  
2019 ◽  
Vol 162 ◽  
pp. 137-144 ◽  
Author(s):  
Limin Li ◽  
Songling Fu ◽  
Xiuxiang Huang ◽  
Qiang Tang ◽  
Ke Peng ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Current Density ◽  
Electron Emission ◽  
High Current Density ◽  
High Current ◽  
Coated Carbon

scholarly journals Model of Field Electron Emission from the Edge of Flat Graphene into Vacuum

2019 ◽  
Vol 10 (1) ◽  
pp. 61-68
Author(s):  
N. A. Poklonski ◽  
A. I. Siahlo ◽  
S. A. Vyrko ◽  
S. V. Ratkevich ◽  
A. T. Vlassov
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Graphene Sheet ◽  
Current Density ◽  
Electron Emission ◽  
Field Effect ◽  
Field Electron Emission ◽  
Graphene Plane ◽  
Field Electron ◽  
Electron Emitters

Graphene-based nanostructures are the promising materials for applications as electron emitters.The aim of the work is to study the field electron emission from the edge of a single graphene plane.In the semi-classical approximation, a model of field electron emission from the edge of a rectangular graphene sheet has been developed.The current density of field electron emission into vacuum from the edge of a flat graphene sheet was calculated depending on the magnitude of the pulling electric field strength.The analysis and comparison of limiting emission currents from graphene and from bulk systems have been carried out.The results of the work can be used in the development of graphene-based field effect cathodes.

scholarly journals High Photocurrent Density and Continuous Electron Emission Characterization of a Multi-Alkali Antimonide Photocathode

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1991
Author(s):  
Jun Dai ◽  
Yikun Ding ◽  
Cunjun Ruan ◽  
Xiangyan Xu ◽  
Hulin Liu
Keyword(s):  
Electric Fields ◽  
Current Density ◽  
Electron Emission ◽  
Continuous Wave ◽  
High Current Density ◽  
Optical Power ◽  
Photocurrent Density ◽  
Maximum Current ◽  
Section Electron

High photocurrent density cathodes that enable small cross-section electron beams are required for high-power terahertz vacuum devices. Multi-alkali antimonide photocathodes may be well suited for generating sub-mm electron beam sources. This paper involves the repeatability, stability, uniformity, and linearity experiments of the multi-alkali antimonide photocathodes electron emission operations under a continuous-wave 450 nm laser with a bias voltage of 5000 V. The effect of heat, electric contact, and cathode surface roughness to emission characterizations is analyzed. The methods to maintain the high-current-density emission and avoid the fatigue of the photocathode are verified. The emission can be repeated with increased optical power. The stable photocurrent density of near 1 A/cm2 and maximum current density of near 1.43 A/cm2 is recorded. The continuous photocurrent density is significantly improved compared to the current density reported in traditional applications. It is found that the current curves measuring at different areas of the photocathode differ greatly after the laser power of 800 mW. The increase in current for some areas may be attributed to the conductive current caused by built-in electric fields between the emission rough area and its adjacent areas.

Electrostatic and Electrodynamic Field Analyses of 33kV Line Insulators

2006 ◽  
Vol 7 (3) ◽  
Author(s):  
Ibrahim A. Metwally ◽  
Md Abdus Salam ◽  
Ali Al-Maqrashi ◽  
Saif AR Sumry ◽  
Saif SH Al-Harthy
Keyword(s):  
Electric Field ◽  
Current Density ◽  
High Current Density ◽  
Experimental Tests ◽  
Finite Element Models ◽  
High Current ◽  
Density Profiles ◽  
Fully Integrated ◽  
Software Modules ◽  
Simulation Results

Electrostatic and electrodynamic field analyses of 33kV line insulators were introduced to compare the electric-field and the current density profiles of commonly used line insulators in Oman; namely, silicone rubber (SiR) and porcelain line post insulators, and porcelain cap and pin insulator string. SLIM software package was used for such simulation, which is a fully integrated collection of software modules that provides facilities for the generation and solution of electromagnetic finite element models. The simulation results reveal that for the electrostatic simulation under pollution conditions, SiR and porcelain line-post insulators give maximum values of the electric field of 360kV/m and 1700kV/m, respectively. The latter value exceeds the recommended electric field level of 500kV/m. For the electrodynamic simulation under pollution conditions, the electric field and the current density are much higher for porcelain insulator compared to those of SiR insulator. The simulation of four cap-pin standard insulator string reveals that there is high electric field (1250kV/m) at the cap-insulator gap which can cause high current density for polluted case. Finally, the trend of the simulation results has been verified by experimental tests, which has been conducted on different 33kV line insulators having different designs and materials.

Void Elongation Phenomena Observed in Polycrystalline Cu Interconnects at a High Current Density Stressing Conditions

1997 ◽  
Vol 473 ◽  
Author(s):  
S. Shingubara ◽  
S. Kajiwara ◽  
T. Osaka ◽  
H. Sakaue ◽  
T. Takahagi
Keyword(s):  
Image Analysis ◽  
Electric Field ◽  
Grain Boundaries ◽  
Morphological Change ◽  
Current Density ◽  
Elevated Temperatures ◽  
High Current Density ◽  
High Current ◽  
Cu Interconnects ◽  
Electric Field Direction

ABSTRACTFormation and morphological change of voids induced by electromigration in polycrystalline Cu interconnects on TiN have been investigated at various current density conditions at elevated temperatures. At first voids were formed at grain boundaries, then they grew further to elongate in the electric field direction. Void elongation parameter (a ratio of void diameters in longitudinal to lateral directions to the electric field) was 2.53 when the current density was 9×106A/cm2, while it was 1.31 when the current density was 3×106A/cm2at 400°C, 50h. Occurrence of void elongation is enhanced with increase in current density, and its relationship to grain boundaries are discussed by FIB-SIM image analysis.

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