scholarly journals Field electron emission from a nanostructured tungsten surface

2021 ◽  
Vol 2064 (1) ◽  
pp. 012059
Author(s):  
P S Mikhailov ◽  
I L Muzyukin
Keyword(s):  
Electric Field ◽  
Electron Emission ◽  
Enhancement Factor ◽  
Field Enhancement ◽  
Sample Surface ◽  
Emission Current ◽  
Emission Area ◽  
Effective Emission Area ◽  
Tungsten Surface ◽  
Tungsten Anode

Abstract In this paper, the electron emission from a nanostructured tungsten surface was investigated. A method for measuring an extremely low current (10−12 – 10−14 A) has been tested. It made possible to reduce the effect of the electric field on the sample surface and to minimize the probability of spontaneous breakdowns. For a detailed study of tungsten fuzz, a point tungsten anode (diameter 90 μm) was used. Field enhancement factor (β = 2000 – 3000) and effective emission area were calculated using the Fowler–Nordheim plots. The pre-breakdown current rise was studied. The emission current waveforms suggest the formation of several emission structures before the breakdown.

scholarly journals Анализ эмиссии электронов с одиночного кремниевого катода в квазивакуумную (воздушную) среду методом атомно-силовой микроскопии

2020 ◽  
Vol 90 (11) ◽  
pp. 1931
Author(s):  
И.Д. Евсиков ◽  
С.В. Митько ◽  
П.Ю. Глаголев ◽  
Н.А. Дюжев ◽  
Г.Д. Демин
Keyword(s):  
Electric Field ◽  
Electron Emission ◽  
Enhancement Factor ◽  
Strong Electric Field ◽  
Theoretical Estimate ◽  
Field Enhancement ◽  
Field Electron Emission ◽  
Field Enhancement Factor ◽  
Radius Of Curvature ◽  
Field Electron

Using atomic force microscopy (AFM), we experimentally examined the features of field-electron emission from a single point-type silicon cathode into a quasi-vacuum (air) medium. In the non-contact AFM operating mode, the current – voltage characteristics (CVCs) of a single cathode with a nanometer radius of curvature of the tip were measured at distances of 10 nm and 20 nm between the cathode tip and the top of the measuring probe. The electric field distribution was simulated both on the surface of the tip of a single cathode and on the surface of the tips of individual cathodes within the array, based on which a theoretical estimate of the field enhancement factor as a function of the cathode-probe distance was made. The field-enhancement factor calculated from the experimental CVCs in the Fowler-Nordheim coordinates is several orders of magnitude higher than its value obtained from theoretical calculations. Such a mismatch between the experimental data and the simulation results indicates the need to take into account additional quantum-size effects, which play an important role in the formation of the field-electron emission current in the nanoscale gap. In particular, deformation of the silicon emitter tip can occur at this scale due to the penetration of a strong electric field into its surface region, which, in turn, causes the distortion of the potential barrier at the interface with the quasi-vacuum medium.

A New Thermionic Cathode Based on Carbon Nanotubes with a Thin Layer of Low Work Function Barium Strontium Oxide Surface Coating

2008 ◽  
Vol 1142 ◽  
Author(s):  
Feng Jin ◽  
Yan Liu ◽  
Scott A Little ◽  
Chris M Day
Keyword(s):  
Work Function ◽  
Current Density ◽  
Enhancement Factor ◽  
Thermionic Emission ◽  
Field Enhancement ◽  
Oxide Coating ◽  
Emission Current Density ◽  
Emission Current ◽  
Strontium Oxide ◽  
Barium Strontium

ABSTRACTWe have created a thermionic cathode structure that consists of a thin tungsten ribbon; carbon nanotubes (CNTs) on the ribbon surface; and a thin layer of low work function barium strontium oxide coating on the CNTs. This oxide coated CNT cathode was designed to combine the benefits from the high field enhancement factor from CNTs and the low work function from the emissive oxide coating. The field emission and thermionic emission properties of the cathode have been characterized. A field enhancement factor of 266 and a work function of 1.9 eV were obtained. At 1221 K, a thermionic emission current density of 1.22A/cm2 in an electric field of 1.1 V/μm was obtained, which is four orders of magnitude greater than the emission current density from the uncoated CNT cathode at the same temperature. The high emission current density at such a modest temperature is among the best ever reported for an oxide cathode.

scholarly journals Study on surface enhanced Raman scattering of Au and Au@Al2O3 spherical dimers based on 3D finite element method

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bao-xin Yan ◽  
Yan-ying Zhu ◽  
Yong Wei ◽  
Huan Pei
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Electric Field ◽  
Raman Scattering ◽  
Enhancement Factor ◽  
Field Enhancement ◽  
Electric Field Enhancement ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

AbstractIn this paper, the surface enhanced Raman scattering (SERS) characteristics of Au and Au@Al2O3 nanoparticle dimers were calculated and analyzed by using finite element method (3D-FEM). Firstly, the electric field enhancement factors of Au nanoparticles at the dimer gap were optimized from three aspects: the incident angle of the incident light, the radius of nanoparticle and the distance of the dimer. Then, aluminum oxide is wrapped on the Au dimer. What is different from the previous simulation is that Al2O3 shell and Au core are regarded as a whole and the total radius of Au@Al2O3 dimer is controlled to remain unchanged. By comparing the distance of Au nucleus between Au and Au@Al2O3 dimer, it is found that the electric field enhancement factor of Au@Al2O3 dimer is much greater than that of Au dimer with the increase of Al2O3 thickness. The peak of electric field of Au@Al2O3 dimer moves towards the middle of the resonance peak of the two materials, and it is more concentrated than that of the Au dimer. The maximum electric field enhancement factor 583 is reached at the shell thickness of 1 nm. Our results provide a theoretical reference for the design of SERS substrate and the extension of the research scope.

scholarly journals Distribution of earth atmospheric electric field in the vicinity of the vehicles for transport petroleum derivates

2006 ◽  
Vol 19 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Alenka Milovanovic
Keyword(s):  
Electric Field ◽  
Human Body ◽  
Enhancement Factor ◽  
Field Enhancement ◽  
Field Enhancement Factor ◽  
Atmospheric Electric Field ◽  
Electric Field Enhancement ◽  
Petrol Station ◽  
Electrode Method ◽  
Petrol Pump

In this paper using Equivalent Electrode Method (EEM) Atmospheric Electric Field (AEF) distribution in the vicinity of the cargo vehicle is approximately numerically determined, when the vehicles are situated on petrol station near by petrol pump and people. The petrol pump is always grounded, but human body and vehicle are treated as grounded or 'floating' electrodes. Several results of electric field enhancement factor for the vehicle including maps of equienergetic curves are presented.

scholarly journals Methods for measuring the local emission characteristics of CNT based multi-tip emitters

2021 ◽  
Vol 2103 (1) ◽  
pp. 012116
Author(s):  
E O Popov ◽  
A G Kolosko ◽  
S V Filippov ◽  
S A Ponyaev
Keyword(s):  
Enhancement Factor ◽  
Field Enhancement ◽  
Emission Characteristics ◽  
Large Area ◽  
Software Complex ◽  
Emission Area ◽  
Current Voltage ◽  
Local Emission ◽  
Current Voltage Characteristics ◽  
Comparison Of The Results

Abstract The work is aimed at obtaining microscopic emission characteristics of individual emission sites of a multi-tip field cathode or large-area emitter (LAFE) based on processing the current-voltage characteristics and emission glow patterns. Processing was carried out on a hardware-software complex for the study of field emission characteristics in real time. The calculation of the microscopic characteristics of the local emission sites — the field enhancement factor and emission area — was carried out by several different algorithms. A comparison of the results showed that the algorithms gave close values of the characteristics, which increases the reliability of the estimates made.

scholarly journals Microconical Structure Formation and Field Emission From Atomically Heterogeneous Surfaces Created by Microwave Plasma–Based Low-Energy Ion Beams

2021 ◽  
Vol 9 ◽  
Author(s):  
Jayashree Majumdar ◽  
Sudeep Bhattacharjee
Keyword(s):  
Work Function ◽  
Field Emission ◽  
Enhancement Factor ◽  
Field Enhancement ◽  
Ion Beams ◽  
Emission Current ◽  
Force Microscopy ◽  
Field Emission Properties ◽  
Argon Ion ◽  
Local Work

We report the formation of self-organized microconical arrays on copper surface when exposed to high flux (5.4 × 1015 cm−2 s−1) of 2 keV argon ion beams at normal incidence. The created microconical arrays are explored for field emission properties. The surface morphologies are investigated by scanning electron microscopy and atomic force microscopy. The local work function variation is analyzed by Kelvin probe force microscopy, and the argon content in the irradiated layer is measured with X-ray Photoelectron Spectroscopy. The average aspect ratio (base width/height) of microstructures for individual irradiated samples is found to increase from 0.7 to 1.5 with a decrease in ion fluence. The ion concentration is highest (3.89 %) for a fluence of 4.7 × 1018 cm−2, which asserts the formation of atomically heterogeneous surface due to subsurface ion implantation. An enhancement in the field emission properties of the argon ion–treated copper substrates at a fluence of 4.7 × 1018 cm−2 with a low turn-on voltage of 2.33 kV and with electron emission current 0.5 nA has been observed. From the Fowler–Nordheim equations, the field enhancement factor is calculated to be 5,561 for pristine copper, which gets enhanced by a factor of 2–8 times for irradiated substrates. A parametric model is considered, by taking into account the modified local work function caused due to structural undulations of the microstructures and presence of implanted argon ions, for explaining the experimental results on the field enhancement factor and emission current.

Template synthesis of metal tungsten nanowire bundles with high field electron emission performance

RSC Advances ◽  
2016 ◽  
Vol 6 (67) ◽  
pp. 62668-62674 ◽  
Author(s):  
Yong Liu ◽  
Kun Lan ◽  
Mahir H. Es-Saheb ◽  
Ahmed A. Elzatahry ◽  
Dongyuan Zhao
Keyword(s):  
Field Emission ◽  
Template Synthesis ◽  
Electron Emission ◽  
Enhancement Factor ◽  
High Field ◽  
Field Enhancement ◽  
Field Electron Emission ◽  
Field Enhancement Factor ◽  
Emission Performance ◽  
Turn On

A H2 reduction-assisted hard-templating approach is demonstrated to synthesize metallic W nanowire bundles. The W nanowire bundles show a low turn-on field of 4.1 V μm−1, a high field enhancement factor up to 3563 and good field emission stability.

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