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Diamond-based electron emission:Structure,properties and mechanisms
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作者 Liang-Xue Gu Kai Yang +10 位作者 Yan Teng Wei-Kang Zhao Geng-You Zhao Kang-Kang Fan Bo Feng Rong Zhang You-Dou Zheng Jian-Dong Ye Shun-Ming Zhu Kun Tang Shu-Lin Gu 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第9期165-177,共13页
Diamond has an ultrawide bandgap with excellent physical properties,such as high critical electric field,excellent thermal conductivity,high carrier mobility,etc.Diamond with a hydrogen-terminated(H-terminated)surface... Diamond has an ultrawide bandgap with excellent physical properties,such as high critical electric field,excellent thermal conductivity,high carrier mobility,etc.Diamond with a hydrogen-terminated(H-terminated)surface has a negative electron affinity(NEA)and can easily produce surface electrons from valence or trapped electrons via optical absorption,thermal heating energy or carrier transport in a PN junction.The NEA of the H-terminated surface enables surface electrons to emit with high efficiency into the vacuum without encountering additional barriers and promotes further development and application of diamond-based emitting devices.This article reviews the electron emission properties of H-terminated diamond surfaces exhibiting NEA characteristics.The electron emission is induced by different physical mechanisms.Recent advancements in electron-emitting devices based on diamond are also summarized.Finally,the current challenges and future development opportunities are discussed to further develop the relevant applications of diamond-based electronemitting devices. 展开更多
关键词 DIAMOND negative electron affinity(NEA) PN junction electron emission
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Nonlinear change of ion-induced secondary electron emission in theκ-Al_(2)O_(3) surface charging from first-principle modelling
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作者 Zhicheng JIAO Mingrui ZHU +2 位作者 Dong DAI Tao SHAO Buang WANG 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第9期40-50,共11页
Secondary electron emission(SEE)induced by the positive ion is an essential physical process to influence the dynamics of gas discharge which relies on the specific surface material.Surface charging has a significant ... Secondary electron emission(SEE)induced by the positive ion is an essential physical process to influence the dynamics of gas discharge which relies on the specific surface material.Surface charging has a significant impact on the material properties,thereby affecting the SEE in the plasma-surface interactions.However,it does not attract enough attention in the previous studies.In this paper,SEE dependent on the charged surface of specific materials is described with the computational method combining a density functional theory(DFT)model from the first-principle theory and the theory of Auger neutralization.The effect ofκ-Al2O3 surface charge,as an example,on the ion-induced secondary electron emission coefficient(SEEC)is investigated by analyzing the defect energy level and band structure on the charged surface.Simulation results indicate that,with the surface charge from negative to positive,the SEEC of a part of low ionization energy ions(such as Ei=12.6 eV)increases first and then decreases,exhibiting a nonlinear changing trend.This is quite different from the monotonic decreasing tendency observed in the previous model which simplifies the electronic structure.This irregular increase of the SEEC can be attributed to the lower escaped probability of orbital energy.The results further illustrate that the excessive charge could cause the bottom of the conduction band close to the valence band,thus leading to the decrease of the orbital energy occupied by the excited electrons.The nonlinear change of SEEC demonstrates a more realistic situation of how the electronic structure of material surface influences the SEE process.This work provides an accurate method of calculating SEEC from specific materials,which is urgent in widespread physical scenarios sensitive to surface materials,such as increasingly growing practical applications concerning plasma-surface interactions. 展开更多
关键词 secondary electron emission charged surface density functional theory defect energy level
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Design of the electron cyclotron emission diagnostic on EXL-50 spherical torus
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作者 王嵎民 谢奇峰 +10 位作者 陶仁义 张辉 薄晓坤 孙恬恬 伦秀春 陈琳 谭伟强 郭栋 邓必河 刘敏胜 the EXL-50 Team 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第3期53-60,共8页
The electron cyclotron emission(ECE)diagnostic system has been developed on the ENN spherical torus(EXL-50).The ECE system is designed to detect radiation emitted by energetic electrons,rather than conventional 1D ele... The electron cyclotron emission(ECE)diagnostic system has been developed on the ENN spherical torus(EXL-50).The ECE system is designed to detect radiation emitted by energetic electrons,rather than conventional 1D electron temperature profile measurement,in the frequency range of 4-40 GHz.The system is composed of five subsystems,each covering a different frequency band,including the C-band(4-8 GHz),X-band(8-12 GHz),Ku-band(12-18 GHz),K-band(18-26.5 GHz)and Kα-band(26.4-40 GHz).The system uses heterodyne detection to analyze the received signals.The K-band and Kα-band subsystems are located horizontally in the equatorial plane of the EXL-50,while the C-band,X-band and Ku-band subsystems are located under the vacuum vessel of the EXL-50.To direct the microwaves from the plasma to the antennas for the horizontal detection subsystems,a quasi-optical system has been developed.For the vertical detection subsystems,the antennas are directly attached to the port located beneath the torus at R=700 mm,which is also the magnetic axis of the torus.The system integration,bench testing and initial experimental results will be thoroughly discussed,providing a comprehensive understanding of the ECE system s performance and capabilities. 展开更多
关键词 electron cyclotron emission spherical torus(ST) EXL-50 energetic electrons
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Analysis of application range of simplified models for field to thermo-field to thermionic emission processes from the cathode
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作者 Li SUN Zhuo DAI +2 位作者 Ming XU Wei WANG Zengyao LI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第9期51-60,共10页
Electron emission plays a dominant role in plasma-cathode interactions and is a key factor in many plasma phenomena and industrial applications.It is necessary to illustrate the various electron emission mechanisms an... Electron emission plays a dominant role in plasma-cathode interactions and is a key factor in many plasma phenomena and industrial applications.It is necessary to illustrate the various electron emission mechanisms and the corresponding applicable description models to evaluate their impacts on discharge properties.In this study,detailed expressions of the simplified formulas valid for field emission to thermo-field emission to thermionic emission typically used in the numerical simulation are proposed,and the corresponding application ranges are determined in the framework of the Murphy-Good theory,which is commonly regarded as the general model and to be accurate in the full range of conditions of the validity of the theory.Dimensionless parameterization was used to evaluate the emission current density of the Murphy-Good formula,and a deviation factor was defined to obtain the application ranges for different work functions(2.5‒5 eV),cathode temperatures(300‒6000 K),and emitted electric fields(10^(5) to 10^(10) V·m^(-1)).The deviation factor was shown to be a nonmonotonic function of the three parameters.A comparative study of particle number densities in atmospheric gas discharge with a tungsten cathode was performed based on the one-dimensional implicit particle-in-cell(PIC)with the Monte Carlo collision(MCC)method according to the aforementioned application ranges.It was found that small differences in emission current density can lead to variations in the distributions of particle number density due to changes in the collisional environment.This study provides a theoretical basis for selecting emission models for subsequent numerical simulations. 展开更多
关键词 electron emission processes application range Murphy-Good theory implicit particlein-cell Monte Carlo collision method
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Investigating the occurrence and predictability of pitch angle scattering events at ADITYA-Upgrade tokamak with the electron cyclotron emission radiometer
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作者 Varsha SIJU Santosh P.PANDYA +9 位作者 S.K.PATHAK Ansh PATEL Umesh NAGORA Shishir PUROHIT Sameer JHA M.K.GUPTA K.TAHILIANI R.KUMAR R.L.TANNA J.GHOSH 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第11期45-57,共13页
This paper describes the experimental analysis and preliminary investigation of the predictability of pitch angle scattering(PAS) events through the electron cyclotron emission(ECE)radiometer signals at the ADITYA-Upg... This paper describes the experimental analysis and preliminary investigation of the predictability of pitch angle scattering(PAS) events through the electron cyclotron emission(ECE)radiometer signals at the ADITYA-Upgrade(ADITYA-U) tokamak. For low-density discharges at ADITYA-U, a sudden abnormal rise is observed in the ECE signature while other plasma parameters are unchanged. Investigations are done to understand this abrupt rise that is expected to occur due to PAS. The rise time is as fast as 100 μs with a single step and/or multiple step rise in ECE radiometer measurements. This event is known to limit the on-axis energy of runaway electrons. Being a repetitive event, the conditions of its repetitive occurrence can be investigated, thereby exploring the possibility of it being triggered and surveyed as an alternate runaway electron mitigation plan. Functional parameterization of such events with other discharge parameters is obtained and the possibility to trigger these events is discussed.PREDICT code is used to investigate the possible interpretations for the PAS occurrence through modeling and supporting the ECE observations. The trigger values so obtained experimentally are set as input criteria for PAS occurrence. Preliminary modeling investigations provide reliable consistency with the findings. 展开更多
关键词 pitch angle scattering anomalous Doppler resonance electron cyclotron emission radiometer diagnostic runaway electrons wave-particle interaction
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Secondary electron emission and photoemission from a negative electron affinity semiconductor with large mean escape depth of excited electrons
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作者 谢爱根 董红杰 刘亦凡 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第4期677-690,共14页
The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are deduced.The methods for obtaining parameters such asλ,B,E_(pom)and the m... The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are deduced.The methods for obtaining parameters such asλ,B,E_(pom)and the maximumδandδat 100.0 keV≥E_(po)≥1.0 keV of a NEASLD with the deduced formulae are presented(B is the probability that an internal secondary electron escapes into the vacuum upon reaching the emission surface of the emitter,δis the secondary electron yield,E_(po)is the incident energy of primary electrons and E_(pom)is the E_(po)corresponding to the maximumδ).The parameters obtained here are analyzed,and it can be concluded that several parameters of NEASLDs obtained by the methods presented here agree with those obtained by other authors.The relation between the secondary electron emission and photoemission from a NEAS with large mean escape depth of excited electrons is investigated,and it is concluded that the presented method of obtaining A is more accurate than that of obtaining the corresponding parameter for a NEAS with largeλ_(ph)(λ_(ph)being the mean escape depth of photoelectrons),and that the presented method of calculating B at E_(po)>10.0 keV is more widely applicable for obtaining the corresponding parameters for a NEAS with largeλ_(ph). 展开更多
关键词 negative electron affinity semiconductor secondary electron emission PHOTOemission the probability secondary electron yield large mean escape depth of excited electrons
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A refined Monte Carlo code for low-energy electron emission from gold material irradiated with sub-keV electrons
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作者 Li-Heng Zhou Shui-Yan Cao +2 位作者 Tao Sun Yun-Long Wang Jun Ma 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2023年第4期79-92,共14页
Considering the significance of low-energy electrons(LEEs;0–20 eV) in radiobiology, the sensitization potential of gold nanoparticles(AuNPs) as high-flux LEE emitters when irradiated with sub-keV electrons has been s... Considering the significance of low-energy electrons(LEEs;0–20 eV) in radiobiology, the sensitization potential of gold nanoparticles(AuNPs) as high-flux LEE emitters when irradiated with sub-keV electrons has been suggested. In this study, a track-structure Monte Carlo simulation code using the dielectric theory was developed to simulate the transport of electrons below 50 keV in gold. In this code, modifications, particularly for elastic scattering, are implemented for a more precise description of the LEE emission in secondary electron emission. This code was validated using the secondary electron yield and backscattering coefficient. To ensure dosimetry accuracy, we further verified the code for energy deposition calculations using the Monte Carlo toolkit, Geant4. The development of this code provides a basis for future studies regarding the role of AuNPs in targeted radionuclide radiotherapy. 展开更多
关键词 Monte Carlo code Secondary electron emission Low-energy electrons
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Field Emission from a Mixture of Amorphous Carbon and Carbon Nanotubes Films 被引量:2
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作者 张新月 姚宁 +1 位作者 王英俭 张兵临 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第8期1484-1486,共3页
A mixture of amorphous carbon and carbon nanotubes films was synthesized on stainless steel plates by a micro- wave plasma enhanced chemical vapor deposition system. The source gases were hydrogen and methane with flo... A mixture of amorphous carbon and carbon nanotubes films was synthesized on stainless steel plates by a micro- wave plasma enhanced chemical vapor deposition system. The source gases were hydrogen and methane with flow rates of 100 and 16sccm,respectively,with a total pressure of 5.0kPa. The surface morphology and the structure of the films were characterized by field emission scanning electron microscopy (SEM) and Raman scattering spectroscopy. Field emission properties of as-deposited film were measured in a vacuum room below 5 ×10^ 5 Pa. The experimental results show that the initial turn-on field is 0. 9V/μm; The current density is 4.0mA/cm2 and the emission sites are dense and uniform at an electric field of 3.7V/μm. These results indicate that such a mixture of amorphous carbon and carbon nanotubes films is a promising material for field emission applications. 展开更多
关键词 amorphous carbon carbon nanotubes film field electron emission
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Laser-assisted water jet machining of high quality micro-trap structures on stainless steel surfaces
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作者 LIU Li YAO Peng +3 位作者 CHU Dong-kai XU Xiang-yue QU Shuo-shuo HUANG Chuan-zhen 《中国光学(中英文)》 EI CAS CSCD 北大核心 2024年第6期1476-1488,共13页
Secondary electron emission(SEE)has emerged as a critical issue in next-generation accelerators.Mitigating SEE on metal surfaces is crucial for enhancing the stability and emittance of particle accelerators while exte... Secondary electron emission(SEE)has emerged as a critical issue in next-generation accelerators.Mitigating SEE on metal surfaces is crucial for enhancing the stability and emittance of particle accelerators while extending their lifespan.This paper explores the application of laser-assisted water jet technology in constructing high-quality micro-trap structures on 316L stainless steel,a key material in accelerator manufacturing.The study systematically analyzes the impact of various parameters such as laser repetition frequency,pulse duration,average power,water jet pressure,repeat times,nozzle offset,focal position,offset distance between grooves,and processing speed on the surface morphology of stainless steel.The findings reveal that micro-groove depth increases with higher laser power but decreases with increasing water jet pressure and processing speed.Interestingly,repeat times have minimal effect on depth.On the other hand,micro-groove width increases with higher laser power and repeat times but decreases with processing speed.By optimizing these parameters,the researchers achieved high-quality pound sign-shaped trap structure with consistent dimensions.We tested the secondary electron emission coefficient of the"well"structure.The coefficient is reduced by 0.5 at most compared to before processing,effectively suppressing secondary electron emission.These results offer indispensable insights for the fabrication of micro-trap structures on material surfaces.Laser-assisted water jet technology demonstrates considerable potential in mitigating SEE on metal surfaces. 展开更多
关键词 laser-assisted water jet 316L stainless steel micro-trap structures "well"structure surface morphology secondary electron emission(SEE) groove depth groove width
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A synthetic diagnostics platform for microwave imaging diagnostics in tokamaks
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作者 李子涵 杨尚川 +5 位作者 徐新航 张立夫 渠承明 李诚普 庄革 谢锦林 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第3期38-45,共8页
Interpreting experimental diagnostics data in tokamaks,while considering non-ideal effects,is challenging due to the complexity of plasmas.To address this challenge,a general synthetic diagnostics(GSD)platform has bee... Interpreting experimental diagnostics data in tokamaks,while considering non-ideal effects,is challenging due to the complexity of plasmas.To address this challenge,a general synthetic diagnostics(GSD)platform has been established that facilitates microwave imaging reflectometry and electron cyclotron emission imaging.This platform utilizes plasma profiles as input and incorporates the finite-difference time domain,ray tracing and the radiative transfer equation to calculate the propagation of plasma spontaneous radiation and the external electromagnetic field in plasmas.Benchmark tests for classical cases have been conducted to verify the accuracy of every core module in the GSD platform.Finally,2D imaging of a typical electron temperature distribution is reproduced by this platform and the results are consistent with the given real experimental data.This platform also has the potential to be extended to 3D electromagnetic field simulations and other microwave diagnostics such as cross-polarization scattering. 展开更多
关键词 synthetic diagnostics tokamak plasmas microwave imaging diagnostics microwave imaging reflectometer electron cyclotron emission imaging
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Acoustical properties of a 3D printed honeycomb structure filled with nanofillers:Experimental analysis and optimization for emerging applications
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作者 Jeyanthi Subramanian Vinoth kumar Selvaraj +3 位作者 Rohan Singh Ilangovan S Naresh Kakur Ruban Whenish 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第5期248-258,共11页
The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E ... The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E 1050-12.The Creality Ender-3,a 3D printer,was used for printing the honeycomb structures,and polylactic acid(PLA)material was employed for their construction.The organic,inorganic,and polymeric compounds within the composites were identified using fourier transformation infrared(FTIR)spectroscopy.The structure and homogeneity of the samples were examined using a field emission scanning electron microscope(FESEM).To determine the sound absorption coefficient of the 3D printed honeycomb structure,numerous samples were systematically developed using central composite design(CCD)and analysed using response surface methodology(RSM).The RSM mathematical model was established to predict the optimum values of each factor and noise reduction coefficient(NRC).The optimum values for an NRC of 0.377 were found to be 1.116 wt% carbon black,1.025 wt% aluminium powder,and 3.151 mm distance between parallel edges.Overall,the results demonstrate that a 3Dprinted honeycomb structure filled with nanofillers is an excellent material that can be utilized in various fields,including defence and aviation,where lightweight and acoustic properties are of great importance. 展开更多
关键词 3D printing Honeycomb structure ACOUSTICS Field emission scanning electron microscope Response surface methodology
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Electron Cyclotron Emission Imaging on the EAST Tokamak 被引量:2
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作者 徐明 徐小圆 +10 位作者 闻一之 马锦秀 谢锦林 高炳西 兰涛 刘阿棣 余羿 何迎花 万宝年 胡立群 高翔 《Plasma Science and Technology》 SCIE EI CAS CSCD 2011年第2期167-171,共5页
An upgraded electron cyclotron emission imaging (ECEI) system consisting of new optics lenses with necessary electronics for receiving and processing signals for two dimension (2D) ECEI diagnostics was installed o... An upgraded electron cyclotron emission imaging (ECEI) system consisting of new optics lenses with necessary electronics for receiving and processing signals for two dimension (2D) ECEI diagnostics was installed on EAST. Hyperboloid lens were adopted in the new system to optimize the spatial resolutions. The mixers array of sixteen elements measured the plasma electron cyclotron emission at eight frequencies simultaneously, and the profiles of the electron temperature and its fluctuation in an area of 20 cm (vertical) × 6 cm (horizontal) could then be analyzed. Evolution of sawtooth precursor and crash in EAST was observed. 展开更多
关键词 electron cyclotron emission imaging hyperboloid lens sawtooth precursor evolution EAST tokamak
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Experimental Study of Electron Emission Characteristics of a Surface Flashover Trigger in a Low Pressure Environment 被引量:1
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作者 胡上茂 姚学玲 陈景亮 《Plasma Science and Technology》 SCIE EI CAS CSCD 2010年第6期748-752,共5页
Characteristics of electron emission induced by a surface flashover trigger device in a low-pressure trigger switch were investigated. A test method to measure the emitted charges from the trigger device was developed... Characteristics of electron emission induced by a surface flashover trigger device in a low-pressure trigger switch were investigated. A test method to measure the emitted charges from the trigger device was developed, and the factors affecting the emitted charges were analyzed. The results indicated that the major emitted charges from the trigger device were induced by surface plasma generated by surface flashover occurring on the trigger dielectric material. The emitted charges and the peak emission current increased linearly with the change in the trigger voltage and bias voltage. The emitted charges collected from the anode were affected by the gap distance. However, the emitted charges were less affected by the anode diameter. Furthermore, the emitted charges and the peak emission current decreased rapidly with the increase in gas pressure in a range from 0 Pa to 100 Pa, and then remained stable or changed slightly when the increase in gas pressure up to 2400 Pa. 展开更多
关键词 emission charges electron emission emission current trigger switch surface flashover
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Impact of exterior electron emission on the self-sustaining margin of hollow cathode discharge 被引量:1
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作者 Tianhang MENG Zhongxi NING Daren YU 《Plasma Science and Technology》 SCIE EI CAS CSCD 2020年第9期2-11,共10页
Hollow cathode researches used to focus on the inner cavity or downstream plume,however,rarely on the gap between the throttling orifice plate and the keeper plate(T-K gap),which was found to impact the self-sustainin... Hollow cathode researches used to focus on the inner cavity or downstream plume,however,rarely on the gap between the throttling orifice plate and the keeper plate(T-K gap),which was found to impact the self-sustaining margin of hollow cathode discharge in this paper.Near the lower margin,the main power deposition and electron emission and ionization regions would migrate from inner cavity and downstream plume to the T-K gap,in which case,the source and destination of each m A current therein matter for the self-sustaining capability.Changing the metal surfaces in the T-K gap with emissive materials proved effective in lowering the lower margin by supplementing auxiliary thermionic emission,compensating electron loss on cold absorbing walls and suppressing discharge oscillations.By doing so,the lower margin of a 4 A hollow cathode was lowered from 1 to 0.1-0.2 A,enabling it to couple with low power Hall thruster without extra keeper current. 展开更多
关键词 hollow cathode self-sustained discharge secondary electron emission ionization oscillations thermionic emission
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Effect of nitrogen on deposition and field emission properties of boron-doped micro-and nano-crystalline diamond films 被引量:1
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作者 L.A.Li S.H.Cheng +3 位作者 H.D.Li Q.Yu J.W.Liu X.Y.Lv 《Nano-Micro Letters》 SCIE EI CAS 2010年第3期154-159,共6页
In this paper,we report the effect of nitrogen on the deposition and properties of boron doped diamond films synthesized by hot filament chemical vapor deposition.The diamond films consisting of micro-grains(nano-grai... In this paper,we report the effect of nitrogen on the deposition and properties of boron doped diamond films synthesized by hot filament chemical vapor deposition.The diamond films consisting of micro-grains(nano-grains) were realized with low(high) boron source flow rate during the growth processes.The transition of micro-grains to nano-grains is speculated to be strongly(weekly) related with the boron(nitrogen) flow rate.The grain size and Raman spectral feature vary insignificantly as a function of the nitrogen introduction at a certain boron flow rate.The variation of electron field emission characteristics dependent on nitrogen is different between microcrystalline and nanocrystalline boron doped diamond samples,which are related to the combined phase composition,boron doping level and texture structure.There is an optimum nitrogen proportion to improve the field emission properties of the boron-doped films. 展开更多
关键词 Chemical vapor deposited diamond film Nitrogen effect Boron doping MICROCRYSTALLINE NANOCRYSTALLINE Electron field emission
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Phase Transformation and Enhancing Electron Field Emission Properties in Microcrystalline Diamond Films Induced by Cu Ion Implantation and Rapid Annealing 被引量:1
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作者 申艳艳 张一新 +5 位作者 祁婷 乔瑜 贾钰欣 黑鸿君 贺志勇 于盛旺 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第8期123-126,共4页
Cu ion implantation and subsequent rapid annealing at 500℃ in N2 result in low surface resistivity of 1.611 ohm/sq with high mobility of 290 cm2 V-1S-1 for microcrystalline diamond (MCD) films. Its electrical field... Cu ion implantation and subsequent rapid annealing at 500℃ in N2 result in low surface resistivity of 1.611 ohm/sq with high mobility of 290 cm2 V-1S-1 for microcrystalline diamond (MCD) films. Its electrical field emission behavior can be turned on at Eo = 2.6 V/μm, attaining a current density of 19.5μA/cm2 at an applied field of 3.5 V/#m. Field emission scanning electron microscopy combined with Raman and x-ray photoelectron mi- croscopy reveal that the formation of Cu nanoparticles in MCD films can catalytically convert the less conducting disorder/a-C phases into graphitic phases and can provoke the formation of nanographite in the films, forming conduction channels for electron transportation. 展开更多
关键词 CU of MCD Phase Transformation and Enhancing Electron Field emission Properties in Microcrystalline Diamond Films Induced by Cu Ion Implantation and Rapid Annealing in by
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Field Emission of SiCN Thin Films Bombarded by Ar^+ Ions 被引量:1
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作者 Ma You\|peng, Li Jin\|chai , Guo Huai\|xi, Lu Xian\|feng, Chen Ming\|an, Ye Ming\|sheng School of Physics and Technology, Wuhan University, Wuhan 430072, Hubei, China 《Wuhan University Journal of Natural Sciences》 CAS 2003年第03A期829-832,共4页
SiCN thin films were synthesized by a radio frequency chemical vapor deposition (RFCVD) system on P\|type Si (1 0 0) wafers using C 2 H 4 , SiH 4 and N 2 as raw materials. In order to get rid of the ... SiCN thin films were synthesized by a radio frequency chemical vapor deposition (RFCVD) system on P\|type Si (1 0 0) wafers using C 2 H 4 , SiH 4 and N 2 as raw materials. In order to get rid of the oxygen absorbed on the surface and improve the characteristics of electron field emission, Ar + ions of low energy were used to bombard the samples. The field emission characteristics of SiCN thin films before and after Ar + bombardment were studied in the super vacuum environment of 10 -6 Pa. It was showed that the turn\|on field (defined as the point where the current\|voltage curve shows a sharp increase in the current density) decreased from 38 V/μm before bombardment to 25 V/μm after bombardment. And the maximum emission current density increased from 159.2 to 267.4 μA/cm 2 . The composition before and after Ar + bombardment was compared using X\|ray photoelectron spectroscopy (XPS). Our results illustrated that the field emission characteristics were improved after the bombardment of Ar + . 展开更多
关键词 SiCN thin films RFCVD electron field emission X\|ray photoelectron spectroscopy (XPS)
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Feedback model of secondary electron emission in DC gas discharge plasmas 被引量:1
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作者 Saravanan ARUMUGAM Prince ALEX Suraj Kumar SINHA 《Plasma Science and Technology》 SCIE EI CAS CSCD 2018年第2期128-133,共6页
Feedback is said to exist in any amplifier when the fraction of output power in fed back as an input.Similarly,in gaseous discharge ions that incident on the cathode act as a natural feedback element to stabilize and ... Feedback is said to exist in any amplifier when the fraction of output power in fed back as an input.Similarly,in gaseous discharge ions that incident on the cathode act as a natural feedback element to stabilize and self sustain the discharge.The present investigation is intended to emphasize the feedback nature of ions that emits secondary electrons(SEs)from the cathode surface in DC gas discharges.The average number of SEs emitted per incident ion and non ionic species(energetic neutrals,metastables and photons)which results from ion is defined as effective secondary electronemission coefficient(ESEEC,Eg).In this study,we derive an analytic expression that corroborates the relation betweenEg and power influx by ion to the cathode based on the feedback theory of an amplifier.In addition,experimentally,we confirmed the typical positive feedback nature of SEEfrom the cathode in argon DC glow discharges.The experiment is done for three different cathode material of same dimension(tungsten(W),copper(Cu)and brass)under identical discharge conditions(pressure:0.45 mbar,cathode bias:-600 V,discharge gab:15 cm and operating gas:argon).Further,we found that theEg value of these cathode material controls the amount of feedback power given by ions.The difference in feedback leads different final output i.e the power carried by ion at cathode(Pi C¢∣).The experimentally obtained value of Pi C¢∣is 4.28 W,6.87 W and9.26 W respectively for W,Cu and brass.In addition,the present investigation reveals that the amount of feedback power in a DC gas discharges not only affect the fraction of power fed back to the cathode but also the entire characteristics of the discharge. 展开更多
关键词 feedback secondary electron emission DC gas discharges power influx by ion at cathode cathode temperature
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Electron emission induced by keV protons from tungsten surface at different temperatures
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作者 Li-Xia Zeng Xian-Ming Zhou +3 位作者 Rui Cheng Yu Liu Xiao-An Zhang Zhong-Feng Xu 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第7期241-246,共6页
The electron emission yield is measured from the tungsten surface bombarded by the protons in an energy range of 50keV–250keV at different temperatures.In our experimental results,the total electron emission yield,wh... The electron emission yield is measured from the tungsten surface bombarded by the protons in an energy range of 50keV–250keV at different temperatures.In our experimental results,the total electron emission yield,which contains mainly the kinetic electron emission yield,has a very similar change trend to the electronic stopping power.At the same time,it is found that the ratio of total electron emission yield to electronic stopping power becomes smaller as the incident ion energy increases.The experimental result is explained by the ionization competition mechanism between electrons in different shells of the target atom.The explanation is verified by the opposite trends to the incident energy between the ionization cross section of M and outer shells. 展开更多
关键词 electron emission X-RAY electronic stopping power work function
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Thermionic Electron Emission Stability of Mo-La_2O_3 Cathode
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作者 周文元 张久兴 +3 位作者 刘燕琴 万小峰 周美玲 左铁镛 《Journal of Rare Earths》 SCIE EI CAS CSCD 2004年第3期395-398,共4页
The carbonizing process and its influence on the thermionic electron emission properties of Mo-La_2O_3 cathode materials were investigated. The carbonized temperature, carbonized time and the pressure of C_6H_6 are ke... The carbonizing process and its influence on the thermionic electron emission properties of Mo-La_2O_3 cathode materials were investigated. The carbonized temperature, carbonized time and the pressure of C_6H_6 are key factors of the carbonizing process. The carbonized ratio of Mo-La_2O_3 cathode increases with the increase of carbonizing temperature at low temperature. The highest carbonized ratio is 19.7% obtained at 1723 K, then the carbonized ratio decreases rapidly if temperature increases further. The carbonized ratio increases with the prolongation of carbonizing time during the process of first 6 min., after that the carbonization ratio changes little with the time increase, and the carbonized ratio increases with the increase of the C_6H_6 pressure when the pressure is low, the maximum carbonized ratio reaches 19.7% at 1.5×10^(-2) Pa, then the carbonized ratio goes down sharply when the C_6H_6 pressure is over 1.5×10^(-2) Pa. The emission properties at different operated temperatures and the emission current stability of FU-6051 tubes (equipped) with Mo-La_2O_3 cathodes were also studied in the article. The study results indicate that the emission can keep stable only when the operating temperature is from 1700 to 1800 K and the carbonized layer must be composed by Mo_2C only. The FU-6051 tubes (equipped) with Mo-La_2O_3 cathodes have excellent stable emission current and the lifetime exceeds 3000 h when the cathode′s carbonized ratio is 19.7% operated at 1773 K. 展开更多
关键词 Mo-La_2O_3 cathode electron emission stability carbonizing LIFETIME rare earths
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