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Littérature scientifique sur le sujet « Field emission gun (FEG) »

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Publié le 31 octobre 2023

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Articles de revues sur le sujet "Field emission gun (FEG)"

Joy, David C. « Microanalysis with a 200keV FEG TEM ». Proceedings, annual meeting, Electron Microscopy Society of America 49 (août 1991) : 700–701. http://dx.doi.org/10.1017/s0424820100087811.

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Introduction The Hitachi HF-2000 is a 200keV cold field emitter TEM, designed to offer both high resolution imaging performance and a nanometer probe-forming mode for microanalytical operation. The purpose of this paper is to report some initial microanalytical results obtained from the HF-2000 installed at the University of Tennessee.General Electron-Optical Parameters The cold field emission gun, which runs at about 5x10-9pA pressure, uses an electrostatic lens configuration and a six stage accelerator. The entire electron gun system is under the control of a dedicated microprocessor which permits all of the operational parameters of the gun to be set, monitored, and adjusted through a keyboard and display. The tip emission current can be adjusted up to 40μA, and the gun voltage ratio (that is the ratio between the voltage on the second anode and the tip extraction voltage) can be varied from 4.5 to 7.5, permitting a significant degree of flexibility in optimizing the optics of the emitter.

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Brock, Judith M., Max T. Otten et Marc J. C. de Jong. « Performance and applications of a field-emission gun TEM/STEM ». Proceedings, annual meeting, Electron Microscopy Society of America 50, n^o 2 (août 1992) : 942–43. http://dx.doi.org/10.1017/s0424820100129346.

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A Field Emission Gun (FEG) on a TEM/STEM instrument provides a major improvement in performance relative to one equipped with a LaB6 emitter. The improvement is particularly notable for small-probe techniques: EDX and EELS microanalysis, convergent beam diffraction and scanning. The high brightness of the FEG (108 to 109 A/cm2srad), compared with that of LaB6 (∼106), makes it possible to achieve high probe currents (∼1 nA) in probes of about 1 nm, whilst the currents for similar probes with LaB6 are about 100 to 500x lower. Accordingly the small, high-intensity FEG probes make it possible, e.g., to analyse precipitates and monolayer amounts of segregation on grain boundaries in metals or ceramics (Fig. 1); obtain high-quality convergent beam patterns from heavily dislocated materials; reliably detect 1 nm immuno-gold labels in biological specimens; and perform EDX mapping at nm-scale resolution even in difficult specimens like biological tissue.The high brightness and small energy spread of the FEG also bring an advantage in high-resolution imaging by significantly improving both spatial and temporal coherence.

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Tomita, T., S. Katoh, H. Kitajima, Y. Kokubo et Y. Ishida. « Development of Field-Emission Gun for High-Voltage Electron Microscope ». Proceedings, annual meeting, Electron Microscopy Society of America 48, n^o 2 (12 août 1990) : 94–95. http://dx.doi.org/10.1017/s0424820100134065.

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It is well known that the combination of a field emission gun (FEG) and a conventional transmission electron microscope (CTEM) is extremely important for nanometer area analysis in analytical electron microscopy. However, the smaller illumination angle and reduced energy spread of FEG than those of a conventional electron gun (W hair pin filament or LaB6) give a slowly damping envelop function in phase contrast transfer function (PCTF). Thus the FEG ensures application not only to analytical microscopy but also to high resolution electron microscopy to improve the information limit.In a high voltage electron microscope (above 200 kV), high-speed vacuum pumps have to be provided below the acceleration tube to get an ultra high vacuum (UHV) around the field emission tip located at the top of the acceleration tube. However, this method is not always the best way to provide UHV because of the poor vacuum conductance caused by the electrodes inside the acceleration tube.

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Mul, P. M., B. J. M. Bormans et L. Schaap. « Design of a Field-Emission Gun for the Phillips CM20/STEM microscope ». Proceedings, annual meeting, Electron Microscopy Society of America 48, n^o 2 (12 août 1990) : 100–101. http://dx.doi.org/10.1017/s0424820100134090.

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The first Field Emission Guns (FEG) on TEM/STEM instruments were introduced by Philips in 1977. In the past decade these EM400-series microscopes have been very successful, especially in analytical electron microscopy, where the high currents in small probes are particularly suitable. In High Resolution Electron Holography, the high coherence of the FEG has made it possible to approach atomic resolution.Most of these TEM/STEM systems are based on a cold field emitter (CFE). There are, however, a number of disadvantages to CFE’s, because of their very small emission region: the maximum current is limited (a strong disadvantage for high-resolution TEM imaging) and the emission is unstable, requiring special measures to reduce the strong FEG-induced noise. Thermal field emitters (TFE), i.e. a zirconiated field emitter source operating in the thermal or Schottky mode, have been shown to be a viable and attractive alternative to CFE’s. TFE’s have larger emission regions, providing much higher maximum currents, better stability, and reduced sensitivity to vacuum conditions as well as mechanical and electrical interferences.

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Murakoshi, H., M. Ichihashi, T. Komoda, S. Isakozawa et T. Kubo. « Field-emission gun and illuminating lens system for 200kV FE-TEM ». Proceedings, annual meeting, Electron Microscopy Society of America 47 (6 août 1989) : 110–11. http://dx.doi.org/10.1017/s0424820100152525.

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Good resolution is obtained with a conventional transmission electron microscope (TEM). Nevertheles, an atomic scale analysis is difficult because of insufficient probe current. A field emission gun (FEG) provides a higher brightness and more monochromatic beam than a thermionic one. Thus, an FEG can be expected to improve the abilities of a TEM. The low energy spread(∼0.5 eV) attainable with the FEG reduces chromatic aberrations and a brighter image can be expected, making more discernible details. In addition, a high beam current is formed in a small spot, enabling precise element analysis at the nanometer level. Moreover, the illuminating angle obtained on a specimen is so small that electron diffraction can be clearly obtained for structure analysis of crystals. Experimental FE-TEMs with lower accelerating voltage than 100kV have already been developed. Using an electron holography technique, micro magnetic flux was observed with a high coherency beam. FE-TEMs with a higher accelerating voltage are required in various fields of material science.

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Olson, N. H., U. Lücken, S. B. Walker, M. T. Otten et T. S. Baker. « Cryoelectron microscopy and image reconstruction of spherical viruses with spot scan and FEG technologies ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 1086–87. http://dx.doi.org/10.1017/s0424820100141809.

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The field emission gun electron microscope (FEG) is a tool that has the potential to achieve near atomic resolution information of biological macromolecules. The FEG provides a beam with higher spatial and temporal coherence and a better phase contrast transfer function than do microscopes with either tungsten or LaB6 filaments. The FEG is also ideal for spot scan imaging applications because it can produce a small, coherent and very bright spot. In spot scan mode the specimen is exposed to an array of nonoverlapping spots rather man a flood beam. This significantly reduces beam-induced specimen drift.Frozen-hydrated samples of cowpea chlorotic mottle (CCMV, Fig. 1A) and cowpea severe mosaic virus (CPSMV, Fig. IB) were examined on a Philips CM12 transmission electron microscope equipped with a standard LaB6 gun and on a Philips CM200 equipped with a field emission gun, respectively. The CM12 was operated at 120kV and was externally controlled by means of a spot scan imaging program which produced a series of 250 nm diameter spots on Kodak SO-163 sheet film.

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Ohi, M., K. Harasawa, T. Niikura, H. Okazaki, Y. Ishimori, T. Miyokawa et S. Nakagawa. « Development of a New Digital Fe SEM ». Proceedings, annual meeting, Electron Microscopy Society of America 48, n^o 1 (12 août 1990) : 432–33. http://dx.doi.org/10.1017/s0424820100180914.

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By combining a conical type field emission gun and an auto gain controlled noise cancelling system, we have developed three types of digital FESEMs equipped with a digital imaging processor and three different sized specimen chambers each with a stage.It is known that when a cold field emission gun (C-FEG) with a W (310) single crystal tip is used at a vacuum pressure of 10-10 torr, the emission current constantly fluctuates by 5 to 10% due to the adsorbed gas, etc. on the tip surface.Since the probe current in an FESEM equipped with this C-FEG fluctuates to the same extent, the noise caused by emission current fluctuation (emission noise) appears on secondary electron images (SEI) and backscattered electron images (BEI).In order to eliminate emission noise, an aperture (noise cancelling aperture or N/C aperture) installed under the C-FEG detects emission current fluctuation and inputs it to the differential amplifier of the video amplifier system for SEI or BEI on conventional FESEMs.With FESEMs, however, when the accelerating voltage is change in the range from 0.5 to 30 kV, the virtual source of an FEG using Butler type electrodes moves several tens of centimeters on the optical axis. Moreover, the probe current is changed from 10-13 to 10-10 A by changing the excitation current of the condenser lens. For these two reasons, there have been adopted such methods as installing an N/C aperture in two positions (under the C-FEG and at the objective lens aperture position) and controlling the amplifier value of the noise cancelling system and condenser lens excitation by ROM data.

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Troyon, Michel, et He Ning Lei. « Electron Trajectories Calculations of an Energy - Filtering Field-Emission Gun ». Proceedings, annual meeting, Electron Microscopy Society of America 48, n^o 1 (12 août 1990) : 192–93. http://dx.doi.org/10.1017/s0424820100179713.

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In many cases, the contribution of beam energy spread to the limitation of the performances of an electron microscope is strong. In the case of the field emission gun (FEG) , Troyon has experimentally shown it is possible to reduce considerably the energy spread by energy filtering at the gun level. The system developed consists basically of a magnetic FEG with a retarding electrode working as the retarding electrode of an energy filter. The principle is recalled in Fig. 1 and the cross section of the accelerator is given in Fig. 2. In this paper, the results of electron trajectories calculations inside the energy filtering field emission gun (EFFEG) are given.Fig. 3 shows that electrons of same energy, but entering the retarding field with different angles, can have exit angles very different. Due to the work function of approximately 4.5 eV the electrons, for an extracting potential Vo = 2 kV, enter in the field of the retarding electrode with an energy smaller than 2 keV. In Fig. 3 trajectories are computed for an electron of 1996 eV. Electrons passing by the nodal points have the same entering and exit angles. Trajectory 1 in Fig. 3 corresponds to an entering radius re = 17.5 μm and an entering semi angle αe = 1.2 mrad. For these re and αe values, at Vr =6 V, the exit semi angle αs = αe . Fig. 3 shows that an electron entering parallely to the axis, even very close to the axis (re = 10 μm) has a larger exit angle than electrons passing by the nodal points.

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Kaneyama, T., M. Kawasaki, T. Tomita, T. Honda et M. Kersker. « The information limit of a 200kv field emission TEM ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 586–87. http://dx.doi.org/10.1017/s0424820100139305.

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The Point resolution of a transmission electron microscope is normally defined by the reciprocal of the spatial frequency of the first zero in the phase contrast transfer function at the Scherzer defocus condition. When a field emission gun (FEG) is used as the electron source, the information limit, that point at which the contrast beyond the first zero goes to zero contrast, becomes equally important. We have investigated the primary microscope parameters that affect the information limit.A 200kV FE-TEM (JEM-2010F) equipped with a ZrO/W shottkey emitter and Gatan Parallel EELS (PEELS) was used for the experiments. The aberration coefficients of the objective lens are Cs = 1mm and Cc = 1.4mm. The specimen used is an evaporated amorphous Ge thin film with small gold islands.The resolution performance of the microscope depends not only on the performance of the objective lens, the high voltage stability, stability of the lens and deflector power supplies, operating parameters of the FEG, and the overall mechanical stability of the microscopes.

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Coened, W. M. J., A. J. E. M. Janssend, M. Op de Beeck, D. Van Dyck, E. J. Van Zwet et H. W. Zandbergen. « Focus-variation image reconstruction in field-emission TEM ». Proceedings, annual meeting, Electron Microscopy Society of America 51 (1 août 1993) : 1070–71. http://dx.doi.org/10.1017/s0424820100151180.

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The use of a field emission gun (FEG) in high resolution TEM (HRTEM) improves the information limit much below the point resolution. This is due to the FEG’s high brightness and low energy spread which yield a very good coherence. In the area between point and information resolution of the FEG-TEM, image interpretation is complicated by the lens aberrations and focus effects, which cause scrambling of the information from the specimen. This problem is solved by ‘holographic’ techniques, which retrieve aberration-corrected amplitude and phase information of the electron wave ϕ at the exit plane of the specimen. We follow the route of ‘in-column’ or ‘nonlinear’ holography by digital processing of a focal series of HRTEM images. Different reconstruction algorithms can be used for that purpose depending on the assumptions that are made in the HRTEM imaging model. We have devised two workable algorithms. A first method, called the “paraboloid method” (PAM), aims at filtering out recursively the nonlinear contributions in the images, so that high-speed linear reconstruction can be applied.

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Thèses sur le sujet "Field emission gun (FEG)"

Dylewski, Benoît. « Caractérisation expérimentale multi-échelles et multi-techniques du rail prélevé en service : de la déformation plastique sévère et des évolutions de microstructure à l'amorçage de fissures par Fatigue de Contact de Roulement ». Electronic Thesis or Diss., Compiègne, 2016. http://www.theses.fr/2016COMP2324.

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Cette thèse est dédiée à la caractérisation de la déformation plastique sévère et des évolutions de la microstructure engendrées dans les rails en service, conduisant à leur fissuration par Fatigue de Contact de Roulement. L’amorçage de ces fissures en surface et leur propagation en profondeur mettent en jeu des phénomènes à l’échelle de la microstructure qui peuvent entrainer à l’échelle macroscopique des écaillages de surface ou même conduire à des ruptures brutales de rails en cours de fonctionnement. Pour améliorer la compréhension de ces différents phénomènes en sous surface, une méthodologie expérimentale multi-échelles et multi-techniques a été conduite sur des rails prélevés en cours de service. Dans un premier temps, la présence d’un gradient tridimensionnel de microstructure, de cristallographie et de propriétés mécaniques engendré par les contacts répétés avec les roues a été mise en évidence dans la tête du rail au cours de son fonctionnement. Par le biais d’une campagne de prélèvement de rails en circulation à différents chargements, les stades de mise en place de ces gradients et la déformation plastique accumulée dans la tête de rail ont ensuite pu être évalués, de même que leurs évolutions par rapport aux passages des roues sur le rail et au développement des fissures. Cette étude contribue ainsi à une meilleure appréhension des mécanismes d’endommagement en fatigue de contact de roulement des rails en fonctionnement et pourra fournir une base de données solide pour les travaux à venir dans le domaine
This work is dedicated to the characterization of severe plastic deformation and microstructure evolution induced in rails in service, leading to cracks initiation by Rolling Contact Fatigue. Initiation of these surface cracks and in-depth propagation involve several phenomena at the microstructure scale which can lead to surface spalling at the macroscopic scale or even to brutal failure of the rail during its service. To improve understanding of these various phenomena beneath the rail surface, an experimental, multi-scales and multi-techniques methodology has been followed on rails removed from service. In the first part of results, the presence of a three-dimensional gradient of microstructure, of crystallography and of mechanical properties induced by the repeated contacts with wheels has been highlighted in a rail head during its service. Then, by means of a field analysis campaign of rails removed from service at several accumulated loads, the different stages of in-depth gradients development and plastic deformation accumulated in the rail head have been estimated in relation with total accumulated tonnage and cracks initiation. This study contributes to improve the understanding of the damage mechanisms in rolling contact fatigue of rails in service and the modeling of rail plasticity and crack propagation by including anisotropy of the running band and effect of in-depth microstructure evolution

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Liška, Ivo. « Coulomb Interactions in Electron Beams in the Vicinity of a Schottky and Cold Field Emission Sources ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233896.

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Dizertační práce se zabývá problematikou výpočtu vlivu coulombovských interakcí částic na parametry emitovaného elektronového svazku v blízkosti Schottkyho a studené katody. Práce poskytuje základní předhled o problematice, popisuje vytvořené modely emisních zdrojů a metodu simulace Monte Carlo. Představuje novou metodu generování vstupních dat, která klade větší důraz na přesnou simulaci emisního procesu. Pozornost je zde věnována zejména vlivu interakcí na energiovou šířku, velikost virtuálního zdroje a jas katody v závislosti na velikosti poloměru hrotu a emisním proudu. Sledováním vývoje energiové šířky bylo zjištěno, že naprostá většina interakcí se odehrává v prostoru do několika mikrometrů od hrotu katody. Závislost spočtené celkové energiové šířky na úhlové intenzitě je ve shodě s dostupnými experimentálními daty. Spočtené energiové rozšíření vlivem coulombovských interakcí bylo srovnáno s hodnotami vypočtenými pomocí vzorců založených na analytických přiblíženích. Bylo zjištěno, že některé z nich přijatelně předpovídají trendy ale nemohou být použity pro kvantitativní odhad.

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Brenac, Ariel. « Développements instrumentaux pour la photoémission inverse ». Grenoble 1, 1987. http://www.theses.fr/1987GRE10010.

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Canon a electron fournissant un faisceau dans la gamme 5 ev-50 ev: resolution en vecteur d'onde de 0,2 a**(-1), courant maximal de 25 microamperes a 20 ev. Les spectres de photoemission inverse resolue angulairement presentent des effets angulaires a 30 ev. A 10 ev les effets angulaires devraient etre plus marques mais de faible rendement du spectrometre a cette energie rend les experiences difficiles. Caracterisation de nouvelles sources d'electrons: electrons emis par effet du champ par une cathode comprenant un grand nombre de micropointes. Ces cathodes fonctionnent a basse temperature. Description du spectrometre uv du vide et de la multidetection des photons

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Liao, Po-Hsinag, et 廖柏翔. « Development of Field Emission Electron Gun for Desktop Electron Microscope ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3d5ybg.

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碩士
國立清華大學
工程與系統科學系
106
With the development of technology, electron microscope has become an important observational tool in different major such as physics, chemistry, biology, and materials engineering. The source of electron microscope, it usually divide into two types, thermionic type and field emission type. Field emission type electron source usually have smaller tip radius than thermal type, so it can produce smaller electron source. Then, electron beam pass by condenser lens, a small spot size source is formed. Therefore, the brightness of the electron gun is much brighter than thermal type source. In addition, field emission source spectral energy distribution is close to monochromatic, and has smaller energy spread. So field emission source has better coherence that lead it obtain higher resolution. Although field-emission type electron gun have above advantages, but it need to maintain in high vacuum condition. Because the tip of the field emission electron gun can easily react with impurities in the air, and lead the needle tip blunt. When the needle tip is blunt, it will cause the field emission gun poor efficiency. So the field emission type electron gun needs lots of high vacuum equipment to maintain it stay in high vacuum condition and high efficiency. The purpose of this research is using cheaper and more convenient ways to produce a field emission electron gun tip. And then set it up on our lab’s group made Desktop Electron Microscope to improve the resolution. In this paper, we successfully fabricated a field electron gun tip using electrolytic machining. The radius of curvature of the electron gun tip is about 100 nm or less, and its reproduction rate is also high. Finally, we also tried to deposit ZrO on the tip to make thermionic (Schottky) type field electron gun. After that, we also design some components installed on our Desktop Electron Microscope to finish field emission microscope.

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YIN, k. M., et 殷開明. « Field emission gun TEM research for Cu-Bi alloys in grain boundary segregation ». Thesis, 1996. http://ndltd.ncl.edu.tw/handle/21098675102269389780.

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Chang, Holin, et 張豪麟. « Failure Analysis of Diffusion Barrier Layer in VLSI Deviceby Field Emission Gun Energy Filter TEM ». Thesis, 1996. http://ndltd.ncl.edu.tw/handle/75194869367329745607.

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Chapitres de livres sur le sujet "Field emission gun (FEG)"

Lich, Ben, Faysal Boughorbel, Pavel Potocek et Emine Korkmaz. « FEG-SEM for Large Volume 3D Structural Analysis in Life Sciences ». Dans Biological Field Emission Scanning Electron Microscopy, 103–15. Chichester, UK : John Wiley & Sons, Ltd, 2019. http://dx.doi.org/10.1002/9781118663233.ch6.

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Brodusch, Nicolas, Hendrix Demers et Raynald Gauvin. « Developments in Field Emission Gun Technologies and Advanced Detection Systems ». Dans Field Emission Scanning Electron Microscopy, 5–12. Singapore : Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-4433-5_2.

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Mook, H. W., et P. Kruit. « Electrostatic in-line monochromator for Schottky Field Emission Gun ». Dans Electron Microscopy and Analysis 1997, 81–84. Boca Raton : CRC Press, 2022. http://dx.doi.org/10.1201/9781003063056-19.

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Actes de conférences sur le sujet "Field emission gun (FEG)"

Chen, Tao, Chen Xue-dong, Xiao-ming Lian et Zhi-chao Fan. « Effect of Ti Additions on Microstructure and Mechanical Properties of Centrifugally Cast 25Cr-35Ni-Nb Alloy ». Dans ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63411.

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The influence of Ti element with the content from 0.018 wt.% to 0.112 wt.% on microstructure and mechanical properties of centrifugally cast 25Cr-35Ni-Nb alloy was investigated in this paper. The experiments were carried out by optical emission spectrometer, metallographic image analyzer, field emission gun scanning electron microscopy (FEG-SEM) equipped with an Oxford INCA energy dispersive X-ray spectrometer (EDS), tensile testing machine and creep testing machine. The results show that the microstructure and high temperature creep rupture properties of as-cast 25Cr-35Ni-Nb alloy are significantly affected by the addition of Ti. No precipitation of Ti carbides was observed in the alloy with the Ti content of 0.018 wt.%, whereas the skeleton (Nb, Ti) C were precipitated at grain boundaries when increasing the Ti content. Under the creep rupture condition of 1100 °C and 17 MPa, the rupture lives of 25Cr-35Ni-Nb alloy with Ti contents ranging from 0.04 wt.% to 0.112 wt.% were relatively higher. In addition, the role of Ti in ethylene pyrolysis furnace tube was also discussed in this paper.

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Spathis, V., et M. C. Price. « Experiments using a light gas gun to investigate the impact melting of gunshot residue analogues ». Dans 2019 15th Hypervelocity Impact Symposium. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/hvis2019-030.

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Abstract In this set of experiments, the versatility of the University of Kent's light gas gun was utilised to obtain a selection of corroborative data regarding the formation and impact of metallic gunshot residues onto high purity silicon wafers. The results from the two experiments are presented. The first experiment investigated how the formation of metallic residues varied as gunshot residue analogues traversed through air under a range of pressures from 0.056 millibar (5.6 Pa) to 1 bar (100 kPa), using solely the energy released during primer ignition; the second involved firing a metallic powder mix of pre-determined composition (via a split-sabot) under vacuum at two velocities- 500 ms-1 and 2000 ms-1. This ensured that there was no ignition or heating of the powders, unlike the first experiment, and so the morphology of the particles collected would be solely due to impact. The residues on the substrates were then analysed using a cold Field Emission Gun Scanning Electron Microscope (FEG) and Energy Dispersive X-ray (EDX) detector. By separating the ignition process of the primers from the residue impacts, it allows for a closer look into the formation of these particles and helps determine whether their varied morphologies are due to the heating caused during the activation and combustion of the primer or whether its due to impact melting. This information can aid in the understanding of metallic particle formation in different pressure environments and give insight into the physical state of firearm residues when they impact a surface. Hydrocode modelling was also incorporated to corroborate the results observed during these experiments and gave results which mimicked the experimental data.

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Wang, L., R. J. K. Wood, H. E. G. Powrie, E. Streit et I. Care. « Performance Evaluation of Hybrid (Ceramic on Steel) Bearings With Advanced Aircraft Engine Oils for Lubrication ». Dans ASME Turbo Expo 2004 : Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53418.

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Hybrid bearings (silicon nitride rolling elements and steel raceways) are being developed for the new generation of gas turbine engines, as they offer weight savings, reduced heat rejection and can operate at higher DN (bore diameter in mm × shaft rotational speed in rpm) values than conventional steel bearings. In the present study, various advanced synthetic aviation oils were tested on a pin-on-disc tribometer. Conditions were chosen to simulate engine low load and ambient start up, where sliding is a factor. The tests used a silicon nitride ball sliding against an M50NiL bearing steel disc. Fresh oils were tested for the hybrid contacts under high sliding speed of 7 ms−1 and normal aircraft engine bearing contact pressure of 2.8 GPa [1]. The results showed that most of the synthetic aviation oils in use today would provide similar protection for the hybrid contacts against scuffing. Initial studies, aimed at identifying the influence of oil degradation and effects of additive depletion are also presented. The oils were ranked based on the contact wear rate. Electrostatic charge measurements were made along with wear, friction and surface temperature measurements to monitor the on-line wear conditions [2–3]. Electrostatic sensing shows promise as a monitoring technique for oil lubricated hybrid contacts. Polishing wear mechanisms and iron-based material transfer from disc to ball were identified by Field Emission Gun Scanning Electron Microscopy (FEG-SEM) and Energy-Dispersive X-ray (EDX) as the dominant degradation process in these hybrid contacts.

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Lin, Kun-Lin, Jian-Shing Luo, Hsiu-Ting Lee et Jeremy D. Russell. « Localized Epoxy Layer Formation on Surface Defect Using a Micro-Brush in a Plucking System ». Dans ISTFA 2009. ASM International, 2009. http://dx.doi.org/10.31399/asm.cp.istfa2009p0126.

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Abstract This paper provides details of a novel method developed to cover a tiny epoxy layer as an intermediate buffer on the site-specific surface defect using a micro-bush on the tip of a glass needle in a plucking system without sample surface damage and localization problems. It describes the method and some real cases. The microstructures are investigated using an FEI Tecnai TF20 field emission gun transmission electron microscopy equipped with a high angle annular dark field detector, an energy dispersive X-ray spectroscopy, and Gatan image filter systems. The paper explains the micro-brushes and buffer layer preparation though figures and illustrations.

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Hawco, Jessica, Elliott Burden, Edison Sripal et Lesley James. « Evaluating the Prospect of Oil Production in Tight Winterhouse Formation Rocks in Western Newfoundland ». Dans SPE Canadian Energy Technology Conference. SPE, 2022. http://dx.doi.org/10.2118/208908-ms.

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Abstract The Winterhouse Formation (Port au Port Peninsula, western Newfoundland, Canada) is a lateral equivalent to the Utica and Macasty formations farther west. With hydrocarbon stains and odours as a guide towards a common and regional upper Ordovician hydrocarbon system, Winterhouse rocks may yet contain their own suite of source reservoir and seal strata, with coarser, sandier beds perhaps playing host to other varieties of conventional and unconventional hydrocarbon traps. Hence, addressing basic properties of fluid transmission is an important and unknown variable that needs to be addressed for this formation. In this pilot study, Mercury Intrusion Porosimetry (MIP) is applied to measure the petrophysical properties of a single tight (low porosity, low permeability) quartz-carbonate sandstone sample from a Winterhouse outcrop. As a tool, Mercury Intrusion Porosimetry is strongly dependent on conformity of sample size and shape as a determinant of pore accessibility. Hence two sample types (i) plugs and (ii) cuttings (both real and artificial) are analyzed to explore aspects of core and cuttings preparation and data reduction work flow measurements of storage and transport properties. For artificial "cuttings" a horizontal 2.5 cm core plug and rock fragments are crushed and sieved to replicate fine and coarse fractions. For porosimetry, a Micromeretrics AutoPore IV porosimeter with a maximum pressure of 33,000 psi is used to determine the porosity, pore size distribution, surface area, and bulk density of all samples. Additionally, the FEI Quanta 650 Field Emission Gun (FEG) SEM is used to take images of the pore structure. Mineralogy is determined from the GXMAP measurement mode within FEI Mineral Liberation AnalyzerTM software. A comprehensive analysis corroborating results from MIP and SEM indicates that for these tight rocks, and namely, outcrop plugs, artificial cuttings, and real drill cuttings from a nearby well, all show a similar spectrum of results, but smaller coarse fragments are recommended for reliability. In terms of the Winterhouse strata, it is clear that some of this rock is very tight and highly cemented, but that it also possesses fractures and high permeability values which may make it a good unconventional reservoir. These porosity-permeability results are simply a beginning in a search to understand the petrophysical properties of the strata on the western coast of Newfoundland. The western part of Newfoundland has seen extensive oil exploration efforts in the last few decades, these efforts have resulted in little success. A large degree of this is due to the complex geological history and overall lack of knowledge concerning the structure and diagenesis of these rocks (Cooper et al, 2001). This study will support the new sampling programs in the hope of gaining new insights into potential oil exploitation.

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Luan, B. F., R. S. Qiu, Z. Zhou, K. L. Murty, J. Zhou et Q. Liu. « Characterization of Hot Deformation Behavior of Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr Using Processing Map ». Dans 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-15186.

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Hot deformation characteristics of forged and β-quenched Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr (N18 alloy) in the temperature range 625–950°C and in the strain rate range 0.005–5 s−1 have been studied by uniaxial compression testing of Gleeble 3500. For this study, the approach of processing maps has been adopted and their interpretation done using the Dynamic Materials Model (DMM). Based on a series of true stress-true strain curves on various temperatures and strain rates, the flow stress has been summarized and both the strain rate sensitivity index (m) and deformation activation energy (Q) have been calculated by the constitutive equations that flow stress and the relationship of Z parameter and flow stress have been established subsequently. Furthermore, the efficiency of power dissipation (⬜) given by [2m/(m+1)] and improved by Murty has been plotted as a function of temperature and strain rate to obtain different processing maps at different true strain rates ranging from 0.1–0.7. Subsequently, the microstructures of the specimens after compression testing were characterized by electron channeling contrast (ECC) imaging techniques used an FEI Nova 400 field emission gun scanning electron microscopy (FEG-SEM). The results showed that: (i) The hyperbolic sine constitutive equation can describe the flow stress behavior of zirconium alloy, and the deformation activation energy and flow stress equation were calculated under the different temperature stages which insists that the deformation mechanism is not dynamic recovery. (ii) The hot processing maps and its validation were analyzed, which indicated that the DMM theory was reliable and could be adopted as useful tool for optimizing hot workability of Zr. The optimum parameters for extrusion and hammer forging were revealed on the processing maps of 830–950°C, 0.048–2.141 s−1 and 916–950°C, 2.465–5 s−1. (iii) The microstructure of the ingot exhibits a typical lamellar Widmanstatten structure. Under the different strain rates, the grains formed by dynamic recrystallization existed normally in the central zone of the compression samples while the no uniformity of grain size increased with the increasing of strain rate. Meanwhile, due to the dynamic recrystallization as a thermal activation process, the grains size and uniformity increased with the increasing of temperature. In brief, microstructure analysis showed that continuous dynamic recrystallization and geometric dynamic recrystallization operated concurrently during the isothermal compressive deformation.

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Lewis, Samantha M., Julian Merrick, Mohamed A. K. Othman, Andrew Haase, Sami Tantawi et Emilio A. Nanni. « A THz-Driven Field Emission Electron Gun ». Dans 2020 45th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz). IEEE, 2020. http://dx.doi.org/10.1109/irmmw-thz46771.2020.9370485.

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Shao, J. H., S. Antipov, S. V. Baryshev, H. B. Chen, M. E. Conde, D. S. Doran, W. Gai et al. « Field emission study using an L-band photocathode gun ». Dans ADVANCED ACCELERATOR CONCEPTS 2016 : 16th Advanced Accelerator Concepts Workshop. Author(s), 2016. http://dx.doi.org/10.1063/1.4965637.

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Getty, Stephanie A., Todd T. King, Rachael A. Bis, Hollis H. Jones, Federico Herrero, Bernard A. Lynch, Patrick Roman et Paul Mahaffy. « Performance of a carbon nanotube field emission electron gun ». Dans Defense and Security Symposium, sous la direction de Thomas George et Zhongyang Cheng. SPIE, 2007. http://dx.doi.org/10.1117/12.720995.

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Eroshkin, Pavel A., et Evgeny P. Sheshin. « Electron gun with field emission cathode for x-ray tube ». Dans 2014 Tenth International Vacuum Electron Sources Conference (IVESC). IEEE, 2014. http://dx.doi.org/10.1109/ivesc.2014.6891972.

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Rapports d'organisations sur le sujet "Field emission gun (FEG)"

Thangaraj, Charles. Gated Field-Emission Cathode Radio-Frequency (RF) Gun. Office of Scientific and Technical Information (OSTI), novembre 2016. http://dx.doi.org/10.2172/1433861.

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Jay L. Hirshfield. Rf Gun with High-Current Density Field Emission Cathode. Office of Scientific and Technical Information (OSTI), décembre 2005. http://dx.doi.org/10.2172/861455.

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McGuire, Gary, Allen Martin et John Noonan. Final Technical Report- Back-gate Field Emission-based Cathode RF Electron Gun. Office of Scientific and Technical Information (OSTI), octobre 2010. http://dx.doi.org/10.2172/991655.

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Zhai, Tongguang, Chi-Sing Man et James Morris. Field Emission Gun Scanning Electron Microscopy with Electron Back Scatter Diffraction for Texture, Formability and Fatigue Studies of Advanced Materials. Fort Belvoir, VA : Defense Technical Information Center, mai 2007. http://dx.doi.org/10.21236/ada484492.

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