Log in

Relevant bibliographies by topics / Emissive cathode / Dissertations / Theses

To see the other types of publications on this topic, follow the link: Emissive cathode.

Dissertations / Theses on the topic 'Emissive cathode'

Author: Grafiati

Published: 31 August 2024

Last updated: 31 July 2025

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Emissive cathode.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Asselin, Daniel Joseph. "Characterization of the Near-Plume Region of a Low-Current Hollow Cathode." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-theses/438.

Full text

Abstract:

Electric propulsion for spacecraft has become increasingly commonplace in recent decades as designers take advantage of the significant propellant savings it can provide over traditional chemical propulsion. As electric propulsion systems are designed for very low thrust, the operational time required over the course of an entire mission is often quite long. The two most common types of electric thrusters both use hollow cathodes as electron emitters in the process of ionizing the propellant gas. These cathodes are one of the main life-limiting components of both ion and Hall thrusters designe

APA, Harvard, Vancouver, ISO, and other styles

2

Sary, Gaétan. "Modélisation d'une cathode creuse pour propulseur à plasma." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30182/document.

Full text

Abstract:

La cathode creuse est un élément clef des propulseurs à plasma. Dans un propulseur à plasma, un gaz propulsif est ionisé dans un canal de décharge puis accéléré hors de celui-ci afin de créer la poussée. Dans le propulseur de Hall en particulier, l'ionisation du gaz est provoquée par l'injection dans le canal de décharge d'un intense courant électronique (de quelques ampères à plus d'une centaine d'ampères). L'élément chargé de fournir le courant électronique de la décharge, la cathode creuse, est crucial dans le fonctionnement du propulseur. Or, celle-ci est souvent idéalisée dans les modèles

APA, Harvard, Vancouver, ISO, and other styles

3

Pagaud, Francis. "Control and stability of magnetised plasma columns : plasma-cathode interactions and helicon plasma operation." Electronic Thesis or Diss., Lyon, École normale supérieure, 2024. http://www.theses.fr/2024ENSL0016.

Full text

Abstract:

Le transport, les ondes et les instabilités sont des problématiques courantes des plasmas magnétisés, à l’origine de problèmes fondamentaux et de limites opératoires pour les plasmas de fusion, les accélérateurs de particules à plasma ou la propulsion plasma. Le contrôle des propriétés du plasma est souhaitable mais complexe. Ce doctorat vise à utiliser une cathode émissive comme nouveau paramètre de contrôle et à comprendre la stabilité du plasma hélicon. Le dispositif expérimental est une enceinte à vide cylindrique de 80 cm de long et 20 cm de diamètre, connecté à un tube source en verre de

APA, Harvard, Vancouver, ISO, and other styles

4

Taillefer, Zachary R. "Characterization of the Near Plume Region of Hexaboride and Barium Oxide Hollow Cathodes operating on Xenon and Iodine." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-dissertations/44.

Full text

Abstract:

The use of electric propulsion for spacecraft primary propulsion, attitude control and station-keeping is ever-increasing as the technology matures and is qualified for flight. In addition, alternative propellants are under investigation, which have the potential to offer systems-level benefits that can enable particular classes of missions. Condensable propellants, particularly iodine, have the potential to significantly reduce the propellant storage system volume and mass. Some of the most widely used electric thrusters are electrostatic thrusters, which require a

APA, Harvard, Vancouver, ISO, and other styles

5

Popov, M. Yu, A. P. Volkov, S. G. Buga, et al. "Nanostructured metal-fullerene field emission cathode." Thesis, Sumy State University, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20585.

Full text

Abstract:

One of the important properties of carbon nanostructures is their cold electron emission ability. Carbon nanotubes and other nanostructures are capable of emitting high currents at relatively low electrical fields. They are already used in functional devices such as field emitters. The conventional method of carbon nanostructured cathodes manufacturing is thin film nanocarbon deposition using CVD process on electrically conducting substrate like metal or doped silicon plates. The alternative way of manufacturing of carbon field emission cathodes is based on a special processing of carbo

APA, Harvard, Vancouver, ISO, and other styles

6

Vaughn, Joel M. "Thermionic Electron Emission Microscopy Studies of Barium and Scandium Oxides on Tungsten." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1279814656.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Lee, Kon Jiun. "Current limiting of field emitter array cathodes." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/19629.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Shen, Xiangqian. "Novel processing routes for oxide cathode emission materials." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/10822.

Full text

Abstract:

An investigation has been carried out into the production of the alkaline earth carbonate and oxide powders and coatings suitable as cathode emission materials by the ethylenediaminetetraacetic acid (EDT A) gel method for potential application as cathode emission materials. The emission performance of thermionic cathodes coated with these materials has been measured, and found to give encouraging results, comparable with conventionally prepared oxide emission materials, despite the former having not been optimised. Amorphous gels of composition Ca-EDTA, Sr-EDTA, Ba-EDTA, [SrO.5 Bao.5J-EDTA and

APA, Harvard, Vancouver, ISO, and other styles

9

Mollart, T. P. "Electron emission processes in cold cathode thermal arcs." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5546/.

Full text

Abstract:

In this Thesis the processes of electron emission from cathode electrodes are studied theoretically, and the applicability of these mechanisms to the non refractory cathodes that can be used to sustain thermal arcs was examined. Apparatus that was used to generate and manipulate thermal arcs along rail electrodes is described in this thesis. Techniques for driving arcs over polished sample electrodes with magnetic or aerodynamic forces are outlined. Scanning electron microscopy was used to study emission site formation on highly polished electrodes with a natural 2.5 nm oxide layer. Theoretica

APA, Harvard, Vancouver, ISO, and other styles

10

Jones, Randolph D. "Circuit model of a low-voltage field emission cathode." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/15631.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Lysenkov, Dmitry. "Optimization of nanostructures for field emission cathodes." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=979952913.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Sanborn, Graham Patrick. "A thin film triode type carbon nanotube field electron emission cathode." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50302.

Full text

Abstract:

The current technological age is embodied by a constant push for increased performance and efficiency of electronic devices. This push is particularly observable for technologies that comprise free electron sources, which are used in various technologies including electronic displays, x-ray sources, telecommunication equipment, and spacecraft propulsion. Performance of these systems can be increased by reducing weight and power consumption, but is often limited by a bulky electron source with a high energy demand. Carbon nanotubes (CNTs) show favorable properties for field electron emission (

APA, Harvard, Vancouver, ISO, and other styles

13

Schlise, Charles A. "Explosive emission cathodes for high power microwave devices /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FSchlise.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Cooper, Joseph Andrew. "Investigation of the effects of process variables on the properties of europium-doped yttrium oxide phosphor." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/20503.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Kandah, Munther Issa. "Particles emission control at graphite cathode in arc ion plating deposition." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ55420.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Kandah, Munther. "Particles emission control at graphite cathode in arc ion plating deposition." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35434.

Full text

Abstract:

In this work, the dependence of the vacuum arc spot velocity on physical and electrical properties of different graphite cathode materials is investigated in the presence of a variable magnetic field. A pulsed arc system is used to perform preliminary experiments on the arc mobility for the different types of graphite for the selection of proper material morphology and the design of a continuous vacuum arc system. The characteristics of arc mobility, erosion rate, and carbon ion flux emitted from the continuous carbon source are then evaluated in view of particle-free diamond-like protective c

APA, Harvard, Vancouver, ISO, and other styles

17

Bajic, Stevan. "Non-metallic cold-cathode electron emission from composite metal-insulator microstructures." Thesis, Aston University, 1989. http://publications.aston.ac.uk/8063/.

Full text

Abstract:

A detailed investigation has been undertaken into a field-induced electron emission (FIEE) mechanism that occurs at microscopically localised `sites' on uncoated, dielectric-coated and composite-coated metallic cathodes. An optical imaging technique has been used to observe and characterize the spatial and temporal behaviour of the populations of emission sites on these cathodes under various experimental conditions, e.g. pulsed-fields, gas environment etc. This study has shown that, for applied fields of 20MVm^-1, thin dielectric (750AA) and composite metal-insulator (MI) overlayers result in

APA, Harvard, Vancouver, ISO, and other styles

18

Hirt, Benjamin David. "Impact of Additives on Thermionic Cathodes." Ohio University Honors Tutorial College / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1524832507214002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Swartzentruber, Phillip D. "MICROSTRUCTURE AND WORK FUNCTION OF DISPENSER CATHODE COATINGS: EFFECTS ON THERMIONIC EMISSION." UKnowledge, 2014. http://uknowledge.uky.edu/cme_etds/41.

Full text

Abstract:

Dispenser cathodes emit electrons through thermionic emission and are a critical component of space-based and telecommunication devices. The emission of electrons is enhanced when coated with a refractory metal such as osmium (Os), osmium-ruthenium (Os-Ru), or iridium (Ir). In this work the microstructure, thermionic emission, and work function of thin film Os-Ru coatings were studied in order to relate microstructural properties and thermionic emission. Os-Ru thin film coatings were prepared through magnetron sputtering and substrate biasing to produce films with an array of preferred orienta

APA, Harvard, Vancouver, ISO, and other styles

20

Wu, Qiong. "Measurements and studies of secondary electron emission of diamond amplified photo cathode." [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337275.

Full text

Abstract:

Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2008.<br>Title from PDF t.p. (viewed on Jul 29, 2009). Source: Dissertation Abstracts International, Volume: 69-12, Section: B, page: 7588. Adviser: Shyh-Yuan Lee.

APA, Harvard, Vancouver, ISO, and other styles

21

Pozdnyakov, D. V., A. V. Borzdov, and V. M. Borzdov. "Calculation of Current-Voltage Characteristics of the Optimized Triode with a Cold Cathode Based on the Ordered Array of Single-Wall Metallic Carbon Nanotubes." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35361.

Full text

Abstract:

The current-voltage characteristics of a triode with the plane-parallel electrodes and a cold cathode based on the ordered array of single-wall metallic carbon nanotubes with open ends have been calculated by means of a numerical solution of both the Poisson equation and the quantum-wave equation. The topological parameters of the triode have been optimized. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35361

APA, Harvard, Vancouver, ISO, and other styles

22

Ayzatskiy, N., A. Dovbnya, V. Zakutin, et al. "Experimental investigation on the time characteristics of an electron beam formed in the magnetron gun with a secondari-emission cathode." Thesis, Национальный научный центр "Харьковский физико-технический институт" (ННЦ ХФТИ), 2007. http://openarchive.nure.ua/handle/document/9244.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Patel, Jay. "GROWTH AND CHARACTERIZATION OF CARBON NANOMATERIALS." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1310148312.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Magnus, Sandra Hall. "An Investigation of the relationship between the thermochemistry and emission behavior of thermionic cathodes based on the BaO-Sc₂O₃-WO₃ ternary system." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/19625.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Sabaut, Lucie. "Cathode commutable à nanotubes de carbone pour tube à rayons X." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX078/document.

Full text

Abstract:

Les systèmes d'imagerie à rayons X (RX) sont des appareils volumineux et contraignants en termes de contrôle du faisceau. L'industrie des tubes électroniques est donc à la recherche de solutions pour assurer la stabilité du courant tout en permettant la miniaturisation du système.Ce travail opte pour l'amélioration de la source d'électrons, en remplaçant l'émission thermoïonique historique par l'émission de champ. En particulier, les cathodes froides à base de nanotubes de carbone possèdent l'avantage de pouvoir délivrer de forts courants (>1A/cm^2), tout en ayant un faible temps de réponse

APA, Harvard, Vancouver, ISO, and other styles

26

Yang, Sen. "Characterization of low voltage cathodo-luminescent phosphors for field emission displays." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/30859.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

O'Neill, Kevin. "Field Emission from Excimer Laser Processed a-Si:H Thin Film Cathodes." Thesis, University of Dundee, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521675.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Pottinger, Sabrina. "Investigation of steady state characteristics of hollow cathode internal plasmas using optical emission spectroscopy." Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/345074/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Knápek, Alexandr. "Metody přípravy a charakterizace experimentálních autoemisních katod." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-233613.

Full text

Abstract:

Téma doktorské práce se zabývá přípravou a popisem katod na bázi autoemise, jenž představují kvalitní a levný elektronový zdroj pro zařízení pracující s fokusovaným elektronovým svazkem. Pro přípravu kompozitní autoemisní katody byla využita elektrochemická metoda výroby. Kompozitní struktura katody zlepšuje proudovou stabilitu ve srovnání s čistě autoemisními katodami na bázi wolframu. Na základě charakterizace katody, jenž byla nově provedena metodou šumové spektroskopie, byla implementována technologická zlepšení stávající výroby. Metoda šumové spektroskopie je založena na analýze emisního

APA, Harvard, Vancouver, ISO, and other styles

30

Munné, Vicente. "Investigation of barium titanate PTCR films for current limiting of field emitter arrays." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19612.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Neuerman, Robert A. "Simulation and design methods for free-electron laser systems." Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Dec/09Dec%5FNeuerman.pdf.

Full text

Abstract:

Thesis (M.S. in Applied Physics)--Naval Postgraduate School, December 2009.<br>Thesis Advisor(s): Colson, William B. ; Blau, Joseph. "December 2009." Description based on title screen as viewed on January 28, 2010. Author(s) subject terms: Free-electron lasers, FEL simulations, undulators, FEL oscillators, FEL amplifiers, diamond field-emitter arrays, field emission cathodes, cathode test cell. Includes bibliographical references (p. 45). Also available in print.

APA, Harvard, Vancouver, ISO, and other styles

32

Forrest, Roy Duncan. "Electron field emission from amorphous semiconductor thin films." Thesis, University of Surrey, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484237.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Little, Scott A. "Experimental and numerical studies of a new thermionic emitter structure based on oxide coated carbon nanotubes operating at large emission currents." Virtual Press, 2007. http://liblink.bsu.edu/uhtbin/catkey/1380104.

Full text

Abstract:

We have developed a thermionic cathode capable of high emission currents. The structure of this cathode is oxide coated carbon nanotubes (CNTs) on a tungsten (W) substrate. This cathode was superior in emission due to the combination of the field enhancement effect from the CNTs and the lowered work function from the semiconducting oxide surface. Such oxide coated CNTs were excellent electron emitters. Conventional electron emission theories, such as Richardson's and Fowler-Nordheim's, did not accurately describe the field enhanced thermionic emission from such emitters. A unified electron emi

APA, Harvard, Vancouver, ISO, and other styles

34

Liu, Xiaotao. "CHARACTERIZATION OF NANOSTRUCTURE, MATERIALS, AND ELECTRON EMISSION PERFORMANCE OF NEXT-GENERATION THERMIONIC SCANDATE CATHODES." UKnowledge, 2019. https://uknowledge.uky.edu/cme_etds/96.

Full text

Abstract:

Scandate cathodes, where scandia is added to the tungsten cathode pellets, have recently received substantial and renewed research interest owing to significantly improved electron emission capabilities at lower temperatures, as compared with conventional dispenser cathodes. However, there are several persistent issues including non-uniform electron emission, lack of understanding regarding scandium’s role in the emission mechanism, and unreliable reproducibility in terms of scandate cathode fabrication. As a result, scandate cathodes have not yet been widely implemented in actual vacuum elect

APA, Harvard, Vancouver, ISO, and other styles

35

Del, Pozo Rodriguez Sofia. "Investigation and optimisation of a plasma cathode electron beam gun for material processing applications." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/13565.

Full text

Abstract:

This thesis describes design, development and testing work on a plasma cathode electron beam gun as well as plasma diagnosis experiments and Electron Beam (EB) current measurements carried out with the aim of maximising the power of the EB extracted and optimising the electron beam gun system for material processing applications. The elements which influence EB gun design are described and put into practice in a thermionic EB gun case study. The relevant principles of plasma EB gun systems, such low-temperature, low-pressure, RF excitation, are described along with the test rigs developed to i

APA, Harvard, Vancouver, ISO, and other styles

36

Serbun, Pavel [Verfasser]. "A systematic investigation of carbon, metallic and semiconductor nanostructures for field-emission cathode applications / Pavel Serbun." Wuppertal : Universitätsbibliothek Wuppertal, 2014. http://d-nb.info/1048757064/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Mroz, Michael V. "Characterization of Morphological and Chemical Properties of Scandium Containing Cathode Materials." Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou158470102410177.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Calderón-Colón, Xiomara Zhou Otto. "Fabrication, characterization and integration of carbon nanotube cathodes for field emission x-ray source." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2721.

Full text

Abstract:

Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.<br>Title from electronic title page (viewed Mar. 10, 2010). "... in partial fulfillment of the requirement for the degree of Doctor of Philosophy in the Curriculum in Applied Science and Engineering." Discipline: Applied and Materials Sciences; Department/School: Applied and Materials Sciences.

APA, Harvard, Vancouver, ISO, and other styles

39

Chalamala, Babu Reddy. "The Physics of Gaseous Exposures on Active Field Emission Microcathode Arrays." Thesis, University of North Texas, 1996. https://digital.library.unt.edu/ark:/67531/metadc278588/.

Full text

Abstract:

The interaction of active molybdenum field emission microcathode arrays with oxygen, water, carbon dioxide, methane, hydrogen and helium gases was studied. Experiments were setup to measure the emission characteristics as a function of gas exposures. The resulting changes in the surface work function of the tips were determined from the Fowler-Nordheim plots. The kinetics of the FEA-gas interaction were studied by observing the ion species originating from the array during and after gas exposures with a high resolution quadrupole mass spectrometer. With the work function data and the mass spec

APA, Harvard, Vancouver, ISO, and other styles

40

Navitski, Aliaksandr [Verfasser]. "Scanning field emission investigations of structured CNT and MNW cathodes, niobium surfaces and photocathodes / Aliaksandr Navitski." Wuppertal : Universitätsbibliothek Wuppertal, 2010. http://d-nb.info/1009494678/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Dong, Chen Dan. "Scaling of ultrafast photon-triggered field emission cathodes composed of arrays of sharpened single-crystal Si pillars." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/100329.

Full text

Abstract:

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 53-55).<br>Ultrafast (<1 ps-long pulses) cathodes with spatially structured emission are an enabling technology for exciting applications such as free-electron lasers, tabletop coherent x-ray sources, and ultrafast imaging. In this thesis, we explore the scaling down and multiplexing limits of ultrafast photon-triggered field emission cathodes composed of arrays of nano-sharp high-aspect-r

APA, Harvard, Vancouver, ISO, and other styles

42

Christy, Larry A. "Field Emission Properties of Carbon Nanotube Fibers and Sheets for a High Current Electron Source." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406819279.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Cheng, An-jen Tzeng Y. "Cold cathodes for application in poor vacuum and low pressure gas environments carbon nanotubes versus zinc oxide nanoneedles /." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/master's/CHENG_AN-JEN_7.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Hudanski, Ludovic. "Modulation d'un faisceau électronique issu d'une cathode à base de nanotubes de carbone - Applications aux tubes hyperfréquences." Phd thesis, Ecole Polytechnique X, 2008. http://pastel.archives-ouvertes.fr/pastel-00004268.

Full text

Abstract:

Les tubes amplificateurs ont été quelque peu oubliés du grand public depuis leur disparition des récepteurs de radio et d'autres équipements à la fin des années 50 et leur remplacement par les composants état solide. Toutefois, il est des régimes de fonctionnement où ils demeurent incontournables, surpassant tous les dispositifs état solide en termes de fréquence de fonctionnement, de puissance, de rendement et de fiabilité. C'est la raison pour laquelle les satellites de télécommunications embarquent à leur bord une centaine de tubes à ondes progressives pourtant lourds et volumineux. Afin de

APA, Harvard, Vancouver, ISO, and other styles

45

Dionne, Martin. "Optimized carbon nanotube array cathodes for thermo-field emission in plasmas: a theoretical model and an experimental verification." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97045.

Full text

Abstract:

In this work we developed a 3-D theoretical model for plasma-enhanced thermo-field emission from nanostructured cathodes in the absence of significant erosion. Our first studies indicated that very dense arrays of vertically-aligned carbon nanotubes (CNT) acting as electron emitters in vacuum could sustain the temperatures resulting from very high surface-averaged current densities such as those found in the cathode spots of arc discharges on non-refractory cathodes. A comparative study of the electron emission models for cold surfaces subjected to strong electric field revealed the existence

APA, Harvard, Vancouver, ISO, and other styles

46

Orozco, Nieto Pedro Francisco. "Manufacturing strategy for high current cold field emission cathodes : floating catalyst chemical vapour deposition grown carbon nanotube fibres and films enhanced by laser patterning and laser purification process." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/278104.

Full text

Abstract:

The aim of this work is to produce a manufacturing strategy for high current (>10 mA) field emission (FE) devices for military (microwave generation) and civilian (particle accelerator electron beam) applications using carbon nanotubes (CNT) as base material. With a particular focus on the relationship of the laser time pulse duration used for cutting CNTs and how this affects the field emission performance. Material selection for this work was narrowed to CNT as they possess unique characteristics such as: high aspect ratio; high thermal conductivity; high chemical stability and high current

APA, Harvard, Vancouver, ISO, and other styles

47

Schmitt, Thorsten. "Resonant Soft X-Ray Emission Spectroscopy of Vanadium Oxides and Related Compounds." Doctoral thesis, Uppsala University, Atomic and molecular physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4290.

Full text

Abstract:

<p>This thesis addresses the electronic structure of vanadium and copper oxides using soft X-ray absorption (SXA) spectroscopy and resonant inelastic X-ray scattering (RIXS) at high brightness synchrotron radiation sources. In RIXS incident photons, tuned to the energy of specific absorption resonances, are inelastically scattered leaving behind a low energy valence excitation in the system studied. Effects of electron localization are reflected by the occurrence of low-energy excitations in form of dd- and charge-transfer excitations that are modelled by cluster calculations. Band-like states

APA, Harvard, Vancouver, ISO, and other styles

48

Vašíček, Martin. "Charakterizace autoemisních zdrojů pro elektronovou mikroskopii." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220188.

Full text

Abstract:

This work deals with the theoretical foundations of electron emission into vacuum, various types of emissions, focused on the cold-emission and Schottky emission and the principle of quantum tunneling. The next part deals with the technical implementation of electron sources with a detailed study of the methodology of laboratory production of cathodes by electrochemical etching and construction of electron microscopes, using field-emission sources. This work also contains methods for measuring, processing and evaluation of electrical characteristics of emission sources.

APA, Harvard, Vancouver, ISO, and other styles

49

ORLIKOWSKI, JEAN-PIERRE. "Contribution a l'etude des cathodes a emission de champ a effet schottky : utilisation a basse tension, dans un canon a lentille magnetique incorporee." Reims, 1990. http://www.theses.fr/1990REIMS013.

Full text

Abstract:

L'objectif du travail qui est presente ici a ete d'etudier les performances a basse tension (10 kv) d'une colonne de microscope electronique a balayage, utilisant une source d'emission intense et parfaitement stable, pour essayer d'obtenir un courant de faisceau electronique important dans des tailles de sonde de l'ordre de 100 nm. Les qualites du faisqceau electronique emis sont en effet primordiales dans plusieurs domaines comme la spectroscopie des electrons auger, la microanalyse x, la microlithographie et, en particulier, le test des circuits integres par stroboscopie du faisceau d'electr

APA, Harvard, Vancouver, ISO, and other styles

50

Cousin, Richard. "Compréhension des mécanismes régissant le fonctionnement d'un tube hyperfréquence de type MILO (Magnetically Insulated Line Oscillator)." Phd thesis, Ecole Polytechnique X, 2005. http://pastel.archives-ouvertes.fr/pastel-00001651.

Full text

Abstract:

Le MILO (Magnetically Insulated Line Oscillator) est une source micro-onde de forte puissance capable de produire des puissances crêtes supérieures au gigawatt à des fréquences de quelques gigahertz. Ce tube hyperfréquence est un oscillateur à champs électrique et magnétique croisés qui ne requiert pas de structure externe pour produire le champ magnétique nécessaire au guidage du faisceau d'électrons. Ceux-ci sont produits par émission explosive à partir d'une cathode de type velours et sont accélérés par la différence de potentiel dans l'espace anode – cathode. L'anode constitue une cavité h

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!