HIGH-CURRENT COLD CATHODE FIELD EMISSION ARRAY FOR ELECTRON LENS APPLICATION. PDF Download
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Languages : en
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During Phase I, the following goals were achieved: (1) design and fabrication of a novel, nano-dimensional CNT field emitter assembly for high current density application, with high durability; (2) fabrication of a ceramic based micro channel plate (MCP) and characterization of its secondary electron emission; and (3) characterizing the CNT/MCP cathode for high field emission and durability. As a result of these achievements, a relatively high current density of ̃1.2 A/cm2 from a CNT cathode and single channel MCP were measured. The emission current was also extremely stable with a peak-to-peak variation of only 1.8%. The emission current could be further enhanced to meet requirements for electron lens applications by increasing the number of MCP channels. A calculation for maximum possible current density with a 1200 channel/cm2 MCP, placed over a cathode with 1200 uniformly functioning CNTs, would be 1̃.46 kA/cm2, neglecting space charge limitations. Clearly this level of emission is far greater than what is needed for the electron lens application, but it does offer a highly comforting margin to account for sub-standard emitters and/or to allow the lesser challenge of building a cathode with fewer channels/cm2. A satisfactory goal for the electron lens application would be a controllable emission of 2-4 mA per channel in an ensemble of 800-1200 uniformly-functioning channels/cm2, and a cathode with overall area of about 1 cm2.
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Languages : en
Pages :
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Book Description
During Phase I, the following goals were achieved: (1) design and fabrication of a novel, nano-dimensional CNT field emitter assembly for high current density application, with high durability; (2) fabrication of a ceramic based micro channel plate (MCP) and characterization of its secondary electron emission; and (3) characterizing the CNT/MCP cathode for high field emission and durability. As a result of these achievements, a relatively high current density of ̃1.2 A/cm2 from a CNT cathode and single channel MCP were measured. The emission current was also extremely stable with a peak-to-peak variation of only 1.8%. The emission current could be further enhanced to meet requirements for electron lens applications by increasing the number of MCP channels. A calculation for maximum possible current density with a 1200 channel/cm2 MCP, placed over a cathode with 1200 uniformly functioning CNTs, would be 1̃.46 kA/cm2, neglecting space charge limitations. Clearly this level of emission is far greater than what is needed for the electron lens application, but it does offer a highly comforting margin to account for sub-standard emitters and/or to allow the lesser challenge of building a cathode with fewer channels/cm2. A satisfactory goal for the electron lens application would be a controllable emission of 2-4 mA per channel in an ensemble of 800-1200 uniformly-functioning channels/cm2, and a cathode with overall area of about 1 cm2.
Author: Kevin L. Jensen
Publisher: John Wiley & Sons
ISBN: 1119051894
Category : Science
Languages : en
Pages : 714
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Book Description
A practical, in-depth description of the physics behind electron emission physics and its usage in science and technology Electron emission is both a fundamental phenomenon and an enabling component that lies at the very heart of modern science and technology. Written by a recognized authority in the field, with expertise in both electron emission physics and electron beam physics, An Introduction to Electron Emission provides an in-depth look at the physics behind thermal, field, photo, and secondary electron emission mechanisms, how that physics affects the beams that result through space charge and emittance growth, and explores the physics behind their utilization in an array of applications. The book addresses mathematical and numerical methods underlying electron emission, describing where the equations originated, how they are related, and how they may be correctly used to model actual sources for devices using electron beams. Writing for the beam physics and solid state communities, the author explores applications of electron emission methodology to solid state, statistical, and quantum mechanical ideas and concepts related to simulations of electron beams to condensed matter, solid state and fabrication communities. Provides an extensive description of the physics behind four electron emission mechanisms—field, photo, and secondary, and how that physics relates to factors such as space charge and emittance that affect electron beams. Introduces readers to mathematical and numerical methods, their origins, and how they may be correctly used to model actual sources for devices using electron beams Demonstrates applications of electron methodology as well as quantum mechanical concepts related to simulations of electron beams to solid state design and manufacture Designed to function as both a graduate-level text and a reference for research professionals Introduction to the Physics of Electron Emission is a valuable learning tool for postgraduates studying quantum mechanics, statistical mechanics, solid state physics, electron transport, and beam physics. It is also an indispensable resource for academic researchers and professionals who use electron sources, model electron emission, develop cathode technologies, or utilize electron beams.
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Category :
Languages : en
Pages : 203
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Book Description
Many cathode applications require a new type of cathode that is able to produce short pulsed electron beams at high emission current. Gated field emitter arrays of micrometer size are recognized as candidates to meet this need and have become the research focus of vacuum microelectronics. Existing fabrication methods produce emitters that are limited either in frequency response or in current emission. One reason is that the structure of these emitters are not sufficiently optimized. In this study, the author investigated the factors that affect the performance of field emitters. An optimum emitter structure, the knife-edge field emitter array, was developed from the analysis. Large field enhancement factor, large effective emission area, and small emitter capacitance are the advantages of the structure. The author next explored various options of fabricating the knife-edge emitter structure. He proposed a unique thin film process procedure and developed the fabrication techniques to build the emitters on (110) silicon wafers. Data from the initial cathode tests showed very low onset voltages and Fowler-Nordheim type emission. Emission simulation based on the fabricated emitter structure indicated that the knife-edge emitter arrays have the potential to produce high performance in modulation frequency and current emission. Several fabrication issues that await further development are discussed and possible solutions are suggested.
Author: Peter W. Hawkes
Publisher: Academic Press
ISBN: 0128134054
Category : Science
Languages : en
Pages : 767
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Book Description
Principles of Electron Optics: Applied Geometrical Optics, Second Edition gives detailed information about the many optical elements that use the theory presented in Volume 1: electrostatic and magnetic lenses, quadrupoles, cathode-lens-based instruments including the new ultrafast microscopes, low-energy-electron microscopes and photoemission electron microscopes and the mirrors found in their systems, Wien filters and deflectors. The chapter on aberration correction is largely new. The long section on electron guns describes recent theories and covers multi-column systems and carbon nanotube emitters. Monochromators are included in the section on curved-axis systems. The lists of references include many articles that will enable the reader to go deeper into the subjects discussed in the text. The book is intended for postgraduate students and teachers in physics and electron optics, as well as researchers and scientists in academia and industry working in the field of electron optics, electron and ion microscopy and nanolithography. - Offers a fully revised and expanded new edition based on the latest research developments in electron optics - Written by the top experts in the field - Covers every significant advance in electron optics since the subject originated - Contains exceptionally complete and carefully selected references and notes - Serves both as a reference and text
Author: Defense Documentation Center (U.S.)
Publisher:
ISBN:
Category : Technology
Languages : en
Pages : 464
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Book Description
Author:
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ISBN:
Category :
Languages : en
Pages : 38
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Book Description
Implementation of "cold cathodes" as an electron source for RF vacuum devices can have a significant impact on many aspects of device operation. Cold Cathode Impact on RF Device Operation: No cathode wearout mechanism * Room temperature operation * Eliminate heater power * High current density operation * Instant turn-on * Eliminate HV modulator * Multi-mode operation * Infinite ON/OFF isolation * Device miniaturization * Increased interaction efficiency * Improved linearity * Decreased harmonic power.
Author: Wei Zhu
Publisher: John Wiley & Sons
ISBN: 0471464090
Category : Technology & Engineering
Languages : en
Pages : 412
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Book Description
Expert coverage of vacuum microelectronics-principles, devices, and applications The field of vacuum microelectronics has advanced so swiftly that commercial devices are being fabricated, and applications are being developed in displays, wireless communications, spacecraft, and electronics for use in harsh environments. It is a rapidly evolving, interdisciplinary field encompassing electrical engineering, materials science, vacuum engineering, and applied physics. This book surveys the fundamentals, technology, and device applications of this nascent field. Editor Wei Zhu brings together some of the world's foremost experts to provide comprehensive and in-depth coverage of the entire spectrum of vacuum microelectronics. Topics include: * Field emission theory * Metal and silicon field emitter arrays * Novel cold cathode materials * Field emission flat panel displays * Cold cathode microwave devices Vacuum Microelectronics is intended for practitioners in the display, microwave, telecommunications, and microelectronics industries and in government and university research laboratories, as well as for graduate students majoring in electrical engineering, materials science, and physics. It provides cutting-edge, expert coverage of the subject and serves as both an introductory text and a professional reference.
Author: Kartik N. Shinde
Publisher: Springer Science & Business Media
ISBN: 3642343120
Category : Technology & Engineering
Languages : en
Pages : 275
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Book Description
The idea for this book arose out of the realization that, although excellent surveys and a phosphor handbook are available, there is no single source covering the area of phosphate based phosphors especially for lamp industry. Moreover, as this field gets only limited attention in most general books on luminescence, there is a clear need for a book in which attention is specifically directed toward this rapidly growing field of solid state lighting and its many applications. This book is aimed at providing a sound introduction to the synthesis and optical characterization of phosphate phosphor for undergraduate and graduate students as well as teachers and researchers. The book provides guidance through the multidisciplinary field of solid state lighting specially phosphate phosphors for beginners, scientists and engineers from universities, research organizations, and especially industry. In order to make it useful for a wide audience, both fundamentals and applications are discussed, together.
Author: Georg Gaertner
Publisher: Springer Nature
ISBN: 3030472914
Category : Technology & Engineering
Languages : en
Pages : 609
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Book Description
This book gives an overview of modern cathodes and electron emitters for vacuum tubes and vacuum electron devices in general. It covers the latest developments in field emission theory as well as new methods towards improving thermionic and cold cathodes. It addresses thermionic cathodes, such as oxide cathodes, impregnated and scandate cathodes, as well as photocathodes and field emitters – the latter comprising carbon nanotubes, graphene and Spindt-type emitter arrays. Despite the rise and fall of the once dominant types of vacuum tubes, such as radio valves and cathode ray tubes, cathodes are continually being improved upon as new applications with increased demands arise, for example in electron beam lithography, high-power and high-frequency microwave tubes, terahertz imaging and electron sources for accelerators. Written by 17 experts in the field, the book presents the latest developments in cathodes needed for these applications, discussing the state of the art and addressing future trends.
Author: Paolo Russo
Publisher: CRC Press
ISBN: 1498741541
Category : Medical
Languages : en
Pages : 1477
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Book Description
Containing chapter contributions from over 130 experts, this unique publication is the first handbook dedicated to the physics and technology of X-ray imaging, offering extensive coverage of the field. This highly comprehensive work is edited by one of the world’s leading experts in X-ray imaging physics and technology and has been created with guidance from a Scientific Board containing respected and renowned scientists from around the world. The book's scope includes 2D and 3D X-ray imaging techniques from soft-X-ray to megavoltage energies, including computed tomography, fluoroscopy, dental imaging and small animal imaging, with several chapters dedicated to breast imaging techniques. 2D and 3D industrial imaging is incorporated, including imaging of artworks. Specific attention is dedicated to techniques of phase contrast X-ray imaging. The approach undertaken is one that illustrates the theory as well as the techniques and the devices routinely used in the various fields. Computational aspects are fully covered, including 3D reconstruction algorithms, hard/software phantoms, and computer-aided diagnosis. Theories of image quality are fully illustrated. Historical, radioprotection, radiation dosimetry, quality assurance and educational aspects are also covered. This handbook will be suitable for a very broad audience, including graduate students in medical physics and biomedical engineering; medical physics residents; radiographers; physicists and engineers in the field of imaging and non-destructive industrial testing using X-rays; and scientists interested in understanding and using X-ray imaging techniques. The handbook's editor, Dr. Paolo Russo, has over 30 years’ experience in the academic teaching of medical physics and X-ray imaging research. He has authored several book chapters in the field of X-ray imaging, is Editor-in-Chief of an international scientific journal in medical physics, and has responsibilities in the publication committees of international scientific organizations in medical physics. Features: Comprehensive coverage of the use of X-rays both in medical radiology and industrial testing The first handbook published to be dedicated to the physics and technology of X-rays Handbook edited by world authority, with contributions from experts in each field
