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Field Emission Electronics
This book is dedicated to field emission electronics, a promising field at the interface between “classic” vacuum electronics and nanotechnology. In addition to theoretical models, it includes detailed descriptions of experimental and research techniques and production technologies for different types of field emitters based on various construction principles. It particularly focuses on research into and production of field cathodes and electron guns using recently developed nanomaterials and carbon nanotubes. Further, it discusses the applications of field emission cathodes in new technologies such as light sources, flat screens, microwave and X-ray devices.
The Formation and Characteristics of a Broad-area Semiconductor Field Emission Cathode
The work is a study of the formation, operation and application of a semiconductor field emission cathode consisting of one or more individual emitting points on a broad area cathode. The material primarily used was germanium. Two methods of forming these cathodes were studied; a vacuum breakdown method and one using radiation from a pulsed ruby laser focused on the cathode surface. The former is the method by which the cathode was first revealed. The latter holds the most promise for making cathodes practical. Both types of cathodes were observed with a scanning electron microscope to aid in understanding the mechanism by which the very regular emitting points are formed. The electrical characteristics of the cathode were studied experimentally and found to agree with theory of semiconductor field emission. A retarding potential analyzer was designed and built to measure the energy distribution for electrons emitted from individual points on the cathode. An electron optical system was used to study the operation of the semiconductor cathode as an electron source for such applications as in a cathode ray tube or similar device requiring a low-current electron beam. (Author).
Field Emission in Vacuum Microelectronics
Field emission is a phenomenon described by quantum mechanics. Its emission capability is millions times higher than that of any other known types of electron emission. Nowadays this phenomenon is experiencing a new life due to wonderful applications in the atomic resolution microscopy, in electronic holography, and in the vacuum micro- and nanoelectronics in general. The main field emission properties, and some most remarkable experimental facts and applications, are described in this book.
Applied Research on Field Emission Cathodes
Effort was directed toward the study of field emission cathodes and their development to a practical electron source. Primary emphasis was on relatively gross structures for use at high power levels. Emission currents to 22 amperes at 390 kilovolts were obtained from single, needle-shaped, tungsten emitters and to 105 amperes at 203 kilovolts from an edge-shaped, tungsten structure. Point cathodes were shown to emit maximum currents in agreement with theoretical prediction based on energy exchange at the cathode and on cathode dimensions. Electrolytic and chemical techniques were developed for fabrication of edge cathodes which were free of cold work and had terminal radii of the order of 0.00001 cm. Electron optical systems appropriate for use with field emitted beams were studied; and basic knowledge of the behavior of adsorbates which improve beam utility by selective emission enhancement in the forward direction was extended. (Author).
Advancing Field Emission Technology for High Power Injectors Operating in Ghz and Beyond
As the next generation of electron injectors pushes to achieve higher gradient fields than ever before (>300 MV/m), they are driven to operate at higher frequencies (C-band through W-band). This shrinks the fabrication dimensions of these cavities, making field emission cathodes (FECs) an electron source of choice. Photoemission and thermionic sources are increasingly less suited as the complex laser transport schemes and heating source powering these injectors cannot provide the necessary beam quality and may cause damage to the cathode or the injector itself. Carbon-based FECs have dominated the field emission sources R&D portfolio at DOD and DOE for the past 30 years across various high-p...
A Novel Emission Electron Microscope for the Study of Field Emission Cathodes and Their Emittance
Vacuum electronic devices (VEDs) serve an important role as high-power and/or high-frequency sources of RF radiation. To access higher power and higher frequency regimes, VEDs will require greater current densities and lower emittance electron beams. Field emission cathodes show tremendous promise in satisfying these needs, but much remains to be learned about how the cathode structure affects the emittance of the resulting beam. Some theoretical work has been published, but no experimental data has been produced to guide and validate these theoretical developments. In this dissertation, I motivate the need for a better understanding of these cathodes for application in VEDs. I show why emit...
