Experiment for Evaluating a K-Band Space TWT Electron Beam
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The electron beam of a K-band space traveling-wave tube (TWT) has been investigated in a beam measurement system in this article. The primary beam emitted from a Pierce-type electron gun is scanned by a Faraday cup probe, and the beam current density distribution and envelope are determined. The spent beam is also diagnosed with a novel retarding field energy analyzer (RFEA) by using the monopulse measurement method, and a comparison of velocity distribution between the experimental result and simulation is presented.Keywords:
Traveling-wave tube
Faraday cup
Electron gun
Envelope (radar)
Vacuum tube
M squared
Klystron
M squared
Beam parameter product
Beam divergence
Gaussian beam
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Based on the second-order moment theory of beam propagation，the properties of Lorentz beam have been investigated. The expressions of the beam waists，the transverse divergence angle and the beam propagation factor have been presented. The transverse beam waist only depends on the corresponding beam parameter. However，the transverse divergence angle and the beam propagation factor are both determined by the two transverse beam parameters. The curves of the beam propagation factor versus the two transverse beam parameters are also given. The numerical results show that variational laws of the beam propagation factor in the x-and y-directions versus the two transverse beam parameters are apparently different，while the variational rule of the integrated beam propagation factor versus the two transverse beam parameters is the composite manifestation of the above cases. In the paraxial case，the beam propagation factor trends to a constant value of 141. With the beam waist being the same，therefore，the divergence of Lorentz beam is 1.41 times that of the Gaussian beam in the paraxial case. Accordingly，Lorentz beam is an appropriate model to describe certain laser sources with high divergence.
M squared
Beam divergence
Beam parameter product
Rayleigh length
Gaussian beam
Divergence (linguistics)
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The scalar beam measurement concept presented in this article is based on scanning the receiver's beam with an isotropic radiating source at three to four parallel cross planes along the presumable optical axis. The receiver is operated in heterodyne mode and the output IF power is recorded for each coordinate point of the radiating source. The collected data provides information for the Gaussian beam profile at the particular distance from the receiver. According to the properties of the fundamental Gaussian beam, the maximum power value is located on the axis of the beam. Therefore, obtaini.ng the coordinates of the beam center (of the maximum intensity) for each measured beam profile allows for the determination of the beam axis orientation. The location of the beam waist and its size can be calculated by solving a system of equations derived from the Gaussian beam theory.
M squared
Gaussian beam
Beam parameter product
Beam divergence
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M squared
Gaussian beam
Beam parameter product
Formalism (music)
Beam divergence
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Abstract The traveling‐wave tube (TWT) is a vacuum device invented in the early 1940s [1,2] used for amplification at microwave frequencies. Amplification is attained by surrendering kinetic energy from an electron beam to a radiofrequency (RF) electromagnetic wave. The demand for vacuum devices has been decreasing largely owing to the advent of solid‐state devices. However, although solid state devices have replaced vacuum devices in many areas, there are still many applications such as radar, electronic countermeasures, and satellite communications that require operating characteristics such as high power (watts to megawatts), high frequency (below 1GHz to over 100 GHz), high efficiency (65% efficient, 100 Watt, Kaband TWTs are commonplace), and large bandwidth that only vacuum devices can provide. The term traveling‐wave tube includes both fast‐wave and slow‐wave devices. This article will concentrate on slow‐wave devices as the vast majority of TWTs in operation around the world fall into thiscategory.
Traveling-wave tube
Vacuum tube
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Microfabricated vacuum-tube THz sources are of great interest for numerous applications such as communications, radar, sensors, imaging, etc. Recently, miniaturized sheet-beam traveling-wave tubes for THz and sub-THz operation have attracted a considerable interest. In this paper, we present the results of modeling and development of medium power (10-100 W) G-band traveling-wave tube amplifiers with a sheet electron beam.
Traveling-wave tube
Vacuum tube
G band
Electron gun
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Demand for high data rate wireless communications is pushing up amplifier power, bandwidth and frequency requirements. Some systems are using vacuum electron devices again because solid-state power amplifiers are not able to efficiently meet the new requirements. The traveling wave tube is the VED of choice because of its excellent broadband capability as well as high power efficiency and frequency. However, TWTs are very expensive on a per watt basis below about 200 watts of output power. We propose a new traveling wave tube that utilizes cathode ray tube construction technology and electrostatic focusing. We believe the tube can be built in quantity for under $1,000 each. We discuss several traveling wave tube slow wave circuits that lend themselves to the new construction. We present modeling results and data on prototype devices.
Traveling-wave tube
Vacuum tube
Cathode ray tube
Current sense amplifier
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This article gives a brief overview of the common vacuum electronic tube amplifiers used in high-power transmitters. Only three types of devices [travelling wave tubes (TWTs) including helix and coupled-cavity types, microwave power modules (MPMs), and klystrons] are covered, with emphasis on the recent advance in the millimeter-wave band.
Klystron
Traveling-wave tube
Vacuum tube
Extremely high frequency
Emphasis (telecommunications)
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Microwave tubes are vacuum electron devices used for the generation and amplification of radio frequencies in the microwave range. An established technology area, the use of tubes remains essential in the field today for high-power applications. The culmination of the author's 50 years of industry experience, this authoritative resource offers you a thorough understanding of the operations and major classes of microwave tubes. Minimizing the use of advanced mathematics, the book places emphasis on clear qualitative explanations of phenomena. This practical reference serves as an excellent introduction for newcomers to the field and offers established tube engineers a comprehensive refresher. Professionals find coverage of all major tube classifications, including klystrons, traveling wave tubes (TWTs), magnetrons, cross field amplifiers, and gyrotrons.
Klystron
Traveling-wave tube
Vacuum tube
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Written by an internationally recognized as an expert on the subject of microwave (MW) tubes, this book presents and describes the many types of microwave tubes, and despite competition from solid-state devices (those using GaN, SiC, et cetera), which continue to be used widely and find new applications in defense, communications, medical, and industrial drying. Helix traveling wave tubes (TWTs), as well as coupled cavity TWTs are covered. Klystrons, and how they work, are described, along with the physics behind it and examples of devices and their uses. Vacuum electron devices are explained in detail and examines the harsh environment that must exist in tubes if they are to operate properly. The secondary emission process and its role in the operation of crossed-field devices is also discussed. The design of collectors for linear-beam tubes, including power dissipation and power recovery, are explored. Discussions of important noise sources and techniques that can be used to minimize their effects are also included. Presented in full color, this book contains a balance of practical and theoretical material so that those new to microwave tubes as well as experienced microwave tube technicians, engineers, and managers can benefit from its use.
Klystron
Traveling-wave tube
Vacuum tube
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