The interaction of transverse electron beam waves with external electromagnetic fields, and the application of this interaction in microwave devices are discussed. In particular, problems involving various aspects of the so-called DCpumped electron beam amplifiers were analysed. Interaction problems in the pump field wereANALYSED BOTH THEORETICALLY AND EXPERIMENTALLY. Considerable attention was devoted to problems of noise theory, a d an expression for the minimum noi e temperature of DC-pumped amplifiers was derived. Research on the problem of designing suitable periodic structures for the input- and output-couplers of transverse field devices was performed. The theory of a harmonic generator based on cyclotron waves was presented. Three tubes were designed and tested. Two of them were cyclotron-wave amplifiers, and the third a synchronous-wave amplifier. They all worked in satisfactory agreement with theory. (Author).

Experimental evidence was accumulated regarding amplification at 600 MHz by means of a thin electron beam and two Cuccia couplers (no pump structures). Gains up to 30 db were readily reproducible, but the RF ower output was less than one milliwatt at a few per cent efficiency. Tuning by the dc magnetic field and by the beam voltage was demonstrated. The process seems to depend upon dc modes excited in the beam by its irregular injection into the magnetic field. Experiments with an oscillator based upon a hollow beam and a single Cuccia coupler are also included. (Author).

Microwave interactions resulting in oscillation and amplification have been observed in cases involving a beam of rotating electrons in a wave guide. The interaction is a cyclotron resonance phenomenon which occurs when the rotating electrons are synchronized with the wave guide fields. Application of a general coupled-mode theory to specific rotating beam configurations is made. The dispersion properties of the normal beam modes and normal circuit modes are considered to find possible cases of synchronism which may result in favorable interactions. The coupled-mode equations are solved for important cases with the help of simplifying approximations to find the propagation constants of the waves which can exist in the system. Application of boundary conditions at the input to the interaction circuit completes the interaction description. An expression for gain for the wave guide circuit mode is defined. These calculations show that both backward-wave oscillation and traveling-wave amplification are possible in this type of device, but that the backward-wave interaction dominates. An experimental device has been built with a rotating electron beam in a rectangular X-band wave guide circuit. Experimental investigations reveal that the device is characterized by a backward-wave oscillation interaction. The observed interaction is found to be consistent with the results of the coupled-mode analysis, and the coupled-mode analysis appears to give an accurate description of the interaction mechanism. Oscillator pulsed power of 720 watts with an efficiency of about 10 percent and frequency tuning with magnetic field between 6.55 and 22.0 kmc has been observed. (Author).

Nonlinear Electron-Wave Interaction Phenomena explores the interaction between drifting streams of charged particles and propagating electromagnetic waves. Of particular concern are the situations in which the wave amplitude is large and there is strong coupling between the charged fluid and the wave. Emphasis is placed on those devices that utilize a defined injected stream of some type. Particle and electromagnetic wave velocities both small and comparable to the velocity of light are considered. Comprised of 16 chapters, this book begins with an introduction to the various classes of devices in which the drifting stream (charged fluid) is composed of electrons and/or ions coupled to a slow electromagnetic wave over an extended region. The discussion then turns to Eulerian versus Lagrangian formulation and radio-frequency equivalent circuits, along with space-charge-field expressions. Subsequent chapters focus on the interaction mechanisms in klystrons, traveling-wave amplifiers, and O-type backward-wave oscillators, as well as crossed-field forward- and backward-wave amplifiers, and traveling-wave energy converters. The book also evaluates multibeam and beam-plasma interactions; phase focusing of electron bunches; pre-bunched electron beams; collector depression techniques; and modulation characteristics. This monograph is designed to serve both as a research monograph for workers in the fields of microwave electron and plasma devices and as a text for advanced graduate students.

Experiments with a rotating electron beam waveguide device have been performed. The device used in this investigation has been found to exhibit a strong transverse wave interaction. The interaction takes place at a frequency which is close to the cyclotron frequency of the electron beam. Frequency measurements indicate that the interaction frequency is slightly less than the cyclotron frequency and that the interaction frequency varies inversely with beam voltage. Both gain and oscillation have been observed. The interaction appears to be of a backwardwave nature. The transverse-wave interaction theory indicates that backward-wave but not forward-wave active coupling may occur. The observed values of gain are less than the calculated values but are within an order of magnitude. The interaction is found to be strong at the cutoff frequencies. This is in agreement with the transverse-wave theory. The interaction appears to be greatly influenced by the reflections in the waveguide circuit. The results of this investigation indicate that strong transverse interactions can occur in fast-wave circuits. Succeeding experimental work will require a circuit which has better transmission over a broad frequency range. This could be easily accomplished with a broadband vacuum window. An improved beam launching system is still needed if beam parameter effects are to be more carefully observed. (Author).

The main theme of this book is the interaction of electrons with electromagnetic waves in the presence of periodic and quasi-periodic structures in vacuum, in view of applications in the design and operation of particle accelerators. The first part of the book is concerned with the textbook-like presentation of the basic material, in particular reviewing elementary electromagnetic phenomena and electron dynamics. The second part of the book describes the current models for beam-wave interactions with periodic and quasi-periodic structures. This is the basis for introducing, in the last part of the book, a number of particle and radiation sources that rest on these principles, in particular the free-electron laser, wake-field acceleration schemes and a number of other advanced particle accelerator concepts. This second edition brings this fundamental text up-to-date in view of the enormous advances that have been made over the last decade since the first edition was published. All chapters, as well as the bibliography, have been significantly revised and extended, and the number of end-of-chapter exercises has been further increased to enhance this book’s usefulness for teaching specialized graduate courses.