[en] The current interest in the frequency stabilization of uhf oscillators is directed toward the implementation of gyrotrons in active plasma diagnostics. Toward this end this paper demonstrates a method which permits consideration in general form of the effect of electron frequency shift on the frequency stability of uhf oscillators using an auxiliary high-Q resonator. The method is used to determine the parameters of a gyrotron model optimized from the viewpoint of frequency stabilization

[en] The parasitic radiation of gyrotrons at harmonics of the operating mode frequency is investigated theoretically. It is shown that, to evaluate the power level of parasitic generation, it is possible to use the theory of gyrotrons with a fixed longitudinal structure of the operating mode field, andthe corresponding nomograms are given. The spectral characteristics of a gyrotron in the mode of generation of self-modulation and stochastic oscillation are analyzed. The evolution of the radiation spectrum of the operating mode is examined in proportion to emergence to the mode of self-oscillation with constant amplitude

[en] The procedure for the calculation of the starting current in a gyrotron with a weakly inhomogeneous external magnetic field is described in detail. The results obtained are valid for gyrotrons operating at an arbitrary cyclotron harmonic and for arbitrary functions describing the axial structure of the RF resonator field and the axial distribution of the inhomogeneity of the external magnetic field. Examples are given for a gyrotron with parameters close to those of the Kernforschungszentrum Karlsruhe (KfK) experiments. (author)

[en] Consideration is given to possibility of using gyrotron as a generator of probing radiation in measurement circuit of plasma ion temperature in toroidal systems of electromagnetic wave scattering. The shape of gyrotron radiation line was measured in frequency range, corresponding to scattered signal

[en] Relativistic gyrotwistrons, which can, in principle, achieve efficiencies in excess of 50%, are promising sources for driving particle accelerators. The optimum operating point for these devices represents a tradeoff between maximizing the available energy and minimizing the deleterious effects of velocity spread. The former increases with Doppler upshift and pitch ratio, while the effects of velocity spread are made worse by both of these quantities. The authors discuss the issues that go into deciding how to achieve maximum efficiency, with particular attention paid to the role of beam current

[en] For various applications the required parameters of sources of powerful microwave radiation lie far beyond the capabilities of existing tubes. This provokes an interest in reconsidering basic principles of relevant microwave sources in order to search for alternative concepts in their development. One of the most promising devices in the short-wavelength region of microwaves is the cyclotron resonance maser (CRM). During the last decade, two important varieties of CRMs have been distinguished, namely, gyrotrons, which operate at frequencies close to cut-off, and cyclotron autoresonance masers (CARMs), which operate at frequencies far from cut-off. When the axial phase velocity of the wave in properly adjusted to the beam voltage and electron pitch-ratio, the efficiency of relativistic CRMs may be high (≥50%). The method of optimizing efficiency based on a partial compensation of the shift in the relativistic electron cyclotron frequency by the change in the Doppler term can be, in principle, accompanied by a corresponding profiling of the external magnetic field and/or the wave phase velocity in a slightly irregular waveguide. These methods can be used in such relativistic CRMs as relativistic gyrotrons, gyroklystrons, gyro-traveling-wave-tubes and gyrotwistrons. The most important point is their sensitivity to a spread in electron parameters. As the beam voltage grows, the operation becomes more sensitive. However, at relatively low voltages such devices are quite tolerant to electron velocity spread

[en] The main theoretical and experimental aspects of electron-cyclotron resonant heating (ECRH) in toroidal systems are presented. Particular stress is put on the ways of injecting microwave power into plasma. The most interesting experimental results on ECRH in toroidal plasmas are considered. In conclusion some prospects are discussed on feasibility of ECRH in large tokamaks of future generations. (author)

No abstract available

[en] The stability of gyrotwistrons against the excitation of parasitic modes is studied. A method is described which can be used to compute the nonlinear saturation amplitude of the parasites when the operating mode is present. An example relevant to driving particle accelerators (near 10 GHz and 500 kV) is discussed

[en] Many types of microwave amplifiers are being considered at various institutions as candidate sources for driving future linear colliders. The choice of operating frequency ranges from 2.85 GHz to 35 GHz. Peak microwave output power and pulse duration also vary widely. Here the authors propose three criteria for evaluating and comparing amplifier options. These are as follows: (1) N_t, the number of amplifiers required to drive an accelerator with a given final energy and a given accelerating gradient; (2) V, the voltage required to operate the microwave amplifier; and (3) η_T, the overall efficiency including the output efficiency of the amplifier, the efficiency of the pulse compression circuit if any is used, and the high voltage modulator pulse-shape efficiency. All of these criteria will affect the cost of a linear collider system. The cost of the microwave amplifiers will, of course, equal the cost of each amplifier (with its associated power supplies, magnets, and pulse compression circuit) multiplied by the number of amplifiers, N_t. The cost of each amplifier and its power supply/modulator will increase with the voltage, V. In fact, the authors have chosen to restrict their consideration of specific amplifiers to those in which V < 1 MV; at voltages above 1 MV very large insulators and more exotic pulsed power supplies such as induction linacs would be required and these might be excessively costly. Overall efficiency will, of course, influence average power consumption as well as the size and cost of power supplies