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New results in the field of high‐frequency gyrotrons, gyro‐multipliers and orotrons allow one to consider these electron devices as promising candidates for the realization of powerful and available sources in Terahertz range. Electron beams with a very high compression of up to a factor of 4,400 have been obtained and selective generation at the 1st–5th cyclotron harmonics have been demonstrated in Large Orbit Gyrotrons (LOGs) at millimeter and submillimeter wavelengths at operating voltages from 50 to 250 kV. When operating at the third cyclotron harmonic (TE3,8 and TE3,9 modes in the first oscillator; TE3,5 mode in the second oscillator) output power levels of 10–20 kW have been obtained in the frequency range of 0.37–0.41 THz. Gyro‐multipliers with self‐exciting low‐frequency sections are proposed and studied theoretically. Low‐voltage orotrons have been demonstrated in the frequency range of 0.1–0.4 THz with output powers of 1.0–0.1 W and typical electrical‐mechanical frequency tunability within an octave range. Using the same voltage, orotrons can achieve higher power and frequency stability within the entire Terahertz range compared with BWOs that are the most widespread devices at these frequencies.

Theory and experiments are reported of the use of a waveguide with a special helical corrugation of its inner surface to provide pulse compression of frequency modulated pulses. Such waveguide has some important advantages over a conventional smooth waveguide as a dispersive delay line for compression of frequency modulated microwave pulses. A compressor using a helically corrugated waveguide can provide generation of nanosecond multi‐gigawatt microwave pulses. Results are presented of experiments at kilowatt power levels that are in good agreement with the theory. The principle exploited in this type of pulse compression is well known and used widely in radar applications. It is based on the propagation of a quasi‐monochromatic wave packet which has a slow (on a period scale) frequency modulation through a dispersive medium, for which the wave group velocity is a function of frequency. For the novel microwave pulse compressor the wave dispersion was synthesized by coupling a TE2,1 mode and a counter‐rota...

A conceptual design is presented for a W-band RF source that should be suitable for testing advanced accelerator structures and related components. The source is an 8 th -gyroharmonic converter, in which 28 MW of Xband power at 11.424 GHz is used to energize and spin up an injected 500 kV, 40 beam in a TE111 cavity; and in which over 10 MW of W-band power at 91.392 GHz is extracted from the beam in a TE811 output cavity. A mode converter is employed to provide a Gaussian output beam.