Ch.-Z. Nguyen1, D.G. Kovtun2

1,2 Volgograd State Technical University (Volgograd, Russia)

O-type traveling wave tube amplifiers are widely used in engineering and science, but multifrequency mode has been little studied, especially for electromagnetic waves in terahertz frequency range. This paper presents esults of processes’s numerical simulation in an O-type traveling-wave tube in the terahertz range in the multifrequency mode based on time domain finite difference method for Maxwell's equations and particle-in-cell method. Analysis of data obtained during the simulation makes it possible to clearly demonstrate the nonlinear interaction of two waves with an electron beam and obtain output power distribution depending on input power.

The cold electrodynamic parameters of the slow-wave system and its optimal geometric dimensions, providing a wide bandwidth and acceptable coupling resistance, are taken from. The absorber used has electrical conductivity σ = 50 Ω−1m−1, which corresponds to the properties of graphite, and its geometry is optimized for amplification of 184 GHz wave.

The introduction of two signals into TWT leads to appearance of interaction already in the initial sections of interaction space. The phenomena are associated with the redistribution of energy between certain components of frequency spectrum, which occurs due to a change in the amplification process of phase relationships between signals, as a result of which individual components’s amplification of the spectrum is accompanied by a weakening of oscillations at adjacent frequencies.

The obtained results show that: a) the output power in double-frequency mode is less than, corresponding to the same distribution of input powers, the sum of two output powers in single-frequency. This can be explained by the fact that some of electrons can simultaneously be in the decelerating phase of one and the accelerating phase of the other wave, b) output wave powers. There is a condition for obtaining the same output powers of two waves: the input power of 184 GHz wave = 0.3 the input power of 180 GHz wave.

Nguyen Ch.-Z., Kovtun D.G. O-type traveling-wave tube double-frequency mode simulation. Electromagnetic waves and electronic systems. 2023. V. 28. № 1. P. 12−20. DOI: https://doi.org/10.18127/j15604128-202301-02 (in Russian)

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