Open AccessQUASI-HARMONIC OSCILLATIONS IN A NONLINEAR TRANSMISSION LINE, RESULTING FROM CHERENKOV SYNCHRONISM
Author(s) -
S. Yu. Karelin,
V. B. Krasovitsky,
I. I. Magda,
V. S. Mukhin,
V. G. Sinitsin
Publication year - 2019
Publication title -
problems of atomic science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.216
H-Index - 17
eISSN - 1562-6016
pISSN - 1682-9344
DOI - 10.46813/2019-122-065
Subject(s) - synchronism , physics , amplitude , transmission line , optics , dielectric , cherenkov radiation , computational physics , voltage , electrical engineering , optoelectronics , quantum mechanics , engineering , detector
Experimental data and results of numerical modeling are presented, concerning excitation of microwave oscillations by a wave of pulsed ‘dc’ current (eventually, a shock wave) traveling through a radially non-uniform coaxial guiding structure. Similar experiments with ‘standard’ structures that involve a nonlinear dielectric insert (ferrite) in the coax and another dielectric, characterized by a smaller dielectric constant, result in appearance of a short radiofrequency pulse, in the form of decaying sinusoidal voltage at the line’s output. The decay is shown to be associated with a lack of velocity synchronism between the principal ‘quasi-TEM’ wave mode in the system and the slow Emode excited by the electromagnetic shock. Numerical experiments within 3-D models have demonstrated possibilities for obtaining radio pulses of various lengths, involving oscillations of a stable frequency and nearly constant amplitude – provided that Cherenkov-type synchronism were satisfied, owing to slowing down of the faster ‘quasiTEM’ mode. To cut its speed down two methods can be suggested, (i) using a dielectric material with a high value of the dielectric permittivity, and (ii) introducing a periodic slow-wave structure whose period would be smaller than the wavelength of the oscillations considered.