Effect of Reflection on Mode Competition and Multi-Frequency Oscillation in a High-Power Sub-THz Gyrotron: Experimental Observation and Theoretical Analysis

Equi-distantly distributed multi-peak frequency spectrum was observed in a high-power 300-GHz band gyrotron for the case of strong reflection off the vacuum window. An oscillation mode different from the design mode can oscillate by adjusting the magnetic field in the cavity. However, a large fracti...

Full description

Saved in:
Bibliographic Details
Published inJournal of infrared, millimeter and terahertz waves Vol. 41; no. 6; pp. 697 - 710
Main Authors Saito, Teruo, Melnikova, Maria M., Ryskin, Nikita M., Tanaka, Shunsuke, Shinbayashi, Ryuji, Yamaguchi, Yuusuke, Fukunari, Masafumi, Tatematsu, Yoshinori
Format Journal Article
LanguageEnglish
Published New York Springer US 01.06.2020
Springer Nature B.V
Subjects
Amplitudes
Classical Electrodynamics
Competition
Converters
Electrical Engineering
Electronics and Microelectronics
Electrons
Engineering
Frequency spectrum
Instrumentation
Peak frequency
Reflected waves
Reflection
Rotation
Reflection
Mode competition
Plasma diagnostics
Gyrotron
Multi-frequency oscillation
Collective Thomson scattering
Online AccessGet full text

Cover

More Information
Summary:Equi-distantly distributed multi-peak frequency spectrum was observed in a high-power 300-GHz band gyrotron for the case of strong reflection off the vacuum window. An oscillation mode different from the design mode can oscillate by adjusting the magnetic field in the cavity. However, a large fraction of the output wave is reflected by the vacuum window. The reflected wave returns to the cavity through an internal mode converter. The azimuthal rotating direction of the reflected wave is opposite to that of the oscillating mode. A theoretical calculation of mode competition between the oscillating co-rotating mode and the counter-rotating mode originating from the reflected wave very well reproduces the observed frequency spectrum. The multi-peak frequency spectrum stems from periodic amplitude oscillation caused by the mode competition between the co-rotating mode and the counter-rotating mode. The frequency interval between the peaks is not simply decided by the round-trip time between the cavity and the vacuum window but determined by the period of the amplitude oscillation.
ISSN:1866-6892
1866-6906
DOI:10.1007/s10762-020-00695-1