Experimental study on performance change in F-band surface-wave oscillator due to slow-wave structure length. (1st September 2021)

• Record Type: Journal Article
• Authors: Aoki, M.; Annaka, Y.; Ogura, K.; Ito, M.
• Is Part Of: Japanese journal of applied physics. Volume 60:Number 9(2021)
• Publication Date: 2021-09-01
• Subjects: Surface-wave oscillator -- Terahertz-wave -- Slow-wave structure -- structure length -- absolute instability -- convective instability -- global instability; Physics -- Periodicals; 621.05
• DOI: 10.35848/1347-4065/ac1de9
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: A surface-wave oscillator (SWO) is a high-power terahertz-wave source based on a slow-wave structure (SWS). A cylindrical corrugated waveguide is used as the SWS. The length of SWS is an important factor in the oscillation. Experiments of the SWO with various length structures are conducted. An instability responsible for the SWO changes depending on the SWS length. For the 200-period SWS, the radiation is due to the absolute instability and depends on the beam current like the temporal growth rate. By contrast, for the 80-period SWS, the radiation is due to the global instability having the current dependence like the spatial growth rate. Compared to the 80-period SWS, the 200-period SWS can improve the radiation power more than seven times in the backward wave oscillation (BWO) region. The maximum BWO power reaches up to about 10 kW and the maximum electric efficiency of 1.5% is obtained.