Abstract-Study on Operation of Oversized Backward Wave Oscillator for Broadband Terahertz Radiation

Min Thu San,  Kazuo Ogura,  Kazuki Kubota,  Yuta Annaka,   Kiyoyuki Yambe,  Akira Sugawara,

https://ieeexplore.ieee.org/document/8280548/

We studied the operation of an oversized backward wave oscillator driven by an electron beam with energy less than 100 keV for terahertz radiation. Cylindrical slow wave structures (SWSs) with rectangular corrugations and annular electron beam are used to generate broadband terahertz radiation. The starting conditions for intense terahertz radiation are examined by varying the beam parameter and the SWS length. Operation frequencies in the range of 0.26-0.34 THz and 0.31-0.39 THz are obtained using two types of SWSs with different corrugation amplitudes. The obtained maximum output power is at the kilowatt level. Characteristics of the beam instabilities in the terahertz-SWSs are examined by comparison between the experimental and numerical results.

Abstract-Experimental study of intense radiation in terahertz region based on cylindrical surface wave resonator

Shaoyan Gong¹, Kazuo Ogura¹, Kiyoyuki Yambe¹, Shintaro Nomizu¹, Akihiro Shirai¹, Kosuke Yamazaki¹, Jun Kawamura¹, Takuro Miura¹, Sho Takanashi¹ and Min Thu San¹
 HIDE AFFILIATIONS
1 Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan

http://scitation.aip.org/content/aip/journal/jap/118/12/10.1063/1.4931371

Periodical corrugations structured on a cylindrical conductor have cylindrical surface waves(CSWs), which are reflected at the corrugation ends and form a CSW-resonator. In this paper, intense radiations in terahertz region based on the CSW-resonator are reported. The CSW-resonators with upper cut off frequencies in the modern IEEE G-band (110–300 GHz) are excited by a coaxially injected annular beam in a weakly relativistic region less than 100 kV. It is shown that there exists an oscillation starting energy for the CSW-resonator. Above the starting energy, very intense terahertz radiations on the order of kW are obtained. The operation frequencies in the range of 166–173 GHz and 182–200 GHz are obtained using two types of CSW-resonator with the different corrugation amplitude. Electromagnetic properties of the CSW-resonator can be controlled by the artificial structure and may play an important role in high-intensity terahertz generations and applications.