Abstract-An Experimental Investigation of a 0.8 THz Double-Beam Gyrotron

Seitaro Mitsudo, Mikhail Glyavin, Eduard Khutoryan, Ilya Bandurkin, Teruo Saito. Yuya Ishikawa, Vladimir ManuilovIrina,  Zotova Alexey Fedotov.  Alexei  Kuleshov.  Svilen Sabchevski, Yoshinori Tatematsu, Vladislav Zaslavsky, Toshitaka Idehara,

https://link.springer.com/article/10.1007%2Fs10762-019-00629-6

In this paper, we present and discuss the new experimental results that characterize the output parameters, and the overall performance of the recently developed 0.8 THz double-beam gyrotron operating at the second harmonic of the cyclotron frequency on the TE8,5 mode. Alongside with this design mode, several other resonances excited at both the fundamental and second harmonic operations in a wide frequency range have been studied. These experiments demonstrate that the usage of a double-beam electron-optical system opens more possibilities for realization of such regimes of operation that otherwise are not accessible in a conventional (single-beam) gyrotron due to a severe competition between the neighboring modes and the narrowness of the zones of a stable single mode operation. Most notably, the results prove that second harmonic operation at higher beam currents and respectively at higher levels of the output power are possible as expected from the preceding theoretical considerations and numerical studies. The results of this study are helpful for getting a better insight in the physics of the operation of the double-beam gyrotrons and suggest some possibilities for further optimization of both the design of the tube and the experimental setup.

Abstract-Rattling of Oxygen Ions in a Sub-Nanometer Sized Cage Convert Terahertz Radiation to Visible Light.

Yoshitake Toda, Shintaro Ishiyama, Eduard Khutoryan, Toshitaka Idehara, Satoru Matsuishi, Peter V Sushko, and Hideo Hosono

http://pubs.acs.org/doi/abs/10.1021/acsnano.7b06277

A simple and robust approach to visualization of continuous wave terahertz (CW-THz) light would open up opportunities to couple physical phenomena that occur at fundamentally different energy scales. Here we demonstrate how nanoscale cages of Ca12Al14O33 crystal enable conversion CW-THz radiation to visible light. These crystallographic cages are partially occupied with weakly bonded oxygen ions and give rise to a narrow conduction band that can be populated with localized, yet mobile electrons. CW-THz light excites a nearly stand-alone rattling motion of the encaged oxygen species, which promotes electron transfer from them to the neighboring vacant cages. When the power of CW-THz light reaches tens of watts, the coupling between forced rattling in the confined space, electronic excitation and ionization of oxygen species and corresponding recombination processes results in emission of bright visible light.