Development of the Multifrequency Gyrotron FU CW GV with Gaussian Beam Output

Abstract

Gyrotron FU CW GV has been developed as a multifrequency gyrotron for operation over the frequency range from 162 to 265 GHz at frequencies separated by steps of approximately 10 GHz. The oscillation modes were selected; the radii of the caustic surfaces for the electromagnetic waves of the modes had similar values in the waveguide, and it was therefore expected that these modes would be converted into Gaussian beams by a mode converter. In reality, more than ten modes oscillated and the Gaussian-like beams were radiated. A double-disk window with variable spacing maintains the transmittance through the window at a high level over a wide range of frequencies. Using this window, output powers of more than 1 kW were observed for almost all the expected modes.

Recent progress in development and application of sub-THz gyrotrons in University of Fukui

“…About Gaussian beam output gyrotrons in FIR-UF, the Gyrotron FU CW I is the first, which was fabricated in Russia [10]. Gaussian beam output gyrotrons developed in FIR-UF are called as Gyrotron FU CW G series [14][15][16][17][18][19]. Gyrotron FU CW GI oscillates in 203 GHz frequency [14] and was used for direct measurement of the energy level of positoronium hyperfine structure [7].…”

“…Gyrotron FU CW GV is a multi-frequency gyrotron [18]. It is of sealed-off type and was constructed by New Japan Radio Company.…”

“…Since 2006, gyrotrons have been developed in FIR-UF for the purpose of applications such as DNP-NMR spectroscopy [5,6], sintering and direct measurement of energy level of positronium hyperfine structure [7]. Gyrotrons developed for this purpose are Gyrotron FU CW series [8][9][10][11][12][13], Gyrotron FU CW G series [14][15][16][17][18][19] and pulsed gyrotrons [20][21][22][23][24][25][26][27][28].…”

Clinical Course of High-Frequency Millimeter-Wave (162 GHz) Induced Ocular Injuries and Investigation of Damage Thresholds

“…Figure 1 shows a block diagram of the exposure system used in this study. A 162-GHz MMW energy source in continuous wave mode was generated by the gyrotron FU CW GV constructed in University of Fukui [11]. A lens antenna (diameter 100 mm) with a 200-mm focal point and 6.5-mm FWHM (full width at half its maximum intensity) beam width was used to deliver MMW to rabbit cornea.…”

Force detection of high-frequency electron spin resonance near room temperature using high-power millimeter-wave source gyrotron

“…The combination with a multifrequency gyrotron, which can generate multiple frequencies by selectively exciting the higher-order cyclotron modes inside the cavity, is a promising method to broaden the frequency range. 25 Force detection can also be combined with other high-power electromagnetic wave sources, such as free electron lasers. 26,27 This study was partially supported by the Murata Science Foundation.…”