H. Tsuchiya

The 1 THz gyrotron at Fukui University

For application of high frequency gyrotrons to high power THz technologies, we are developing THz CW gyrotron, FU CW Series. Gyrotron FU CW I with 12 T liquid He free superconducting magnert has already been developed applied for material processing, for example, ceramics sintering. The second gyrotron of the series, Gyrotron FU CW II with an 8 T superconducting magnet has been constructed and the operation test was successfully carried out. The gyrotron will used for enhancement of the sensitivity of 600 MHz proton-NMR by use of dynamic nuclear polarization (DNP). The designed operation mode of the gyrotron is TE2,6 at the second harmonic. The corresponding frequency is 394.6 GHz. The real operation frequency is 394.3 GHz at TE06 mode, because of fabrication error of the diameter of the cavity. The operation is in complete C W at the output power of around 30 W or higher at the TE06 cavity mode. There are many other operation modes at the fundamental and the second harmonic. Typical output power of the fundamental and the second harmonic are higher than 100 W and 20 W, respectively. The highest frequency observed up to the present is 443.5 GHz at the second harmonic operation of TE6,5 mode. The measured results are compared with the theoretical consideration. The third gyrotron, Gyrotron FU CW III with 20 T superconducting was just constructed and ther operation test will start soon. Maximum frequency of higher then 1 THz and output power of several hundred watt are expected.

Development of a THz gyrotron

A gyrotron with a 21 T pulse magnet achieved the breakthrough of 1 THz. This is the first result of high frequency operation in the world beyond 1 THz. In addition, new gyrotron series in FIR FU, University of Fukui, so-called gyrotron FU CW series is being developed. Such a present status of high frequency gyrotron in FIR FU will be introduced.

Development of an Ultra High Frequency Gyrotron with a Pulsed Magnet

An ultra‐high frequency gyrotron is being developed as a THz radiation source by using a pulsed magnet. We have achieved the highest field intensity of 20.2 T. High frequency operation at the second harmonic will achieve 1.01 THz; the corresponding cavity mode is TE6,11,1. On the other hand, an ultra‐high power gyrotron with a pulsed magnet is also being developed as a millimeter to submillimeter wave radiation source. The gyrotron is a large orbit gyrotron (LOG) using an intense relativistic electron beam (IREB). A pulsed power generator “ETIGO‐IV” is applied for generation of the IREB. A prototype relativistic LOG was constructed for fundamental operation. The output of the LOG will achieve 144 GHz and 9 MW; the corresponding cavity mode is TE1,4,1. Cavities for 2nd and 4th harmonic operations were designed by numerical simulation for achievement of higher frequency. The progress of development for prototype high frequency gyrotrons with pulsed magnets is presented.

The Experimental Results and Theoretical Analysis of a THz Gyrotron Using a 21 T Pulse Magnet at FIR FU

The experimental tests of a gyrotron using a 21 T pulse magnet have achieved 1 THz at second harmonic operation. The operation conditions of the gyrotron at the THz regime are investigated. The single mode operation at second harmonic and frequency of 1 THz has been clarified with the theoretical results. This achievement and understanding of operating condition of gyrotron at 1 THz will be useful for designing of our next CW I THz gyrotron, Gyrotron FU CW III.

Development of CW THz gyrotrons in FIR FU

A gyrotron with a 21 T pulse magnet achieved the breakthrough of 1 THz. This is the first result of high frequency operation in the world beyond 1 THz. In addition, new gyrotron series in FIR FU, University of Fukui, so-called Gyrotron FU CW Series is being developed. Such a present status of high frequency gyrotron in FIR FU will be introduced.

Development of a THz gyrotron using a pulse magnet

An ultra-high frequency gyrotron is being developed by using a pulse magnet. We have achieved the highest field intensity of 20.2 T. High frequency operation at the second harmonic will achieve 1.01 THz. Corresponding cavity mode is TE/sub 6,11,1/. The results of the first trial for a THz gyrotron are presented.

Development of a terahertz gyrotron using a high field pulse magnet

Summary form only given. Development of a THz gyrotron is described. A pulse magnet using a condenser bunk (6 mF, 10 kV) generates a high magnetic field up to 25 T in the room temperature bore of a cryostat whose diameter is 85 mm. A demountable gyrotron tube is installed on the axis of the cryostat. The gyrotron achieve high frequency operations up to 680 GHz by fundamental resonance and up to 1.3 THz by its second harmonics. Detailed experimental results are presented.