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International Conference on infrared and Millimeter Waves

作者： T. H. Chang N. C. Chen C. F. Yu C. T. Fan T. Idehara Department of Physics National Tsing Hua University Hsinchu Taiwan Research Center of Development of Far-Infrared Region Fukui University of Technology Fukui Japan

ISBN: (纸本)9781424454167

The gyrotron backward-wave oscillator (gyro-BWO) is a frequency tunable scheme at millimeter/terahertz regime. The continuous frequency tuning can be achieved by varying either the magnetic field or the beam voltage in a non-resonant structure. With a growing interest in terahertz-wave regime, gyro-BWO should be preferably operated with high-order mode due to the power-handling capability. Then the upcoming difficulty would be the terahertz interaction circuit as well as the severe transverse mode competition.

关键词： Frequency Gyrotrons Oscillators Physics Nuclear magnetic resonance Tunable circuits and devices Magnetic fields Electrons Electrochemical machining Plasma measurements

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Broadband design for 203-GHz TE02/TE03 gyrotron backward-wave oscillator

Broadband design for 203-GHz TE02/TE03 gyrotron backward-wav...

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International Conference on infrared and Millimeter Waves

作者： Nai-Ching Chen Tsun-Hsu Chang Toshitaka Idehara Ching-Pin Yuan Department of Physics National Tsing Hua University Hsinchu Taiwan Research Center of Development of Far-Infrared Region Fukui University of Technology Fukui Japan

This study proposes a broadband interaction structure for a fundamental harmonic TE 02 203-GHz gyrotron backward-wave oscillator (gyro-BWO). Unlike the present terahertz tunable gyrotron which achieves the tunability by interacting with a series of high order axial modes, the gyro-BWO operates with single (fundamental) axial mode in frequency tuning and has the advantage of smooth and broadband tuning. The interaction structure is designed to be low resonance for a reflective gyro-BWO (forward-wave extraction), which eliminates the major difficulty of a normal gyro-BWO, i.e. mode converter for backward-wave extraction. Numerical investigations indicate that the reflective TE 02 gyro-BWO is capable of generating a peak power of 2.8 kW corresponding to 22.6% interacting efficiency with a 3dB-tuning-bandwidth of 7.3 GHz at beam current I b = 0.5 A and beam voltage V b = 25 kV. For high power handling capability, the interaction structure could be scaled up and operate with TE 03 mode using same electron beam. The reflective TE 03 gyro-BWO yields a peak power of 2.5 kW and 5.7 GHz tuning bandwidth.

关键词： Tellurium Tuning Gyrotrons Oscillators Frequency Resonance Power generation Voltage Electron beams Bandwidth

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Characterization of zinc magnesium stannate phosphor fine particles synthesized by electromagnetic wave heating

Characterization of zinc magnesium stannate phosphor fine pa...

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International Conference on Vacuum Nanoelectronics (IVNC)

作者： M. Kitaura S. Tani S. Mitsudo K. Fukui Fukui National College of Technology Sabae Fukui Japan Research Center of Development of for Infrared Region University of Fukui Fukui Japan Department of Electrical and Electronics Engineering University of Fukui Fukui Japan

The paper presents the preparation of of zinc magnesium stannate phosphor Zn 2(1-x) Mg 2x SnO 4 :Mn powder by using high power 28 GHz electromagnetic wave heating. The sample was characterised using XRD.

关键词： Zinc Magnesium Phosphors Electromagnetic scattering Electromagnetic heating Resistance heating Furnaces infrared heating X-ray scattering Heat engines

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A Frequency tunable Gyrotron, Gyrotron FU CW IV

A Frequency tunable Gyrotron, Gyrotron FU CW IV

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International Conference on infrared and Millimeter Waves

作者： I. Ogawa T. Idehara T. H. Chang S. Kobayashi T. Saito Research Center for Development of Far-Infrared Region Fukui University Fukui Japan Department of Physics National Tsing Hua University Hsinchu Taiwan Research Center for Development of Far-Infrared Region Fukui University of Technology Fukui Japan

A sensitive NMR spectroscopy using a dynamic nuclear polarization (DNP) is an effective method to enhance the sensitivity of such versatile analytical technique. Its high performance realization requires a frequency tunable and powerful radiation source. A new gyrotron is developed with the aim of achieving the wide frequency tuning. The gyrotron FU CW IV operates at magnetic fields in the range of between 4.9 T and 5.2 T, and continuous frequency tuning in 6 GHz interval can be realized.

关键词： Gyrotrons Frequency measurement Magnetic fields Magnetic field measurement Spectroscopy Frequency synthesizers Tuning

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High field ESR of P-doped Si for Quantum Computing Application

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Journal of Physics: Conference Series 2009年第2期150卷

作者： M Song M Jeong T Ueno B Kang K Sugiyama K Tanaka A Matsubara S Lee S Mitsudo T Mizusaki M Chiba Department of Physics Korea Advanced Institute of Science and Technology Daejeon 305–701 Republic of Korea Graduate School of Medicine Kyoto University Kyoto 606–8507 Japan Graduate School of Engineering University of Fukui Fukui 910–8507 Japan Research Center for Low Temperature and Materials Sciences Kyoto University Kyoto 606–8502 Japan Research Center for Development of Far-Infrared Region University of Fukui Fukui 910–8507 Japan Toyota Physical and Chemical Research Institute Nagakute Aichi 480–1192 Japan

We measured ESR of phosphorous-doped silicon with a low concentration of P, n, at high magnetic fields and low temperatures to investigate the states of nuclear spin. A sample with n = 6.52 × 1016 /cm3 was studied at 2.85 T (80 GHz) from 30 K to 2.3 K by field-modulating cw-ESR for a fixed 0 dB power. As the temperature was lowered, the out-of-phase signal appeared around 18 K, reached at a maximum intensity at 13 K, and disappeared around 6 K. The out-of-phase signal is referred to the field modulation. The in-phase signal started to change from the derivative of absorption spectrum at high temperatures to absorption-like shape around 15 K and asymmetry of intensity for two peaks of hyperfine-separated signals increased as temperatures was lowered. Below 10 K, the saturation of the in-phase signal started to appear. We speculate that the asymmetry is caused by saturation effect and dynamic nuclear polarization of 31P nuclear spin due to drastic change of electron T1.

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Hysteresis in mode competion in the high power 170 GHz CW gyrotron for ITER

Hysteresis in mode competion in the high power 170 GHz CW gy...

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IEEE International Conference on Plasma Science (ICOPS)

作者： O. Dumbrajs T. Idehara Association Euratom-Tekes Helsinki University of Technology Finland Research Center for Development of Far-Infrared Region University of Fukui Fukui Japan

Summary form only given. In gyrotrons hysteresis is the phenomenon that causes the amplitude of oscillations to lag behind the magnetic field and the voltage, so that operation regions of modes for rising and falling magnetic field and voltage are not the same. Understanding of hysteresis is important in connection with mode competition, frequency tuning, voltage overshooting, amplitude modulation of the signal, etc. Measurements of hysteresis with respect to accelerating voltage in a multimode coaxial gyrotron have been performed at the Forschungszentrum Karlsruhe. The first devoted experimental verification of different hysteresis phenomena in CW low- power gyrotrons operating in a single mode has been done at the research center for development of Far-infrared Region of Fukui University. Just recently, researchers from the Japan Atomic Energy Agency have observed a clear hysteresis effect with respect to magnetic field in mode competition in the 170 GHz CW gyrotron for ITER. In the present work the single mode hysteresis calculations are generalized to multimode case with particular emphasis on mode competition. A hysteresis map is calculated in the plane "frequency mismatch - dimensionless current" for the operating TE m,p mode and the parasitic TE m-1,p mode .The theory is illustrated by a number of specific examples. In particular, it is shown how the hysteresis loop observed in experiment can be described theoretically.

关键词： Magnetic hysteresis Gyrotrons Oscillators Magnetic fields Voltage measurement Plasmas Frequency measurement

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Frequency tunable gyrotron using backward-wave components

Frequency tunable gyrotron using backward-wave components

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International Conference on infrared and Millimeter Waves

作者： T.H. Chang T. Idehara I. Ogawa L. Agusu S. Kobayashi Research Center for Development of Far-Infrared Region Fukui University of Technology Fukui Japan Department of Physics National Tsing Hua University Hsinchu Taiwan

We present a frequency tunable scheme for the gyrotron at millimeter/submillimeter regime. Unlike step-tunable type where oscillation jumps discretely in different transverse modes, this scheme allows a smooth tuning within a single transverse mode using its backward-wave component. The characteristics of backward-wave interaction will be shown. A proof of principle experiment was conducted with a sealed cavity. The result shows the oscillation frequency smoothly transitions over a wide range of 6 GHz from 134 to 140 GHz. The proposed mechanism is capable of producing medium output power with broad frequency tunability up to sub-terahertz region.

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development of a 300 GHz material processing system

Development of a 300 GHz material processing system

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International Conference on infrared and Millimeter Waves

作者： S. Mitsudo Y. Kobayashi T. Idehara T. Saito S. Sano T. Ueda Research Center for Development of Far-Infrared Region University of Fukui Fukui Japan Fukushin kougyou Co. Ltd. Fukui Japan National Institute of Advanced Industrial Science and Technology Aichi Japan

The effective characteristics of high frequency and strong electric field processing were observed. One of the interesting effects is so called non-thermal effect or microwave effect. In order to widely study the non-thermal effect of ceramics sintering, we developed a material processing system by using a 300 GHz gyrotron. Successful submillimeter wave sintering of partially stabilized zirconia ceramics was obtained.

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Propagating mode analysis and field reconstruction in the corrugated waveguides of a high power electron cyclotron heating system

Propagating mode analysis and field reconstruction in the co...

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International Conference on infrared and Millimeter Waves

作者： T. Shimozuma H. Idei M. A. Shapiro R. J. Temkin S. Kubo Y. Yoshimura H. Igami H. Takahashi T. Notake S. Ito S. Kobayashi Y. Mizuno Y. Takita T. Mutoh National Institute for Fusion Science Gifu Japan Research Institute for Applied Mechanics Kyushu University Fukuoka Japan Plasma Science and Fusion Center Massachusetts Institute of Technology Cambridge MA USA Research Center for Development of Far-Infrared Region University of Fukui Fukui Japan

A new method is proposed to analyze mode contents of high power electromagnetic waves that are propagating through corrugated waveguides in the electron cyclotron resonance heating (ECH) system for nuclear fusion devices. The method was applied to a 168 GHz transmission line of the ECH system in Large Helical Device (LHD) to evaluate the waveguide misalignment. Mode contents of the propagating wave could be well obtained, and the wave field in the waveguide was reconstructed by using the information of each mode.

关键词： Electromagnetic waveguides Heating Electromagnetic scattering Transmission line measurements Power transmission lines Millimeter wave technology Cyclotrons

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Millimeter and Submillimeter wave sintering of ceramics

Millimeter and Submillimeter wave sintering of ceramics

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32nd International Conference on infrared and Millimeter Waves, and 15th International Conference on Terahertz Electronics (IRMMW-THz 2007), part 1

作者： Seitaro Mitsudo Kazuki Sakai Toshitaka Idehara Tasaburo Saji Teruo Saito Saburo Sano Development of Far Infrared Region University of Fukui Fukui-shi Fukui Japan Research Center for Development of Far Infrared Region University of Fukui Japan National Institute of Advanced Industrial Science and Technology

ISBN: (纸本)9781424414383

The effect characteristic of high frequency and strong electric field processing was observed. One of interest effects is so called non-thermal effect or microwave effect. In order to widely study the non-thermal effect of ceramics sintering. We developed a material processing system by using a 300 GHz gyrotron. This system consists of a 300 GHz, 3.5 kW, CW gyrotron (Gyrotron FU CW I) with a cryogen-free 12 T superconducting magnet, a corrugated circular waveguide and applicator. Boron carbide is one of advanced materials and is being used in a wide rage of applications. 24 GHz microwave processing for boron carbide ceramics were performed. Enhanced sintering (non-thermal effect) was observed.

关键词： Gyrotrons Boron compounds Ceramics Millimeter wave technology Submillimeter wave technology

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