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High power sub terahertz gyrotrons are under development in FIR-FU for application to CTS. Succeeding to more than 50 kW second harmonic oscillation power at 350 GHz with a demountable tube, a sealed-off gyrotron was newly fabricated and its performance test is now on going.
A versatile and compact sub-THz second harmonic gyrotron with output parameters suitable for various spectroscopic studies is under development now at FIR FU Research Center. Here we present and discuss the results of the initial computer-aided design (CAD) of this novel prospective member of the Gyrotron FU CW series.
For direct measurement on hyperfine structure of positronium, high power sub-THz radiation sources, Gyrotrons FU CW V and FU CW VIII have been developed. FU CW V is a frequency fixed gyrotron operating at 203.3 GHz for the proof-of-principle experiment and FU CW VIII a frequency continuously tunable gyrotron to measure directly the energy difference between orth- and para states of positronium.
We had reported the results of application that the terahertz wave irradiation to an experimental transplanted prostate cancer model mouse using the gyrotron. We irradiated the 107 or 203 GHz wave (22.56W/cm2×20 min=27,180 J/cm2), resepectively, against the tumor model BALB-c-nu/nu strain, mail, 12 week old mouse at 43 degree C, which to rising time for 10 min and to keeping the temperature at 43...
Gyrotron FU CW Series which consists of 9 gyrotrons, has been designed and constructed as high power THz radiation sources and completed operational tests successfully in the Research Center for Development of Far Infrared Region, University of Fukui (FIR FU). The gyrotron series covers wide frequency range in sub-THz to THz region. Gyrotrons included in the series can operate in continuous wave (CW)...
Analytical estimations and the results of numerical analysis of the electron beam parameters in the reverse moderate power (15 kV/1A) Magnetron Injection Gun (MIG) for a coaxial 394.6 GHz gyrotron are presented. The design of the MIG with a movable inner rod is discussed, and the influence of emitter roughness is analyzed.
The gyrotron, Gyrotron FU CW IV continues to produce output radiation in the wide range of magnetic fields from 4.9 T to 5.2 T, and continuous frequency tuning in 6 GHz interval from 134 GHz to 140 GHz can be realized. This type of gyrotron will play an important role as a high power radiation source with the function of continuous frequency tuning to the applications in the fields of millimeter to...
Antenna-coupled GaAs Schottky barrier diode (SBD) detectors used at 180 GHz band were fabricated using micro-fabrication techniques, and radiation frequency of a gyrotron at the University of Fukui (Gyrotron FU CW IV) was measured by a harmonic mixing using the LO wave of 88.0899 GHz. The radiation frequency of gyrotron was found to be 176.077 GHz.
Two sealed-off gyrotron tubes for high power THz spectroscopy are designed and constructed. One of them will be used for ESR echo experiment in sub-THz region, and another for 600 MHz DNP-NMR experiment etc. Both gyrotrons are named Gyrotron FU CW IIA and Gyrotron FU CW VIIA, because their cavities have same shapes as Gyrotrons FU CW II and FU CW VII. Both tubes are installed in 8T superconducting...
We have applied the terahertz wave irradiation to an experimental transplanted prostate cancer model mouse using the gyrotron. We irradiated the 107 or 203 GHz wave (22.56 W/cm2 times 20 min = 27,180 J/cm2), resepectively, against the tumor model BALB-c-nu/nu strain, mail, 12 week old mouse at 43 degree C, which to rising time for 10 min and to keeping the temperature at 43 degree C for 10 min, respectively...
We have developed a millimeter wave pulsed electron spin resonance (ESR) spectrometer by using a high power radiation source gyrotron. As the first, we introduce a high power millimeter wave pulse forming system by using light controlled semiconductor shutters. Nanoseconds millimeter wave pulses (15 ns and 27 ns) were realized with the microseconds order arbitrary delay time tau.
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 and application of material heating, we developed a material processing system by using a 300 GHz gyrotron. This system are consisted of a 300 GHz,...
A novel high power sub-terahertz gyrotron operating at second harmonic resonance was designed. This gyrotron is intended for use as a probe beam source for collective Thomson scattering diagnostics in nuclear fusion plasma research. The resonant cavity mode, cavity radius, and its length were optimized from various aspects such as resonant frequency, coupling between the electron beam and the RF-electric...
Gyrotron FU CW V operating at the fundamental cyclotron resonance is used for measurement of hyperfine structure on positronium. The gyrotron delivers high power radiation with the frequency of 203.2 GHz and output power of 0.7 kW under CW operation mode. This radiation can be used for direct measurement of energy level transition of positronium, because expected energy level difference is near 203...
For application to many kind of spectroscopy and other research subjects in sub-THz to THz region, relatively high power CW radiation sources are needed and requested. For response to the request, we are intending to develop a compact CW THz gyrotron as one of gyrotrons included in our recent gyrotron FU CW series. The design was completed. The gyrotron operates at low voltage and low current because...
High power THz radiation sources - gyrotrons are being applied to high power THz technologies including enhancement of NMR sensitivity by a dynamic nuclear polarization, direct measurement of hyperfine structure of positronium, X-ray detected magnetic resonance measurement, sub-THz ESR echo spectroscopy and new medical technology. In this paper, such applications of THz gyrotrons are presented.
We have developed the Gyrotron FU CW VII for 300 MHz and 600 MHz DNP-NMR spectroscopy. For high frequency DNP-NMR experiment, high power sub-THz radiation sources are required. Gyrotron is able to emit enough power and appropriate frequency in sub-THz region for DNP. This Gyrotron emits electromagnetic waves with high power and appropriate frequency for each DNP-NMR spectroscopy (used cavity modes...
A 300 GHz fully continuous wave gyrotron FU CW I has been developed for application to material processing in the submillimeter wave range. The output power from this gyrotron has not reached the designed one. As a reason of power shortage, it is considered that the electron beam radius shifts from the optimum radius due to installation of additional gun coils to suppress a large anode current. For...
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...
This study proposes a broadband interaction structure for a fundamental harmonic TE02 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...
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