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In LHD, an ECH system for fusion-relevant plasma heating has been greatly progressed with the development of megawatt gyrotrons. Net power of 3.7 MW could be injected into LHD. For stable operation, a new position and profile monitor of the mmw-beams in evacuated transmission lines is developed.
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...
The latest gyrotron included Gyrotron FU CW Series, Gyrotron FU CW III is introduced in detail. It consists of a 20T superconducting magnet, a demountable gyrotron tube, a 30 kV, 0.5 A, CW power supply for electron gun and additional coils in a gun region. The gyrotron has achieved the breakthrough of 1 THz and frequency step tunability up to around 540 GHz for fundamental operations and up to 1.08...
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...
On the basis of successful development of Gyrotron FU CW II, a similar gyrotron FU CW IIA is being developed for both 600 MHz and 300 MHz DNP-NMR experiments at the University of Warwick in UK. The frequencies of the gyrotron are 394.6 GHz at the second harmonic and 200 GHz at fundamental that correspond to frequencies 600 MHz and 200 GHz DNP-NMR spectroscopy. The output powers are around 30 W and...
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...
Summary form only given. Recently, medium power, sub-THz gyrotrons were developed for application to DNP-NMR experiment for enhancing the sensitivity of NMR. In FIR FU, 394.6 GHz CW gyrotron FU CW II which is the second gyrotron of Gyrotron FU CW Series has been developed for DNP/NMR at 600 MHz under a collaboration with Institute of Protein Research, Osaka University. The output power and the frequency...
Recently, a gyrotron in FIR FU with a 21 T pulse magnet achieved the breakthrough of 1 THz. In the gyrotron, a demountable gyrotron tube is installed on the center axis of 21 T pulse magnet. In the operation test, a high voltage pulse is applied to electron gun installed in the region of the additional coils for controlling the injection point of electron beam in the cavity region. When B in the cavity...
Summary form only given. Dynamic nuclear polarization (DNP) method can enhance the sensitivity of NMR for extending its application to wide fields including analysis of protein molecule and study on material surface. For this objective, it is needed to develop high power sub-THz radiation sources which operate in long time CW mode. We have already developed a 395 GHz CW gyrotron for 600 MHz proton...
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