Continuously Frequency Tunable High Power Sub-THz Radiation Source—Gyrotron FU CW VI for 600 MHz DNP-NMR Spectroscopy

Idehara, T.; Kosuga, K.; Agusu, La; Ikeda, Ryosuke; Ogawa, I.; Saito, T.; Matsuki, Yoh; Ueda, Kazuyuki; Fujiwara, Toshimichi

doi:10.1007/s10762-010-9643-y

Cited by 76 publications

(40 citation statements)

References 21 publications

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“…The smooth tuning range obtained in these experiments was equal to or greater than 1 GHz. Following these results, other gyrotrons using a similar magnetic tuning scheme have been built as described in [14], [15].…”

mentioning

confidence: 99%

Operation of a Continuously Frequency-Tunable Second-Harmonic CW 330-GHz Gyrotron for Dynamic Nuclear Polarization

Torrezan

Shapiro

Sirigiri

et al. 2011

IEEE Trans. Electron Devices

163

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Abstract-The design and operation of a frequency tunable continuous-wave (CW) 330-GHz gyrotron oscillator operating at the second harmonic of the electron cyclotron frequency are reported. The gyrotron has generated 18 W of power from a 10.1-kV 190-mA electron beam working in a TE -4,3 cylindrical mode, corresponding to an efficiency of 0.9%. The measured start oscillation current over a range of magnetic field values is in good agreement with theoretical start currents obtained from linear theory for successive high order axial modes TE -4,3,q , where q = 1 to 6. Also, the observed frequency range in the start current measurement is in reasonable agreement with the frequency range calculated from numerical simulations. The minimum start oscillation current of the device was measured to be 33 mA. A continuous tuning range of 1.2 GHz was observed experimentally via a combination of magnetic, voltage, and thermal tuning. The gyrotron output power and frequency stabilities were assessed to be ±0.4% and ±3 ppm, respectively, during a 110-hour uninterrupted CW run. Evaluation of the gyrotron microwave output beam pattern using a pyroelectric camera indicated a Gaussian-like mode content of 92% with an ellipticity of 28%. The gyrotron will be used for 500-MHz nuclear magnetic resonance (NMR) experiments with sensitivity enhanced by dynamic nuclear polarization (DNP).Index Terms-Dynamic nuclear polarization (DNP), nuclear magnetic resonance (NMR), second cyclotron harmonic, submillimeter wave, terahertz, tunable gyrotron.

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mentioning

confidence: 99%

Operation of a Continuously Frequency-Tunable Second-Harmonic CW 330-GHz Gyrotron for Dynamic Nuclear Polarization

Torrezan

Shapiro

Sirigiri

et al. 2011

IEEE Trans. Electron Devices

163

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“…It is quite an improvement as the gyrotron reported in 1994 was operating at a frequency of 95 GHz with a frequency stability of 100 ppm [46]. The same group from Fukui, Japan reported in 2010 a wide range (1.5 GHz) continuous tunable gyrotron working at 394.6 ± 0.6 GHz [37]. Unfortunately in this work, no stability test results nor measurement sensitivity gain have been reported.…”

Section: Gyrotronmentioning

confidence: 74%

“…The devices that are widely used as a microwave source in EPR/NMR experiments are gyrotrons [37], [38]. The gyrotron was invented in the Radiophysics Institute in Gorky (now the Applied Physics Institute in Nizhny Novogorod) in the 1960s [39].…”

Section: Gyrotronmentioning

confidence: 99%

The Microwave Sources for EPR Spectroscopy

Hruszowiec¹,

Nowak

Szlachetko

et al. 2017

JTIT

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Abstract-Rapid development of many scientific and technical disciplines, especially in material science and material engineering increases a demand for quick, accurate and cheap techniques of materials investigations. The EPR spectroscopy meets these requirements and it is used in many fields of science including biology, chemistry and physics. For proper work, the EPR spectrometer needs a microwave source, which are reviewed in this paper. Vacuum tubes as well as semiconductor generators are presented such as magnetron, klystron, traveling wave tube, backward wave oscillator, orotron, gyrotron, Gunn and IMPATT diodes. In this paper main advantages of gyrotron usage, such as stability and an increased spectral resolution in application to EPR spectroscopy is discussed. The most promising and reliable microwave source is suggested.

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“…It beyond the scope of the present paper to analyze the mechanical feasibility of manufacturing of such a cavity. We only note that in the case of cylindrical cavities the fabrication error smaller than 1μm has been reported [16]. The cavity described in [13] was fabricated with the precision 0.2μm [17].…”

Section: Analysis Of Mode Competitionmentioning

confidence: 98%

Design of an Optimized Resonant Cavity for a Compact Sub-Terahertz Gyrotron

Dumbrājs

Idehara

Sabchevski

2010

J Infrared Milli Terahz Waves

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Coherent sources of radiation in the sub-terahertz and the terahertz frequency range are in great demand for various spectroscopic studies (e.g. electron spin resonance spectroscopy, DNP/NMR spectroscopy etc.). The required levels of the output power as well as the needed specific spectral characteristics make the gyrotrons the most promising and high-performance devices for such applications. Recently, an initial design of a versatile second harmonic gyrotron utilizing a compact cryo-free 8 T superconducting magnet has been accomplished. In this paper we present an optimized resonator for this gyrotron. Instead of a regular (cylindrical) part as in the conventional cavities it contains an uptapered section. Such configuration offers a significant increase of the efficiency and improves the overall performance of the tube. We outline briefly the underlying theory, present and discuss the results of the numerical experiments carried out during the optimization process.

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Continuously Frequency Tunable High Power Sub-THz Radiation Source—Gyrotron FU CW VI for 600 MHz DNP-NMR Spectroscopy

Cited by 76 publications

References 21 publications

Operation of a Continuously Frequency-Tunable Second-Harmonic CW 330-GHz Gyrotron for Dynamic Nuclear Polarization

Operation of a Continuously Frequency-Tunable Second-Harmonic CW 330-GHz Gyrotron for Dynamic Nuclear Polarization

The Microwave Sources for EPR Spectroscopy

Design of an Optimized Resonant Cavity for a Compact Sub-Terahertz Gyrotron

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