THE FIRST EXPERIMENT OF A THz GYROTRON WITH A PULSE MAGNET

Idehara, T.; Tsuchiya, H.; Watanabe, Osamu; Agusu, La; Mitsudo, S.

doi:10.1007/s10762-006-9084-9

Cited by 158 publications

(62 citation statements)

References 19 publications

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“…We anticipate that gyrotrons will be useful to at least the 1GHz 1 H NMR frequency regime (~660 GHz for electrons) or higher. For example, a gyrotron was recently operated in pulsed mode at a frequency of a 1.03 THz [32].…”

Section: Introductionmentioning

confidence: 99%

250GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR

Bajaj

Hornstein

Kreischer

et al. 2007

Journal of Magnetic Resonance

162

130

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In this paper, we describe a 250 GHz gyrotron oscillator, a critical component of an integrated system for magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments at 9T, corresponding to 380 MHz 1 H frequency. The 250 GHz gyrotron is the first gyro-device designed with the goal of seamless integration with an NMR spectrometer for routine DNP-enhanced NMR spectroscopy and has operated under computer control for periods of up to 21 days with a 100% duty cycle. Following a brief historical review of the field, we present studies of the membrane protein bacteriorhodopsin (bR) using DNP-enhanced multidimensional NMR. These results include assignment of active site resonances in [U-13 C, 15 N]-bR and demonstrate the utility of DNP for studies of membrane proteins. Next, we review the theory of gyro-devices from quantum mechanical and classical viewpoints and discuss the unique considerations that apply to gyrotron oscillators designed for DNP experiments. We then characterize the operation of the 250 GHz gyrotron in detail, including its long-term stability and controllability. We have measured the spectral purity of the gyrotron emission using both homodyne and heterodyne techniques. Radiation intensity patterns from the corrugated waveguide that delivers power to the NMR probe were measured using two new techniques to confirm pure mode content: a thermometric approach based on the temperaturedependent color of liquid crystalline media applied to a substrate and imaging with a pyroelectric camera. We next present a detailed study of the mode excitation characteristics of the gyrotron. Exploration of the operating characteristics of several fundamental modes reveals broadband continuous frequency tuning of up to 1.8 GHz as a function of the magnetic field alone, a feature that may be exploited in future tunable gyrotron designs. Oscillation of the 250 GHz gyrotron at the second harmonic of cyclotron resonance begins at extremely low beam currents (as low 12 mA) at frequencies between 320-365 GHz, suggesting an efficient route for the generation of even higher frequency radiation. The low starting currents were attributed to an elevated cavity Q, which is confirmed by cavity thermal load measurements. We conclude with an appendix containing a detailed description of the control system that safely automates all aspects of the gyrotron operation.

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Section: Introductionmentioning

confidence: 99%

250GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR

Bajaj

Hornstein

Kreischer

et al. 2007

Journal of Magnetic Resonance

162

130

View full text Add to dashboard Cite

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“…При заданном токе инжекции это позволяет обеспечить условия самовозбуждения при относительно низкой дифракционной добротности рабочего резонатора, что ведет к существенному снижению доли омических потерь. В последние годы достигнут существенный прогресс в создании гиротронов субтерагерцового и терагерцового диапазонов [1][2][3][4][5][6]. При работе на основной гармонике гирочастоты в традиционной схеме цилиндрического гиротрона [1-4], а также при работе на гармониках гирочастоты в так называемом гиротроне с большой орбитой [5,6] полу-чено терагерцовое излучение с мощностью несколько киловатт.…”

Section: поступило в редакцию 29 марта 2016 гunclassified

Оптимизация Условий Самовозбуждения Терагерцовых Гиротронов На Основе Увеличения Времени Жизни Циклотронных Осцилляторов В Рабочем Пространстве С Пониженным Напряжением

Ginzburg¹,

Глявин²,

Зотова³

et al. 2017

Письма В Журнал Технической Физики

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Предложен метод снижения стартовых и рабочих токов коротковолновых гиротронов путем приложения тормозящего потенциала непосредственно к рабочему резонатору. Указанный эффект достигается за счет увеличения времени жизни электронов в рабочем пространстве. При заданном токе инжекции это позволяет обеспечить условия самовозбуждения при относительно низкой дифракционной добротности рабочего резонатора, что ведет к существенному снижению доли омических потерь. DOI: 10.21883/PJTF.2017.02.44187.16273

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confidence: 99%

“…Therefore, they are considered to be available powerful sources that have the potential to bridge the so-called terahertz gap. Only four institutes have developed gyrotron generated frequencies above 0.3 THz at output powers over 1 kW: the University of Sydney in Australia [20], Fukui University in Japan [21], the Institute of Applied Physics (IAP) of the Russian Academy of Sciences (RAS) in Russia [22], and the Massachusetts Institute of Technology in the United States [23].…”

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confidence: 99%

Generating 0.42 THz radiation from a second harmonic gyrotron

Yang

et al. 2011

Chin. Sci. Bull.

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Gyrotrons are high powered coherent electromagnetic radiation sources, and are considered to be available powerful sources that have the potential to bridge the so-called terahertz gap. In the University of Electronic Science and Technology of China, a second harmonic gyrotron has been designed, manufactured, and tested. The gyrotron generated radiation at a 0.423 THz frequency in 5 s pulses with an 8.1 Tesla magnetic field, with a power per pulse of about 4.4 kW. To date this is the highest frequency recorded for vacuum electronic devices in China. The gyrotron design, operation and measurements are presented. Terahertz (THz) waves, electromagnetic radiation between far infrared and millimeter wavelengths, have very important academic and application values. The characteristics of THz waves are used in a large and increasing number of applications. These applications include fundamental scientific research (physics, chemistry, etc.), many interdisciplinary fields (biophysics, etc.), radar, communication, material processing, and medical diagnostics and therapy. However, because there is a lack of reliable sources and detectors of terahertz radiation, most applications are still experimental. Consequently, current investigations on terahertz waves are concentrated on sources (electronics sources and optical sources), detectors, transmission, and applications [1,2]. In China, terahertz waves have become an active research area over the last 10 years [3,4]. Important achievements have been made, such as the THz vacuum electronic devices developed in the University of Electronic Science and Technology of China [5,6], the THz quantum cascade lasers (QCL) developed in the Shanghai Institute of Microsystem and Information Technology [7,8], the THz superconducting detector in the Nanjing University [9,10], the THz optical sources research carried out in Tianjin University [11] and Nankai University [12], the THz time-domain spectroscopy methodology and related application researches carried out in the Capital Normal University [13,14], the THz-material interaction carried out in the Shanghai Jiao Tong University and Institute of Physics, Chinese Academy of Sciences [15], and so on [1618].In this paper, we report on initial experiments on a second harmonic gyrotron developed at the University of Electronic Science and Technology of China (UESTC), which generated radiation at a frequency of 0.423 THz in 5 s pulses, with a power per pulse of about 4.4 kW. To date this is the highest frequency recorded for vacuum electronic devices in China.Gyrotrons are fast-wave vacuum electronic devices, based on the interaction of electronics gyrating in external magnetic fields with fast waves. There is no need for the slow-wave circuits used extensively in traditional vacuum electronic devices. Gyrotrons can have physical dimensions much larger than the operating wavelength, so they have higher output power and higher efficiency than traditional vacuum electronics devices [19]. Therefore, they are considered to be available powerf...

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THE FIRST EXPERIMENT OF A THz GYROTRON WITH A PULSE MAGNET

Cited by 158 publications

References 19 publications

250GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR

250GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR

Generating 0.42 THz radiation from a second harmonic gyrotron

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