Recent Developments on High-Power Gyrotrons—Introduction to This Special Issue

Thumm, M.

doi:10.1007/s10762-010-9754-5

Cited by 42 publications

(10 citation statements)

References 42 publications

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“…YROTRON oscillators are vacuum electron devices that have delivered MW power levels at millimeter wavelengths [1], and kW power levels in the THz or submillimeter band [2], [3]. The lack of other sources able to match these power levels in the abovementioned bands, with the exception of much bulkier free electron lasers, makes the gyrotron the oscillator of choice in many applications such as plasma heating [1], materials processing [4], diagnostics [5], spectroscopy [6], and in non-lethal weapons [7].…”

Section: Introductionmentioning

confidence: 99%

“…The lack of other sources able to match these power levels in the abovementioned bands, with the exception of much bulkier free electron lasers, makes the gyrotron the oscillator of choice in many applications such as plasma heating [1], materials processing [4], diagnostics [5], spectroscopy [6], and in non-lethal weapons [7]. Although the main attractiveness of the gyrotron resides in its power, some applications would also benefit from having a frequency tunable generator.…”

Section: Introductionmentioning

confidence: 99%

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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

161

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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

161

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“…In the circular waveguide, the TE 11 mode energy is concentrated relatively in a specific region. [7][8][9][10] When the waveguide radius is the same, the TE 11 mode can focus the energy of millimeter wave on a region of 0.5 times the waveguide area, and the power density can be improved under the condition of limited output power. Therefore, TE 11 is selected for this experiment.…”

Section: Introductionmentioning

confidence: 99%

Design and high‐power test of the transmission line for millimeter wave deep drilling

Wang

Niu

Chen

et al. 2020

Int J Numerical Modelling

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A numerical synthesis method for optimization of the key components of the transmission line for high-power fusion gyrotron is proposed in this paper.Combined with the analysis method, an algorithm has been developed for the waveguide to provide higher power transformation efficiency, which is 99.447% and 99.9721% for the TE 01 -TE 11 mode converter and TE 11 taper, respectively. The synthesis method has been tested for the designed key components of transmission line to transfer the electromagnetic wave from the gyrotron output port to the specified position of the sample to be heat. The experimental results show that the output mode is in excellent agreement with theoretical calculation. The details are presented for the circular waveguide mode converter and the layout of the whole system.

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“…A set of two gyrotrons will be operated by a single main high voltage power supply (HVPS) and two sets of acceleration grid power supplies: body power supplies (BPS) and anode power supplies (APS) for triode gyrotron. EU, Russia, and Japan procure 8 gyrotrons [1][2][3] and EU and India procure 8 and 4 sets of power supply systems. RF power from gyrotron is coupled into TL to transmit from RF building to launchers on the vacuum vessel.…”

Section: Introductionmentioning

confidence: 99%

A study of mode purity improvement in the ITER relevant transmission line

Oda

Ikeda

Kajiwara

et al. 2015

EPJ Web of Conferences

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Abstract. In JAEA, mode conversion by corrugated waveguide system which is ITER relevant TL system was studied. To evaluate the alignment method for TL assembly, the mode content of middle section of TL was measured while assembly of the TL test stand. Then 5% of LP01 mode purity degradation was found in the long straight section though it was just assembly of 2m straight WGs. Indeed, the mode conversion calculation showed that 5% of mode conversion may occur when the straight section causes 1.0 mm of periodic deflection. To minimize the deflection, the alignment method with adjustment of both position and angle of the WG piece utilizing the laser beam reflection was applied for the TL re-assembling. The mode purity in the same section was improved and mode purity degradation was less than 1%. Finally 93% of LP01 mode purity was achieved at the end of long TL. Next the effect of mode purity by high-power long-pulse operation in TL was studied. Since the TL components are heated during the high-power RF operation, the TL causes deformation due to thermal expansion and deformed TL section induces significant mode conversion loss. The 170GHz gyrotron provided high-power (400kW) and long pulse (500sec) into TL and the beam profile at TL end was measured both before and after the long pulse operation. The mode purity at TL end was 91% before the long pulse and it decreased to 84% after the pulse. The temperature distribution and displacement of TL components were also measured. The measured displacement shows that the vertical sections became S-bend structures and mode conversion loss was estimated. The estimated total mode conversion loss in deformed long TL system was 8%. The estimated value showed good agreement with measurement of mode purity.

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Recent Developments on High-Power Gyrotrons—Introduction to This Special Issue

Cited by 42 publications

References 42 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

Design and high‐power test of the transmission line for millimeter wave deep drilling

A study of mode purity improvement in the ITER relevant transmission line

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