Efficient Frequency Step-Tunable Megawatt-Class &lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$D$ &lt;/tex-math&gt;&lt;/inline-formula&gt;-Band Gyrotron

Samartsev, A.; Avramidis, Konstantinos A.; Gantenbein, G.; Dammertz, G.; Thumm, M.; Jelonnek, John

doi:10.1109/ted.2015.2433016

Cited by 22 publications

(4 citation statements)

References 12 publications

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“…The third possibility (which is rarely used due to the additional technical complications that it introduces) involves changing the dimensions and the shape of the cavity mechanically or by temperature control of the expansion/contraction of the resonator [52]. Efficient multi-frequency gyrotrons that are step-tunable in wide frequency ranges have been demonstrated in numerous experiments [50,[53][54][55][56][57][58][59][60]. An already classical but still impressive example of a stepwise tunability in a wide frequency band is the GYROTRON V developed at the University of Sydney [53].…”

Section: Characteristic Features Of the Gyrotrons And Their Radiationmentioning

confidence: 99%

The Gyrotrons as Promising Radiation Sources for THz Sensing and Imaging

et al. 2020

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The gyrotrons are powerful sources of coherent radiation that can operate in both pulsed and CW (continuous wave) regimes. Their recent advancement toward higher frequencies reached the terahertz (THz) region and opened the road to many new applications in the broad fields of high-power terahertz science and technologies. Among them are advanced spectroscopic techniques, most notably NMR-DNP (nuclear magnetic resonance with signal enhancement through dynamic nuclear polarization, ESR (electron spin resonance) spectroscopy, precise spectroscopy for measuring the HFS (hyperfine splitting) of positronium, etc. Other prominent applications include materials processing (e.g., thermal treatment as well as the sintering of advanced ceramics), remote detection of concealed radioactive materials, radars, and biological and medical research, just to name a few. Among prospective and emerging applications that utilize the gyrotrons as radiation sources are imaging and sensing for inspection and control in various technological processes (for example, food production, security, etc). In this paper, we overview the current status of the research in this field and show that the gyrotrons are promising radiation sources for THz sensing and imaging based on both the existent and anticipated novel techniques and methods.

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Section: Characteristic Features Of the Gyrotrons And Their Radiationmentioning

confidence: 99%

The Gyrotrons as Promising Radiation Sources for THz Sensing and Imaging

et al. 2020

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“…The step-frequency tunable KIT gyrotron has been operated in 3 ms-pulses with 11 modes in the frequency range starting from 111.6 to 169.2 GHz. The corresponding cavity modes, electron beam parameters, output powers and efficiencies (without depressed collector) are summarized in table 7 [134]. The results at 111.6 and 155.9 GHz were obtained using a shorter cavity with lower diffractive Q (850 compared to 1200).…”

Section: Frequency-tunable Gyrotrons In Eumentioning

confidence: 99%

High-power gyrotrons for electron cyclotron heating and current drive

Thumm¹,

Денисов²,

Sakamoto³

et al. 2019

Nucl. Fusion

141

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In many tokamak and stellarator experiments around the globe that are investigating energy production via controlled thermonuclear fusion, electron cyclotron heating and current drive (ECH&CD) are used for plasma start-up, heating, non-inductive current drive and MHD stability control. ECH will be the first auxiliary heating method used on ITER. Megawatt-class, continuous wave (CW) gyrotrons are employed as high-power millimeter (mm)-wave sources. The present review reports on the worldwide state-of-the-art of high-power gyrotrons. Their successful development during the past years changed ECH from a minor to a major heating method. After a general introduction of the various functions of ECH&CD in fusion physics, especially for ITER, Section 2 will explain the fast-wave gyrotron interaction principle. Section 3 discusses innovations on the components of modern long-pulse fusion gyrotrons (magnetron injection electron gun (MIG), beam tunnel, cavity, quasi-optical output coupler, synthetic diamond output window, single-stage depressed collector) and auxiliary components (superconducting magnets, gyrotron diagnostics, high-power calorimetric dummy loads). Section 4 deals with present megawatt-class gyrotrons for ITER, W7-X, LHD, EAST, KSTAR and JT-60SA, and also includes tubes for moderate pulse length machines as, ASDEX-U, DIII-D, HL-2A, TCV, QUEST and GAMMA-10. In Section 5 the development of future advanced fusion gyrotrons is discussed. These are tubes with higher frequencies for DEMO, multi-frequency (multi-purpose) gyrotrons, stepwise frequency tunable tubes for plasma stabilization, injection-locked and coaxial-cavity multi-megawatt gyrotrons, as well as sub-THz gyrotrons for collective Thomson scattering (CTS). Efficiency enhancement via multi-stage depressed collectors, fast oscillation recovery methods and reliability, availability, maintainability and inspectability (RAMI) will be discussed at the end of this section.

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“…A first successful implementation into a megawatt-class D-band (111.6 GHz-165.7 GHz) short-pulse prototype gyrotron operating at 10 different frequency steps and related results from experiments at short pulses (ms) have been reported in [22,23]. The fundamental issue in the Brewsterangle technology is the production of a diamond disc with a sufficiently large axis.…”

Section: Gyrotron Randd and Advanced Developmentsmentioning

confidence: 99%

Conceptual design of the EU DEMO EC-system: main developments and R&D achievements

et al. 2017

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For the development of a DEMOnstration Fusion Power Plant the design of auxiliary heating systems is a key activity in order to achieve controlled burning plasma. The present heating mix considers Electron Cyclotron Resonance Heating (ECRH), Neutral Beam Injection (NBI) and Ion Cyclotron Resonance Heating (ICRH) with a target power to the plasma of about 50MW for each system. The main tasks assigned to the EC system are plasma breakdown and assisted start-up, heating to L-H transition and plasma current ramp up to burn, MHD stability control and assistance in plasma current ramp down. The consequent requirements are used for the conceptual design of the EC system, from the RF source to the launcher, with an extensive R&D program focused on relevant technologies to be developed. Gyrotron: the R&D and Advanced Developments on EC RF sources are targeting for gyrotrons operating at 240GHz, considered as optimum EC Current Drive frequency in case of higher magnetic field than for the 2015 EU DEMO1 baseline. Multipurpose (multi-frequency) and frequency step-tunable gyrotrons are under investigation to increase the flexibility of the system. As main targets an output power of significantly above 1MW (target: 2MW) and a total efficiency higher than 60% are set. The principle feasibility at limits of a 236GHz, conventional-cavity and, alternatively, of a 238GHz coaxial-cavity gyrotron are under investigation together with the development of a synthetic diamond Brewster-angle window technology. Advanced developments are ongoing in the field of multi-stage depressed collector technologies. Transmission Line (TL): Different TL options are under investigation and a preliminary study of an evacuated quasi-optical multiple-beam TL, considered for a hybrid solution, is presented and discussed in terms of layout, dimensions and theoretical losses. Launcher: Remote Steering Antennas have been considered as a possible launcher solution especially under the constraints to avoid movable mirrors close to the plasma. With dedicated beam tracing calculations, the deposition locations coverage and the wave absorption efficiency have been investigated, considering a selection of frequencies, injection angles and launching points. An option for the EC system structure is proposed in clusters, in order to allow the necessary redundancy and flexibility to guarantee the required EC power in the different phases of the plasma pulse. Number and composition of the clusters are analysed to have high availability and therefore maximum reliability with a minimum number of components.

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Efficient Frequency Step-Tunable Megawatt-Class <inline-formula> <tex-math notation="LaTeX">$D$ </tex-math></inline-formula>-Band Gyrotron

Cited by 22 publications

References 12 publications

The Gyrotrons as Promising Radiation Sources for THz Sensing and Imaging

The Gyrotrons as Promising Radiation Sources for THz Sensing and Imaging

High-power gyrotrons for electron cyclotron heating and current drive

Conceptual design of the EU DEMO EC-system: main developments and R&D achievements

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