ECRH for W7-X: Transmission Losses of High-Power 140-GHz Wave Beams

Erckmann, V.; Kasparek, W.; Gantenbein, G.; Hollmann, Frank; Jonitz, L.; Noke, F.; Purps, F.; Weissgerber, M.; Greifswald, W X Ecrh Team at Ipp; Karlsruhe, W X Ecrh Team at Fzk; Stuttgart, W X Ecrh Team at Ipf

doi:10.13182/fst09-a4049

Cited by 10 publications

(4 citation statements)

References 13 publications

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“…We have therefore installed retroreflectors to test the full distance transmission by transmitting the high-power beams half way in forward direction and then back via the reflectors to the dummy load. Total losses of 2.6 ± 0.4% were measured for 10 reflections over a total length of about 40 m, which is close to the theoretical minimum losses of 2.7% [39]. …”

Section: High-power Microwave Transmissionsupporting

confidence: 80%

Steady state ECRH for next step superconducting fusion devices

Erckmann

2009

Fusion Engineering and Design

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a b s t r a c tControlled plasma start-up, heating towards thermonuclear fusion temperatures and steady state discharge control in advanced configurations is a major challenge for both, stellarators and tokamaks. Electron Cyclotron Resonance Heating (ECRH) and current drive (ECCD) plays a key role in the steady state operation scenarios of the ITER and JT-60 SA tokamaks as well as for the W7-X stellarator. The physics demands as well as the key technology of the different ECRH-systems, which are similar in frequency and have continuous wave (cw) capability, are presented. Advanced solutions for future ECRH-systems are discussed.

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Section: High-power Microwave Transmissionsupporting

confidence: 80%

Steady state ECRH for next step superconducting fusion devices

Erckmann

2009

Fusion Engineering and Design

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“…Table 3 shows theoretical ohmic losses estimation for a TL of several ideal surface copper mirrors with 90° bends: the incident wave polarization can be chosen appropriately (if the bends are kept in one plane along the whole TL path) to halve the losses (saving 3-7% of 50 MW means sparing 1-2 gyrotrons). The contribution of polarizers is not included [34]. A second main source of loss is the beam truncation reported in table 4 for two different MBTL mirror radius.…”

Section: Transmission Line (Tl)mentioning

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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“…Building on Wendelstein 7-X experience of 30 min high-power pulse duration test [31], stray radiation and absorbed or trapped power could lead to overheating of beam-line components. Thus, validation of the remote steering design concept needs to be followed up by highpower long pulse duration tests.…”

Section: Fig 32mentioning

confidence: 99%