Characterization of 3-strap antennas in ASDEX Upgrade

Bobkov, V.; Bilato, R.; Colas, L.; Dux, R.; Faudot, E.; Faugel, H.; Fünfgelder, H.; Herrmann, A.; Jacquot, J.; Kallenbach, A.; Milanesio, Daniele; Maggiora, Riccardo; Neu, R.; Noterdaeme, J.-M.; Ochoukov, R.; Pütterich, T.; Tierens, W.; Zhang, W.; Team, EUROfusion Mst

doi:10.1051/epjconf/201715703005

Cited by 14 publications

(19 citation statements)

References 11 publications

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“…We refer the interested reader to [8] for the analysis of the antenna behavior during the experiment and the comparison with numerical predictions.…”

Section: Analysis Of the Resultsmentioning

confidence: 99%

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Analysis of the ASDEX Upgrade 3-strap antenna with TOPICA code: Curved vs. flat 3D geometry

2017

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Abstract. Before the 2015/2016 experimental campaign, the ASDEX Upgrade (AUG) 2-strap ICRF antennas with tungsten-coated limiters were replaced by 3-strap antennas. The main goal of the 3-strap launcher was to reduce the release of tungsten (W) in order to improve the ICRF operation, which appeared to be troublesome after the all-W wall installation [1]. In this paper, we analyse the behaviour of the 3-strap antenna with the help of TOPICA code [2], a numerical tool able to take into account a realistic antenna geometry and an accurate plasma description. By loading an experimental plasma profile from the AUG campaign, we characterize the antenna both in terms of input parameters and of radiated fields. In particular, we compare TOPICA results obtained with a simplified 3D flat model adopted during the design phase with the exact 3D curved geometry installed on the AUG experiment. In particular, the curved model predicts a lower coupling to plasma and higher RF electric fields with slightly different distribution in front of the launcher. The capability to include a fully 3D curved model is of great importance to correctly account for all geometrical effects on the antenna performances. The advantages and disadvantages of both geometrical representations are eventually outlined, trying to estimate how the curvature of the antenna can affect code predictions. Comparisons between measured experimental results and simulated ones are presented in [8].

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“…We refer the interested reader to [8] for the analysis of the antenna behavior during the experiment and the comparison with numerical predictions.…”

Section: Analysis Of the Resultsmentioning

confidence: 99%

“…The advantages and disadvantages of both geometrical representations are eventually outlined, trying to estimate how the curvature of the antenna can affect code predictions. Comparisons between measured experimental results and simulated ones are presented in [8]. …”

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confidence: 99%

Analysis of the ASDEX Upgrade 3-strap antenna with TOPICA code: Curved vs. flat 3D geometry

2017

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“…Also, to the extent permitted by finite DC resistivity, a DC potential difference may be established between the antenna sheath and the far-field sheath governed in part by the DC plasma current which will flow between these two surfaces. DC currents associated with applied ICRF power have been observed in many experiments (Van Nieuwenhove & Oost 1992;Bobkov et al 2017b;Perkins et al 2017Perkins et al , 2019Myra et al 2020). DC current flow will be discussed in more detail in § 6.6.…”

Section: Magnetically Connected Far-field Sheathsmentioning

confidence: 99%

A tutorial on radio frequency sheath physics for magnetically confined fusion devices

Myra

2021

J. Plasma Phys.

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Radio frequency (RF) sheaths occur under a wide variety of conditions when RF waves, material surfaces and plasma coexist. RF sheaths are of special importance in describing the interaction of ion cyclotron range of frequency (ICRF) waves with the boundary plasma in tokamaks, stellarators and other magnetic confinement devices. In this article the basic physics of RF sheaths is discussed in the context of magnetic fusion research. Techniques for modelling RF sheaths, their interaction with RF wave fields and the resulting consequences are highlighted. The article is intended as a guide for the early-career ICRF researcher, but it may equally well serve to provide an overview of basic RF sheath concepts and modelling directions for any interested fusion scientist.

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“…An example of this is shown in Fig. 5, in which large unbalanced image currents on the antenna limiters and ∥ fields in front of the antenna limiters (calculated by TOPICA [3]) are generated when is too small (case (a)) or too large (case (c), see [23] for more details). Numerical simulations show that the 3-strap antenna even with non-optimized settings (i.e.…”

Section: Reduce Rf-specific Impuritiesmentioning

confidence: 99%

Recent progress on improving ICRF coupling and reducing RF-specific impurities in ASDEX Upgrade

et al. 2017

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Abstract. The recent scientific research on ASDEX Upgrade (AUG) has greatly advanced solutions to two issues of Radio Frequency (RF) heating in the Ion Cyclotron Range of Frequencies (ICRF): (a) the coupling of ICRF power to the plasma is significantly improved by density tailoring with local gas puffing; (b) the release of RF-specific impurities is significantly reduced by minimizing the RF near field with 3-strap antennas. This paper summarizes the applied methods and reviews the associated achievements.

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Characterization of 3-strap antennas in ASDEX Upgrade

Cited by 14 publications

References 11 publications

Analysis of the ASDEX Upgrade 3-strap antenna with TOPICA code: Curved vs. flat 3D geometry

Analysis of the ASDEX Upgrade 3-strap antenna with TOPICA code: Curved vs. flat 3D geometry

A tutorial on radio frequency sheath physics for magnetically confined fusion devices

Recent progress on improving ICRF coupling and reducing RF-specific impurities in ASDEX Upgrade

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