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Optimized phasing conditions to avoid edge mode excitation by ICRH antennas

Part of: Invited Contributions from the 18th European Fusion Theory Conference Focus on Fusion

Published online by Cambridge University Press:  03 December 2020

V. Maquet Open the ORCID record for V. Maquet [Opens in a new window]  and
A. Messiaen Open the ORCID record for A. Messiaen [Opens in a new window]
V. Maquet*
Affiliation:
Laboratory for Plasma Physics – ERM/KMS, Avenue de la Renaissance 30, B-1000, Brussels Université Libre de Bruxelles, Avenue F.D. Roosevelt 50, B-1050, Brussels
A. Messiaen
Affiliation:
Laboratory for Plasma Physics – ERM/KMS, Avenue de la Renaissance 30, B-1000, Brussels
*
†Email address for correspondence: [email protected]
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Abstract

An ion cyclotron resonance heating (ICRH) antenna system must launch radio frequency (RF) power with a wavenumber spectrum which maximizes the coupling to the plasma. It should also ensure good absorption while minimizing the wave interaction with the plasma edge. Such interactions lead to impurity release, whose effect has been measured far from the antenna location (Klepper et al. 2013; Wukitch et al. 2017; Perkins et al. 2019) and can involve the entire scrape-off layer. In the normal heating scenario, for which the frequency of the waves launched by the antenna is larger than the ion cyclotron frequency of the majority ions $\omega > \omega _{\textrm {ci},\textrm {maj}}$, release of impurities due to ICRH can be affected by minimizing the low $|k_{\parallel }| < k_0$ power spectrum components of the antenna. Impurity release can be the result of low central absorption of the waves or power transfer from the fast to the slow wave due to the presence of a confluence in the plasma edge. In ASDEX Upgrade (AUG), a reduction of heavy impurity release by ICRH in the plasma was qualitatively well correlated to the parallel electric field and RF currents flowing around the antenna (Bobkov et al. 2017). In this article, we first show a correlation between the reduction in impurity release by ICRH in AUG and the rejection of the low $|k_{\parallel }| < k_0$ region of the antenna power spectrum. We show that the same correlation holds for results obtained in the Alcator C-Mod tokamak. Finally, using this idea, we reproduce ICRH induced impurity release behaviour in a not yet published experiments of JET, and make predictions for ITER and DEMO.

Keywords

plasma heatingICRHedge modes
Type
Research Article
Information
Journal of Plasma Physics , Volume 86 , Issue 6 , December 2020 , 855860601
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Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press

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References

REFERENCES

ANSYS 2020 High frequency structure simulator. Available at: www.ansys.com.Google Scholar
Berro, E. A. & Morales, G. J. 1990 Excitation of the lower-hybrid resonance at the plasma edge by ICRF couplers. IEEE Trans. Plasma Sci. 18 (1), 142–148.Google Scholar
Bobkov, V., Aguiam, D., Bilato, R., Brezinsek, S., Colas, L., Czarnecka, A., Dumortier, P., Dux, R., Faugel, H., Fünfgelder, H., et al. 2019 Impact of ICRF on the scrape-off layer and on plasma wall interactions: from present experiments to fusion reactor. Nucl. Mater. Energy 18, 131–140.Google Scholar
Bobkov, V., Aguiam, D., Bilato, R., Brezinsek, S.,Colas, L., Faugel, H., Fünfgelder, H., Herrmann, A., Jacquot, J., Kallenbach, A., et al. 2016 a Making ICRF power compatible with a high-z wall in ASDEX upgrade. Plasma Phys. Control. Fusion 59 (1), 014022.Google Scholar
Bobkov, V., Bilato, R., Colas, L., Dux, R., Faudot, E., Faugel, H., Fünfgelder, H., Herrmann, A., Jacquot, J., Kallenbach, A., et al. 2017 Characterization of 3-strap antennas in ASDEX upgrade. In EPJ Web of Conferences, vol. 157, 03005.Google Scholar
Bobkov, V., Braun, F., Dux, R., Herrmann, A., Faugel, H., Fünfgelder, H., Kallenbach, A., Neu, R., Noterdaeme, J.-M., Ochoukov, R., et al. 2016 b First results with 3-strap ICRF antennas in ASDEX upgrade. Nucl. Fusion 56 (8), 084001.Google Scholar
Bures, M., Brinkschulte, H., Jacquinot, J., Lawson, K., Kaye, A & Tagle, J. 2000 The modification of the plasma edge and impurity production by antenna phasing during ICRF heating on jet. Plasma Phys. Control. Fusion 30, 149.Google Scholar
Czarnecka, A., Durodié, F., Figueiredo, A. C. A., Lawson, K. D., Lerche, E., Mayoral, M. L., Ongena, J., Van Eester, D., Zastrow, K. D., Bobkov, V. L., et al. 2012 Impurity production from the ion cyclotron resonance heating antennas in jet. Plasma Phys. Control. Fusion 54 (7), 074013.CrossRefGoogle Scholar
Cziegler, I., Terry, J. L., Wukitch, S. J., Garrett, M. L., Lau, C. & Lin, Y. 2012 Ion-cyclotron range of frequencies in the scrape-off-layer: fine structure radial electric fields. Plasma Phys. Control. Fusion 54 (10), 105019.Google Scholar
Klepper, C. C., et al. 2013 RF sheath-enhanced beryllium sources at jet's ICRH antennas. J. Nucl. Mater. 438, S594–S598. Proceedings of the 20th International Conference on Plasma-Surface Interactions in Controlled Fusion Devices.Google Scholar
Lawson, W. S. 1992 Coaxial and surface modes in tokamaks in the complete cold-plasma limit. Plasma Phys. Control. Fusion 34 (2), 175–189.Google Scholar
Messiaen, A., Beuken, J.-M., De Keyser, L., Delvigne, T., Descamps, P., Durodie, F., Gaigneaux, M., Jadoul, M., Koch, R., Lebeau, D., et al. 1989 Effect of antenna phasing and wall conditioning on ICRH in TEXTOR. Plasma Phys. Control. Fusion 31 (6), 921–939.CrossRefGoogle Scholar
Messiaen, A., Koch, R., Bhatnagar, V. P., Vandenplas, P. E. & Weynants, R. R. 1984 Analysis of the plasma edge radiation by ICRH antenna. In Commission of the European Communities, (Report), vol. 1, pp. 315–329. EUR.Google Scholar
Messiaen, A., Koch, R., Weynants, R. R., Dumortier, P., Louche, F., Maggiora, R. & Milanesio, D. 2010 Performance of the ITER ICRH system as expected from TOPICA and ANTITER II modelling. Nucl. Fusion 50 (2), 025026.CrossRefGoogle Scholar
Messiaen, A. & Maquet, V. 2020 Coaxial and surface mode excitation by an ICRF antenna in large machines like DEMO and ITER. Nucl. Fusion 60 (7), 076014.CrossRefGoogle Scholar
Murphy, A. B. 1990 Waves in the edge plasma during ion cyclotron resonance heating. Fusion Engng Des. 12 (1–2), 79–92.CrossRefGoogle Scholar
Myra, J. R., D'Ippolito, D. A., Russell, D. A., Berry, L. A., Jaeger, E. F. & Carter, M. D. 2006 Nonlinear ICRF-plasma interactions. Nucl. Fusion 46 (7), S455.CrossRefGoogle Scholar
Perkins, R. J., Hosea, J. C., Taylor, G., Bertelli, N., Kramer, G. J., Luo, Z. P., Qin, C. M., Wang, L., Xu, J. C. & Zhang, X. J. 2019 Resolving interactions between ion-cyclotron range of frequencies heating and the scrape-off layer plasma in east using divertor probes. Plasma Phys. Control. Fusion 61 (4), 045011.CrossRefGoogle Scholar
Ragona, R., Messiaen, A., Ongena, J., Van Eester, D., Van Schoor, M., Bernard, J.-M., Hillairet, J. & Noterdaeme, J.-M. 2019 A travelling wave array system as solution for the ion cyclotron resonance frequencies heating of DEMO. Nucl. Fusion 60 (1), 016027.CrossRefGoogle Scholar
TFR Group, et al. 1985 Comparison of two $k_{\parallel }$ antenna configurations for ICRH experiments in TFR. In Proceedings of the 12th European Conference on Controlled Fusion and Plasma physics, vol. 9F, p. 108.Google Scholar
Van Eester, D., Crombé, K. & Kyrytsya, V. 2013 Ion cyclotron resonance heating-induced density modification near antennas. Plasma Phys. Control. Fusion 55, 12.CrossRefGoogle Scholar
Van Nieuwenhove, R., Koch, R & Van Oost, G. 1994 Observation of plasma expulsion from a powered screenless ICRF antenna. In 21st EPS Conference on Controlled Fusion and Plasma Physics (Montpellier, 1994) 18B II, vol. 976.Google Scholar
Wukitch, S., et al. 2017 Towards ICRF antennas compatible with high performance plasmas: characterization and mitigation of ICRF antenna–plasma edge interaction. In The 22nd Topical Conference on Radio-Frequency Power in Plasmas, Aix-en-Provence, France. Inv-08.Google Scholar