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A detailed comparison of antenna impedance measurements on ASDEX Upgrade with the ion cyclotron range of frequencies antenna code TOPICA

(2015) NUCLEAR FUSION. 55(11).
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Abstract
New antenna diagnostics on the ASDEX Upgrade, in the form of voltage and current probe pairs on the feeding lines of each ion cyclotron range of frequencies antenna, close to the input ports, have made it possible to study in detail the behavior of the ASDEX Upgrade two-strap antenna under changing loading conditions, and compare these measurements with the results of simulations using the TOPICA code. The present work extends previous studies by using the input impedance (more precisely, the complex voltage reflection coefficient Gamma) on each antenna port for comparison, instead of the more commonly used loading resistance or coupled power. The electron density profiles used for the simulation were reconstructed from the deuterium-carbon-nitrogen interferometer and lithium beam emission spectroscopy measurements, edge-localized mode-synchronized and averaged over time intervals from 10 to 200 ms depending on the case; 112 cases were compared from seven ASDEX Upgrade discharges with widely different plasma parameters and two operating frequencies (30 and 36.5 MHz). Very good agreement in vertical bar Gamma vertical bar was found with the measurements on antenna 3 (<3% averaged over a shot), and good agreement was found with antennas 1 and 2 (<10%); the code reproduced the correct trend in loading resistance R-L in a significant majority of cases, although the discrepancies in the absolute values were rather high (up to similar to 50%) due to high reflection. Sources of discrepancy are discussed.
Keywords
coupling, PLASMAS, antenna impedance, POWER, ion cyclotron range of frequencies, WAVES, ICRF ANTENNA, PERFORMANCE

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Chicago
Stepanov, Ivan, Jean-Marie Noterdaeme, V Bobkov, H Faugel, D Coster, D Milanesio, R Maggiora, et al. 2015. “A Detailed Comparison of Antenna Impedance Measurements on ASDEX Upgrade with the Ion Cyclotron Range of Frequencies Antenna Code TOPICA.” Nuclear Fusion 55 (11).
APA
Stepanov, I., Noterdaeme, J.-M., Bobkov, V., Faugel, H., Coster, D., Milanesio, D., Maggiora, R., et al. (2015). A detailed comparison of antenna impedance measurements on ASDEX Upgrade with the ion cyclotron range of frequencies antenna code TOPICA. NUCLEAR FUSION, 55(11).
Vancouver
1.
Stepanov I, Noterdaeme J-M, Bobkov V, Faugel H, Coster D, Milanesio D, et al. A detailed comparison of antenna impedance measurements on ASDEX Upgrade with the ion cyclotron range of frequencies antenna code TOPICA. NUCLEAR FUSION. 2015;55(11).
MLA
Stepanov, Ivan et al. “A Detailed Comparison of Antenna Impedance Measurements on ASDEX Upgrade with the Ion Cyclotron Range of Frequencies Antenna Code TOPICA.” NUCLEAR FUSION 55.11 (2015): n. pag. Print.
@article{6999506,
  abstract     = {New antenna diagnostics on the ASDEX Upgrade, in the form of voltage and current probe pairs on the feeding lines of each ion cyclotron range of frequencies antenna, close to the input ports, have made it possible to study in detail the behavior of the ASDEX Upgrade two-strap antenna under changing loading conditions, and compare these measurements with the results of simulations using the TOPICA code. The present work extends previous studies by using the input impedance (more precisely, the complex voltage reflection coefficient Gamma) on each antenna port for comparison, instead of the more commonly used loading resistance or coupled power. The electron density profiles used for the simulation were reconstructed from the deuterium-carbon-nitrogen interferometer and lithium beam emission spectroscopy measurements, edge-localized mode-synchronized and averaged over time intervals from 10 to 200 ms depending on the case; 112 cases were compared from seven ASDEX Upgrade discharges with widely different plasma parameters and two operating frequencies (30 and 36.5 MHz). Very good agreement in vertical bar Gamma vertical bar was found with the measurements on antenna 3 (<3% averaged over a shot), and good agreement was found with antennas 1 and 2 (<10%); the code reproduced the correct trend in loading resistance R-L in a significant majority of cases, although the discrepancies in the absolute values were rather high (up to similar to 50%) due to high reflection. Sources of discrepancy are discussed.},
  articleno    = {113003},
  author       = {Stepanov, Ivan and Noterdaeme, Jean-Marie and Bobkov, V and Faugel, H and Coster, D and Milanesio, D and Maggiora, R and Siegl, G and Bilato, R and Brambilla, M and Verdoolaege, Geert and Braun, F and Fünfgelder, H and D'Inca, R and Suttrop, W and Kallenbach, A and Schweinzer, J and Wolfrum, E and Fischer, R and Mlynek, A and Nikolaeva, V and Guimarais, L},
  issn         = {0029-5515},
  journal      = {NUCLEAR FUSION},
  keywords     = {coupling,PLASMAS,antenna impedance,POWER,ion cyclotron range of frequencies,WAVES,ICRF ANTENNA,PERFORMANCE},
  language     = {eng},
  number       = {11},
  pages        = {16},
  title        = {A detailed comparison of antenna impedance measurements on ASDEX Upgrade with the ion cyclotron range of frequencies antenna code TOPICA},
  url          = {http://dx.doi.org/10.1088/0029-5515/55/11/113003},
  volume       = {55},
  year         = {2015},
}

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