TY - GEN
T1 - LH power modulation experiment on JET
AU - Baranov, Y.
AU - Kirov, K.
AU - Goniche, M.
AU - Mailloux, J.
AU - Mayoral, M. L.
AU - Ongena, J.
AU - Nave, F.
PY - 2009
Y1 - 2009
N2 - LH power modulation was recently used at JET to quantify experimentally the LH current drive efficiency and power deposition. A new approach was applied for the analysis of the amplitude and phase of electron temperature T e perturbations δTe(kωo) at different harmonics k of the modulation frequency ωo. A solution of the Fokker-Planck equation combined with heat transport modelling was used to study the dependence of the ratio of the perturbation of different harmonics k and n, δTe(kωo)/δT e(nωo), and the phase shift of the harmonics δφ(kωo) on the plasma parameters and electron distribution function plateau width, which is directly connected to the current drive efficiency. The results of the modelling were compared with the experimental data to estimate the current drive efficiency. In addition, LH power deposition profiles were deduced from the radial dependence of δφ(ωo). The maximum of the LH power deposition becomes more peripheral and with a reduced current drive efficiency at higher densities. In H-Mode plasmas, at pedestal densities above the LH accessibility limit, a large fraction of the power is absorbed beyond the separatrix. Finally, the experimental power deposition profiles are more peripheral than the calculated ones obtained from combined ray tracing and Fokker-Planck Plank modelling. The experimental results indicate that the LH power spectrum in the plasma is modified, with more power in the high N∥ components.
AB - LH power modulation was recently used at JET to quantify experimentally the LH current drive efficiency and power deposition. A new approach was applied for the analysis of the amplitude and phase of electron temperature T e perturbations δTe(kωo) at different harmonics k of the modulation frequency ωo. A solution of the Fokker-Planck equation combined with heat transport modelling was used to study the dependence of the ratio of the perturbation of different harmonics k and n, δTe(kωo)/δT e(nωo), and the phase shift of the harmonics δφ(kωo) on the plasma parameters and electron distribution function plateau width, which is directly connected to the current drive efficiency. The results of the modelling were compared with the experimental data to estimate the current drive efficiency. In addition, LH power deposition profiles were deduced from the radial dependence of δφ(ωo). The maximum of the LH power deposition becomes more peripheral and with a reduced current drive efficiency at higher densities. In H-Mode plasmas, at pedestal densities above the LH accessibility limit, a large fraction of the power is absorbed beyond the separatrix. Finally, the experimental power deposition profiles are more peripheral than the calculated ones obtained from combined ray tracing and Fokker-Planck Plank modelling. The experimental results indicate that the LH power spectrum in the plasma is modified, with more power in the high N∥ components.
UR - https://www.scopus.com/pages/publications/73449133355
U2 - 10.1063/1.3273763
DO - 10.1063/1.3273763
M3 - Conference contribution
AN - SCOPUS:73449133355
SN - 9780735407534
T3 - AIP Conference Proceedings
SP - 343
EP - 346
BT - Radio Frequency Power in plasmas - Proceedings of the 18th Topical Conference
T2 - 18th Topical Conference on Radio Frequency Power in plasmas
Y2 - 24 June 2009 through 26 June 2009
ER -