TY - JOUR
T1 - An ITER-relevant passive active multijunction launcher for lower hybrid current drive in JET-grade plasmas
AU - Belo, Jorge H.
AU - Bibet, Philippe
AU - Bizarro, João P.S.
AU - Bertrand, Bernard
AU - Cesario, Roberto
AU - Corona, Mauro
AU - Finburg, Paul
AU - Kaye, Alan S.
AU - Leguern, Frederic
AU - Lioure, Alain
AU - Mailloux, Joelle
AU - Mirizzi, Francesco
AU - Ongena, Jef
AU - Portafaix, Christophe
AU - Testoni, Pietro
AU - Tuccillo, Angelo A.
AU - Vallet, Jean Claude
AU - Walton, Bob
AU - Warren, Robert J.
AU - Wilson, David J.
PY - 2011/8
Y1 - 2011/8
N2 - Lower hybrid current drive (LHCD) has been demonstrated to be an important actuator for controlling the current profiles of advanced tokamak plasmas, either in fully non-inductive or in hybrid regimes. To continue such scenario development in JET, and most notably towards extrapolations for ITER, an upgrade of its LH launcher is required to deliver more power (>5 MW) and to deal with a broad array of density situations at the plasma edge more consistently. These may range from steep gradients to ELM activity; extend from as low as the cut-off density nec to large and fast density variations and give rise to strong and rapid reflections of RF power. The passive active multijunction (PAM), advocated as the LH launcher concept for ITER, is claimed to be more resilient to such conditions, run with increased efficiency near nec and even with a small vacuum gap, being also specially appropriate for long pulse operation - all conditions hampering traditional designs. In addition, some of this leverage has been confirmed experimentally at the ITER-relevant FTU with the first PAM ever deployed, and more recently with Tore Supra's PAM. The JET version addressed in this study, with the latter focusing on the physics that drives and supports the adopted technical solutions, allows the injection of up to 5.2 MW at 3.7 GHz and N ∥peak = 1.9. With directivities better than 70%, reflection coefficients below 2% even for ∼nec and power densities comparable to those foreseen for ITER at 5 GHz, it would validate this concept in ITER-relevant scenarios.
AB - Lower hybrid current drive (LHCD) has been demonstrated to be an important actuator for controlling the current profiles of advanced tokamak plasmas, either in fully non-inductive or in hybrid regimes. To continue such scenario development in JET, and most notably towards extrapolations for ITER, an upgrade of its LH launcher is required to deliver more power (>5 MW) and to deal with a broad array of density situations at the plasma edge more consistently. These may range from steep gradients to ELM activity; extend from as low as the cut-off density nec to large and fast density variations and give rise to strong and rapid reflections of RF power. The passive active multijunction (PAM), advocated as the LH launcher concept for ITER, is claimed to be more resilient to such conditions, run with increased efficiency near nec and even with a small vacuum gap, being also specially appropriate for long pulse operation - all conditions hampering traditional designs. In addition, some of this leverage has been confirmed experimentally at the ITER-relevant FTU with the first PAM ever deployed, and more recently with Tore Supra's PAM. The JET version addressed in this study, with the latter focusing on the physics that drives and supports the adopted technical solutions, allows the injection of up to 5.2 MW at 3.7 GHz and N ∥peak = 1.9. With directivities better than 70%, reflection coefficients below 2% even for ∼nec and power densities comparable to those foreseen for ITER at 5 GHz, it would validate this concept in ITER-relevant scenarios.
UR - https://www.scopus.com/pages/publications/80051649059
U2 - 10.1088/0029-5515/51/8/083017
DO - 10.1088/0029-5515/51/8/083017
M3 - Article
AN - SCOPUS:80051649059
SN - 0029-5515
VL - 51
JO - Nuclear Fusion
JF - Nuclear Fusion
IS - 8
M1 - 083017
ER -