Developing high performance RF heating scenarios on the WEST tokamak

Marc Goniche (1, 2) , Clarisse Bourdelle (1, 2) , J.F. Artaud (1, 2) , Jean-Michel Bernard (1, 2) , Jérôme Bucalossi (1, 2) , Laurent Colas (1, 2) , Corinne Desgranges (1, 2) , Delpech Léna (1, 2) , P Devynck (1, 2) , V. Bobkov (3) , J. Gaspar (4) , C.C. Klepper (5) , E Lerche (6) , S. Shiraiwa (7) , L. Vermare (8) , G.M. Wallace (9)

1 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
2 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique
3 max planck institute fur plasmaphysics
4 AMU - Aix Marseille Université
5 ORNL - Oak Ridge National Laboratory [Oak Ridge]
6 LPP - Laboratory for Plasma Physics
7 PPPL - Princeton Plasma Physics Laboratory
8 LPP - Laboratoire de Physique des Plasmas
9 MIT Plasma Science and Fusion Center

High power experiments, up to 9.2 MW with LHCD and ICRH, have been carried out in the full tungsten tokamak WEST. Quasi non inductive discharges have been achieved allowing to extend the plasma duration to 53s at medium density (ne=3.7×10 19 m-3). Apart few pulses post-boronization, the plasma radiation is rather high (Prad/Ptot~50%) and is dominated by W. This fraction does not vary as the RF power is ramped up and, against expectations, it is quite similar in ICRH and/or LHCD heated plasmas. Hot L mode plasmas (Te(0)>3keV) with a confinement time following the ITER L96 scaling are routinely obtained, confirming the weak aspect ratio dependence of this scaling law. Tungsten accumulation is generally not an operational issue on WEST. Nonetheless, 25% of the of the discharges are affected by a rapid collapse of the central electron temperature which occurs when a slight decrease of Te leads to enhanced radiation causing flat or hollow current profiles. To this respect LHCD-only discharges are compared to ICRH and ICRH/LHCD discharges.

Domaines: Physique [physics]

Marc Goniche, Clarisse Bourdelle, J.F. Artaud, Jean-Michel Bernard, Jérôme Bucalossi, et al.. Developing high performance RF heating scenarios on the WEST tokamak. FEC 2020 - 28th IAEA fusion energy conference, May 2021, E-conference, France. ⟨cea-03520558⟩