Berlin 2014 – scientific programme
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P: Fachverband Plasmaphysik
P 2: Magnetic Confinement I
P 2.3: Topical Talk
Monday, March 17, 2014, 11:25–11:50, SPA HS202
Characterisation of plasma start-up using ECRH in preparation of W7-X operation — •M. Preynas1, H. P. Laqua1, M. Otte1, T. Stange1, T. Wauters2, H.T. Kim3, D. Aßmus1, H. Igami4, S. Kado5, S. Kobayashi5, S. Kubo4, T. Mutoh4, K. Nagasaki5, T. Shimozuma4, and Y. Yoshimura4 — 1IPP, D-17491 Greifswald, Germany — 2Ass. Euratom-Belgian State, LPP-ERM/KMS, 1000 Brussels, Belgium — 3EURATOM/CCFE Fusion Ass., Abingdon, OX14 3DB, UK — 4NIFS, Toki 509-5292, Japan — 5IAE, Kyoto University, Japan
Although Electron Cyclotron Resonance Heating (ECRH) is used for pre-ionization and plasma breakdown in both tokamaks and stellarators, a complete theoretical model taking into account all the main physical processes is still missing. The main purpose is to insure reliable plasma start-up in the upcoming operation of W7-X stellarator. In addition to the standard scenario corresponding to on-axis heating in X2-mode, off-axis heating and X3-mode scenarios are also requested to insure plasma operation at lower magnetic field. In order to clarify the dominant physical process in the initial start-up phase governing the breakdown time, dedicated plasma start-up experiments were performed on several stellarators: WEGA, Heliotron-J and LHD. The DYON code, initially developed to simulate plasma burn-through in tokamaks, has been extended for stellarator application. The experimental characterization is presented and compared with first modeling results. Finally, extrapolation for plasma start-up scenario on W7-X is discussed.