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P: Fachverband Plasmaphysik

P 20: Invited talks V

P 20.1: Invited Talk

Friday, April 1, 2022, 11:00–11:30, P-H11

On the hunt for a reactor-relevant scenario for W7-X — •Golo Fuchert for the W7-X team collaboration — Max-Planck-Institut für Plasmaphysik, Greifswald, Germany

The optimized stellarator Wendelstein 7-X (W7-X) aims to demonstrate a steady-state reactor-relevant scenario. Already the first divertor experiments at W7-X gave initial insights in how such a scenario could potentially look like, which key questions need to be answered in order to improve the performance of W7-X, and if the scenarios that will be developed can also teach us something about a potential reactor. A starting point of scenario development is the understanding of operational limits. Obviously it has to be physically possible to run a particular scenario. Here, mainly limitations arising from the ECR heating physics and the power balance (radiative density limit) have been identified in the first experimental campaigns of W7-X and essentially follow theoretical expectations. Furthermore, a reactor-relevant scenario should combine good energy confinement, steady-state conditions and divertor detachment. All three criteria have been achieved individually. Good confinement seems to depend on reduced turbulent transport in plasmas with steep density gradients. Steady-state plasmas have been achieved at moderate densities and heating powers. And detachment was demonstrated at high densities. But combining all three into an integrated scenario is a challenge that will guide the experimental exploration of W7-X for the foreseeable future. On this path, the flexibility of the magnetic configuration offers unique opportunities, but increases the complexity of the task at hand.