S. Thiede (P): Trying to understand heat transport in the SOL of W7-X from thermography

• Sebastian Thiede (IPP Bereich Greifswald (E3))

Efficient power exhaust is one of the most important aspects of magnetic confinement devices. Plasma-facing components (PFCs) often need to be operated at their material limits, exposed to high heat fluxes of up to 10MW/m². Many devices, including W7-X, monitor them with infrared cameras, obtaining the surface temperature of PFCs throughout an experiment which can be used for overload protection. But often the physically more interesting quantity is the heat flux incident on the targets. This talk will discuss how we can infer approximate surface-heat fluxes from surface-temperature measurements and how we may draw conclusions about heat transport in the scrape-off layer (SOL) from them.

R. Stucchi (P): On the nonlinear excitation of zonal flows by Alfvén eigenmodes

• Riccardo Stucchi (IPP-Garching)

Employing nonlinear gyrokinetic theory, we investigate the nonlinear excitation of zero frequency zonal flows by Alfven eigenmodes in a tokamak burning plasma. In particular, we refine previous analytical formulations for the beat driven zonal flow in the simplified case of well circulating particles in circular geometry and we formulate a semi-analytical approach for the same zonal flow valid in general axis-symmetric toroidal geometry. The work is currently focused on further understanding the nonlinear generation process by exploiting the simplified analytical expressions and by coding up the semi-analytical approach into the LIGKA code. Future work including the comparison with ORB5 simulations, the investigation of the nonlinear saturation regime and the assessment of the impact of such zonal flows on the plasma confinement is foreseen.