This work will be done in cooperation with the Max-Planck Institute for Plasma physics in Greifswald.

Wendelstein 7-X (W7-X) is the most advanced stellerator to date. Handling the power exhaust of high-energy plasma is one of the biggest challenges. With the island divertor concept, multiple helical magnetic island chains are generated at the plasma boundary for guiding the power and particle exhausts. These island chains are predominantly intersected by 10 divertor plates [1], where most heat fluxes are deposited. To ensure safe operation, the surface temperatures of the divertor plates are constantly monitored by the 10 calibrated wide-angle Infra-red cameras [2].

In the previous experimental campaign of W7-X, the inertially cooled test divertor units (TDUs) were installed to prepare for steady-state operation in the upcoming campaign with water-cooled high heat flux (HHF) components [3]. The perpendicular heat flux onto the divertor plates was calculated from the measured surface temperature evolution using the 2D explicit heat diffusion solver THEODOR (THermal Energy Onto DivertOR) code [4, 5]. To calculate the heat flux of the water-cooled HHF divertor for the next campaign, we need further development of the THEODOR code.

In the current stage of the code, thermal properties of only one material (i.e. graphite for TDUs) are allowed. However, in order to simulated the heat diffusion process inside the plasma-facing components (PFCs), multiple materials as applied in the PFCs should be implemented in the code, including the interlayer and the heat sink. The water-removed heat loads should also be treated properly as a cooling coefficient at the bottom bound of the calculation domain. Finally, the code should be benchmarked with existing finite element analysis, and be used for the next campaign for fast heat flux calculation.

The candidate is expected to have good programming skills in Python and C++. The candidate must be fluent in English.

Thesis supervisor will be Yu Gao from the Max-Planck Institute for Plasmaphysics in Greifswald.

This thesis topic is assigned.

References:

[1] Renner H. et al 2004 Fusion Sci. Technol. 46 318

[2] Jakubowski M. et al 2018 Rev. Sci. Instrum. 89 10E116

[3] Peacock A. et al 2014 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 42, NO. 3

[4] Herrmann A. et al 1995 Plasma Phys. Control. Fusion 37 17

[5] Gao Y. et al 2019 Nucl. Fusion 59 (2019) 066007 (15pp)