Structural optimisation of the DEMO alternative divertor configurations based on FE and RBF mesh morphing

Area of Science:

• Nuclear Fusion Engineering
• Plasma Physics
• Structural Mechanics

Background:

• Tokamak design, like for the DEMO fusion reactor, is complex due to multidisciplinary physics and engineering requirements.
• Toroidal field (TF) coils are critical for plasma confinement and must withstand significant electromagnetic forces.
• Advanced divertor configurations (ADCs) necessitate TF coil shape adaptations due to larger structural requirements.

Purpose of the Study:

• To adapt the shape of toroidal field coils for advanced divertor configurations in the DEMO tokamak.
• To investigate structural optimization strategies for TF coils under demanding operational loads.
• To reduce the high static membrane stress levels in TF coils.

Main Methods:

• A structural optimization procedure was applied to the reference TF coil shape.
• The strategy involved achieving an iso-stress profile for each coil.
• Radial basis functions mesh morphing was used to transform the baseline finite element model.

Main Results:

• Candidate TF coil shapes were determined for each advanced divertor configuration case.
• Static membrane stress levels during magnetization were significantly reduced from over 700 MPa to below 450 MPa.
• The optimized shapes facilitate the integration of larger divertor structures within the TF coils.

Conclusions:

• The applied structural optimization strategy successfully adapted TF coil shapes for ADCs.
• The optimized designs offer improved structural performance by reducing stress concentrations.
• This approach provides a pathway for designing robust TF coils for future fusion reactors.