Speaker
Description
The EUROfusion consortium is currently investigating the feasibility of a compact tokamak to be used as a Volumetric Neutron Source (VNS) with the aim of creating a reactor-relevant environment in terms of neutron fluence and high energy neutron to test key components of the different breeding blanket concepts.
In order to meet the design requirements in terms of plasma current and its equilibrium, a design option entirely based on High Temperature Superconducting (HTS) coils have been proposed and it is currently under investigation. In particular, the toroidal and poloidal field coils would be wound with the LASSO cable concept, proposed and tested by the Swiss Plasma Center (SPC). In this design, the HTS tapes are wound in stacks which are then placed in grooves made of stainless-steel, which provide the mechanical support for the coils. The stacks are insulated and cooled indirectly with supercritical helium which would flow in dedicated pipes in the winding pack. Therefore, the coils are not based on the ‘classical’ cable-in-conduit conductor concepts, where the fluid flow is in direct contact with the strands/tapes and for which several numerical models have been already developed and validated in the past.
The present work is then focused on the assessment of the capability of currently available models to follow challenging, i.e., fast, transients, such as the quench propagation in such coils. The indirect cooling and the presence of a large fraction of stainless steel in the winding pack may induce thermal gradients both in the axial and in the transverse direction, especially during the quench propagation, thus an hybrid approach based on a detailed 3D model of a portion of the winding pack -where the quench is propagating- coupled with a simplified 1D model of the winding pack elsewhere is proposed, in order to accurately, yet efficiently, follow the transient.
