Speaker
Description
There are many applications, companies and institutes pursuing and building large and high field REBCO magnets for a variety of applications, for example the toroidal field coils of a tokamak. Using a classical external dump for discharge and quench protection presents several problems, such as very high voltages. Whether or not these magnets can be protected using internal non-insulation or partial insulation technology is an ongoing debate in the HTS and magnet communities. Tokamak Energy have pioneered partial insulation for high stored energy density fusion magnets. In this talk we will discuss the physical and engineering parameters that are necessary to successfully control a discharge in the event of a quench of a large scale and high stored energy REBCO magnet. These includes critical current margin, normal state conductivity, thermal conductivity, heat capacity, protection voltage, mechanical properties and many others. To explore this, we present the results of several electromagnetic-thermal and stress simulations, highlighting the failure modes and where the window for success can be found. We will present on how balancing the necessary parameters against one another, and selecting appropriate materials and technologies, can result in a safe discharge, successfully extracting the stored magnetic energy from a large coil. Having identified a technology path on protecting coils of this scale and stored energy, we present the first experimental results on validating this approach in real magnets. We will show how experimentally validated simulation tools predict that ReBCO coils of the scale necessary for a fusion power plant are protectable with partial insulation technology.
