One of the biggest challenges in making energy production by magnetic fusion a reality is in generating a strong enough magnetic field to contain the hot plasma. The required magnetic field strengths and the magnets required to produce them are very large, even larger if the plasma has to be constrained in small volumes like those predicted for ARC reactors. Another challenge is the irradiation of structural and non-structural components by fusion generated neutrons. Most neutrons are absorbed in the blanket and radiation shields, however, a small fraction reach reactor elements and could lead to loss of functional properties of such elements in the long term. Superconducting materials are needed in order to produce high enough magnetic fields to be able to confine the plasma. Several materials can be exploited with this aim. One of the initiatives that are underway within the Joint Research Agreement between Eni and CNR is about the identification, modelling, synthesis, characterization of pristine and particles irradiated new superconducting materials, in particular the Fe-based superconductors, for harsh fusion environments. In the present paper we summarize the actions planned to face such technological challenges and make Magnetic Fusion a reality.
The magnetic fields needed for applications such as nuclear fusion plants are in the range between 8 T and 20 T. In such conditions, superconducting materials are needed instead of Copper in order to build magnets for plasma confinement. Between the different superconductors studied and developed to date, it is necessary to identify which ones have, even potentially, the characteristics necessary for this type of application. The main parameter defining the performance of a superconductor is its engineering critical current density (Je), i.e. the critical current (current which can be carried without dissipation) a superconductor can carry divided by the total conductor section. Fig. 1 shows the Je as a function of the magnetic field for "technical" superconductors, i.e. available in long lengths, at low temperatures (4.2 K) for applications in high magnetic fields.