Effective field in large size superconducting cables for fusion

Abstract

The magnetic field is not constant over the cross-section of cable superconductors. This work assesses different cable layouts from round to rectangular and square cross-section to define and compare their current sharing temperature and effective magnetic field. We discuss of the effective field vs cable layout parameters, the pros and cons applicable to fusion. One of the most important challenges is to control the plasma in fusion reactors is design high performance superconducting magnets. Fusion was achieved in JET reactor but actually a self-sustained fusion is the goal to make new fusion energy plants. The project which could achieve this self-sustained fusion reaction is ITER reactor. ITER most powerful magnets are the toroidal field coil and the central solenoid coil. The magnetic fields of these coils are generated through CICC made with superconducting materials. The material treated in this work is Nb3Sn. The TF coils and its conductors are described to have an idea about how they work and the importance of its effective magnetic field. This Master Dissertation tries to identify what are the best cross-section layout for different rectangular and square cross-section conductors, as compared to the round shape conductors employed in ITER reactor. The work is simulated through a MATLAB software. The simulations can describe the magnetic field distribution in different shaped conductors which share the same area. Once we have the magnetic field distribution we can simulate the critical current density distribution and finally the electric field distribution. With the different electric field distributions for different temperatures we found the current sharing temperature where the electric field average in the conductor is equal to the critical electric field. Finally, when we obtain the Tcs we can calculate the effective magnetic field for each aspect ratio of rectangular shapes and compare it with round conductors to draw conclusions.