Fig. 2. Nb3Sn bounds of superconductivity
While fabrication advancements have led to the optimisation of NbTi cabling [27], the fundamental design has not changed since it’s creation at the Rutherford Appleton Laboratory [36, 51]. The Rutherford cable is the most widely used cable type in accelerator magnets [26, 51]. A Rutherford cable is composed of fully transposed twisted composite strands, shown below in Figure 3 [34]. The cable critical current Ic is normally the sum of each strand’s critical current [53]. The Rutherford cable is still used today because it is permeable to liquid coolants due to its braided structure and the two layers of fully transposed strands limit nonuniform current distribution within the cable, caused by the cables self field and the flux linkage between strands [51]. There are three highly stressed sections of a Rutherford cabled pulsed solenoid, the copper wire matrix around the filaments, the epoxy reinforcement and the cable (or core strip) midplane. [8, 23, 46]