The process superconducting material developed with NbTi alloy composite superconductors must be encased or embedded in an ordinary good conductor to provide a low resistance bypass for sudden transition to normal at certain lines. In addition, encasement is important in preventing the leap of magnetic field lines. In other words, suitable basic materials must be used in order to reduce losses and improve stability. The choice of the base material depends on conflicting requirements. The theory of Wilson and his colleagues shows that a highly conductive matrix allows thinner wires to be used, but its multistrand cables must be twisted more tightly. According to the Germans, the main reason for choosing high conductive oxygen free copper as the superconducting material NbTi alloy's matrix material is that when the superconducting state appears instantaneous disturbance due to the local temperature rise, the transport current can be moved to the matrix, so that the joule heat that has appeared can be kept at a sufficiently small degree. However, it has been pointed out that copper, which has good stabilization properties, has not been able to adequately limit the induced current.
Introduction saw titanium alloy superconductors of raw material and manufacturing cost is much lower than other superconducting materials: this superconducting materials in stranding, winding assembly and other application before it can be to improve the performance of a superconductor heat treatment process: it bends down and close to the advantages of steel strength, these excellent performance will keep NbTi superconducting alloys - quite a long period to continue in the future Widely used.
The resistivity of high purity aluminum is lower than that of oxygen free copper at any magnetic field intensity. It must be pointed out that at higher field strengths, it makes more sense. Because of the low resistivity of aluminum, the joule heat is reduced by shunt and the disturbance of the magnetic field is controlled when aluminum is used as the matrix.
The composite design of multi-core complex is carried out before hot extrusion. The design is based on the parameter requirements of finished superconducting wire, such as wire diameter, core diameter, copper ratio, etc., to calculate the size of cladding barrier layer, NBi bar and extrusion times. In the multi-core composite line, NbTi core-wires are closely arranged, and from the core to the outside, they are arranged in hexagonal layers. The number of roots of each layer forms an arithmetic series in turn.
