Limiting currents in superconducting composites

Results of numerical and analytical calculations of the process of current charging into a round superconducting composite with properties homogenized over cross section are presented. A wire with real volt-ampere characteristics approximated by an exponential dependence was considered. Calculations were carried out for various rates of current charging, volt-ampere characteristics, matrix materials, heat transfer coefficients, and other parameters. The results showed the existence of characteristic limiting value of current below which the wire remains in a superconducting state if the current charging ceases and above which it changes into a normal state; this current is somewhat less than a quench current. The existence of a finite value for limiting current at any low heat transfer from a surface was also shown. In addition, the analytical solution of the problem is given. It made it possible to formulate the stability criterion from which the dependence of limiting currents on initial parameters follows.<
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