Study On The Superconducting Strand And Cable’s Mechanical-Electrical Model

Materials whose resistance will become zero when temperature is below their critical temperatures. This kind of phenomena is called superconducting phenomena. And this kind of materials are called superconducting materials. Due to theirs current-carrying capacity without resistance, perfect diamagnetism and the Josephson effect, the superconducting materials are widely used in energy, transportation, information, medical technology, scientific instrument and so on. ITER(InternationaI Thermonuclear Experimental Reactor) is one of the word’s biggest multidisciplinary engineering project. The design of the magnetic system involves in lots of superconductivity physics, superconducting materials and superconducting mechanics’research. CICC(Cable in conduit conductor) is the foundation of the magnetic system and the degradation performance of CICC is one of the crucial issue in reliability design and safety operation. Due to the multistage twisted structure, the performance of is complicated to study. As the base component of CICC, the study on the NbsSn strand’s critical current can be influenced by the strain, temperature, magnetic, the n value and so on. Therefor the study on the superconducting strands and cable is very necessary.In this paper the NbaSn is chosen as the basic object to be studied. The strand is simplified as elastically rod. Base on the elastic rod theory, strand’s equilibrium equation is obtained. Both the Transverse electromagnetic load and the thermal load have been considered in this paper. The 2D model is calculated in order to obtain the relevant mechanical performance. After that the 3D model is studied also.When study the strand’s electrical properties, the average integral method is employed to obtain the voltage-current characteristic curve. The Summers’s law is employed to gain the correlated quantities of the critical current density. Then the calculated result is expanded to the whole cable level to analyze the CICC’s degradation performance. After that the cable’s degradation performance influenced by void fraction, n-value, twisted angle, characteristic wavelength, temperature, magnetic field have been studied respectively.By the end of the article, a 3D circuit network model is adopted to study the degradation performance of CICC. Not only the contact resistance between the superconducting filament and the matrix but also the contact resistance between the matrix elements has been considered. The superconducting filament and the metal matrix are simplified as resistor elements respectively. Base on the Kirchhoff s law, the constitutive equations are acquired. Solve the constitutive equations to analyze the strand’s transmission characteristics.The results indicate that decreasing the void fraction in a reasonable range can lead a performance promotion at a certain extent. And it can be obtained qualitatively that increasing the n value also can decrease the performance degradation. The performance degradation can be decreased by increasing the twisted angle and the characteristic wavelength either. In addition decreasing both the temperature and magnetic field or increasing the thickness of the Ta can decrease the performance degradation as well. At last it can be obtained that considering the copper’s influence or the contact forms can deepen the current transfer.Through the research it can be expected to make more reasonable and accurate prediction about the degradation performance of CICC.