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The influence of the current density (Jc) and magnetic flux density (B) on the losses in a superconductive tube fed by a transport current in incomplete current penetration is examined. The losses in the superconducting tube are calculated and compared with the measurements taken on a sample whose characteristic [J.sub.c](B) is already calculated.

To use high-Tc superconductors for alternating current transport, it is important to evaluate AC losses. The influence of .Jc(13) on the self field losses in a superconductive tube fed by a transport current in incomplete penetration is studied for two reasons. First, superconducting power cables have a geometry that resembles a tube and second, for high-temperature superconductors, the variation of .Jc(B) is important especially for low magnetic fields like self field. An analytical calculation of the distribution of the magnetic field B(r, t) by using a linearized law Jc(B) is presented. From B(r, t) one deduces .J(r, t) and E(r, t). The analytical expressions of those were used to calculate the analytical instantaneous power p(t). The losses in the superconducting tube are the average value of p(t). They are numerically calculated and compared with the measurements taken on a sample whose characteristic Jc(B) was previously measured. With the linear model, the calculated losses are closer to the measured losses than for the Bean model, but the Jc(B) identification remains the main problem. [ABSTRACT FROM AUTHOR]

Thermal aspects of a novel high temperature superconducting motor design are examined for use in the propulsion of an aero-vehicle. To simplify the refrigeration, focus is on conduction cooling of the superconducting material directly from the cold head of the cryocooler. A brief description of the motor is followed by an analysis of the conduction cooling apparatus. An experimental setup has been developed, including a cryocooler, a cryostat, and a mockup of the HTS motor, to validate the system model. [ABSTRACT FROM AUTHOR]

Current high temperature superconducting (HTS) wires exhibit high current densities enabling their use in electrical rotating machinery. The possibility of designing high power density superconducting motors operating at reasonable temperatures allows for new applications in mobile systems in which size and weight represent key design parameters. Thus, all-electric aircrafts represent a promising application for HTS motors. The design of such a complex system as an aircraft consists of a multi-variable optimization that requires computer models and advanced design procedures. This paper presents a specific sizing model of superconducting propulsion motors to be used in aircraft design. The model also takes into account the cooling system. The requirements for this application are presented in terms of power and dynamics as well as a load profile corresponding to a typical mission. We discuss the design implications of using a superconducting motor on an aircraft as well as the integration of the electrical propulsion in the aircraft, and the scaling laws derived from physics-based modeling of HTS motors. [ABSTRACT FROM AUTHOR]