Carl H. Rosner

Characteristics and a New Application of High‐Field Superconductors

This paper presents a simple physical and mathematical model and experimental support of the manner in which magnetic flux penetrates into a high‐field superconductor. Based on this model a new device using high‐field superconductors in their bulk form called a superconducting magnetic flux compressor is proposed. Present theory suggests that magnetic field strengths approaching the critical field strength of a high‐field superconductor (> 100 kOe) should be attainable using the apparatus and techniques described. It was found experimentally with the particular high‐field superconductors tested that compressed field strengths of 15 kOe could be achieved. Beyond this value anomalous magnetic flux jumping occurred that limited the field strengths obtainable. The characteristic conditions under which magnetic flux jumping is found are discussed. The experimental results also suggest that heat is generated when a high‐field superconductor is exposed to an alternating magnetic field well below the critical fie...

Flux‐Jumping Behavior of Some Niobium‐Tin Solenoids

Oscillographic and X‐Y recorder observations have been made of the flux‐jumping pattern in several superconducting Nb3Sn solenoids at magnetic fields ranging from 15 to above 100 kG at 4.2°K. It is noted that flux jumping is much more frequent in these solenoids than is observed in Nb–Zr solenoids. The flux‐jump pattern extends throughout the high‐field region. It can be modified, however, by gross rate changes in current increase, as well as by application and removal of external fields which change the induced magnetization.Frequent quenching of the Nb3Sn superconducting solenoids does not seem to alter the flux‐jump behavior appreciably. The relationship of a superconductive transition to flux jumps occurring just prior to the transition is discussed.It is suggested that the more frequent but often lower‐amplitude flux jumps in these niobium‐tin solenoids contribute to the smaller coil degradation effect noticed as compared to niobium‐zirconium solenoids. To eliminate, or at least minimize this effect,...

Relating Measurements on Short Superconducting Wires to Solenoid Performance

ABS>A method for determining the critical current-field characteristics of short wire samples in superconducting solenoids is presented. The method consists in increasing the magnetic field and current simultaneously at constant but independent rates. In this way the actual field-current history of a wire at any point in a solenoid can be simuZr wire determined by, this method are presented. (C.E.S.)

``Coil Simulation'' Testing of Niobium‐Tin Wire Samples

The coil simulation test in which the current and field are increased simultaneously along predetermined straight current field lines is used to evaluate the superconducting critical current vs field characteristics of Nb-Sn wires in a solenoid. The critical current field characteristics are presented. (C.E.S.)