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Sections of the superconducting magnets of the SIS100 particle accelerator, under construction at the Facility for Antiproton and Ion Research (FAIR), the Society for Heavy Ion Research (GSI), Darmstadt, are going to be connected with the by-pass lines. Each line will be used to transfer a two-phase helium flow and an electric current. The electric current will be carried by four pairs of superconducting Nuclotron-type cables. Fast-ramping currents are expected to cause the generation of heat within the cables. In this work the results of a numerical thermal analysis of a bus-bar are presented. The amount of heat transferred from the environment was found based on geometric dimensions of the line and applied insulation. The amount of hysteresis loss, generated in the cable during the operation under most demanding regime of the operation of the accelerator, was calculated. According to the amount of the generated heat, the amount of the hysteresis loss is low in relation to the heat generated in the superconducting magnets. Also it was found that the cable used in the line still retains a large margin of current-carrying capacity.

Superconducting magnets in the SIS100 particle accelerator require the supply of liquid helium and electric current. Both are transported with by-pass lines designed at Wrocław University of Technology. Bus-bars used to transfer an electric current between the sections of the accelerator will be encased in a steel shell. Eddy currents are expected to appear in the shell during fast-ramp operation of magnets. Heat generation, which should be limited in any cryogenic system, will appear in the shell. In this work the amount of heat generated is assessed depending on the geometry of an assembly of the bus-bars and the shell. Numerical and analytical calculations are described. It was found that heat generation in the shell is relatively small when compared to other sources present in the accelerator and its value strongly depends on the geometry of the shell. The distribution of eddy currents and generated heat for different geometrical options are presented. Based on the results of the calculations the optimal design is proposed.

Magnetic fields can be effectively shielded with superconducting tapes. They can be used either to attenuate a magnetic field or to improve its homogeneity. In this paper, magnetic field changes, due to the presence of a superconducting shield, are investigated. Both experimental and model results are shown. Specimens were subjected to a low-frequency ac magnetic field (up to 45 Hz). Attenuation of the field inside a shielded cavity was observed. The dependence of the shielding effect on the magnetic field strength and frequency was analyzed. A computer model of a shield has been developed. The additional increase of the shielding effect was observed above a certain threshold frequency depending on the geometry and material properties of a screen. The size and limits of this increase were investigated. It was observed to be linear in some frequency intervals. The interval of magnetic field amplitude, in which magnetic field attenuation is constant, becomes thinner at higher frequencies. Analyzed shields may find multiple applications in devices where dc and low-frequency magnetic fields are present. Their construction is uncomplicated, and they are relatively cheap. Medicine and science can greatly benefit from this simple and reliable method of magnetic field attenuation.

In the work we present experimental results of ac magnetization losses measurements performed in the presence of a dc-bias magnetic field. Both ac and dc magnetic fields were coaxial and directed perpendicularly to the flat surface of sample tapes. The HTS tapes used in our experiments are commercially available composite tapes, namely a BSCCO-2223/Ag multifilamentary tape and an YBCO-123 coated conductor tape. The measurements were carried out with a sinusoidally varying magnetic fields at frequency range of about 21-113 Hz, and amplitudes up to 100 mT. The superimposed a dc-bias magnetic field was of the order of up to 50 mT. At a certain magnetic field amplitude, and at a certain dc bias magnetic field, a distinguish minimum in ac losses is observed. Occurrence of the ac loss minima differs considerably for two studied sample tapes.

Background The pathogenesis of morbidity and mortality associated with intervention of the biliary system in patients with obstructive jaundice is unknown. Mechanical jaundice initiates the development of morphological changes in hepatocytes with concomitant disturbances in metabolism. These are followed by changes in enzyme activity in hepatocytes and peripheral blood. Material and methods Wistar rats were divided into three groups: group 1, sham-operated controls; group 2, rats with permanent jaundice; and group 3, rats with temporary mechanical jaundice. The animals were examined at 2 weeks (groups A), 4 weeks (groups B) and 6 weeks (groups C) after surgery. We explored the impact of induced mechanical jaundice on the activity of selected urea cycle enzymes (arginase [E.C.3.5.3.1] and ornithine transcarbamoylase (OTC) [E.C.2.1.3.3]). Results Mechanical jaundice was found to induce changes in hepatocytic metabolism, which in turn led to disturbances in the urea cycle and the process of transamination. After relief of the mechanical jaundice (recanalization of the common bile duct), the urea cycle activity in the liver was greatly increased despite the normalization of the basic biochemical indices. Conclusion The results of the experiment confirmed the hypothesis that long-term mechanical jaundice causes lasting disturbances in hepatocytic metabolism. We conclude that the rate of nitrogen metabolism is higher after recanalization of the bile duct.

Recent advances in the measurements with sensitive magnetic field sensors made the issue of magnetic shielding important. The application of high temperature superconductors allows to obtain full shielding in zero field cooling conditions for DC and low frequency magnetic fields by the means of the Meissner effect. However, currently used conventional bulk magnetic shields maintain full shielding only in low magnetic fields—up to approximately 10 mT. In this paper, it is proposed to apply an additional screen made of a coated superconducting tape in order to increase the magnetic field interval of full shielding region. Computer model of such set of screens was created in Matlab and validated experimentally. Improvement of shielding quality was observed experimentally and calculated with the model.

There are three kinds of AC losses in superconducting wires, transport current losses, magnetization losses and total losses. The first losses are caused by the AC transport currents flowing in the wires, the second caused by the AC external magnetic fields which the wires are subject to and the third caused by the combination of the transport currents and external magnetic fields. The measuring methods are divided in electric and calorimetric methods. Generally speaking, the electric methods are sensitive and precise but have some problems to measure false losses if the electromagnetic environments of the wires are not well defined. On the other hand, the calorimetric methods can measure the real losses but are not so sensitive or precise as the electric methods. In the paper, electrical methods for AC loss characterization of the HTS wires are reviewed. The AC loss data of Bi2223/Ag sheathed and YBCO tapes are also presented and the loss characteristics are studied.