Heat generation by eddy currents in a shell of superconducting bus-bars for SIS100 particle accelerator at FAIR

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

Calculation of inductances and induced currents in cryogenic by-pass line for SIS100 particle accelerator at FAIR

Quality of electric current delivered to the magnets of a particle accelerator is essential for safety and reliability of its operation. Even small discrepancies strongly affect the properties of particle beams. One of the sources of the disturbances is the appearance of induced currents caused by the electromagnetic interactions between the elements of the machine. In this paper the calculations of induced currents in by-pass lines of a SIS100 particle accelerator are presented. In order to find the values of the currents the self-inductances and mutual inductances of the by-pass lines are found. Due to the complex geometry of the line, especially of Ω-shaped dilatations, the numerical approach was employed. The calculations show that the size of induced currents increases with the distance between the cables in an individual bus-bar. The maximum discrepancy of the magnetic field in a dipole magnet is found to be 7.7 μT. The decrease of distance between the cables allows one to obtain a discrepancy of 1.2 μT

Numerical assessment of thermal behaviour of a superconducting bus-bar with a Nuclotron-type cable

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

Rozejście mięśni prostych brzucha u kobiet we wczesnym połogu

Aim of study: Diastasis recti abdominis is a widening of the linea alba leading to separation of the recti muscles. This abnormality concerns mainly women during their perinatal period. The objective of this study is to determine the incidence of diastasis recti abdominis in women during their early postpartum period. We also attempted to verify the relationship between the women’s linea alba width and the number of their deliveries. Methods: In this study, data from medical interviews as well as the results of a diastasis recti test among 52 women between their 3rd and 5th day after delivery were analysed. Pearson’s Chi2 and Spearman’s correlation tests were used to search for relationships between variables. Results: Among the 52 women, 33 (63%) demonstrated increased separation of recti muscles (a positive diastasis recti test at the level of the umbilicus). Statistical analysis indicated a moderate positive correlation between the width of linea alba and the number of deliveries (r = 0.4; p < 0.05). Diastasis recti abdominis occurred in 14 of the 28 primigravidas (50%) and in 19 of the 24 multigravidas (79%; p < 0.05). Conclusions: The results of this study indicate that over half of the women in the early postpartum period had diastasis of the recti abdominis muscles. In multiparous women, there may be a higher risk of diastasis recti abdominis occurrence.Cel pracy: Rozejście mięśni prostych brzucha to poszerzenie kresy białej i rozsunięcie brzuśców mięśni prostych na boki. Problem ten najczęściej dotyczy kobiet w ciąży i po porodzie. Celem pracy było sprawdzenie częstości występowania rozstępu mięśni prostych brzucha u kobiet we wczesnym połogu oraz odpowiedź na pytanie, czy istnieje zależność pomiędzy szerokością kresy białej a liczbą przebytych porodów. Metody: W pracy wykorzystano dane z wywiadu oraz wyniki testu na rozpoznanie rozejścia mięśni prostych brzucha wykonanego u 52 kobiet będących między trzecią a piątą dobą po porodzie. Do zbadania zależności między zmiennymi wykorzystano test niezależności chi2 Pearsona. Do określenia siły związku pomiędzy cechami zastosowano współczynnik korelacji rangowej Spearmana. Wyniki: U 33 z 52 kobiet (63%) stwierdzono rozejście mięśni prostych brzucha na wysokości pępka. Analiza statystyczna wykazała umiarkowaną dodatnią zależność pomiędzy szerokością kresy białej a liczbą przebytych porodów (r = 0,4; p < 0,05). Rozejście mięśni prostych brzucha dotyczyło 14 z 28 pierworódek (50%) oraz 19 z 24 wieloródek (79%; p < 0,05). Wnioski: Wyniki niniejszej pracy wskazują, że problem rozejścia mięśni prostych brzucha dotyczył ponad połowy kobiet we wczesnym połogu. U wieloródek może istnieć większe ryzyko wystąpienia rozejścia mięśni prostych niż u pierworódek