Upgrade of SULTAN/EDIPO for HTS Cable Test

AbstractCRPP hosts two unique conductor test facilities SULTAN (SUpraLeiter TestANlage) and EDIPO (European DIPOle). They allow the test of high current superconductors in high magnetic fields (SULTAN 11 T, EDIPO 12.5 T). In both facilities sample currents up to 100 kA can be supplied by means of a NbTi transformer. Presently the facilities are upgraded for the test of high current high-temperature superconductor (HTS) samples. For HTS conductor testing at temperatures between 20 and 50K, the heat flux between the HTS sample under test and the NbTi transformer needs to be limited to around 10W per conductor leg by means of an HTS adapter connecting them. The second required upgrade is the supply of intermediate temperature helium (20-50 K) to the HTS test conductor. It is mandatory that the helium gas coming from the HTS conductor under test can be returned to the cryoplant as cold gas (T < 20K). To reach this goal a tube-in-tube heat exchanger has been manufactured in which 4.5K helium coming from the cryoplant is in counter flow with the warm gas leaving the HTS test conductor

Computational Fluid Dynamics of Reacting Flows at Surfaces: Methodologies and Applications

This review presents the numerical algorithms and speed-up strategies developed to couple continuum macroscopic simulations and detailed microkinetic models in the context of multiscale approaches to chemical reactions engineering. CFD simulations and hierarchical approaches are discussed both for fixed and fluidized systems. The foundations of the methodologies are reviewed together with specific examples to show the applicability of the methods. These concepts play a pivotal role to enable the first-principles multiscale approach to systems of technological relevance

H(T) Phase Diagram in Nb3Sn: A Different Behavior in Single Crystals, Polycristalline Samples and Multifilamentary Wires

A comparative study of magnetic behavior in a DC magnetic field up to 19 Tesla has been undertaken on different Nb3Sn samples, i.e. single crystals, polycrystal samples and multifilamentary wires. From the 1st and 3rd harmonics of the AC magnetic susceptibility a peak effect was experimentally observed in the single crystal and in the polycrystal, whereas this phenomenon is absent in the measured wires. The corresponding H vs T phase diagram reveals a different behavior between wires on one hand and polycrystalline and single crystal samples on the other. In particular, from the 3rd harmonics it has been observed that vortex thermally activated flux creep phenomena are relevant in the wires, whereas the static critical state models are more appropriate to describe single crystals.Comment: 9 pages, 9 figures, to be published on Advances in Cryogenic Engineering, Vol. 51-52 (CEC-ICMC05, Keystone, Colorado, 28 August-3 September 2005

Transport Properties and Exponential n-values of Fe/MgB2 Tapes With Various MgB2 Particle Sizes

Fe/MgB2 tapes have been prepared starting with pre-reacted binary MgB2 powders. As shown by resistive and inductive measurements, the reduction of particle size to a few microns by ball milling has little influence on Bc2, while the superconducting properties of the individual MgB2 grains are essentially unchanged. Reducing the particle size causes an enhancement of Birr from 14 to 16 T, while Jc has considerably increased at high fields, its slope Jc(B) being reduced. At 4.2K, values of 5.3*10^4 and 1.2*10^3 A/cm^2 were measured at 3.5 and 10 T, respectively, suggesting a dominant role of the conditions at the grain interfaces. A systematic variation of these conditions at the interfaces is undertaken in order to determine the limit of transport properties for Fe/MgB2 tapes. The addition of 5% Mg to MgB2 powder was found to affect neither Jc nor Bc2. For the tapes with the highest Jc values, very high exponential n factors were measured: n = 148, 89 and 17 at 3.5, 5 and 10T, respectively and measurements of critical current versus applied strain have been performed. The mechanism leading to high transport critical current densities of filamentary Fe/MgB2 tapes based on MgB2 particles is discussed.Comment: Presented at ICMC 2003, 25-28 May 200

Optimisation of ITER Nb3Sn CICCs for coupling loss, transverse electromagnetic load and axial thermal contraction

The ITER cable-in-conduit conductors (CICCs) are built up from sub-cable bundles, wound in different stages, which are twisted to counter coupling loss caused by time-changing external magnet fields. The selection of the twist pitch lengths has major implications for the performance of the cable in the case of strain sensitive superconductors, i.e. Nb3Sn, as the electromagnetic and thermal contraction loads are large but also for the heat load from the AC coupling loss. Reduction of the transverse load and warm-up cool-down degradation can be reached by applying longer twist pitches in a particular sequence for the sub-stages, offering a large cable transverse stiffness, adequate axial flexibility and maximum allowed lateral strand support. Analysis of short sample (TF conductor) data reveals that increasing the twist pitch can lead to a gain of the effective axial compressive strain of more than 0.3 % with practically no degradation from bending. For reduction of the coupling loss, specific choices of the cabling twist sequence are needed with the aim to minimize the area of linked strands and bundles that are coupled and form loops with the applied changing magnetic field, instead of simply avoiding longer pitches. In addition we recommend increasing the wrap coverage of the CS conductor from 50 % to at least 70 %. The models predict significant improvement against strain sensitivity and substantial decrease of the AC coupling loss in Nb3Sn CICCs, but also for NbTi CICCs minimization of the coupling loss can be achieved. Although the success of long pitches to transverse load degradation was already demonstrated, the prediction of the combination with low coupling loss needs to be validated by a short sample test.Comment: to be published in Supercond Sci Techno

Correlations between atazanavir Ctrough and hyperbilirubinemia: a case report

<p>Abstract</p> <p>Introduction</p> <p>Hyperbilirubinemia is a common side effect of the antiretroviral agent atazanavir but is generally reversible upon discontinuation of treatment. We used therapeutic drug monitoring to investigate the occurrence of hyperbilirubinemia in a 49-year-old Hispanic man infected with HIV, following an overdose of ritonavir in ritonavir-boosted atazanavir therapy.</p> <p>Case presentation</p> <p>A 49-year-old Hispanic man with HIV who had received several highly active antiretroviral therapy regimens over a number of years including atazanavir-containing regimens, was diagnosed with hyperbilirubinemia. An inappropriate doubling of ritonavir boosting resulted in a high atazanavir C_troughand an initial rise in bilirubin plasma levels. Bilirubin levels later decreased, probably as a consequence of enzyme induction, while atazanavir plasma concentrations remained elevated.</p> <p>Conclusion</p> <p>This article describes an occurrence of hyperbilirubinemia in a man infected with HIV and supports the importance of therapeutic drug monitoring in investigations of hyperbilirubinemia among patients receiving antiretroviral agents. That the patient tolerated exceptionally high atazanavir levels further strengthens the tolerability profile of this drug.</p

TCV divertor upgrade for alternative magnetic configurations

The Swiss Plasma Center (SPC) is planning a divertor upgrade for the TCV tokamak. The upgrade aims at extending the research of conventional and alternative divertor configurations to operational scenarios and divertor regimes of greater relevance for a fusion reactor. The main elements of the upgrade are the installation of an in-vessel structure to form a divertor chamber of variable closure and enhanced diagnostic capabilities, an increase of the pumping capability of the divertor chamber and the addition of new divertor poloidal field coils. The project follows a staged approach and is carried out in parallel with an upgrade of the TCV heating system. First calculations using the EMC3-Eirene code indicate that realistic baffles together with the planned heating upgrade will allow for a significantly higher compression of neutral particles in the divertor, which is a prerequisite to test the power dissipation potential of various divertor configurations