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The critical current of an internal tin Nb3Sn wire developed by Oxford Instruments, Superconducting Technology for International Thermonuclear Experimental Reactor (ITER) (OST type-I, billet No. 7567) has been studied under axial strain at fields between 12 and 19 T at 4.2 K. Simulating the situation in a cable in conduit, where thermally induced compressive strain is important, a single wire (strand) was jacketed with AISI 316L stainless steel. The reinforced wire shows an important increase in ɛm, the applied strain where Ic reaches its maximum, from 0.25% to 0.57%. In addition the irreversibility limit, ɛirr, is improved from 0.50% applied strain to >1.10%. It could also be shown that the Ic at zero intrinsic strain is almost identical. This demonstrates that jacketing does not influence the physical parameters of the original wire. Experimental data of the bare wire has been well fitted by different strain functions. However, it was not possible to model the data of the jacketed wire. There are indications that only models which take into account the multidimensional character of strain are able to describe the behavior but further development is required

The determination of cardiac output (CO) during mechanical circulatory support (MCS) is crucial since low-output syndrome is the main cause of death in such patients. A new uncalibrated pulse contour method (PCM) named PRAM (pressure recording analytical method) has recently been introduced in the clinical practice and validated in animals, humans, and patients assisted with axial flow pumps. The figure …

JT-60SA is a fully superconducting coil tokamak to be built under the framework of the EU-JA Broader Approach Agreement, and it aims to contribute to the complement of the ITER experiments and to the DEMO reactor design by the study of steady-state high-beta plasma experiments. The conceptual design of the JT-60SA tokamak and the peripheral systems has been carried out in close collaboration of EU and Japan from middle of 2006, and the JT-60SA Conceptual Design Report which involves an analysis of plasma physics and engineering design is summarized in May 2007. This paper intends to present an overall view of the JT-60SA project, and the latest design status of the key engineering issues such as superconducting magnets, divertor target, plasma heating devices, and magnet power supplies.

This article details a case report of a traumatic aortic arch false aneurysm after blunt chest trauma. Thoracic aorta false aneurysms are a rare and life-threatening complication of aortic surgery, infection, genetic disorders and trauma.

The case is reported of a patient who underwent cardiac surgery for pulmonary valve stenosis as a child, and presented as an adult with signs and symptoms of severe congestive heart failure. The left ventricle showed an increased trabecular pattern in the region of the apex, the mitral annulus was severely dilated with mitral incompetence, the right ventricular out-flow tract (RVOT) was largely dilated with aneurysm of both pulmonary arteries, and there was evidence of pulmonary valve incompetence. Previously, rare cases have been reported of persistent left ventricular non-compaction in patients with congenital left or RVOT obstruction. Non-compaction of the ventricular myocardium is an inherited autosomal dominant disorder; to date, four genes and one genetic locus have been found to be associated with non-compacted ventricular myocardium. The condition is characterized by arrhythmias, thromboembolic events and heart failure, but affected individuals may not be symptomatic. The present case represented a strange association between non-compacted left ventricle, mitral annular dilation with persistence of a normal leaflet and subvalvular mitral valve apparatus, and RVOT dilation with pulmonary artery aneurysms.

Measurement of systemic blood flow is of crucial importance in patients on mechanical circulatory support (MCS). We reported the case of a 65-year-old female patient in severe cardiogenic shock undergoing left (Jarvik 2000 axial flow pump) and right (Levitronix-Centrimag centrifugal pump) ventricular assist device implant. Evaluation of blood flow was obtained by ultrasonic flowmetry, continuous thermodilution technique, and pressure recording analytical method (PRAM). This pulse contour system allows beat-by-beat systemic blood flow assessment from the analysis of radial artery pressure waveform. At a Jarvik pump speed ≤ 10 000 rotations per minutes (rpm), thermodilution and PRAM showed similar blood flow values. At a Jarvik pump speed ≥11 000 rpm, the aortic valve did not open and PRAM did not provide blood flow values due to nonpulsatile blood flow. The present paper describes the first experience with PRAM in a single patient on MCS. Further studies are required to assess the validity of PRAM as an additional monitoring system in the setting of ventricular assist device support. Perfusion (2007) 22, 63-66.

We reconsider the problem of the measurements of the microwave complex surface impedance in thin superconducting films deposited on SrTiO3 substrates. We perform measurements of the complex surface impedance Z(s)(') = R-s(') + i Delta X-s(') of thin YBa2Cu3O7-delta films deposited by laser ablation on SrTiO3 substrates. The typical oscillations due to the strong temperature variation of the SrTiO3 permittivity are confirmed in R-s(') and observed in Delta X-s('). The effects of the SrTiO3 substrate are evident even well below the superconducting transition temperature of YBa2Cu3O7-delta. Similarly to previous works, we describe the overall response in terms of impedance transformations. We extend the known results by (i) considering the measurements of the imaginary part, (ii) comparing the measurements to the absolute dc resistivity measured on the same sample, and (iii) suggesting a method for measuring the intrinsic thin film surface impedance by adjusting the substrate impedance. To demonstrate the feasibility of microwave measurements of intrinsic properties of films grown onto SrTiO3 substrates, we check the proposed method by measuring the field dependent surface impedance before and after removal of the substrate resonance.

Two short length samples have been prepared and tested in SULTAN to benchmark the performance of high current density, advanced Nb3Sn strands in the large cable-in-conduit conductors (CICC) for ITER. The cable pattern and jacket layout were identical to the toroidal field model coil conductor (TFMC), tested in 1999. The four conductor sections used strands from OST, EAS, OKSC and OCSI respectively. The Cu:non-Cu ratio was 1 for three of the new strands, compared to 1.5 in the TFMC strand. The conductors with OST and OKSC strands had one Cu wire for two Nb3Sn strands, as in TFMC. In the EAS and OCSI conductors, all the 1080 strands in the cable were Nb3Sn. A dc test under relevant load conditions and a thermal-hydraulic campaign was carried out in SULTAN. The CICC performance was strongly degraded compared to the strand for all the four conductors. The current sharing temperature at the ITER TF operating conditions (jop = 286 A/mm2, B = 11.15 T) was lower than requested by ITER.

It is well assessed that the cable in conduit conductors (CICC) performances are affected by the current distribution among their strands. In many experiments, during Tcs measurements, it has been evidenced that a current re-distribution among the cable sub-stage bundles appears just before the conductor transition. This is deduced mainly from the change of the magnetic field measured in the conductor proximity, even with a constant cable transport current. This paper presents the experimental evidence that the current begins to re-distribute well before any detectable voltage development. Such a phenomenon, repeatable and depending on the overall transport current, has been observed by means Hall probe arrays. These probes have been designed with suitable sensitivity and distribution, to permit also the reconstruction of the current distribution inside the CICC by means of the solution of the inverse magnetostatic problem. Some results from the experimental data taken from the NbTi BusBar III and the Poloidal Field Insert samples, tested respectively in the TOSKA facility at FZK, and in SULTAN at PSI in 2004, are discussed here.

The 'NAFASSY' (NAtional FAcility for Superconducting SYstems) facility is designed to test wound conductor samples under high-field conditions at variable temperatures. Due to its unique features, it is reasonable to assume that in the near future NAFASSY will have a preeminent role at the international level in the qualification of long coiled cables in operative conditions. The magnetic system consists of a large warm bore background solenoid, made up of three series-connected grading sections obtained by winding three different Nb3Sn Cable-in-Conduit Conductors. Thanks to the financial support of the Italian Ministry for University and Research the low-field coil is currently under production. The design has been properly modified to allow the system to operate also as a stand-alone facility, with an inner bore diameter of 1144 mm. This magnet is able to provide about 7 T on its axis and about 8 T close to the insert inner radius, giving the possibility of performing a test relevant for large-sized NbTi or medium-field Nb3Sn conductors. The detailed design of the 8 T magnet, including the electro-magnetic, structural and thermo-hydraulic analysis, is here reported, as well as the production status. © 2015 IOP Publishing Ltd.

Bus Bar III (BBIII) is a curvilinear NbTi full-size ITER-type multistrand superconducting cable 7 m long, tested in 2004 at Forschungszentrum Karlsruhe, Germany. The sample was cooled with a forced helium flow and was equipped with many electromagnetic and thermal-hydraulic sensors, to acquire as wide as possible an experimental database, aimed at getting a benchmark for the validation of the THELMA code, a computer tool for the analysis of CICC prototypes and magnets, recently developed and presently under validation. This code can compute the current distribution among the macrostrands used to represent the cable, taking into account their superconducting behavior, as well as the temperature and the magnetic field distribution. The paper deals with the application of THELMA to some tests on BBIII useful for the electromagnetic model validation and presents in detail the analysis setting-up, the results, its critical aspects and limits. A comparison is shown between the measured and the computed waveforms of the electromagnetic data.

Current reconstruction in cable-in-conduit conductors (CICC) cables is a crucial issue to determine cables performance in working conditions, and must be performed using inverse problem approaches as direct measurement is not feasible. The current distribution has been studied for the ITER Poloidal Field Insert Sample (PFIS) conductor using annular arrays of Hall probes placed in three different locations along the sample during the test campaign at the SULTAN facility. The measurement apparatus is also described in the paper, together with the approach to current reconstruction. (c) 2005 Elsevier B.V. All rights reserved.

Publisher Summary This chapter illustrates the design and manufacturing of the insert coil and also gives a description of the test facility layout. A magnet wound with a sub-size NbTi conductor has been realized to study its characteristics in view of the realization of the full-size conductor for the ITER Poloidal Field Coils. The coil has been designed and constructed by ENEA and Ansaldo CRIS, with a conductor provided by Europa Metalli Superconductor and consisting of 36 Ni-coated strands twisted in a three stage cable, jacketed and compacted in a SS round tube. A self consistent unit has been manufactured assembling the insert module and its mechanical supporting structure, to allow easy installation inside the background magnet of the ENEA test facility where the coil will be tested under representative conditions for the ITER PF magnets. After having determined stability conditions with uniform transport current, the same rims will be repeated parametrically varying non-uniform current distribution inside the cable. The same kind of measurements will then be repeated after reversing the helium flow. This will cause the transition region to move along the conductor length, owing to the interplay between the self-field profile and the steep temperature profile along the conductor length.

The Poloidal Field Conductor Insert (PFCI) of the International Thermonuclear Experimental Reactor (ITER) has been designed in the EU and is being manufactured at Tesla Engineering, UK, in the frame of a Task Agreement with the ITER International Team. Completion of the PFCI is expected at the beginning of 2005. Then, the coil shall be shipped to JAERI Naka, Japan, and inserted into the bore of the ITER Central Solenoid Model Coil, where it should be tested in 2005 to 2006. The PFCI consists of a NbTi dual-channel conductor, almost identical to the ITER PF1 and PF6 design, 45 m long, with a 50 mm thick square stainless steel jacket, wound in a single-layer solenoid. It should carry up to 50 kA in a field of 6 T, and it will be cooled by supercritical He at 4.5 K and 0.6 MPa. An intermediate joint, representative of the ITER PF joints and located at relatively high field, will be an important new item in the test configuration with respect to the previous ITER Insert Coils. The PFCI will be fully instrumented with inductive and resistive heaters, as well as with voltage taps, Hall probes, pick-up coils, temperature sensors, pressure gauges, strain and displacement sensors. The test program will be aimed at DC and pulsed performance assessment of conductor and intermediate joint, AC loss measurement, stability and quench propagation, thermal-hydraulic characterization. Here we give an overview of the preparatory work toward the test, including a review of the coil manufacturing and of the available instrumentation, a discussion of the most likely test program items, and a presentation of the supporting modeling and characterization work performed so far.

A short sample of the NbTi cable-in-conduit conductor (CICC) manufactured for the ITER PF insert coil has been tested in the SULTAN facility at CRPP. The short sample consists of two paired conductor sections, identical except for the sub-cable and outer wraps, which have been removed from one of the sections before jacketing. The test program for conductor and joint includes DC performance, cyclic load and AC loss, with a large number of voltage taps and Hall sensors for current distribution. At high operating current, the DC behavior is well below expectations, with temperature margin lower than specified in the ITER design criteria. The conductor without wraps has higher tolerance to current unbalance. The joint resistance is by far higher than targeted.

The Bus Bar III (BBIII), fabricated within the Toroidal Field Model Coil Task of the International Thermonuclear Experimental Reactor (ITER), was tested at the Forschungszentrum Karlsruhe, Germany, in the spring of 2004. The BBIII consists of an approximately 7 m long NbTi dual-channel conductor with a thick square stainless steel jacket, cooled by forced flow supercritical He. It was energized with currents up to 80 kA and operates in its self magnetic field (up to /spl sim/0.8 T). The BBIII was instrumented with Hall-probe heads and arrays, voltage rings and longitudinal voltage taps for electro-magnetic measurements, in order to get experimental data to be used for the validation of a recently developed hybrid thermal-hydraulic electro-magnetic code (THELMA), as well as for the assessment of the possibility of performing a reliable reconstruction of the current distribution in the conductor cross section under controlled conditions. In the tests, current ramps at different rates were applied to characterize the conductor time constants, while two different resistive heaters (one upstream of the BBIII inlet, another one directly on the BBIII jacket) were separately operated in order to approach current sharing in the conductor and to observe the related current re-distribution. In this paper, a summary of the collected experimental results is presented, with particular emphasis on those aspects more relevant for the forthcoming THELMA analysis.

Background: Acute myocardial ischemia and infarction due to retrograde dissection of the aortic root reaching the coronary ostia is a potentially fatal condition. Surgical treatment of these patients relies on the re-establishment of an adequate coronary blood flow and on the rescue of jeopardized myocardium. This article reports the results of a selected group of 24 patients with type A acute aortic dissection and coronary artery dissection. We review our experience and illustrate our approach to this condition, which evolved over a 15-year period. Methods: Between July 1985 and March 2000, 24 patients from a total of 211 (11.3%) treated for acute type A aortic dissection had dissection of at least one of the coronary ostia. There were 14 men and 10 women. The mean age was 65.5 years (median 61.7; range 41-78 years). The right coronary artery was involved in 11 patients, the left in 4 patients, and both coronary arteries in 9 patients. At admission, 16 patients had Q waves (66%), inferior in 6 (25%) and anterior, lateral, septal, or posterior in 10 (41%). All procedures were done on an emergency basis within 10 hours (median 4 hours) after initial chest pain and within 2 hours after the patient's arrival. Results: Hospital mortality was 20% (5 patients); 3 patients could not be weaned from cardiopulmonary bypass and died intraoperatively, and 2 patients died postoperatively of low cardiac output. Conclusions: As illustrated in this study, direct coronary repair is a safe alternative to bypass grafting. Aggressive myocardial resuscitation together with early operation is a key factor in the management of these patients. (J Thorac Cardiovasc Surg 2001;121:552-60)

Background: The platelet glycoprotein IIb/IIIa inhibitor tirofiban hydrochloride improves outcome in patients with acute coronary syndrome. Nevertheless, a considerable number of patients require emergency or urgent coronary artery bypass grafting and may be at increased risk of postoperative bleeding after treatment with this molecule. The aim of this study is to evaluate the incidence of bleeding complications among patients undergoing bypass grafting after treatment with tirofiban. Methods: We investigated the influence of the molecule on postoperative bleeding after cardiac surgery, comparing 2 groups of patients undergoing emergency or urgent coronary artery bypass grafting: group A (n = 20) received tirofiban, and group B (n = 68) received conventional therapy with intravenous heparin up until the operation. A total of 88 patients underwent coronary artery bypass surgery within 2 hours of ceasing the hemodynamic study. Clinical outcome, chest tube outputs, bleeding complications, transfusion requirements, platelet and hemoglobin counts, and clinical complications were examined. Results: Bleeding differences were noted between the 2 groups at 8, 16, and 24 hours postoperatively. The incidence of blood, platelet, and fresh frozen plasma transfusions was higher in the control group. Postoperative thrombocytopenia was preserved in group A (199.5 ± 70.4 vs 150.6 ± 33.4 103/mL, P

We analyze the voltage–current ( V – I ) characteristics of the YBCO films grown above the CeO 2 /NiO/Ni 89 V 11 structure to study the dissipative mechanisms limiting the critical current in these structures. The analysis is performed on the shape of the V – I characteristics, emphasizing the voltage behavior as a function of the bias current. The complex behavior of the fluxon dynamics is described in connection to the reduced pinning force measured on the YBCO films grown on these metallic flexible substrates.

A crucial issue for a superconducting coil in order to be safely used in the magnetic system of a fusion reactor is stability against all foreseen disturbances. To simulate the fusion machine conditions, including off-normal events, e.g. plasma disruptions, the energy deposition has to be spread over a "long length" cable in conduit conductor (CICC) and a background magnetic field is needed. We have therefore designed and built an experiment consisting of an instrumented NbTi test module inserted in a pair of co-axial pulsed copper coils. A 0.6 m diameter superconducting coil provides a background magnetic field up to 3 T. Calibration of the energy inductively coupled between the pulsed coils and the module has been obtained measuring the system temperature increase just after the pulse by means of thermometers positioned along the conductor. Stability vs. operating current I/sub op/ has been examined for different helium temperatures and different background magnetic fields. The finite element code Gandalf for the stability and quenching transients analysis in forced flow cooled superconducting coils has been run to check the matching with the experimental results. (3 refs).

This paper describes the results of the measurements performed in June 2011 on a NbTi cable-in-conduit conductor curved joint in the ENEA Superconductivity Laboratories (C.R. Frascati). The effectiveness of the joint design, patented by ENEA, had been already verified for the Nb3Sn EDIPO conductor; in this case, it has been applied to a NbTi cable-in-conduit conductor. The joint was manufactured and instrumented by ENEA, using part of a JT-60SA toroidal field conductor sample (namely the TFCRS) produced by Luvata Italy and successfully tested in SULTAN. For testing purposes, the NbTi 'shaking hands'-type joint was hosted in a variable temperature cryostat with a background superconducting magnet. The sample was used as the secondary coil of a transformer having the background magnet as primary coil. Measurements were preceded by preliminary code simulation studies computed in the Matlab workspace, and by 3-D finite element method analyses, to estimate the test requirements and its feasibility. The joint resistance value, found to be less than 2 nΩ has been derived both by the sample current decay time constant evaluation and by calorimetric calculations. After a short description of the joint design and fabrication, as well as of the test instrumentation and geometry, the joint resistance evaluation will be presented, together with the data analysis procedures and results. © 2012 IEEE.

The European and the Korean contributions to the ITER Project in terms of cable-in-conduit conductors have been assigned to the Italian Consortium for Applied Superconductivity (ICAS). ICAS' charter members are: ENEA, with the role of general supervision and monitoring, CRIOTEC Impianti S.r.l., in charge of jacketing activities, and TRATOS Cavi S.p.A., with the duty of cable manufacturing. The ITER production consists of about 40 km of Nb3Sn toroidal field (TF) conductor and 22 km of NbTi poloidal field (PF) conductor, for coils 1 and 6. As part of the EU contribution to the construction of the JT-60SA Japanese Tokamak Reactor, ICAS is also in charge of producing about 28 km of NbTi TF conductor, required for the whole TF magnet system. Thanks to the high level and unique expertise available at ICAS, the consortium has been also assigned to manufacture the ITER Central Solenoid conductor samples to be tested in SULTAN for the final, positive, assessment of the updated design. In the present paper, the steps leading to the successful qualification of the main production processes will be described. What is more, the manufacturing of the first conductor unit lengths of the 'production phase,' i.e., the ones that will be wound to operate in the actual ITER TF and JT-60SA TF superconducting magnets, will be reported. The fabrication of the ITER CS conductor samples will be illustrated as well. © 2012 IEEE.

The on-going construction of the ITER and JT-60SA tokamak reactors requires the production of a large quantity of Cable-In-Conduit Conductors (CICCs) to be employed in the superconducting magnets for plasma confinement and control. A new company, named ICAS (Italian Consortium for Applied Superconductivity), was established thanks to the large expertise in this field that has been present in Italy for nearly three decades. ICAS is a consortium among ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development) and two Italian private companies: CRIOTEC Impianti, which owns an 850m long jacketing line for CICCs, and TRATOS Cavi, which has a large experience in cable manufacturing for various applications. ICAS' current activities are aimed at supplying to Fusion for Energy the European quote of ITER TF and PF conductors and the whole JT-60SA TF conductor quantity, as well as at supplying to the Korean Domestic Agency about 19 km of ITER TF conductor. This paper offers an overview of ICAS' technical capabilities and facilities, and outlines the first outcomes from the first productions.

FAST (Fusion Advanced Studies Torus), the Italian proposal of a Satellite Facility to ITER, has been the object of an intense re-design activity aimed at verifying the feasibility of a superconducting solution for its magnet system. One of the most difficult and critical obstacles is represented by the central solenoid (CS) magnet, due to the rapid variation of the current and magnetic field (up to 40 T/s) foreseen so far in the reference scenario. The associated losses induced in the CS magnets should be dissipated by the flow of helium that cools the conductors. Nonethe- less, even the losses depend on the conductor design, therefore, not only the thermal-hydraulics of the Cable-in-Conduit Conduc- tors (CICCs) but also the strand properties, should be considered to identify the best design capable to sustain the transient in the CS magnets, keeping the scenario originally foreseen for the resistive configuration of the machine unaltered. The present paper discusses the electromagnetic and thermal-hydraulic behavior of the CICC design envisaged for the FAST CS magnet in the H-mode scenario, and identifies the possible strategies to make a superconducting solution sustainable.

With the aim of clarifying the relationship between lattice deformations and superconducting properties of Nb3Sn technological wires we have carried out high-energy x-ray diffraction experiments at the European Synchrotron Radiation Facility (ESRF) in Grenoble on individual samples of multi-filamentary internal-tin-type Nb3Sn wires. In particular, a test probe developed at the University of Geneva allowed us to perform these experiments at 4.2 K, while applying an axial tensile load to the specimen. In this way, the lattice parameter values of all the constituents (Nb3Sn, Nb, Cu) were determined, in both the parallel and orthogonal directions with respect to the applied load axis, as a function of the applied strain. The experiments were performed on industrial wires, which were reinforced by a stainless steel outer tube, applied before the Nb3Sn reaction heat treatment, in order to evaluate the effect of an additional pre-compression strain. The relation between the microscopically determined crystalline lattice deformations and the measured applied strain is discussed as a basis for the analysis of the superconducting performances of Nb3Sn wires subject to mechanical loads.

The full-matrix set of combined temperature (4.2–14 K) and applied axial strain (εa) data for the bulk pinning force of a technological Nb3Sn wire (OST type-I) has been studied at fields up to 19 T by combining transport (variable εa) and magnetic (variable T) measurements. Some length of the wire was also jacketed with AISI 316L stainless steel, in order to apply a radial strain and to simulate the thermally induced axial compressive strain that the Nb3Sn wires experience in a cable-in-conduit-conductor (CICC). Within the framework of the unified scaling law, raw scaling data for the effective upper critical field B*c2(T, ɛ), have been used in order to experimentally determine the strain function, s(ε), of both the bare and the jacketed wires. A direct testing of the various proposed models for s(ε) has been carried out, including the power law, the deviatoric description and the polynomial form. All models adequately fit to the s(ε) of the bare wire, but in the jacketed wire none of them is able to describe the tensile strain region above the Ic maximum, where the enhanced radial compression cannot be neglected. The origin of the onset of a reduced Bc2 is also discussed.

Biaxially aligned YBa 2 Cu 3 O 7−y thick films were obtained by Pulsed Laser Deposition on cube textured non-magnetic Ni-V metallic substrates, with NiO as a first buffer layer. The critical temperature and critical current density at 77K and self field of the YBCO thick film grown on an epitaxial CeO 2 /NiO buffer layer architecture are 90.5K and 0.6 MA/cm 2 , respectively.

In modeling the properties of superconducting multifilamentary strands, transverse resistivity plays a crucial role in the definition of the coupling losses in ac regime, as well as of the current transfer length, that affects the transport properties of Nb3Sn wires subject to bending strain. We present the first direct measurement of the interfilament transverse resistance in superconducting strands from room temperature to 4.2 K. Results have been compared to the transverse resistance of a sample on which the outer copper stabilization layer has been removed by chemical etching, obtaining interesting indication on the preferential current paths within the wire cross section. An excellent agreement between experimental data and theoretical models has been found in describing the whole strand, while improvements are required in modeling the filamentary region alone.

We performed magnetic characterizations, using a vibrating sample magnetometer, of an internal tin-type Nb3Sn technological strand. In order to compare the properties of this sample under different strain conditions, the same strand was tested under compression, obtained by swaging and compacting into thin stainless steel tubes before the heat treatment, as well as after a complete relaxation of the filament strain components, by chemical etching of the Cu and bronze matrix components. In particular, we analysed the Kramer extrapolated upper critical field Bc2K, and the zero-field critical temperature Tc(0) and its distribution, for all the samples. In order to clarify the effect of the strain due to both the stainless steel reinforcement and the copper matrix thermal pre-compression, we compared our experimental results with the predictions from well established scaling laws based on uniaxial models. Good agreement has been found with measured critical temperature Tc and extrapolated upper critical field Bc2K values, with proper choice of fit parameters. On the other hand, we observed a broadening of the superconducting Tc transition with increasing strain. This has to be ascribed to the effect of radial strain components, which cannot be neglected in the present work.

We report on the effect of bending strain on the transport properties of multifilamentary Nb3Sn strands having twisted or untwisted superconducting filaments in order to clarify some aspects of the current transfer process within the wire cross section. Critical current measurements were performed on internal tin Nb3Sn strands, which were inserted and compacted inside thin stainless steel tubes before the heat treatment. With the application of a maximum bending strain of 0.5%, the strands with twisted filaments present a degradation of the critical current and of the n-index, while an enhancement of the performances is observed for the untwisted strands. The experimental results are interpreted in relation to the predictions of Ekin’s model.

A facility for the characterization of superconducting strands at variable temperatures has been recently upgraded at ENEA. Measurement of transport properties of superconducting strands can be now carried out in the temperature range from 3.5 K to 15 K, with stability less than 10 mK, and in magnetic fields up to 12.5 T, covering a range of critical currents between a few Amperes, up to about 300 A. In this study we present the results of a measurement campaign carried out on NbTi wires, aimed also at comparing the performances of some available candidate strands, to be used in the design of the Toroidal Field Coils of the JT60-SA Tokamak, as well as in the design of the ITER high field Poloidal Field Coils, PF1 & 6. We measured strands with different diameters, and with Cu-nonCu ratios ranging between about 1.5, up to about 7. The measurements showed the critical behavior of the NbTi in the range of relatively high temperatures (T > 5.5 K) and high magnetic fields (B > 6 T), typical for large coils in fusion reactors, where Cable-in-Conduit Conductors are used and where temperature margins of at least 1K are required for a sound design. The experimental results highlighted the need for an optimization of the numerical fits normally used to predict NbTi critical current densities, starting from measurements performed at 4.2 K. Based on our results, we conclude that fit parameters for each NbTi strand should be inferred from experimental characterizations in the temperature and magnetic field range of interest for the design.

We report a case of false aneurysm of the left ventricle occurring subsequently to the placing of a vent sump line through the apex during an aortic valve procedure; the diagnosis was made twelve months later during a routine echocardiographic examination. The lesion was successfully repaired. This case recommend the use of other routes of venting in order to reduce the incidence of such complications.

In the framework of the DEMOnstration fusion power plant (DEMO) design coordinated by the EUROfusion consortium, a pre-conceptual design of the superconducting magnet system has been developed. For the toroidal field coils (TFCs), three winding pack (WP) options have been proposed; exploring different winding approaches (pancakes vs. layers), and manufacturing techniques (react & wind vs. wind & react Nb3Sn). Thermal-hydraulic and mechanical analyses on the three WPs have produced encouraging results, with some critical issues to be solved in future studies and optimizations. The experimental tests on TF prototype short sample conductors have demonstrated a limited performance degradation with electro-magnetic cycles and significantly lower effective strains than most of the large-size Nb3Sn conductors reported in literature. The toroidal field quench protection circuit has been studied, starting from different topologies and focusing on the most promising one. Two designs are also presented for the central solenoid magnet, with preliminary evaluations on the AC losses during the plasma breakdown. Finally, the design of a TF winding pack based on HTS conductors and the experimental tests on “fusion-relevant” HTS cables are illustrated.

The ENEA conductor for the EU DEMO Nb3Sn toroidal field (TF) magnets, cooled by supercritical He, features a rectangular cross section with two small pressure relief channels ('holes'), separated from the cable bundle by means of a flat spiral, twisted together with the last cabling stage. A well-instrumented short sample of the ENEA TF conductor has been tested in SULTAN at SPC, Villigen (Switzerland) in 2016, aimed at its thermal-hydraulic characterization, and the test results are presented here. A correlation for the friction factor in the small holes is derived, best fitting the results of a set of computational fluid dynamics simulations. The new correlation (combined with existing correlations for the He friction factor in the bundle region) is shown to allow a proper reproduction of the measured hydraulic characteristic of the conductor. The heat slug propagation tests are used to calibrate the hole-to-bundle heat transfer coefficient in the 4C thermal-hydraulic code and to estimate the characteristic length for the homogenization of the He temperature on the conductor cross section, following a localized thermal perturbation. © 2002-2011 IEEE.

In an attempt to improve understanding between pinning behaviour and underlying microstructures, results of the investigation on multifilamentary Cu/Nb-47w%Ti alloy are presented. Wire was drawn to final size without intermediate stage thermomechanical treatments. Cold worked structure was subjected to isothermal annealing at 648 K for various annealing times between 2 minutes to 100 hours. Microstructural and compositional features were studied by transmission electron microscopy, TEM, and analytical TEM equipped with EDS analyzer. The pinning behavior was monitored by the maximum volume pinning force determined using transport current measurements at 4.2 K up to 9 T. According to the present results, the average grain boundary spacing remained rather constant at 45 nm throughout all annealing times while the average grain boundary width increased from the initial dimension of 1 nm to 1.8 nm after 100 hours as a result of precipitation processes at grain boundaries. Further, distributions of the grain boundary widths changed from a sharp shape to a wider spectrum of widths. The precipitation process created titanium concentration gradients in the vicinity of the grain boundaries. As the annealing time increased, the sharp gradients became shallower and Ti concentrations as low as 35 w% Ti were observed after 40 hours. High field pinning at 9 T was associated with structures having a mean grain boundary width of 1.2 nm and titanium concentration gradients on a scale of 2.5 to 5 nm from the grain boundaries. Mid magnetic field pinning was favored by microstructures having titanium gradients on a scale of 5-10 nm and the mean width of 1.5 nm while improved low field pinning at 3 T was associated with microstructures having the mean width of 1.8 nm, shallow gradients and titanium concentrations as low as 35 w% inside of the grains.

The Toroidal field coils (TFC) of the EUROFusion DEMO reactor call for Nb3Sn conductor with high field and high current. Another major requirement is cost-effectiveness, to keep the ratio of investment to electric power in the same range of the competing energy sources (fission, hydro, coal, gas, etc.). The TFC proposed by the Swiss Plasma Center (SPC) is based on a double-layer Nb3Sn/NbTi winding. A react-and-wind flat cable is the core of the Nb3Sn conductor, with six grades to minimize the cost and maintain a roughly constant temperature margin of 1.5 K over the winding cross section. A short length section of the high grade Nb3Sn conductor has been manufactured using relevant industrial cabling equipment. One hundred kilograms of 1.5-mm Nb3Sn strand has been procured at WST with average Jc up to 15% higher than specified (Jc≥ 1000A/mm2 at 12 T/4.2 K). A dedicated cabling line has been set up at TRATOS cavi (Italy), producing over 350 m of dummy cable and about 13 m of superconducting cable. The assembly of the cable into a conduit by longitudinal laser welding of two steel profiles is demonstrated, including the QA procedures. A test sample has been prepared at SPC by heat treating straight sections of the cable and encasing it into a steel jacket after the heat treatment to minimize the thermal strain. The test was carried out in three test campaigns at the EDIPO facility at SPC. The test program includes Dc performance at the relevant operating conditions. An assessment of the conductor test results in terms of strand performance suggests that the applicable thermal strain is less than -0.33%. The performance is stable upon load cycles. © 2002-2011 IEEE.

The experience gained in the past for the ITER toroidal field model coil conductor and the results obtained so far have led to the definition of an upgraded full size prototype conductor, based on advanced Nb3Sn strand, and entirely manufactured in the European Union (EU). Samples for the characterization in the Sultan facility have been prepared by Luvata (Italy) following the conductor layout defined by ITER. ENEA was responsible for conductor fabrication. Since the conductor layout was new, a full size copper dummy conductor has been preventively produced for the setting of the cabling and jacketing tools. Then, a total of four full size superconducting cables have been prepared by using Nb3Sn advanced strands produced by Oxford Instruments (OST) and European advanced superconductors (EAS), by internal tin and bronze technology, respectively. The details of manufacturing procedures will be described in this paper.

A case of asymptomatic aortic valve fibroelastoma was diagnosed by transthoracic and transesophageal echocardiography in a 77-year-old man. A 2nd tumor was found at surgery. Both fibroelastomas were removed surgically without aortic valve replacement. During surgical excision of a cardiac fibroelastoma, the entire area surrounding the lesion should be inspected carefully for additional lesions. Such lesions can be missed on echocardiographic evaluation.

This paper reports the main outcomes of the 2013 design activities for the toroidal field magnet of the European nuclear fusion reactor DEMOnstration Power Plant (DEMO). Within the current project plan, the manufacture of full-size conductor prototypes during 2014 and their test during 2015 are foreseen, aimed at the assessment of the proposed cable-in-conduit-conductor technologies. Industrial partners have been thus already involved at this early stage, and the preliminary cabling trials performed are illustrated here. As far as the coil design assessment is concerned, one of the main aspects to be investigated is the mechanical performance of the magnet, considering its large size and the high electromagnetic forces involved. An overall 3-D finite-element model of the coil has been set up, and mechanical stress analysis has been carried out for a selected instant of the plasma scenario after the computation of the electromagnetic loads within a full 3-D system model, including central solenoid and poloidal field coil contributions. The resulting loads have been mapped on the finite-element-method model, making use of a novel mesh-independent interpolator based on radial basis functions. The results reported here highlight a quite high level of stress, which is close to the acceptance limits, in some regions of the steel casing. Further investigations and assessments are required, but the most critical areas are clearly identified.

Thermo-hydraulic modeling of cable in conduit conductors (CICC) contains one main uncertainty in the heat exchange coefficient used in the different possible fluid regimes. Nowadays validation of codes, by comparison with data from experiments involving long length instrumented conductors, is one of the main technique for assessing the design tools for the large magnets foreseen in the next generation fusion machines. To this purpose, a broad disturbance scenario has to be investigated to confirm the magnet's stability versus normal and off-normal working conditions. In this paper a comparison between the predictions of the code Gandalf and the data obtained from an instrumented NbTi conductor module is carried out.

The characterization of the critical current Ic in superconducting NbTi and Nb3Sn strands is carried out through a four-probe technique. Besides the dependence on temperature and magnetic field, which can be measured with a standard Variable Temperature Insert, the Ic of Nb3Sn samples is also sensitive to axial strain. For this measurement, specially dedicated probes can be used, among them we recall the Walters spring insert. Both systems and corresponding experimental techniques are here described.

As the test of the PFC1 is foreseen in 2006 at JAERI Naka, Japan, it is essential to consider in detail the lessons learned from the short NbTi sample tests, as well as the issues left open after them, in order to develop a suitable test program of the PFC1 aimed at bridging the extrapolation gap between measured strand and future PF coil performance. Here we consider in particular the following issues: 1) the actual possibility to quench the PFCI conductor in the T-CS tests before quenching the intermediate joint, 2) the question of the so-called sudden or premature quench, based on SULTAN sample results, applying a recently developed multi-solid and multi-channel extension of the Mithrandir code to a short sample analysis; 3) the feasibility of the AC losses calorimetry in the PFCI.