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Long-time exposure to galactic cosmic rays is one of the most problematic threats for a manned mission in the deep space. In the last decades, several studies of active superconducting magnetic shields were performed leading to the proposals of apparently promising magnetic configurations. However, as the interaction of energetic particles with the materials composing the magnets was not taken into account, the contribution of secondary particles to the astronauts’ radiation dose was neglected, and, consequently, the actual effectiveness of the shields was overestimated. In the frame of the EU-FP7-SR2S project, a study of superconducting space radiation shield was performed associating the optimization of the magnetic configuration with Monte–Carlo simulation of the dose reduction. It was found that most of the magnetic shields proposed in previous works are not adequate, and a novel configuration, transparent to radiation, was proposed based on toroids arranged with their axes perpendicular to the spacecraft axis. Compared to other shields with the same shielding power, such a configuration results in lower magnetic field at the superconductor and very light design. [ABSTRACT FROM PUBLISHER]

The “magnetic window” is considered a promising means to eliminate reentry communications blackout. Nevertheless, a numerical analysis is needed detailing the efficacy of the window under nonuniform magnetic fields generated by a magnet. For this purpose, the electromagnetic wave transmission characteristics are obtained using the hybrid matrix method. A two-Gaussian model for the plasma sheath density is assumed. The sheath is modeled by partitioning into slabs, for which the magnetic field and electron density in each slab are assumed uniform. Various plasma parameter values and magnetic field strengths are used. The numerical results show that, compared with uniform magnetic fields, a wider stopband in the transmission response is formed using nonuniform magnetic fields; the stopband width depends on the range between the maximum and the minimum magnetic field strengths. Therefore, the frequency hoped for in the magnetic window in the left passband using uniform magnetic field may be located in the stopband arising from the nonuniform magnetic field. [ABSTRACT FROM PUBLISHER]

In electric vehicles, passengers sit very close to an electric system of significant power. The high currents achieved in these vehicles mean that the passengers could be exposed to significant magnetic fields (MFs). One of the electric devices present in the power train are the batteries. In this paper, a methodology to evaluate the MF created by these batteries is presented. First, the MF generated by a single battery is analyzed using finite-elements simulations. Results are compared with laboratory measurements, which are taken from a real battery, to validate the model. After this, the MF created by a complete battery pack is estimated, and results are discussed. [ABSTRACT FROM PUBLISHER]

What is the ultimate limit to high fields in superconducting magnets for particle accelerators? In this paper we review the present status of the technology, outlining the main limitations. We first analyse the needed margin for operating a magnet in an accelerator. We then review the relation between current densities, coil widths, and fields in the magnets build so far. The issue of stress and the dependence on the coil lay-out is then discussed: a careful optimization between current density and coil width can be needed to keep the forces and associated strain within acceptable limits. The main issues related to cable lay-out (strand diameter, filament size) are then discussed. We conclude by giving a hint on the requirements on a HTS conductor, and a summary of Nb-Ti and Nb3Sn. [ABSTRACT FROM PUBLISHER]

The Nijmegen High Field Magnet Laboratory (Nijmegen HFML) presently offers to its users 33 T in two 32 mm bore resistive magnets, 32 T in a 50 mm bore resistive magnet and 30 T in a 50 mm bore hybrid magnet. To comply with the users' demand for ever higher magnetic fields without having to resort to hybrid magnets, a new resistive 20+ MW magnet has been designed and is now being constructed, which will deliver 38 T in a 32 mm bore. The magnet consists of five Florida-Bitter coils and one outer Bitter coil. The two innermost coils (A1 and A2, CuAg conductor) are electrically in parallel. The outer coil (E, Cu conductor) has an outer diameter set to 1 m. The length of this coil is about 670 mm and it weighs almost 3000 kg, indicative of the huge amount of conductor material needed for 40 T class resistive magnets. An important issue is the necessity to reduce the slit factor, i.e. the locally high current density in a winding at a slit in a Bitter disk. We therefore decided to implement the modified Weggel stacking scheme for the A, B and C coils, implying a noninteger number of disks per turn, e.g. 11 13/25 for the B coil. Also, a new compact (1.3 m outer diameter, 1.4 m height) housing has been designed, able to withstand the combined stress due to the maximum fault force of 2.1 MN (occurring when the C coil fails) and the effect of 40 bar differential water pressure. The new magnet is expected to be commissioned in the fourth quarter of 2012. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to present an up to date review of the status of the European DIPOle (EDIPO) project—whose objective is to build a new facility to perform both DC and AC tests of large force flow superconductor samples in high magnetic background field (up to \sim12.5 T)—as well as an outlook on the final commissioning of the magnet in CRPP-PSI foreseen for 2012. Concerning the actual status, the results presented focus on the recent steps carried out in the manufacturing of the magnet assembly, in particular the cold mass assembly, its impregnation and the final acceptance tests. Moreover, results are reported regarding the identification and repair of an inter-turn short carried out on EDIPO Pole 1 in the second half of 2010. As far as the commissioning of EDIPO is concerned, an up-to-date report is provided on the preparation of the facility at CRPP (e.g. mechanical structures, high temperature current leads, quench detection, control system, etc.) as well as its acceptance and final commissioning (e.g. magnet reception tests, commissioning program, etc.) [ABSTRACT FROM PUBLISHER]

A benchmarking experiment was conducted to compare strain measurement facilities at the National Institute of Standards and Technology (NIST) and the University of Twente. The critical current of a bronze-route Nb3Sn wire, which was fabricated for the International Thermonuclear Experimental Reactor (ITER), was measured as a function of axial strain and magnetic field in liquid helium at both institutes. NIST used a Walters' spring strain device and University of Twente used a bending beam (“Pacman”) apparatus. The ITER bronze-route wire investigated had a very high irreversible strain limit that allowed comparing data over a wide range of applied strain between -1% and +1%. Similarities of the data obtained by use of the two apparatuses were remarkable, despite the many differences in their design and techniques. [ABSTRACT FROM PUBLISHER]

This paper investigates design, modeling, simulation, and control issues related to self-propelled endoscopic capsule navigated inside the human body through external magnetic fields. A novel magnetic propulsion system is proposed and fabricated, which has great potential of being used in the field of noninvasive gastrointestinal endoscopy. Magnetic-analysis model is established and finite-element simulations as well as orthogonal design are performed for obtaining optimized mechanical and control parameters for generating appropriate external magnetic field. Simulated intestinal tract experiments are conducted, demonstrating controllable movement of the capsule under the developed magnetic propulsion system. [ABSTRACT FROM AUTHOR]

We present a new method for improving the magnetic loss properties of a certain class of isotropic vector hysteresis models based on the Mayergoyz model. We show that the Mayergoyz model possesses the necessary features for representing vector hysteresis but falls short of satisfying the loss property under rotating magnetic fields with magnitudes close to saturation. Therefore, we propose a new simple method to improve the loss property of the Mayergoyz model while keeping the essential features of the model. The method is based on removing the irreversible process persisting at saturation and hence correcting the magnetization behavior of the Mayergoyz model. We present thorough discussions about the properties of the new model as well as numerical results supported by experiments. [ABSTRACT FROM AUTHOR]

A planar single-pole head generating a large head field was investigated to improve head field distribution with a steep field gradient. Good writing performance is generally difficult for a narrow track writer. This work presents a novel design of the main pole shape, the three-step-slope, to achieve a high gradient and strong write head field for terabit recording. Furthermore, the medium design was investigated to increase head-to-medium interaction for achieving a high field gradient and narrow field distribution. A soft guard band in the recording layer and a cross-track groove on the SUL surface were effective for improving the field gradient [ABSTRACT FROM AUTHOR]

This paper, starting from previous experiences in modeling the magneto-mechanical behavior of magnetoelastic materials, faces the problem of loss evaluation of a magnetostrictive device. Measurements and simulations in a prototype actuator are here presented and compared, showing a general good agreement. The model is consequently used for a reliable loss separation. The effects of magnetization bias, preload and supply frequency on electric and magnetic losses are deepened and discussed. [ABSTRACT FROM AUTHOR]

We present large-scale computations of currents induced in the human body, arising from an external low-frequency magnetic-field source. The calculations are performed using the Ex-SPFD approach; an extension of the classical SPFD approach, that can handle arbitrarily shaped magnetic-field sources and highly conductive material inside the computational domain. In order to sufficiently resolve even small organs such as the eye, very fine spatial resolution is needed. Such fine resolution results in very large systems of equations. Problems consisting of up to 200 millions of unknowns are presented. [ABSTRACT FROM AUTHOR]

A comparative, computational study of the modeling of transcranial magnetic stimulation (TMS) and electroconvulsive therapy (ECT) is presented using a human head model. The magnetic fields from a typical TMS coil of figure-eight type is modeled using the Biot-Savart law. The TMS coil is placed in a position used clinically for treatment of depression. Induced current densities and electric field distributions are calculated in the model using the impedance method. The calculations are made using driving currents and wave forms typical in the clinical setting. The obtained results are compared and contrasted with the corresponding ECT results. In the ECT case, a uniform current density is injected on one side of the head and extracted from the equal area on the opposite side of the head. The area of the injected currents corresponds to the electrode placement used in the clinic. The currents and electric fields, thus, produced within the model are computed using the same three-dimensional impedance method as used for the TMS case. The ECT calculations are made using currents and wave forms typical in the clinic. The electrical tissue properties are obtained from a 4-Cole-Cole model. The numerical results obtained are shown on a two-dimensional cross section of the model. In this study, we find that the current densities and electric fields in the ECT case are stronger and deeper penetrating than the corresponding TMS quantities but both methods show biologically interesting current levels deep inside the brain. [ABSTRACT FROM AUTHOR]

Presents a study which observed the magnetophoresis of diamagnetic cells under gradient magnetic fields in a culture medium. Methodology; Results; Discussion.