Yoke Geometry Research Articles

Yoke geometry study using pulsed field magnetization on superconducting joined bulk Gd-Ba-Cu-O

Conditions for obtaining high-quality superconducting joint in Gd-Ba-Cu-O bulk superconductors were investigated, and the effects of PFM properties of the joined bulk and the change of yoke geometry in magnetization were examined. For a good superconducting joint fabricated by the local melting method using sintered Er-Ba-Cu-O, the J c-B property and multiple Hall sensors indicates that the joined part is the preferential field penetration path. PFM was performed using a changed geometry of yoke in which concentrated long pulse to the joined part, but the result was equivalent to the trapped field before the changing yoke because the volume of the yoke was reduced. This is the first attempt to approach an effective PFM method for the joined bulk from the viewpoint of a changed geometry of yoke.

Strength Analysis on Yoke Single Point Mooring with Finite Element Method

Analysis of stresses and deformations in the Single Point Mooring (SPM) yoke structure using the Finite Element Method (FEM) aims to determine and understand the stress distribution and deformation of the yoke, so that offloading activities comply with safety standards. The finite element method is a numerical modeling technique used to predict the behavior of a system by dividing an object into a number of elements that can be analyzed independently. This study uses 3 geometric models, namely single point mooring yoke geometry aged 0, 20, and 30 years. The results of the analysis will assist in understanding the stresses and deformations that occur in the SPM yoke structure. To simulate the tension of the ship during unloading, tensions of 75, 100, and 125 tons are represented. For each geometry, the greatest stress and deformation values found are 89 MPa for the 0-year model, 89.2 MPa for the 20-year model, 97.1 MPa for the 30-year model, respectively, and 0.08 mm for the 0-year model, 0.10 mm for the 20-year model, 0.11 mm for the 30-year model. This investigation demonstrates that the observed stress levels and deformations comply with safety standards.

Dynamics loading by swinging bells—Experimental and numerical investigation of the novel yoke–bell–clapper system with variable geometry

The dynamics of swinging bells is a timely problem considered when the bell’s supporting structures are designed or monitored. The geometry of a yoke and the magnitude of an excitation force are crucial parameters determining a yoke–bell–clapper system response for a given shape and size of the bell. This paper presents the novel yoke–bell–clapper system with variable geometry and adjustable excitation force. A mathematical model based on the existing prototype is introduced. The mathematical model is validated, and then the influence of the yoke geometry and excitation force on the system response is assessed. The simulations are done using a sample-based approach. The system that undergoes investigation is non-linear, piecewise, and discontinuous. The derived mathematical model can reliably predict the ringing scheme of a bell and associated reaction forces in the supports.

Reduction of AC Loss in HTS Coils of Superferric Magnets for Rapid-Cycling Synchrotrons by Changing Cross-Section of Coils and Iron Yoke Geometry

We have been studying the potential of energy consumption reduction in rapid-cycling synchrotrons (RCSs) by using superferric magnets with coils wound with high temperature superconductor (HTS). By conducting three-dimensional electromagnetic field analyses on superferric magnets with different coil cross-sections and iron yoke geometries, ac loss of each magnet design was estimated. Rough estimations of the iron loss were also conducted to obtain overall energy consumption of each magnet design. By the comparison, influence of coil cross-section and iron yoke geometry on electricity consumption of the magnet were evaluated.

Impact of Annular Yoke Geometry on Performance of a Dynamo-Type HTS Flux Pump

Flux pumps provide a contact-free method of energizing dc currents in superconducting coils. Since a predictive quantitative theory for dynamo-type flux pumps does not exist yet, the optimization of device designs must proceed through empirical experiment. In this paper, we investigate the effect of varying the annular width of the iron stator yoke within a high-temperature superconducting dynamo. Reducing the dimensions of this iron yoke reduces the mass of cold iron within the dynamo, and hence has advantages in terms of weight, cryogenic efficiency, and eddy current losses. In this paper, we have investigated the dc output from an experimental high-temperature superconductor (HTS) dynamo in which the annular width of the iron yoke Δr is varied across a factor of four. Varying this dimension affects the reluctance of the magnetic circuit formed between the rotor and stator. We have shown that the dynamo output is surprisingly insensitive to the size of the iron yoke. The maximum current output (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sc</sub> ) is independent of Δr at all flux gaps. At the closest magnet-stator flux gap, a fourfold increase in Δr results in only a ~30% increase in the open circuit voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> ) and internal resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ) of the dynamo. Our results indicate that the smallest yoke studied (Δr = 6 mm) can be utilized with a 25.4-mm Nd-Fe-B rotor magnet, without adverse impact on the electrical performance of this type of HTS dynamo.

Development of Wide-Aperture Quadrupole Magnets for Plasma Experiments in the FAIR Project

Heavy ion heating and expansion and laboratory planetary sciences experiments are designed by the high energy density matter generated by heavy ion beams collaboration to study matter under extreme conditions of temperature and pressure at the FAIR facility in Darmstadt, Germany. A special final focusing system has to be installed at the end of the high energy density matter generated by heavy ion beams beam line for strong transverse focusing. To provide a focal spot of the size of a millimeter or less, a large focal angle is needed and, consequently, large-aperture high-gradient quadrupole magnets have to be used in the final focusing system. The Institute for High Energy Physics has considered the basic principles of the development of these magnets. The main parameters of the quadrupole are: the central gradient is 33 T/m; the inner diameter of the coil is 240 mm; the effective length of the magnet is 2 m; and the operating mode is dc. Design features of these quadrupole magnets are detailed: the superconducting wire, 2- and 3-D optimization of the coil and yoke geometry, and mechanical analysis. Preliminary considerations are given on the parameters of the protection and cooling systems of the magnets.

Impact of the Rotor Yoke Geometry on Rotor Losses in Permanent-Magnet Machines

This paper presents a study on the rotor losses of surface-mounted permanent-magnet (PM) machine with fractional-slot windings. Two rotor losses sources are considered: the losses due to the slot opening (without currents in the stator) and due to the magneto motive force harmonics (mounting a rotor with demagnetized PMs). The rotor losses are measured at no load and under load. It is shown that the rotor losses under load are lower than considering the sum of the two contributions. This phenomenon is investigated using both analytical models and finite-element-based simulations. Then, the impact of the rotor geometry on the rotor losses is considered, and some design advices are reported.

Parametrization-invariant Wald tests

Parametrization-invariant versions of Wald statistics are introduced, based on yoke geometry. The construction is illustrated by several examples. In the case of simple null hypotheses, formulae are given for generalized Bartlett corrections of these geometric Wald statistics which bring their null distributions close to their large-sample asymptotic distributions.

Magnetic designs of 2-in-1 Nb/sub 3/Sn dipole magnets for VLHC

The paper presents the results of a conceptual design study of double aperture Nb/sub 3/Sn dipole magnets for VLHC based on the cos-theta and common coil geometry with cold and warm iron yoke. The study included an optimization of the iron yoke geometry to achieve the maximum transfer function, small fringe fields and low-order field harmonics as well as an optimization of the coil geometry to correct a quadrupole field component (normal or skew) inevitable for 2-in-1 magnet designs.

Magnetic design and analysis of the SSC High Energy Booster dipole magnets

This paper presents key magnetic design considerations and analyses performed on the Superconducting Super Collider (SSC) High Energy Booster dipole magnets (HDM). The design considerations include: optimization of the cell cross section to establish low magnetic field harmonic content and specified field strength throughout a wide range of cable azimuthal sizes; effects of wedge geometry and cable stacking procedures on the field harmonics; and effects of yoke geometry and material variations on the central field strength and harmonics of the magnet.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>