18 research outputs found
Magnetic flux distribution in a three-dimensional inductive network of Josephson junctions
No full textThe magnetic response of three-dimensional Josephson junction networks to constant or slowly varying external magnetic fields is studied. General equations are written for complex networks made of n elementary cubic cells, each cell containing 12 resistively shunted ideal Josephson junctions. The magnetic-flux distribution in the network is calculated numerically as a function of the external magnetic field for different values of superconducting quantum interference device parameter, network size, and external magnetic-field direction. The magnetic-flux distribution in the network is graphically shown, first for increasing and then for decreasing values of the external magnetic flux
Utilizing Helicoidal and Translational Symmetries Together in 2-D Models of Twisted Litz Wire Strand Bundles
No full textIn this article, a helicoidally symmetric 2-D model of a twisted litz wire strand bundle is studied. Suitable foundations for compatibility tools are presented to use such a model as a part of a larger system which does not follow a helicoidal symmetry. A measure for the symmetricity of a field is proposed. This provides the foundations for the coupling of helicoidally symmetric and translationally symmetric models with good understanding of the introduced approximation error.Peer reviewe
A Database for Storing Magnet Parameters and Analysis of Quench Test Results in HL-LHC NbSn Short Model Magnets
No full textIn recent years, several Nb3Sn high field magnet prototypes have been designed and tested in preparation for the LHC Luminosity upgrade and also for the potential Future Circular Collider (FCC). In this paper we present a Microsoft Excel -based database tool for storing magnet design parameters and results from quench protection tests. The hierarchical and flexible structure of the relational database allows for systematic and coherent analysis of the test data from different magnet assemblies and works as a practical reference for magnet design evolution. Data from quench protection heater tests in several high-field Nb3Sn magnet prototypes has been stored in the database. We use this data to validate the quench simulation assumptions used in FCC 16 T dipole magnet design
Effect of cell type on convergence of wave propagation schemes
No full textWe examine the effect of the cell type on the accuracy of Yee-like schemes. The approach is built over an error bound introduced for the discrete counterparts of the constitutive laws. We specify which geometric properties of the cells have an effect on the approximation errors. The convergence properties of different cell types are demonstrated with numerical examples.</p
2-D Axisymmetric FEM-Based Approach for Identifying Dimension- and Frequency-Independent Material Parameters of Mn-Zn Ferrites
No full textA 2-D axisymmetric finite element (FE) method based approach is presented for identifying intrinsic, dimension- and frequency-independent, electromagnetic material parameters of Mn-Zn ferrite cores. The parameters include the DC conductivity, complex permittivity and complex permeability both for the grains and the grain-boundaries. The FE model is utilized for solving the full-wave electromagnetic field problem in a cross-section of a ferrite core placed in a dielectric setting while accounting for the grain-scale microstructure. Dielectric impedance measurements are carried out for ferrite cores over a frequency range of 1 kHz - 10 MHz. The intrinsic material parameters are identified by fitting the FE model parameters such that the modeled impedances match with the measured ones. A model with dimension- and frequency-independent electromagnetic material parameters is able to reproduce only the low frequency behaviour before the occurrence of dimensional resonance. In order to model the resonance behaviour as well, a frequency-dependent term is introduced to the imaginary part of the reluctivity to account for “excess” magnetic losses.Peer reviewe
