Numerical Investigation on the Thermo-Mechanical Behavior of HTS Tapes and Experimental Testing on Their Critical Current

This work extends to second generation Rare-Earth Barium-Copper-Oxide ((Re)BCO) tapes an experimental proce- dure previously developed to analyze the impact of double bending at room temperature on the performance of Bismuth-Strontium- Calcium-Copper-Oxide (BSCCO) tapes. The modified procedure is applied to measure the critical current of a commercial (Re)BCO tape subjected to bending around a cylindrical mandrel first on one side, then on the other side, followed by the cooldown to cryogenic temperature. In the bending phase, mandrels of decreasing diame- ter are used to identify the minimum curvature leading to a signif- icant reduction of the tape critical current. Furthermore, a novel finite element model is developed to complement the experimental results. The model simulates the double bending at room tempera- ture, the following straightening of the sample, and its cooldown to cryogenic conditions. The coupled thermo-mechanical numerical model together with the temperature-dependent mechanical prop- erties allow investigating the combination of thermal contraction effects and bending loads in the whole domain of the problem. The experimental and numerical results obtained help to give a better insight in the distribution of the strain and stress components inside the (Re)BCO tape and to evaluate their impact on the conductor electrical performance in relevant operating condition

Towards a Muon Collider

A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work.Comment: 118 pages, 103 figure

Towards a muon collider

A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work

Erratum: Towards a muon collider

The original online version of this article was revised: The additional reference [139] has been added. Tao Han’s ORICD ID has been incorrectly assigned to Chengcheng Han and Chengcheng Han’s ORCID ID to Tao Han. Yang Ma’s ORCID ID has been incorrectly assigned to Lianliang Ma, and Lianliang Ma’s ORCID ID to Yang Ma. The original article has been corrected

Towards a muon collider

A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work

Two-Dimensional Anisotropic Model of YBCO Coated Conductors

The ability of second-generation YBCO coated conductor (CC) tapes to transport high current densities at high temperature, i.e., up to 77 K, and at very high magnetic fields, i.e., above 20 T, are pushing the use of these tapes in various applications, from magnet to power system technologies. An accurate study of their quench behavior is mandatory for the design and safe use of cables and magnets manufactured with this ceramic superconducting material. A new 2-D finite-element method (FEM) numerical quench model, which is called anisotropic model of YBCO CCs, was built for this purpose in the COMSOL Multiphysics environment. One of the most difficult issues in the modeling of the YBCO tapes with the FEM is their high aspect ratio due to the very small thickness of the YBCO layer, about 1 \u3bcm. In the model developed, the problem of the high aspect ratio of the tape is tackled by multiplying the tape thickness by a constant factor and then compensating the heat and electrical balance equations through the introduction of material anisotropic properties. The FEM model is validated by comparison with literature experimental data on minimum quench energy and normal zone propagation velocity

Design and Testing of a Magnetically Levitated Conveyor

A conveyor device aimed at moving objects placed on a translating chain is studied. Losses, friction and noise reduction are the main objectives, which are obtained by magnetically levitating the chain with the aid of a system of permanent mag-nets placed on the chain and on the beam. A stable vertical levita-tion was obtained, while the horizontal instability was managed reducing the allowed gap between the chain and the beam. A cus-tomized three-phase drive unit was also realized in order to re-duce the size and the inertia of the conveyor. A prototype was built and tested in order to verify the outcomes of the design

Design and testing of a magnetic suspension for a 90\ub0 horizontal bend conveyor

Purpose A conveyor device is studied with the aim to reduce the friction between the inner surface of the beam and the chain. The lower is the friction between the chain and the beam, the lower is the surface wear. The magnetic repulsion force among permanent magnets placed on the beam and on the chain is utilized to reduce friction. Design/methodology/approach The considered magnetic suspension is realized with permanent magnets in repulsive configuration; it is designed by solving a constrained optimization problem, with reference to the geometry of the 90\ub0 horizontal bend FlexLink WL322 conveyor. Flux density field and its gradient are evaluated using volume integral equation method, allowing to calculate the forces acting on the chain and the stiffness of the magnetic suspension. Findings The magnetic suspension prototype was manufactured and tested. The experimental and calculated values of the forces acting on the chain compares well. A stable horizontal equilibrium of the chain was obtained during both static and dynamical tests. Research limitations The quasi-static model used neglects the dynamical interactions among the elements of the chain, the permanent magnets and loads weight during motions and the eddy current losses in the aluminium beam. However the dynamical tests on the prototype show that the chain motion is regular up to the nominal velocity all along the conveyor with the exception of the trailing edge of the 90\ub0 curve. Practical implications The tests on the prototype show the possibility of a removal or at least a reduction of the friction force between the chain and the inner side of the beam by means of a passive magnetic suspension. As a consequence a reduction of noise and vibrations and an increase of the mean-time-to-failure is expected. Originality/value Prototype testing shows that the unavoidable vertical instability of the magnetic forces has no practical consequence since, re-ducing the allowed vertical gap, the chain is stabilized by the gravitational force