Marcus Lorentzon

Bio: Marcus Lorentzon is an academic researcher from CERN. The author has contributed to research in topics: Neutron scattering & Neutron source. The author has an hindex of 1, co-authored 1 publications receiving 4 citations.

Effect of Applied Compressive Stress and Impregnation Material on Internal Strain and Stress State in Nb 3 Sn Rutherford Cable Stacks

Abstract: The Nb3Sn superconductor in accelerator magnets must resist high mechanical stresses. In order to better understand the effect of the coil impregnation system on the stresses exerted on the strain-sensitive Nb3Sn superconductor, we have measured the elastic strain evolution in the conductor constituents under externally applied loads. For this purpose, a dedicated load frame that enables rotation of the sample load axis with respect to the neutron scattering geometry was installed in the Stress-Spec beamline at the neutron source Heinz Maier-Leibnitz FRM II. The Nb3Sn- and Cu-loading strains were measured in situ by neutron diffraction under monotonic and cyclic compressive loading. So-called ten-stack samples composed of Nb3Sn Rutherford type cables with different impregnation and coil blocks extracted from an 11 T dipole short model coil were investigated.

The 16 T Dipole Development Program for FCC and HE-LHC

Abstract: A future circular collider (FCC) with a center-of-mass energy of 100 TeV and a circumference of around 100 km, or an energy upgrade of the LHC (HE-LHC) to 27 TeV require bending magnets providing 16 T in a 50-mm aperture. Several development programs for these magnets, based on Nb3Sn technology, are being pursued in Europe and in the U.S. In these programs, cos–theta, block-type, common-coil, and canted–cos–theta magnets are explored; first model magnets are under manufacture; limits on conductor stress levels are studied; and a conductor with enhanced characteristics is developed. This paper summarizes and discusses the status, plans, and preliminary results of these programs.

Effect of Epoxy Volume Fraction on the Stiffness of Nb 3 Sn Rutherford Cable Stacks

Abstract: For the optimization of Nb3Sn superconducting accelerator magnet design and assembly parameters the stress-strain behavior of the coils needs to be known. We have measured the stiffness of Nb3Sn Rutherford cable stacks with different epoxy volume fraction. The cable stack stiffness is strongly dependent on the load direction. The highest stiffness of about 95 GPa is measured in axial direction, as predicted by the rule of mixtures. In transverse load direction the stiffness is stress dependent, and about half of the axial stiffness. As expected the stiffness of the cable stacks increases with decreasing epoxy volume fraction. The stiffness of a conductor block extracted from an already cold tested 11 T dipole coil is comparable to that of a ten-stack sample with similar epoxy volume fraction.

Texture in Superconducting Magnet Constituent Materials and Its Effect on Elastic Anisotropy

Abstract: The materials used in superconducting magnet coils and in the structural magnet constituents are textured to various extents. This causes an angular dependence of the Young's moduli that needs to be taken into account when predicting the stress and strain distribution in the magnets. We have measured by neutron diffraction the texture in metallic materials typically used in superconducting magnets. Based on the neutron diffraction data the elastic anisotropy of the different materials has been calculated. Among the materials studied, the extruded Al oxide dispersion strengthened Cu coil wedges exhibit the strongest elastic anisotropy of 37%. The Young's moduli calculated from single crystal elastic constants and grain orientation distributions are compared with highly accurate Young's moduli derived experimentally from resonance tests.