Toward an Improved High Strength, High RRR CMS Conductor

Abstract

CMS (Compact Muon Solenoid) is a general-purpose detector designed to run at the CERN Large Hadron Collider (LHC), including a 4-layer superconducting solenoid with 6 m diameter by 12.5 m long free bore operated at 4 T and at 4.5 K. The Rutherford type superconductor, stabilized by high purity 99.998% aluminum, is reinforced by aluminum alloy sections welded to the superconductor by electron beam. Due to the high magnetic forces at nominal field inside the winding pack, the conductor itself represents a main structural component to get a self-supporting winding structure. In view of an upgrade oriented to a possible new project, an improvement of the mechanical performances of the reinforced conductor starting from the CMS concept has been considered, aimed to increase the reachable field based on an optimized layout.

Effect of thermo-mechanical processing on the material properties at low temperature of a large size Al-Ni stabilized Nb-Ti/Cu superconducting cable

“…Further cryogenic tensile study at a strain rate similar to what is experienced by the material in operational situation, can give a decisive answer on this topic. In a previous study by the authors [5] the average mechanical values obtained were compared with results of earlier studies on the CMS and ATLAS solenoid conductor [6,7,19,18]. Our values were found to be slightly lower than the gross of measurements conducted on the Al-0.1%Ni stabilizer material in the development of the CMS and ATLAS solenoid conductor.…”

“…aluminum alloy 6061, which exhibits a R p0.2 at 4.2 K / R p0.2 at 293 K ratio of 1.8 -1.9 in a T4 temper state [17]. A slight inconsistency of the results obtained here with the results obtained on the Al-Ni material in the development of the CMS and ATLAS solenoid conductors, reporting a ∼1.5 ratio [18,7], could therefore be the result of the material's strain rate sensitivity due to a different measurement speed. Further cryogenic tensile study at a strain rate similar to what is experienced by the material in operational situation, can give a decisive answer on this topic.…”

3D FEM Modeling of the Moil Ends of the LHC Main Dipole

“…Two main components constitute the heads: the spacer and the superconducting winding. The spacers are machined in G11 epoxy-fiber glass pipes and the raw material has been submitted to mechanical tests in order to Table I [4]. It is worth remarking the difference in azimuthal modulus between the material used to produce the inner layer spacers and the one used for the outer layer.…”

Experience Gained From the Construction, Test and Operation of the Large 4-T CMS Coil

“…Another clear advantage would be of staying in a nearly fully elastic state, thus exhibiting constant properties with time in terms of mechanical properties and RRR [22].…”