Status of the LHC superconducting cable mass production

Abstract

Abstract-Six contracts have been placed with industrial companies for the production of 1200 tons of the superconducting (SC) cables needed for the main dipoles and quadrupoles of the Large Hadron Collider (LHC). In addition, two contracts have been placed for the supply of 470 tons of NbTi and 26 tons of Nb sheets. The main characteristic of the specification is that it is functional. This means that the physical, mechanical and electrical properties of strands and cables are specified without defining the manufacturing processes. Facilities for the high precision measurements of the wire and cable properties have been implemented at CERN, such as strand and cable critical current, copper to superconductor ratio, interstrand resistance, magnetization, RRR at 4.2 K and 1.9 K. The production has started showing that the highly demanding specifications can be fulfilled. This paper reviews the organization of the contracts, the test facilities installed at CERN, the various types of measurements and the results of the main physical properties obtained on the first batches. The status of the deliveries is presented.

Coupling Current and AC Loss in LHC Superconducting Quadrupoles

“…These results are consistent with inter-strand resistance values in excess of 50 estimated from AC loss measurements. To limit the field errors in the LHC main quadrupole, we require an greater than 20 , and conductance differences smaller than 0.1 MS between parts of the magnet coils [4]. This value represents a good compromise between field advance and multipole errors (small), AC loss (small) and premature quenches due to current distribution (not an issue at the required ramp-rate).…”

Critical Current Measurements of the Main LHC Superconducting Cables

“…Finally, contracts were awarded to six companies, and were signed at the end of 1998. A review of the R&D and supply of these cables can be found in [2], [3]. Already in the R&D phase a collaboration with BNL was set-up to measure the critical current of short samples of cables.…”

Investigation of the periodic magnetic field modulation in LHC superconducting dipoles

“…The oxidation process of the strand coating developed at CERN for the superconducting cables for the LHC is expected to guarantee a minimum value for equal to 20 [12]. This is actually the case as it can be seen in Table IV for values deduced from measurements performed on prototypes and first pre-series dipoles.…”

“…In addition, the largest spread in values is observed inside short dipole models whereas all results obtained in long dipoles are very close. This result can be explained by the oxidation process of the strand coating (SnAg ) developed at CERN for the superconducting cables of the 3rd generation prototypes, pre-series and series magnets [12].…”