High Temperature Superconductors in the LHC

Sabrina El Yacoubi — Thu, 27 Nov 2014 14:37:07 +0000

High Temperature Superconductors in the LHC
by Amalia Ballarino (CERN)

Maquette of High Temperature Superconducting Link of the type needed at LHC Point 7. Image credits: CERN

Superconducting links in accelerator systems enable powering of the cryo-magnets from remote power converters. The development carried out within Task 5 of the EuCARD Work Package7 aims at providing such technology for the remote powering of LHC magnets.

The use of High Temperature Superconductors (HTS) in Superconducting Links has the great benefit of enabling the development of a powering system where superconductors can be operated with a generous temperature margin. To enable the use of superconductors with tape geometry, a novel concept of cable optimized for DC electrical transmission (Twisted-Pair Cable) has been developed and demonstrated [1], [2]. A cabling machine enabling the controlled assembly of km-long Twisted Pair cables - made from superconductors with different mechanical characteristics - has been conceived, assembled and commissioned at CERN. A full-scale 5 m long prototype link has been made at CERN and successfully tested in nominal conditions at the University of Southampton [3]. A 20 m-long full scale link is being assembled at CERN, where it will be tested in nominal and transient conditions.

The main outcomes of this activity are: (1) the development of a novel concept of superconducting cable for electrical transmission that can be made from any of the HTS tape-conductors today available (BSCCO 2223, YBCO or MgB2); (2) the development of a new cabling machine for the controlled assembly of the cable; (3) the development of a full superconducting link system that could be used at LHC Point 7 for the powering of the superconducting magnets. The developed technology could be applied for feeding any superconducting system requiring currents in the 1 kA range at any temperature from liquid nitrogen to liquid helium.

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EuCARD

HTS

Superconductors

issue 5

A step towards Next Generation Magnets

Margarita Synanidi — Thu, 20 Nov 2014 16:20:30 +0000

A step towards Next Generation Magnets
by Luca Bottura (CERN)

A Roebel cable prototype, inserted in a sample holder and ready for test at low temperature and high field in the CERN FRESCA test facility. Image credit: J. Fleiter, CERN

The Future Magnets, Work Package 10 of EuCARD-2 is exploring the use of High Temperature Superconductors (HTS) materials in future accelerator magnets: YBCO and BSCCO. Both YBCO and BSCCO were found to have not only a high critical temperature, but also a very high critical field, exceeding 100 T. This is what makes them especially interesting for high field accelerator magnet applications.

Following an evaluation performed by the EuCARD2 WP10 team, and the associated laboratories in the US and Japan, it was decided that the European program would focus on YBCO tapes, assembled in Roebel bars or, as an option, stacked tapes. YBCO is a material produced by one of the industrial partners of EuCARD-2 (Bruker HTS), and has potential for use both in very high field applications beyond the scope of WP10, such as Nuclear Magnetic Resonance magnets, as well as power applications such as Fault Current Limiters or high current power transmission cables. Accelerator magnets require high current, and the Roebel bar is a way devised by KIT to assemble multiple YBCO tapes in a high current transposed conductor. Samples of such conductors were already tested at CERN at cryogenic conditions (4.2 K) and intense field (10 T), showing the desired high current carrying capability. The EuCARD2 WP10 will produce samples of YBCO Roebel bars in the coming months.

As for the alternate material, EuCARD2 makes a significant contribution by providing the precursor powders necessary for the production of the BSCCO-2212 superconducting wire.

The question for the coil cross section is yet open for both Roebel bars and Rutherford cables; the magnet geometry for making the optimal use of the current carrying capacity of the superconductor, and respecting the engineering limits of the materials, is not necessarily the same.

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accelerating-news-arc.web.cern.ch - HTS

High Temperature Superconductors in the LHC

A step towards Next Generation Magnets