High point for CERN and high-temperature superconductors

Amalia Ballarino is named the Superconductor Industry Person of the year 2006.

The CERN project leader for the high-temperature superconducting current leads for the LHC, Amalia Ballarino, has received the award for "Superconductor Industry Person of the Year". This award, the most prestigious international award in the development and commercialization of superconductors, is presented by the leading industry newsletter "Superconductor Week". Amalia Ballarino was selected from dozens of nominations from around the world by a panel of recognized leading experts in superconductivity. "It is a great honour for me," says Amalia Ballarino. "It has been many years of hard work, and it’s a great satisfaction to see that the work has been completed successfully."

Amalia Ballarino has been working on high-temperature superconducting materials since she arrived at CERN in 1997. The high-temperature superconducting (HTS, see box) current leads are used in the LHC to transfer current from the room-temperature power converters to the thousands of superconducting magnets operating at liquid helium temperature. The LHC is equipped with more than 1000 HTS leads, representing the first real large-scale commercial application of HTS materials in the world. As Project Manager, Amalia Ballarino has been responsible for the leads from the initial HTS materials testing and selection to the engineering design and collaboration with industry and laboratories all around the world for the manufacturing and testing of the final series production. "The challenge of the project has been enormous, starting from the very beginning when it was not at all obvious that the HTS material would achieve the performance required for this very large-scale application", says Amalia Ballarino. "The effort made at CERN in the optimization and design of these components has been such that now HTS leads are considered the natural solution for any electrical system operating at cryogenic temperatures."

Bringing electrical current from the room-temperature power system into the extremely cold environment poses the engineering challenge of how to transport large amounts of electricity while minimizing the amount of power dissipated into the cryogenic system. Thanks to its zero resistance and its low thermal conductivity, the use of HTS material incorporated in the colder part of the leads allows an important saving in cooling power. Using HTS leads in the LHC has reduced the heat load into the liquid helium environment by a factor greater than ten with respect to conventional self-cooled leads.

The high-temperature superconducting material used in the LHC current leads is a compound of bismuth (Bi-2223), which operates in the LHC leads in a temperature range of between 50 K and 4.2 K. This material is produced in the form of a multi-filamentary tape, where the superconducting filaments are embedded in a silver alloy matrix of relatively low thermal conductivity. The tape is made with a mechanical deformation process that aligns the superconducting grains within the silver matrix and thus minimizes obstacles to current flow.

"I’m grateful to the LHC management for having entrusted me with this high-tech project that simply had to work – both for reducing costs of the LHC and for the good of the HTS industry at large!", underlines Amalia Ballarino. "I also wish to thank my colleagues, the specialists in the TS Department, whose expertise in brazing, welding and surface treatments has enabled elegant solutions to be found to a number of difficult problems – and of course the technicians in our small section for their able support throughout this challenging project".

See also "Superconductor Week" Press release.