HTS at CERN & LHC Current Leads

Contact: Dr. Amalia Ballarino    (AT-MEI-SD)   
Physics of HTS
HTS materials
HTS leads
Resistive leads
Other activities


HTS materials have already been used to demonstrate a variety of applications. In the field of large-scale applications, where high currents and long lengths are required, power transmission cables, fault current limiters, transformers, motors and generators have been made using both 1st and 2nd generation HTS. For small-scale applications, where more specialized properties of HTS tend to be used, examples are detection systems and analog and digital processing.

Different type of materials are commercially available today:

  • Bi-2223 (Bi2Sr2Ca2Cu2Ox) multi-filamentary tape (1st generation superconductor). This material is available on the market in long (about 1 km) lengths. The tape, which is typically about 4 mm wide and 0.2 mm thick, is produced with the Powder In Tube (PIT) process. It has a silver alloy matrix, which is reinforced either by alloying or by attachment to a metallic substrate to improve its strength tolerance.

  • Bi-2212 (Bi2Sr2CaCu2Ox) multi-filamentary wire and tape (1st generation superconductor). It is also available in long lengths. Having a high critical field, it is particulary suited for high current or high field applications at temperatures below 20 K, such as inserts in high field magnets.

  • Y-123 (YBa2Cu3O7-x) coated conductors (2nd generation superconductor), where a bi-axially textured superconductor is coated on a flexible ribbon. This material is in these days becoming available on the market in lengths of about 100 meters. It is expected to replace the Bi-2223 because of its higher critical temperature and field and the lower cost of raw materials.

  • Bulk melt-textured Y-123 and melt-cast processed Bi-2212 materials for novel applications such as magnetic bearings, magnetic shields, flywheels and current limiters.

  • MgB2 in the form of bulk, tape and wire. It can be produced either with in-situ (reaction between Mg and B) or ex-situ (sintering of MgB2 powders) processes. It has a relatively low critical temperature (39 K), but a high potential in view of the low cost of raw materials and manufacturing processes. It is becoming available in long lengths in the form of wire and tape.

In the LHC we take advantage of the unique properties of the HTS material to reduce considerably the heat in-leak via the current leads. Stacks of Bi-2223 tape in a silver-gold matrix are used to feed more than 3 MA of current to the superconducting magnets operating at liquid helium temperature. The LHC current leads, which represent the first application of HTS material for accelerator technology, provide a unique opportunity to demonstrate the value of incorporating HTS materials into a large scale system

last changed: 2005-11-23 webmaster: Amalia Ballarino