Current Leads for the LHC Magnet System

The LHC current lead project is now entering into the stage of procurement of the components for integration into the machine. About 3300 current leads with ratings ranging from 60 A to 13000 A will be required for powering the numerous electrical circuits. The main design choices have been taken on the basis of the outcome of an intensive R&D program covering the characterization of suitable High Temperature Superconducting (HTS) materials for current leads, the validation of lead design options and the measurement of the thermo-electrical performance of prototypes tested under various operating conditions. Helium gas cooled leads integrating HTS material at the colder end will be used for high current leads (currents ³  600 A), while the corrector dipole magnets (60 A - 120 A) will be powered via specifically designed conduction-cooled resistive leads. An outline of the retained designs will be presented, together with required schedule for lead manufacture

Application of High Temperature Superconductors to Accelerators

Since the discovery of high temperature superconductivity, a large effort has been made by the scientific community to investigate this field towards a possible application of the new oxide superconductors to different devices like SMES, magnetic bearings, flywheels energy storage, magnetic shielding, transmission cables, fault current limiters, etc. However, all present day large scale applications using superconductivity in accelerator technology are based on conventional materials operating at liquid helium temperatures. Poor mechanical properties, low critical current density and sensitivity to the magnetic field at high temperature are the key parameters whose improvement is essential for a large scale application of high temperature superconductors to such devices. Current leads, used for transferring currents from the power converters, working at room temperature, into the liquid helium environment, where the magnets are operating, represent an immediate application of the emerging technology of high temperature superconductivity. The LHC, currently under construction at CERN, will transfer more than 3 million ampères of current through leads having high temperature superconducting sections, thus providing a unique opportunity to incorporate these materials into large scale systems. The status of this project and the cost-benefit consequence of its application will be reported

Large-Capacity Current Leads

Feeding superconducting magnets with reliable low-loss devices is a key issue for any cryo-electrical system. Conventional or HTS current leads can be used, and cooling methods, materials, and geometries can be chosen to optimize the thermo-electrical performance of the system. The LHC magnets are powered via more than 3000 current leads transporting altogether about 3 MA of current. With thousands of leads, the LHC lead project represents today the largest project of its kind ever undertaken. Following a review of the LHC lead project, an overview of the choices that can be made for the optimization of large capacity current leads is presented. Examples are given of other leads for large scale magnet systems for which the use of HTS is being envisaged

HTS Current Leads: Performance Overview in Different Operating Modes

High Temperature Superconducting (HTS) current leads have become, in the last few years, a valid choice for the powering of superconducting magnet systems. After the construction and test of more than a thousand of HTS leads for the Large Hadron Collider, with a consequent improved confidence in the long-term and large scale operation of these devices, it is being envisaged to equip several other large superconducting magnet systems with this type of lead. The approach used in the optimization and design of such leads must take into account the requirements of the electrical and cryogenic systems as well as the local environment. The paper summarizes the results of the analysis made on HTS current leads, with special attention to the optimization process to be followed in different scenarios that include both DC and pulsed operation. Case studies are also presented and discussed. The calculation of the optimum performance in the various operating conditions was made assuming a lead design of the type used for LHC

HTS Current Leads for the LHC Magnet Powering System

Among the different applications of the emerging High Temperature Superconducting (HTS) technology, current leads represent a key development component. In this field the state of maturity of the conductor is such as to satisfy both a wide range of design requirements and those of economic viability. The LHC superconducting magnets will be powered through HTS current leads transferring in total more than 3 MA of current. The R&D program undertaken at CERN and in industry to experimentally validate different design assumptions has led to major progress towards design choices for the different HTS leads of the LHC magnet system. Test results, merits of design variants and major milestones for the LHC leads manufacture will be reported

High Temperature Superconducting Current Leads for the Large Hadron Collider

The Large Hadron Collider (LHC) will be equipped with about 8000 superconducting magnets. Some 3380 leads will feed the currents ranging from 60 to 13000 A. To reduce the heat inleak into the liquid helium, CERN aims to use High Temperature Superconducting material for leads having current ratings between 600 and 13000 A. Specifications have been written for 13000 A current leads, incorporating a High Temperature Superconducting section, for the main magnets of the LHC, and contracts have been placed with several firms for the supply of prototypes for comparative testing. The leads used for feeding locally the 60 and 120 A dipole orbit correctors will be conventional conduction cooled resistive leads. An optimized lead of variable cross section has been tested, and an integral design has been initiated. This report describes the design status of the current leads for the LHC, emphasizing, for the different solutions, the principle of optimization and the choice of the cooling methods

Tests Results on the First 13 kA Prototype HTS Leads for the LHC

Prototypes of 13 kA HTS current leads for the Large Hadron Collider (LHC) have been specified by CERN and produced by several manufacturers. The specification defines the required thermo-electric performance and the geometric limitations imposed by the LHC infrastructure. A report is given of the results obtained from extensive tests on these leads

Test results on the first 13 kA prototype HTS leads for the LHC

Prototypes of 13 kA HTS current leads for the Large Hadron Collider (LHC) have been specified by CERN and produced by several manufacturers. The specification defines the required thermo-electric performance and the geometric limitations imposed by the LHC infrastructure. A report is given of the results obtained from extensive tests on these leads. (7 refs)

Design and Tests on the 30 to 600 A HTS Current Leads for the Large Hadron Collider

Some 800 correction magnets of the Large Hadron Collider will be individually powered. Each of them needs a pair of current leads. To reduce the heat leak through these leads, the current has been chosen as low as reasonably possible, 30 to 600 A. For the same reason CERN started in-house a development of current leads using commercial bulk BSCCO-2212 material.This paper discusses the design and the test results of this lead. We tested several prototypes, measured the heat leak through the lead, studied and tested what happens if the lead is brought to critical temperature causing it to quench