Powering the superconducting magnets of the LHC arcs and long straight sections is performed with more than 1000 electrical terminals supplying currents ranging from 120 A to 13'000 A and distributed in 44 cryogenic electrical feedboxes (DFB). Where space in the LHC tunnel is sufficient, the magnets are powered by locally installed cryogenic electrical feedboxes. Where there is no space for a DFB, the current will be supplied to the magnets by superconducting links (DSL) connecting the DFBs to the magnets on distances varying from 76 m to 510 m. Conceptual design of the Cryogenic Electrical Feedboxes and the Superconducting Links of LHCGoiffon T. , Lyngaa J., Metral L., Perin A. , Trilhe P., van Weelderen R. AT Department, CERN, CH-1211 Geneva 23Powering the superconducting magnets of the LHC arcs and long straight sections is performed with more than 1000 electrical terminals supplying currents ranging from 120 A to 13'000 A and distributed in 44 cryogenic electrical feedboxes (DFB). Where space in the LHC tunnel is sufficient, the magnets are powered by locally installed cryogenic electrical feedboxes. Where there is no space for a DFB, the current will be supplied to the magnets by superconducting links (DSL) connecting the DFBs to the magnets on distances varying from 76 m to 510 m.

specific R&D programme in these domains.engineering challenge in applied superconductivity and cryogenicsf and has thus required a unprecedented luminosity of 1034 cm·2.s·l. Therefore, the LHC also represents a major it will provide proton-proton collisions with a center-of-mass energy of 14 TeV and at an below 2 K,3 to be installed in the 26.7 km circumference tunnel of the present LEP collider, ring of high-field, twin-aperture superconducting magnets2 operating in superfluid helium December 1994, will be the next major research facility in high-energy physics} Based on a operation, including response of the system to transients such as current ramp and discharge, industrial PLCs connected to an industrial supervision system. We report on performance in cooldown of the 109 kg cold mass. The system is fully instrumented, controlled by dedicated and auxiliary magnet circuits, as well as a 120 kW liquid nitrogen vaporizer for controlled also includes 15 kA, 1.6 kA, 500 A, 250 A and 50 A current lead pairs for powering of main installed capacities of 120 W @ 1.8 K and 10 g/s supercritical helium at 4.5 K. The system built and are operating a dedicated cryogenic system feeding the LHC Test String, with cryomagnets. Based on existing large-capacity cryogenic infrastructure, we have designed, providing refrigeration at the 1.9 K, 4.5-to-20 K, and 50·to-75 K levels to the LHC of the machine lattice. This also corresponds to the length of the elementary cooling loops testing and operation of a 50-m long superconducting magnet string, representing a half-cell A maj or milestone in the preparation of the Large Hadron Collider (LHC) proj ect is the ABSTRACT

The Large Hadron Collider (LHC) now under commissioning at CERN is a 26.7 km collider based on several thousand high-field superconducting magnets, the majority of which operating in superfluid helium below 2 K and some isolated magnets operating in normal helium at 4.5 K. Four superconducting links (DSLs) of about 76 m in length and one of about 517 m in length, were designed, constructed and installed over a three year period. Their purpose is to transport current over long distances whenever underground LHC space constraints prevents to put power converters, current feed boxes and magnets in each others' proximity. The four 76 m long DSLs transport current between current feed boxes and several of the isolated magnets, whereas the 517 m long DSL transports current between two current feed boxes. The links are comprised of cryogenic, vacuum-insulated, transfer lines housing one or more superconducting cables. The operating temperatures are about 5 K for the DSL part that houses the cable and about 60 K for the heat shield. Their commissioning and performance results at first operational experience in the beginning of 2008 are discussed.