Commissioning and First Operation of Superconducting Links at the Large Hadron Collider (Lhc)

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.

Commissioning of the Cryogenics of the LHC Long Straight Sections

“…The usage of superconducting links was a world first for powering accelerator magnets. The commissioning of the four 76 m long superconducting links located in IR1 and in IR5 was performed without encountering specific problems [5]. Their performance was very close to the estimated values and they became rapidly operational.…”

“…At the DFBAs the beam tubes emerge from the continuous cryostat of the arc and pass then through superconducting magnets that are installed between stretches of room temperature sections and operate in saturated liquid helium at 4.5 K. These magnets are named sequentially according to their position relative to the IP and are referred to as standalone magnets (SAM). These magnets are powered either by local feedboxes called DFBMs [3,4] (in most LSSs) or remotely, when this first configuration is not possible (only in IP 1 and 5), through superconducting links (DSL) [3,5] of a length of 76 m. The links are themselves powered by special feedboxes: the DFBLs [3,4]. A superconducting link of a length of 517 m is also installed in IR3 where space does not allow the local installation of the power supplies for corrector magnets circuits.…”