| Paper |
Title |
Page |
| WEPKF021 |
Non-destructive Testing of Bus-bar Joints Powering LHC Superconducting Magnets, by Using Gamma Sources
|
1642 |
| |
- B. Skoczen
CERN, Geneva
- J. Kulka
AGH, Cracow
|
|
| |
The main LHC superconducting magnets (dipoles and quadrupoles) are powered by using Rutherford type cables, stabilized electrically and thermally with copper profiles. The portions of cables are connected to each other by a soft soldering technique (Sn96Ag4) with the overlapping length corresponding to one pitch of the superconducting strands. The splice constitutes a ?composite? structure with the interchanging layers of Sn96Ag4 and NbTi superconductor, located inside a Cu cage. In order to assure a high level of reliability (failure probability not exceeding 10-8) for some 10000 connections in the LHC, a non-destructive technique of checking the quantity of solder in the joint is planned to be implemented. The technique is based on a gamma ray source (241_Am) and the detection is position-sensitive in the transmission mode. 5 scintillating detectors of gamma rays are used and their accumulated length corresponds to the length of the radioactive source (120 mm). The method can be used in-situ, the equipment being optimized and portable, with implementation of direct on-line operation mode. The relevant criteria of acceptance of the splices have been defined. The first results of application of this technique will be shown.
|
|
| WEPKF022 |
Electro-mechanical Aspects of the Interconnection of the LHC Superconducting Corrector Magnets
|
1645 |
| |
- J.-P.G. Tock, D. Bozzini, F. Laurent, S. Russenschuck, B. Skoczen
CERN, Geneva
|
|
| |
In addition to the main 1232 bending dipoles and 474 focusing and defocusing quadrupoles, more than 6800 superconducting corrector magnets are included in the LHC machine. They are housed in the superfluid helium enclosures of the main cryomagnets. Among them, the closed orbit correctors (sextupole and octupole) are integrated in the main quadrupole helium vessel and they are powered via an externally routed cryogenic line (line N). During the assembly, these corrector magnets have to be connected according to a complex electrical scheme based on the optical requirements of the LHC machine. Along the 27-km long LHC machine, 440 interconnection boxes are installed and will allow the powering of the correctors by means of a 42-wires auxiliary bus-bar cable, of which the corresponding wires have to be routed to the SSS from the interconnection box. Stringent requirements in terms of volume, mechanical resistance, electrical conductance and insulation, reliability, and respect of the electrical schematics apply during the assembly and splicing of the junctions inside the line-N box. The activities and their sequence, aiming at ensuring the fulfilment of these requirements are presented. The planned activities (assembly, ultrasonic welding, general and electrical inspection, and electrical qualification) and the interactions between the various intervening teams are described.
|
|
| WEPKF037 |
Structural Analysis of an Integrated Model of Short Straight Section, Service Module, Jumper Connection and Magnet Interconnects for the Large Hadron Collider
|
1684 |
| |
- S. Dutta, J. Dwivedi, A. Kumar, H.C. Soni
CAT, Indore (M.P.)
- B. Skoczen
CERN, Geneva
|
|
| |
The Short Straight Section (SSS) of the Large Hadron Collider (LHC) houses a twin quadrupole.The cryogens are fed to the SSS through a Jumper Connection between service modules of Cryogenic Distribution Line (QRL) and SSS.A Finite Element analysis has been performed in collaboration with CERN for the unified model of SSS of LHC,consisting of cold mass, cold supports,vacuum vessel and its bellows, interconnects, jumper connection and alignment jacks. The model has been developed to understand coupling between the quadrupole magnet and the service module due to ground motion and during the realignment or global smoothening of the LHC arc. The model incorporates experimental stiffness values for support posts, internal pipes and jacks and calculated stiffness for magnet-to-magnet interconnects. The computation space and time has been reduced by executing a two step linear static analycal approach with an initial trial analytical approach cycle in which the program estimates the behavior of the flexibles. A special routine is developed within ANSYS,using APDL which selects the correct secant stiffness of flexibles(by applying a user interactive logical algorithm)from their non-linear force displacement characteristics.
|
|
| WEPLT027 |
Connection Cryostats for LHC Dispersion Suppressors
|
1885 |
| |
- S. Marque, T. Colombet, M. Genet, B. Skoczen
CERN, Geneva
|
|
| |
The lattice of the Large Hadron Collider (LHC) being built at CERN is based on 8 standard arcs of 2.8 km length. Each arc is bounded on either side by Dispersion Suppressors connected to the arc by connection cryostats providing 15m long drift spaces. As for a dipole magnet, the connection cryostat provides a continuity of beam and insulation vacuum, electrical powering, cryogenic circuits, thermal and radiation shielding. In total 16 modules will be constructed. The stringent functional specification has led to various analyses. Among them, a light mechanical structure has been developed to obtain a stiffness comparable to a dipole magnet, for alignment purpose. Thermal studies, included λ front propagation, have been performed to ensure a cooling time down to 1.9K within the time budget. A special cooling scheme around the beam tubes has been chosen to cope with heat loads produced during operation. We will report on the general design of the module and on the manufacturing process adopted to guarantee the tight alignment of the beam tubes once the module installed in the machine. Special emphasis will be given on thermo-mechanical analysis, λ front propagation and on beam-tubes cooling scheme.
|
|