| |
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.
|
|