DEVELOPMENT OF SUPERCONDUCTING DIPOLE MAGNET WITH IDEAL ARCH STRUCTURE USING LARGE KEYSTONE ANGLE CABLE

A superconducting dipole magnet with an ideal arch structure has been designed and developed for applications to big hadron collider accelerators. The dipole magnet has an aperture of 5 cm in inner coil diameter and the straight section of 1 m. The magnet can produce magnetic field of 6.6 tesla at the normal operation current of 5,890 A. We have developed a cable which has the large keystone angle of 3.1 degrees and fits to the ideal arch structure of 5 cm inner diameter of the magnet. The cable for the inner coil is composed of 23 strands whose diameter is 0.808 mm having filaments of 6 J.1IIl diameter. The fabrication of the cable has not met with serious problems and the degradation by cabling is less than 3 %. At the excitation test, the frrst R&D dipole magnet has several quenches up to the operation current, and reached to the Ie limit at the tenth quenches. The training will be reduced with tight collaring.