Abstract

Abstmcl-The LHC dispersion suppressors and matching sections will be cquipped with individually powered superconducting quadrupoles with an aperture of 56 m m . In order t o optimise t h e parameters and cost of t h e magnets and of their powering, t h e quadrupole has been designed on the basis of a 8.2 m m wide Rutherford-type cable for a nominal current of 5300 A , corresponding t o a gradient of 200 T / m at 1 . 9 K . In order t o validate t h e design two 1-m singleaperture quadrupoles and one twin-aperture quadrupole have been built and tested. In this report we describe t h e construction features of t h e magnets and present t h e results of t h e magnet tests. I n d m 7'emn.s-LHC, Quadrupole, Superconducting Magnets

A series of similar one meter long superconducting dipole models for the LHC is being manufactured and tested since 1995 for exploring design variants and assembly parameters. Until the end of 1997 all magnets of this series were based on a coil geometry subdividing the conductors in five distinctive winding blocks. In order to cope with new requirements of magnetic field distribution and coil design flexibility, one additional block has been added in the beginning of 1998. A significant number of models of both types have been built and tested, some of them re-built in a different version, adding up in more than 40 models tested so far. The paper reviews the performance of these two different coil designs in terms of manufacture, training behaviour and temperature margins as well as mechanical behaviour and magnetic field quality. THE MODELSThe regular CERN in-house model program for the development of the LHC dipoles was started in 1995 with the fabrication of 1m-long single-aperture magnets, socalled MBSMS. The design of the MBSMS models, presented in previous conference papers [1] [2], is based on circular collars of 197 mm outer diameter placed inside a vertically split yoke, held together by a bolted shrinking cylinder for easy re-assembly of the structure. COIL GEOMETRY:DESIGN FEATURESThe LHC dipole coils consist of two superposed layers, an internal layer and an external one. Each layer is subdivided in blocks of conductors separated by copper spacers. The two coil geometries tested on the models are shown in Fig.1 below.The first 13 magnets have been built with the 5-block version of the Yellow Book [3], consisting in 3 blocks of conductors in the inner layer and two in the outer layer ( fig.1a). As from MBSMS15, the coil design has undergone a substantial evolution, being replaced by a 6-block one, consisting in four blocks of conductors in the inner layer and two in the outer layer (fig.1b). The last 6 magnets have been built according to this 6-block geometry. Magnetic designThe original 5-block coil cross-section was optimized using deterministic techniques with the CERN program ROXIE [4]. First a preliminary geometric modelling was done with a given choice on cable dimensions and conductor blocks, thereafter the model was iterated to find an acceptable solution for field quality and peak field/main field ratio. This coil design however did not ensure sufficient tunability and flexibility for later field adjustments like compensating the persistent current multipoles at injection and fine-tuning of field quality. In particular a further compensation of the b3 term, if required, would have been impossible because the copper wedges would become too small at the inner edge. Moreover the performance of the magnets with 5-block coils and laboratory tests indicate that the stress distribution in the inner block of the inner layer is not favourable. With the implementation of genetic algorithms in ROXIE in 1997 [5] it was possible to make an extended the search for more appropriate designs consider...

Abstract-The ATLAS B0 model coil has been developed and constructed to verify the design parameters and the manufacture techniques of the Barrel Toroid coils (BT) that are under construction for the ATLAS Detector. Essential for successful operation is the mechanical behavior of the superconducting coil and its support structure. In the ATLAS magnet test facility, a magnetic mirror is used to reproduce in the model coil the electromagnetic forces of the BT coils when assembled in the final Barrel Toroid magnet system. The model coil is extensively equipped with mechanical instrumentation to monitor stresses and force levels as well as contraction during a cooling down and excitation up to nominal current. The installed set up of strain gauges, position sensors and capacitive force transducers is presented. Moreover the first mechanical results in terms of expected main stress, strain and deformation values are presented based on detailed mechanical analysis of the design.

transducers and presents the main results of the measurements. principles, describes the design, fabrication and the calibration of the force acquisition system. This paper reviews the magnet mechanical design magnet quenching were also performed with a high sampling rate excitation. Dynamic measurements of forces and temperatures during stresses and axial forces in the coils during assembly, cooldown and mechanical force transducers based on strain gauges to monitor azimuthal parameters, as well as the final model magnet were instrumented with field of 9.7 T. Short mechanical models, made to check the assembly model, which was entirely constructed at CERN, reached at 1.8 K a peak to initiate studies of lower field magnets for a 7 TeV collider machine. This A twin-aperture dipole model made with standard SSC cables was launched