M. Kuchnir

Tests of full scale SSC R&D dipole magnets

Four full-scale SSC (Superconducting Super Collider) research and development dipole magnets, incorporating successive mechanical design improvements, have been quench-tested. Three of the magnets are heavily instrumented with sensors to measure their mechanical behavior and verify the effectiveness of the mechanical improvements and with multiple voltage taps to locate the origin of quenches. The last two magnets of this series reach the SSC design operating field of 6.6 T in two or fewer quenches. Load cells and motion sensors show that in these two magnets the azimuthal clamping stress is higher at zero current and drops more slowly with excitation that in previous long magnets, and that the axial motion of the coil upon excitation has been greatly reduced. Quenches are found to originate preferentially in several locations, suggesting other design improvements. >

Performance of full-length SSC model dipoles: Results from 1988 tests

Over the past year, magnets that meet the SSC field and quench training criteria have been developed as a result of the detailed understanding of magnet performance made possible by tests on a series of model magnets. The SSC dipole magnet design is a cos θ style coil with a 4-cm aperture and a magnetic length of 16.6 m. The design operating field is 6.6 T at a current of 6.5 kVA. Design, fabrication, and testing of full-length model magnets has been a cooperative effort among the SSC Central Design group and three major national laboratories: BNL, FNAL, and LBL.

Full length prototype SSC dipole test results

Results are presented from tests of the first full length prototype SSC dipole magnet. The cryogenic behavior of the magnet during a slow cooldown to 4.5K and a slow warmup to room temperature has been measured. Magnetic field quality was measured at currents up to 2000 A. Averaged over the body field all harmonics with the exception of b 2 and b 8 are at or within the tolerances specified by the SSC Central Design Group. (The values of b 2 and b 8 result from known design and construction defects which will be corrected in later magnets.) Using an NMR probe the average body field strength is measured to be 10.283 G/A with point to point variations on the order of one part in 1000. Data are presented on quench behavior of the magnet up to 3500 A (approximately 55% of full field) including longitudinal and transverse velocities for the first 250 msec of the quench.

Results of magnetic field measurements of 40 mm aperture 17-m long SSC model collider dipole magnets

Magnetic field measurements have been made on twelve 17-m-long, 40-mm-aperture R&D superconducting dipoles. Data on dipole field strength, multipole coefficients, and alignment have been obtained. The data indicate that the magnets as built are generally within the expectations for this design. >

Test results of BNL built 40-mm aperture, 17-m-long SSC collider dipole magnets

Eleven 17-m-long, 40-mm-aperture SSC (Superconducting Super Collider) R&D superconducting collider dipole magnets, built at BNL (Brookhaven National Laboratory), have been extensively tested at BNL and Fermilab during 1990-1. Quench performance of these magnets and details of their mechanical behavior are presented. Although the quench performance of the most recent magnets shows slightly more quenches than expected, there is now a better understanding of the mechanical behavior of these magnets. The baseline design leads to reasonable quench performance. The quench performance of the DC series magnets seems to indicate a strong sensitivity to change in design parameters, key among them being the collar-yoke interference and the coil end loading. >

Tests of Fermilab built 40 mm aperture full length SSC dipole magnets

Several 40 mm aperture, 17 m long dipoles have been built by Fermilab as developmental prototypes for the Superconducting Super Collider. These magnets differ from those manufactured at Brookhaven National Laboratory in that they have an external inner-outer coil splice design, a collet style end clamp assembly, a new, analytically designed minimum stress coil end design, and a new insulation system which does not employ shims or shoes. In addition, the magnets were built using production-style tooling. The magnets were tested at the Fermilab Magnet Testing Facility. In this paper quench testing and mechanical measurement results are presented and analyzed with emphasis on the design and fabrication features of these magnets.

Experimental Evaluation of Design Features of a Cryostat for an Ironless cosine theta SSC Magnet

A conceptual design for an iron-less cosθ SSC magnet cryostat has identified several areas for experimental study. Included are bowing of thermal radiation shields due to cooldown and warmup; thermal performance of the suspension systems; cryostat thermal performance; structural responses to decentering forces between the coil and the steel vacuum vessel; and response of thermal shields to forces due to quench induced eddy currents. Studies were carried out with 6m long thermal bowing and magnetic effects models, a suspension heat leak measurement dewar and a 12m long thermal model. The models incorporate important features of the conceptual cryostat design. The details of the test arrangements, procedures and results are presented.