Search

Dipole magnets for the R&D of SSC were built and tested at Fermilab. The magnetic field properties were studied using short models and full scale models. Effect of coil size variation, insulation material, shimming and eddy current are discussed. >

Eighteen 5-cm-aperture, 15-m-long Superconducting Super Collider (SSC) dipole magnet prototypes have been produced and cold tested. On each prototype, the dependence of harmonic field coefficients on magnetic current was measured as part of a study of the magnetic field quality. For most of the magnets, the observed behavior conforms to what can be expected from the effects of persistent magnetization currents and iron yoke saturation. A few prototypes, however, exhibited anomalies during current ramp at 4 A/s which can be attributed to large cable eddy currents. >

The authors summarize the mechanical performance of the most recent 5-cm-aperture, 15-m-long SSC dipole magnet prototypes. The magnets were produced at Brookhaven National Laboratory (BNL) and Fermi National Accelerator Laboratory (FNAL) under contract with the Superconducting Super Collider Laboratory (SSCL). The BNL magnets rely on a horizontally split yoke with collared ends, while the FNAL magnets rely on a vertically split yoke with collet-style end clamps. Magnets of both designs are equipped with strain gauges enabling measurement of the azimuthal pressures exerted by the coils against the collar poles as well as the axial forces transmitted from the coil ends to the end plates. A comparison of the mechanical behaviors measured by the strain gauges is presented. How the behavior of the 5-cm-aperture magnets compares to that of the 4-cm-aperture prototypes is also discussed. >

The quench performance and ramp rate sensitivity of 18 5-cm-aperture, 15-m-long Superconducting Super Collider (SSC) dipole magnet prototypes are discussed. All the magnets appear to reach a quench plateau near their extrapolated short sample current limit and well in excess of the operating current with very little training. Most of the magnets, however, exhibit a dramatic degradation of their quench current as a function of ramp rate, which, for the most part, can be attributed to large cable eddy currents. >

Several 40-mm-aperture, 17-m-long dipoles have been built by Fermilab as developmental prototypes for the Superconducting Super Collider (SSC). These magnets 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. Quench testing and mechanical measurement results are presented and analyzed with emphasis on the new design and fabrication features of these magnets. The performance of these magnets was very good from a quench and mechanical behavior standpoint. The magnets did not exhibit excessive training behavior and only one training quench was below the nominal operating current. The coil prestress remained positive to >7 T in both magnets and most of the quenches originated in the high field region of the pole turn. >

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. >

Magnetic field measurements have been performed at Fermilab on 1.5 m magnetic length model dipoles for the Superconducting Supercollider (SSC). Harmonic measurements are recorded at room temperature before and after the collared cell is assembled into the yoke and at liquid helium temperature. Measurements are made as a function of longitudinal position and excitation current. High field data are compared with room temperature measurements of both the collared coil and the completed yoked magnet and with the predicted fields of both the body of the magnet and the coil ends. The effects of yoking and cold testing agree well with predictions. One of the two cold-tested dipoles satisfies the SSC specification for sextupole/decapole. >

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. >

Over the last two years corrections have been made for the skew quadrupole moment in 530 of the 774 installed dipoles in the Tevatron. This process of modifying the magnets in situ has inherent risk of degrading the performance of the superconducting accelerator. In order to manage the risk, as well as to ensure the corrections were done consistently, formal quality tools were used to plan and verify the work. The quality tools used to define the process and for quality control are discussed, along with highlights of lessons learned.

In early 2003 it was realized that mechanical changes in the Tevatron dipoles had led to a deterioration of the magnetic field quality that was hindering operation of the accelerator. After extensive study, a remediation program was started in late 2003 that will continue through 2005. The mechanical and magnetic effects are discussed. The readjustment process and experience are reported, along with other observations on aging magnets.

Four full-scale SSC (Superconducting Super Collider) development dipole magnets have been tested for mechanical and quench behavior. Two are of a design similar to that of previous magnets but contain a number of improvements, including more uniform coil size, higher prestress, and a redesigned inner-outer coil splice. One exceeds the SSC operating current on the second quench, but the other appears to be limited by damaged superconductor to a lower current. The other two magnets are of alternate designs. One trains erratically and fails to reach a plateau, and the other reaches a plateau after four quenches. >

The time behavior of the sextupole component of the Tevatron superconducting dipoles under ramping conditions was studied. Large time-dependent sextupole corrections are necessary to maintain constant chromaticities in the Tevatron. The authors discuss the implementation and results of these corrections in terms of emittance growth and intensity loss during the Tevatron ramp. >

Polyimide with epoxy impregnated glass tape was used in Fermilab baseline design of several SSC Collider dipole magnets which were used in the SSC Accelerator Systems String Test (ASST). Later in the magnet R&D program several magnets were built using conductor insulation in which adhesive that cures at 140/spl deg/C was coated directly on the polyimide film. Some alternate materials for coil end parts and coil winding were also tested. The data taken during the tests of these magnets are compared with results from 10-stack studies of the two insulation systems and design expectations and correlated with changes in assembly methods. >

Measurements of more than 1000 new magnets are needed for the main injector project at Fermilab. In order to achieve efficiency and accuracy in measurements, a database-driven design was chosen for control of the measurement system. A relational database will be used to describe the measurement subjects and equipment. A logbook system defined in the database will provide for prescription of measurements to be carried out, and a comment database for less-structured information. The operator interface will be built on X-windows. >

A systematic series of measurements of the time decay of the sextupole component of the magnetic field in a full-length SSC (Superconducting Super Collider) dipole magnet prototype was carried out in order to characterize the mechanisms involved. At least two mechanisms have been isolated. The first is a slow logarithmic decay which is independent of the excitation history of the magnet. This component is stopped by a decrease of the magnet temperature and is identified with flux creep. The second component, which is not yet fully understood, only appears when the magnet is pre-cycled to a high level of current, and cannot be stopped by decreasing the magnet temperature. The first component is attributed to flux creep in the superconductor. The authors are currently developing a model of demagnetization caused by shifting/transport currents in the superconducting cables that could account for the secondary component. >

Construction and testing of the components for the new Tevatron D0/B0 low beta insertion are nearly complete. The devices include superconducting cold iron quadrupoles utilizing a two-shell, cos2 theta coil geometry with a 7.6-cm aperture. The maximum design gradient is 1.41 T/cm at an operating current of 4832 A. They have the highest current density with the highest peak field on the winding of any quadrupole yet built. The authors summarize the quench performance and ramp rate sensitivity of the two-shell design and relate the performance characteristics to the relevant aspects of design and fabrication. >

For the Fermilab Tevatron low beta insertions installed in 1990-1 as part of a luminosity upgrade, approximately 35 superconducting cold iron quadrupoles were built utilizing a two-layer cos 2 theta coil geometry with a 76-mm-diameter. The field harmonics and strengths of these magnets, determined by measurement at cryogenic conditions, are presented. Evidence for a longitudinal periodic structure in the remanence field is shown. >

Measurements of the magnetic field angle along the length of collider dipole magnets are discussed. These superconducting magnets were built at Fermilab for the Superconducting Super Collider (SSC) by Fermilab and General Dynamics personnel. These measurements were made at four stages in the assembly and test sequence. The data show that changes can occur both during installation in the cryostat and as a result of cold testing. Most of the changes during installation are correlated with the welding of the tie bar restraints, but the changes observed as a result of the cold testing can be attributed to changes in the magnetization of the iron laminations. >

During 1992 at Fermilab, a series of nine 50-mm-aperture, 15-m-long, SSC superconducting dipole magnets, designed jointly by Fermilab, Brookhaven National Laboratory, and the SSC Laboratory, have been built and successfully cold tested. Seven of these dipole magnets, designated for the Accelerator System String Test (ASST) carried out at SSCL in Dallas, were assembled at Fermilab by General Dynamics personnel, and have achieved the nominal operating current level without significant training.1,2 In addition, a series of four R&D magnets (DCA320 323) were manufactured at Fermilab to test an alternative insulation schemes. In this paper we present the quench performance of these four R&D magnets, which were cold tested at the Fermilab Magnet Test Facility at nominal temperatures of 4.35 K, 3.85 K, and 3.50 K. An extended characterization test was performed on one of these magnets (DCA322). During this test the magnet was successfully cooled down to superfluid He temperature (1.8 K) and reached a field B ≥ 9.5 T.

Thirteen 16 m long, 50 mm aperture SSC dipole magnets, designed jointly by Fermilab, Brookhaven National Laboratory, Lawrence Berkeley Laboratory and the SSC Laboratory, have been built at Fermilab. The first nine magnets have been fully tested to date. The allowed harmonics are systematically shifted from zero by amounts larger than the specification. The unallowed harmonics, with the exception of the skew sextupole, are consistent with zero. The magnet-to-magnet RMS variation of all harmonics is much smaller than the specification.

In the fabrication of both 40 and 50 mm collider dipole superconducting magnets, surveys of the direction of the magnetic field along their length have been taken. This data besides being used for certifying compliance with the specifications for the finished magnet, yields interesting information on the straightness and rigidity of the coil placement between some stages in their manufacture and testing. A discussion on the measuring equipment and procedures is given. All of the 40 mm magnets that were built or cryostat at Fermilab have at least one of these surveys, and a summary of the data on them is presented. Most of the 50 mm magnets built and cold tested at Fermilab have been surveyed before and after insertion in the cryostat and before and after being cold tested. A summary of this data is also presented.

This paper presents preliminary results of magnetic field measurements made on a series of 50 mm aperture 15 m long SSC collider dipole magnets designed and manufactured at Fermi National Accelerator Laboratory (Fermilab) for use in the Superconducting Super Collider Laboratory (SSCL) Accelerator System String Test. The magnets were assembled by Fermilab and General Dynamics personnel, and were tested at the Magnet Test Facility (MTF) at Fermilab. Measurements of the dipole field angle, dipole field strength, and field shape parameters at various stages in magnet construction and testing are described.

In this paper we present results of quench testing of full length SSC dipole magnets at Fermilab. The data are from the first six of a series of thirteen 15 m long, 50 mm aperture SSC dipole magnets which are being built and tested at Fermilab. These magnets were designed jointly by Fermilab, Brookhaven Laboratory, Lawrence Berkeley Laboratory and the SSC Laboratory. Among the major goals for this series of magnets are to transfer magnet production technology to the lead vendor for the Collider Dipole Magnet, the General Dynamics Corporation, and to demonstrate industrial production by the vendor. The first magnet in the series, DCA311, was built by Fermilab technicians to establish assembly procedures. The second magnet, DCA312, was the “technology transfer magnet and was built jointly by Fermilab and General Dynamics technicians. The next seven, DCA313-319 are being built by General Dynamics personnel using Fermilab facilities and procedures. However, Fermilab personnel still operate the major tooling, provide the welders, perform assembly of items that would not be part of production magnets (e.g. voltage taps), and oversee the QA program. Five of these 7 GD-built magnets will be used in the Accelerator Systems String Test (ASST) to be carried out in Dallas later this year. The last four magnets, DCA320-323, are being built by Fermilab alone.”

A series of full-scale demonstration SSC collider dipole magnets were built for the ASST (Accelerator System String Test). These magnets, DCA311 through DCA319, have 50 mm aperture and 15 m magnetic length with 6.6 Tesla uniform field. For the support structure of the W6733B cross section[1], the Fermilab design uses a vertical split[2] in the yoke. The end sections of the magnet have solid spacers and are supported by collet clamps[3]. The splices between inner and outer coils are made in preforms which lie outside of the high field region. The magnets were produced in pipeline fashion with no intentional major changes between magnets. As a part of the technology transfer program, the last 7 magnets were built by General Dynamics personnel using the magnet construction facilities of Fermilab, while the first two magnets were built entirely by Fermilab personnel.

During the last two years, nine 4‐cm aperture, 17‐m‐long dipole magnet prototypes were produced by Brookhaven National Laboratory (BNL) under contact with the Superconducting Super Collider (SSC) Laboratory. These prototypes are the last phase of a half‐decade‐long R&D program, carried out in collaboration with Fermi National Accelerator Laboratory and Lawrence Berkeley Laboratory, and aimed at demonstrating the feasibility of the SSC main‐ring dipole magnets. They also lay the groundwork for the 5‐cm‐aperture dipole magnet program now underway. After reviewing the design features of the BNL 4‐cm‐aperture, 17‐m‐long dipole magnets, we describe in detail the various steps of their fabrication. For each step, we discuss the paramaters that need to be mastered, and we compare the values that were achieved for the nine most recent prototypes. The data appear coherent and reproducible, demonstrating that the assembly process is under control. We then analyze the mechanical behavior of these magnets during cooldown and excitation, and we attempt to relate this behavior to the magnet features. The data reveal that the mechanical behavior is sensitive to the collar‐yoke interference and that the magnets exhibit somewhat erratic changes in coil end‐loading during cooldown.

Over the last year, several 4-cm-aperture, 17-m-long dipole magnet prototypes were built by Brookhaven National Laboratory (BNL) under contract with the Superconducting Super Collider (SSC) Laboratory. These prototypes are the last phase of a half-decade-long R & D program, carried out in collaboration with Fermi National Accelerator Laboratory and Lawrence Berkeley Laboratory, and aimed at demonstrating the feasibility of the SSC main ring magnets. They also lay the ground for the 5-cm aperture dipole magnet program to be started soon. After reviewing the design features of the BNL 4-cm-aperture, 17-m-long dipole magnets, we describe in detail the various steps of their fabrication. For each step, we discuss the parameters that need to be mastered, and we compare the values that were achieved for the five most recent prototypes. The data appear coherent and reproducible, demonstrating that the assembly process is under control.

Several 17-meter-long SSC R&D dipole magnets, instrumented with numerous voltage taps on the inner quarter coils, have been tested. These magnets, protected with quench heaters, differed in mechanical details as well as in the cables used for the winding. The voltage taps enabled us to measure longitudinal and azimuthal quench propagation velocities. Summary plots of these velocities are presented showing that, even though the Fourier conduction model doesn’t apply, the mechanism of the quench is reproducible from magnet to magnet. Correlations are established between the velocities and the fraction of short sample. After showing that for currents higher than 5000 A the magnet is self-protected, we investigate the relation between the number of MIITs and the quench characteristics.

Tests have been completed on three prototype magnets and two production magnets to be used for the Tevatron DO/BO low-β insertion. These cold iron, two shell quadrupoles are made of 36 strand Rutherford type NbTi superconducting cable. Magnet field gradients well in excess of the design 1.41 T/cm have been achieved at a transfer function of 0.291 T/cm/kA. Quench performance at 4.2 K and 3.7 K and magnetic multipole measurement data are presented and discussed.

Data on the persistent current residual fields in Tevatron dipoles and quadrupoles are presented. The data are compared to the doublet theory of persistent current fields and an estimate is given for the multipole fields expected in the Superconducting Super Collider (SSC) dipole proposed by Fermilab.

Proposed colliding beam particle accelerators for high energy physics research will employ superconducting accelerator rings. The rings' superconducting magnet systems must provide the required magnetic function, have low refrigeration load, operate with very high reliability and be manufacturable at a low cost. The cryogenic aspects of a conceptual design for a 5T field, 5cm aperture, 12m long superconducting dipole magnet suitable for a 20 TeV proton-proton collider are presented.

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. >

A design, construction, and testing program for model magnets is underway at Fermilab to evaluate alternatives in the development of small aperture magnets. The most thoroughly developed of these programs utilizes a set of model magnets based on the Tevatron quadrupoles and dipoles as a standard. These 7.6cm aperture model magnets, approximately 64cm long, have construction or material changes which are to improve quality and/or cost effectiveness. There are also superconductor parameter changes, as well as construction and materiai parameters, which impact or give insight into the choices of material specifications and construction parameters for the 5cm aperture model magnet series which are prototype candidates for the Superconducting Super Collider (SSC) ring magnets. The test program consists of performance test quenching of the windings at various temperatures until the cable critical current is reached. The quality of the magnetic field (Fourier coefficients) B(n) and quenching current is measured versus ramp rate, dB/dt, intensity, B, magnet temperature, and conductor parameters. The magnetization of the windings is measured as a function of these same parameters. There are also other special measurements made, i.e., deflection of coils. Two 5cm diameter aperture SSC candidate dipoles without iron are being prototyped: (a) a two layer, 6kA/turn version and (b) a single layer 10kA/turn model. In addition, there is a collaborative effort between KEK and FNAL in the development of a 10T (dipole, a longer range model) magnet program.

The results obtained during the evolution of the design, construction, and testing program of the design "B" dipole, are presented here. Design "B" is one of the original three competing designs for the Superconducting Super Collider "SSC" arc dipoles. The latest design "B" cross-section The final design parameters were as follows: air cored (less than a few percent of the magnetic field derived from any iron present), aluminum collared, two layered winding, 5.5T maximum operating field, and a 5cm cold aperture. There have been fourteen 64cm long 5cm aperture model dipoles cold tested (at 4.3K and less) in this program so far. There was a half length full size (6m) mechanical analog (M-10) built and tested to check the cryostat's mechanical design under ramping and quench conditions. Several deviations from the 'Tevatron' dipole fabrication technique were incorporated, for example the use of aluminum collars instead of stainless steel. The winding technique variations explored were "dry winding," a technique with the cable covered with Kapton insulation only and "wet winding" where the Kapton was covered with a light coat of "B" stage epoxy. Test data include quench currents, field quality (Fourier multipole co-efficients), coil magnetization, conductor current performance, and coil loading. Quench current, loss per cycle, and harmonics were measured as a function of the magnitude and rate of change of the magnetic field, and helium bath temperature.

Results are presented from tests of the third full-scale development dipole magnet for the Superconducting Super Collider (SSC) and from a retest of a 4.5-m model magnet of the same design mounted in an SSC cryostat. The 4.5-m magnet showed consistent quench performance between its original tests in boiling liquid helium in a vertical dewar and the current tests in forced-flow helium in a horizontal cryostat. Little or no retraining was observed over several thermal cycles. The full-length magnet required 12 quenches to train to its short-sample limit of 6800 A and displayed a reasonably stable quench plateau following training. Data are presented on quench behavior as a function of current and temperature, and on azimuthal and longitudinal loading of the coil by the support structure. >

At Fermilab we have operated a production line for the fabrication of 901 21 foot long superconducting dipoles for use in the Energy Saver/Doubler. At any one time 772 of these dipoles are installed in the accelerator and 62 in beamlines; the remainder are spares. Magnetic field data are now available for most of these dipoles; in this paper we present some of these data which show that we have been able to maintain the necessary consistency in field quality throughout the production process. Specifically we report harmonic field coefficients, showing that the mechanical design permits substantial reduction of the magnitudes of the normal and skew quadrupole harmonic coefficients; field shape profiles; integral field data; and field angle data. Details of the measurement apparatus and procedures are described elsewhere.

The measurement system and procedures used to test more than 900 superconducting dipole magnets and more than 275 superconducting quadrupole magnets for the Fermilab Energy Saver are described. The system is designed to measure nearly all parameters relevant to the use of the magnets in the accelerator including maximum field capability and precision field measurements. The performance of the instrumentation with regard to precision, reliability, and operational needs for high volume testing will be described. Previous reports have described the measurement system used during development of the Saver magnets from which this system has evolved.

The Fermilab Energy Saver/Doubler (Tevatron) accelerator contains 216 superconducting quadrupole magnets. Before installation in the Tevatron ring, these magnets plus an additional number of spares were extensively tested at the Fermilab Magnet Test Facility (MTF). Details on the results of the tests are presented here.

We have experimentally simulated the wedge regions of the winding of the Superconducting Super Collider dipole and studied the propagation of quenches in them. This study is relevant for proper selection and design of the quench protection scheme. The windings of these 16.6 m long dipoles incorporate copper wedges in order to achieve the required magnetic field uniformity, and the delay that they impose on the transverse spreading of normal zones is one of the needed data that we present here. Quenches under constant currents were triggered with spot heaters, and their development recorded from voltage taps strategically located. Currents as high as 6 kA were used. Under zero magnetic field conditions the delays are too long for self-protecting schemes.

At an energy of 1 TeV the superconducting cable in the Energy Saver dipole magnets will be operating at ca. 96% of its nominal short sample limit; the corresponding number in the quadrupole magnets will be 81%. All magnets for the Saver are individually tested for maximum current capability under two modes of operation; some 900 dipoles and 275 quadrupoles have now been measured. The dipole winding is composed of four individually wound coils which in general come from four different reels of cable. As part of the magnet fabrication quality control a short piece of cable from both ends of each reel has its critical current measured at 5T and 4.3K. In this paper the authors describe and present the statistical results of the maximum field tests (including quench and cycle) on Saver dipole and quadrupole magnets and explore the correlation of these tests with cable critical current.

The first 16.5 m long SSC dipole magnet (D00001) had its field intensity measured as a function of position with a custom made NMR magnetometer. A short description of the probe is presented. The data obtained (most of it near 2 T spaced apart by one inch) shows an average transfer function of 1.02830 T/KA with position dependent values deviating from the average by up to .00130 T/KA revealing contruction inhomogeneities that were measured with a sensitivity of 25 ppM.

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.

The test facility used for R&D testing of full scale development dipole magnets for the SSC is described. The Fermilab Magnet Test Facility, originally built for production testing of Tevatron magnets, has been substantially modified to allow testing also of SSC magnets. Two of the original six test stands have been rebuilt to accommodate testing of SSC magnets at pressures between 1.3 Atm and 4 Atm and at temperatures between 1.8 K and 4.8 K and the power system has been modified to allow operation to at least 8 kA. Recent magnets have been heavily instrumented with voltage taps to allow detailed study of quench location and propagation and with strain gage based stress, force and motion transducers. A data acquisition system has been built with a capacity to read from each SSC test stand up to 220 electrical quench signals, 32 dynamic pressure, temperature and mechanical transducer signals during quench and up to 200 high precision, low time resolution, pressure, temperature and mechanical transducer signals. The quench detection and protection systems is also described.

Magnet Design B for the Superconducting Super Collider (SSC) consists of a 5 cm diameter collared coil assembly 12 m long with concentric aluminum thermal shields at 10 K and 80 K, a G-10 post type support system and a minimal iron vacuum vessel located at a large radius from the coil. In order to determine the behavior of such a magnet under both direct current and quenching conditions, a 6 m model was built using Tevatron tooling to produce a 7.6 cm diameter coil. The dc operation demonstrated that the post type suspension has acceptable rigidity. Distortions in the aluminum thermal shield during quench resulted from stresses in the material below the yield values. Temperature increases in the thermal shield due to eddy currents were larger than those calculated using simple assumptions, demonstrating the value of using a model to verify eddy current behavior in complex situations.

A 40-mm-aperture, 17-m-long Superconducting Super Collider (SSC) model dipole was assembled at Brookhaven National Laboratory (BNL) and tested initially at Fermi National Accelerator Lab (FNAL) and later at BNL. At BNL an extended cycle test was devised to examine the magnet’s performance through numerous cold tests and thermal cycles. This paper discusses the magnet’s mechanical and quench performance and magnet field measurements during the tests.

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.