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Calculations have indicated that the simple macro composite conductor that comprises copper with a stainless steel sheath may be the best to use in high field pulsed magnets > 50 T. The recently commissioned wire fabrication facility of the Clarendon Laboratory can finish this type of conductors to the required size and cold work, after industrial preprocessing. The conductors have strengths in excess of 1.2 GPa. Ln this paper we describe the facility and the mechanical and electrical characterisation of the wires. We also report on bur measurements of the temperature distribution in a macro composite wire during and after a typical pulse.

Here, we report the development of the CICC joint design for the 36-T Series-Connected Hybrid Magnet. A novel solder-less single-box praying-hands joint has been designed to meet the mission of the SCH. A prototype sample joint, Florida Solder-less Joint A (FSJ-A), was manufactured and tested. The low DC resistance confirmed the feasibility of the concept design. In addition, a simple model describing the current transient behavior of the pray-hand joint is presented. A comparison with the experimental data is also included.

The National High Magnetic Field Laboratory in Tallahassee, Florida, USA has designed, built and tested a high field, split pair, Repetitively Pulsed Magnet (RPM) suitable for neutron scattering experiments. RPM magnets have the advantage of lower average power and lower construction costs than DC magnets. The NHMFL RPM program intends to build magnets with higher field and larger scattering space than those available elsewhere. Details of design and testing of the first prototype are presented

The NHMFL hybrid magnet system, which was designed to produce steady field in excess of 45 T in a 32-mm, room-temperature bore, was first tested in December 1999. Since then, the system has served users of the NHMFL at the full design currents in both the superconducting outsert (10 kA) and the resistive insert (67 kA), reaching a combined field of 45.2 T. This magnet system combines both superconducting and resistive magnet technologies, which, whether taken together or separately, define new states of the art. Operating alone, the superconducting outsert has been charged repeatedly to 10 kA, corresponding to a maximum field of nearly 16 T at its 710-mm winding i.d. More recently, operation of the outsert has been limited to 8 kA as a consequence of degradation suffered during an “unprotected” quench, but insert upgrades and higher-current operation (up to 74 kA) have allowed the system to provide 45 T to users still. Because the system was designed from the outset as a facility rather than an experiment, there is a minimum of instrumentation––in fact there is none internal to the steel vessel housing the superconducting magnet. Therefore, projections of internal conditions in the superconducting magnet are deduced from detailed analysis of observations from coil voltage taps and various external temperature sensors and pressure transducers. We present these with comments regarding their value in future magnet design as well as an introduction for more complete analysis by complex computer codes.

The conceptual design and fabrication details of a conduction-cooled high temperature superconducting (HTS) reciprocating magnetic separator are reported. Reciprocating magnetic separators are used in the purification of kaolin clay. The HTS coil is 0.30 m in length and has a 0.25 m inner diameter. The central operating magnetic field is a nominal 3.0 T with a design operating current of 126 A. In terms of combined size and magnetic field strength, this is one of the largest HTS magnets ever fabricated, possessing a stored energy >0.1 MJ. The HTS magnet is conduction cooled via one single-stage G-M cryocooler with a nominal operating temperature of 30 K. The HTS conductor uses a stainless steel reinforced Bi-2223 material. Salient features and results of the electromagnetic, thermal, and quench protection analyses are discussed.

The National High Magnetic Field Laboratory in Tallahassee, FL, USA, is designing a high field magnet for condensed matter physics with the field perpendicular to the access tube. The traditional approach to such magnets is to build a split pair of solenoids. Various novel alternate approaches have been examined and compared with split pairs. A particularly attractive option consists of concentric nested Bitter coils tilted 45 degrees to the axis. By energizing the coils in opposition, the axial components of field from the various coils can be made to cancel resulting in a purely transverse field. Preliminary designs including field, power and stress estimates are presented.

Low temperature composite superconductors stabilized with extra large cross-section pure aluminum are currently in use for the Large Helical Device in Japan, modern big detectors such as ATLAS at CERN, and other large magnets. In these types of magnet systems, the rated average current density is not high and the peak field in a region of interest is about 2-4 T. Aluminum stabilized superconductors result in high stability margins and relatively long quench times. Appropriate quench analyses, both for longitudinal and transverse propagation, have to take into account a rather slow diffusion of current from the superconductor into the thick aluminum stabilizer. An exact approach to modeling of the current diffusion would be based on directly solving the Maxwell's equations in parallel with thermal diffusion and conduction relations. However, from a practical point of view, such an approach should be extremely time consuming due to obvious restrictions of computation capacity. At the same time, there exist certain ways that simplify mathematical models for the thermal and electromagnetic diffusion processes for the purpose of rapidly calculating the propagation velocity and effective simulating of quench behavior. These models explained here were tested and applied to quench simulation in the above-mentioned magnet systems.

The NHMFL hybrid magnet was successfully tested to 45.1 T in an air bore as designed on June 26, 2000. The magnet consists of a cable-in-conduit superconducting outsert producing 14.3 T in a 616 mm bore and a Florida-Bitter resistive insert providing 30.8 T in a 32 mm bore. The insert was tested without the outsert in May 1999. The combined system was tested in December 1999 reaching a peak field of 44 T in an air bore. Physics experiments were run in December 1999 at 45 T using dysprosium pole piece flux concentrators. During the first and second quarters of 2000 modifications were made to the cryogenic system and the resistive insert. Test results of the resistive insert from December 1999 to June 2000 are presented along with a discussion of the possibilities of upgrading the insert to reach a total field of 50 T. Scientific experiments are scheduled up to 45 T in a clear bore starting July 3, 2000. A spare set of resistive coils is under construction.

The muon collider is a new idea for lepton colliders. The ultimate energy of an electron ring is limited by synchrotron radiation. Muons, which have a rest mass that is 200 times that of an electron can be stores at much higher energies before synchrotron radiation limits ring performance. The problem with muons is their short life time (2.1 /spl mu/s at rest). In order to operate a muon storage ring large numbers of muons must be collected, cooled and accelerated before they decay to an electron and two neutrinos. As we see it now, high field superconducting solenoids are an integral part of a muon collider muon production and cooling systems. This report will describe the design parameters for superconducting and hybrid solenoids that are used for pion production and collection, RF phase rotations of the pions as they decay into muons and the muon cooling (reduction of the muon emittance) before acceleration.

The problem of optimizing the design of magnet systems to simultaneously satisfy a set of constraint equations for field, geometry, protection, and stability while minimizing the total system cost is considered. A mathematical description of the problem is given, along with details concerning possible constraint algorithms and cost functions. Rules for the optimal selection of magnet technology (potted, ventilated, and cable-in-conduit coils) are presented. The resulting sets of equations can be solved by different numerical methods; the final choice is based on considerations of functional form as well as computational speed and accuracy. Depending on the choice of constraint equations, the resulting problem may or may not be smooth, and may or may not admit multiple minima. The choice of minimization algorithm can be tailored to the situation at hand to yield optimal performance. We present results pertaining to an alternating-field solenoid system being considered by the MuCool collaboration. The system design requires consideration of field profile, magnet stability, magnet structure, and protection, as well as total cost. A key application of the optimization code is the analysis of cost trade-off with respect to the imposed constraints, and examples are given in the alternating-solenoid case.

Since 1994 the National High Magnetic Field Laboratory in Tallahassee, FL has built numerous high field DC magnets for condensed matter physics and other research. Our user community is now requesting various special purpose high field magnets that are at various stages of design and development. Concepts under consideration include the following: 1) AC modulation (0.1 T AC to 100 Hz) at 27 T DC for dc Haas van Alphen; 2) AC gradient (0.05 T/cm) at 27 T DC for force magnetometry, 3) >20 T radial access magnet for two angle rotation, 4) 18 cm bore high field*field gradient magnet for levitation of large samples and 5) 50 mm bore magnet with uniform field*field gradient for precision levitation. Design concepts. field magnitude and quality, stresses, power densities and construction status will be presented for these various systems.

The Muon-Electron Conversion experiment, to be built at Brookhaven National Laboratory, requires a complex set of solenoids to generate the required field profile. Field magnitude, gradient and oscillations must all be controlled along the /spl sim/27 meter curved beamline to allow for optimal capture of /spl pi/ and /spl mu/ particles, the sign and momentum selection of appropriate /spl mu/ particles, and their transport to the detector region. The solenoid system is designed to yield the required field profile in an efficient and cost-effective manner. A critical concern is the removal of field gradient reversals along the beamline. The system is decomposed into a large number of simple solenoids of equal current density, whose dimensions vary so as to obtain the required field contribution. Analysis of the field influence of cosmic ray shielding is provided, along with the field footprint of the entire system. Structural aspects are discussed, in particular relating to magnetic forces and cryostat requirements.

The National High Magnetic Field Laboratory (NHMFL) is building a 25 T, 52 mm bore resistive magnet with field uniformity and stability of 1 ppm over a 1 cm diameter spherical volume (DSV). Upon completion the unshimmed magnet's homogeneity was 48 ppm over 1 cm DSV. It has since been ferro-shimmed to 12 ppm over 1 cm DSV and we are in the process of shimming to the 1 ppm level. Details of the design, construction, shimming and stabilizing are presented.

Construction of the NHMFL hybrid magnet is complete. The resistive insert was tested to full current without the background field from the superconducting magnet on May 17, 1999. Tests of the combined system have been scheduled for October 1999. The resistive insert fits into the 616 mm bore of the 14 T outsert superconducting magnet. The insert consists of a five coil, axially cooled Florida-Bitter design. The two innermost coils are electrically in parallel and this pair is in series with the other four coils. The magnet design uses Florida-Bitter disks made of Cu-Ag, Cu-Be, Cu-Zr and Cu sheet and is heavily based upon the high field resistive magnets previously built at the NHMFL. Details of the coil design, construction and testing are presented.

Superconducting solenoids are integral part of the proposed muon collider and Higgs factory. Superconducting solenoids that produce inductions up to 15 T will be used to capture pions that are produced by a proton beam impinging on a target contained within the solenoid. After the pions are captured they are phase rotated and allowed to decay to muons. The phase rotation and pion decay channel keeps the pions and muons captured in a 1.25 T rotation system. Superconducting solenoids will also be integral part of the muon cooling system. Within the muon cooling channel, which is projected to be up to 300 meters long, solenoidal fields up to 30 T are needed. This report presents the latest thoughts on how superconducting solenoids will be used as part of the muon collider.

Protection of large energy stored epoxy impregnated magnets requires careful design and analysis of protection heaters which are attached to the winding of a solenoid at a specified radial position (usually the winding outer surface) and at periodic circumferential locations. The heaters can be activated passively or actively depending on the desired protection scheme. The heaters are insulated from the winding by glass cloth and in some cases are sandwiched between the winding and a steel overband for structure support. An update report on the National High Magnetic Field Laboratory (NHMFL) efforts on quench heaters design, simulation and analysis is presented. All protection analysis discussed is based on internal dump.

Results will be presented of the testing to stress failure of a series of small, 10mm bore pulse magnets reinforced with different varieties and thickness’ of carbon composite. The field reached at failure allows a calculation of the stresses generated within the carbon fiber and a consequent comparison with computer models of highly stressed composite reinforced magnets. Where necessary, empirical corrections can be made in light of the experimental results. It will be shown that an accurate estimation of the radial and axial elastic modulus of the composite is of paramount importance in the modeling of stress transfer throughout the shell. The future utility of composites will be discussed together with an examination of the alternatives.

The major philosophies of pulse magnet design are discussed. Two of these are compared in terms of the von Mises stress generated within the winding at equal fields. The shortcomings of the use of fiber reinforcement in magnets is described and a method for utilizing it more effectively by the fabrication of multiple layers of composite of different moduli is suggested. A number of examples are given of the stress reduction effects on particular magnet designs that can be obtained by using this method.

An update report on the National High Magnetic Field Laboratory (NHMFL) magnet analysis code is presented. Among the recent improvements to the code is the ability to address complex conductors, windings and reinforcements in terms of thermal and magnetic diffusion. In this article we present several examples showing the capabilities of this code. For example copper/stainless steel, Cu/SS wires that are used in pulse magnets as an alternative to other conductors such as CuAg or CuNb have shown to have excellent thermal and mechanical properties. It was found that the rule of mixtures holds in predicting their properties. As a result it is expected that wires that have 10%Cu and 90%SS will essentially keep the SS high modulus and strength. However the 10% copper will improve the conductivity of this reinforcement that it can act as quench-back circuit in case of a quench. In this study we simulated a quench of a high field (20 T) magnet system and varied the Cu/SS ratio. The modeling results show that 5%Cu is enough to make the reinforcement act as quench-back circuit.

We discuss a preliminary design for a superconducting magnetic suspension system for measurement of drag on rotationally symmetric bodies in liquid helium. Due to its diamagnetic properties, a superconducting model (for example made or coated with Nb) is inherently stable against disturbances. In addition, drag measurement may be achieved by a passive technique, where the body is allowed to deflect from its neutral position under the influence of drag. The resulting shift in flux is detected via a superconducting pickup coil. The pickup coil may he connected either to a SQUID, or a secondary loop wound around a Hall probe.

A 25 Tesla resistive magnet with homogeneity of 1 ppm over 10 mm diameter spherical volume is being designed at the National High Magnetic Field Laboratory in Tallahassee, FL. The magnet consists of three concentric axially cooled Bitter stacks connected electrically in series. It will produce a peak field of 24.1 T in a 50 mm warm bore while consuming 15 megawatts of power and 25 T at 16.3 MW. Each of the stacks is designed to have a high uniformity by itself so the tolerance in axial positioning is not critical. Details of the magnet design, sensitivity to manufacturing tolerances and current distribution between cooling rings is presented.

The purpose of this analysis is to have a powerful but simple to use computing tool that can help characterize the thermal vs, mechanical performance of conductors, The analysis covers thermal diffusion, eddy current heating, and magneto-resistance in both micro composite and macro composite conductors. In micro composites such as CuAg, CuNb or a copper matrix reinforced with steel filaments, the reinforcement is distributed on a small scale and thus both reinforcement and matrix can be assumed to track the same temperature during the pulse, In a macro-composite conductor such as a jacketed stainless steel copper, the steel temperature will lag the copper temperature significantly during a short pulse due to the finite diffusivity time, As a result, the first detailed examination of the use of copper stainless steel, CuSS macro-composite conductors fi pulse magnets has been performed. The material has shown promising indications of superior mechanical and thermal performance when compared to the more expensive conductors CuAg and CuNb [1]-[3].

Design and optimization of pulsed magnets requires development of computer codes that can analyze a multi-coil magnet system magnetically, thermally and mechanically. We present a FORTRAN computer code "Xheat" that can be used to design a multi-circuit pulsed magnet using one or more conductors and reinforcement materials. Xheat is circuit solver that can analyze nonlinear magnetically coupled LR and LRC circuits yielding currents, voltages and temperature distributions in the magnet winding as a function of time. The power source can be one or more of the following: (i) a capacitor bank, (ii) a current source, or (iii) a voltage source. A finite difference technique is used to calculate the properties after a small time step as a function of the temperature at that time. Eddy currents and magnetoresistance are included in resistance calculations. Xheat writes an input file to an elastic and plastic stress calculation codes that can generate stresses, strains and displacement in all magnet layers at the midplane.

We describe in detail a 30 Tesla, 32 mm warm bore, 15 MW resistive magnet which was put into operation at the National High Magnetic Field Laboratory in Tallahassee, FL in March 1995. The magnet consists of three concentric axially-cooled Bitter stacks connected electrically in series. This magnet employs a substantial new development in Bitter magnet technology which allows high current densities without the usually accompanying high stresses. Details of magnet optimization, design, construction, testing and operation are presented. We also report on operating experience with the 27 T magnets.

The program at the National High Magnetic Field Laboratory for the design and development of 1 GHz class NMR magnets is described. The parameters are given for a 1.066 GHz magnet incorporating an HTS inner coil. The design of the related wide bore 900 MHz conventional superconductor magnet is described. Aspects of the technology development program supporting these designs are presented.

A new concept in cooling hole design in Bitter disks that allows for much higher power densities and results in considerably lower hoop stresses has been developed and successfully tested at the National High Magnetic Field Laboratory (NHMFL) in Tallahassee, FL. The new cooling hole shape allows for extreme power densities (up to 12 W/mm/sup 3/) at a moderate heat flux of only 5 W/mm/sup 2/. The new concept also reduces the hoop stress by about 30-50% by making a Bitter disk compliant in the radial direction through staggering small width and closely spaced elongated cooling holes. Finally, the design is optimized for equal temperature.

The world's first 33 Tesla resistive magnet is being designed and built at the National High Magnetic Field Laboratory in Tallahassee, FL. Completion of the magnet is expected in the fourth quarter of 1995. It will produce a peak on-axis field greater than 33 Teslas in a 32 mm warm bore while consuming 20 megawatts of power. This magnet consists of two small concentric parallel coils (poly-Bitter) in series with two larger Bitter coils. Details of optimization calculations and the resulting magnet design and construction are presented.

The primary consideration in the design and development of high field resistive and pulsed coil (30-100 tesla) is the stress and strain level in the winding and the reinforcement. Under such high loading conditions particularly for pulse coils, it is expected that the conductor material will exceed its elastic limit. The technique used here to calculate stresses beyond the elastic limit in a multi-region solenoid geometry is: The maximum load at the mid-plane is divided into many small load steps. When each load step is applied to the winding, the stresses and the strains are calculated based on the material properties at the end of the previous load step. If the effective stress in any region exceeds the elastic limit then the modulus of this region is redefined based on the slope of the stress-strain curve at that point. Using this technique of superposition, the stresses and strains are repeatedly calculated until maximum loading is reached. The procedure can also be reversed simulating the tail of a magnetic pulse, resulting in the conductor being under compression and the reinforcement in tension. It is possible to apply different cycles of loading and unloading using different elastic limits.

A 20 tesla, three coil, 200 mm bare, 20 MW resistive magnet is being designed at the National High Magnetic Field Laboratory in Tallahassee, FL., USA, in cooperation with the High Magnetic Field Laboratory of Grenoble, France. The outer two coils are axially-cooled and are connected electrically in series producing a central field of 11.27 T in a 365 mm warm bore while consuming 13.5 MW of power. The 6.5 MW inner coil (insert) is a poly-Bitter design with two sub-cells connected electrically in parallel and they together are connected in series to the two outer coils. The field of the inner coil is 8.78 T resulting in a 20 T total field in a 200 mm warm bore. All four coils are made of hard copper.

The National High Magnetic Field Laboratory is responsible for the design and construction of a large bore 900 MHz NMR magnet. The magnet's protection system consists of an active quench detector circuit controlling a persistent switch electrically in series with the magnet. The quench heater network is electrically in parallel with this persistent switch and powered when the switch is resistive. Heater network design entails a definition of the design constraints required to operate the 900 MHz magnet, a review of the material properties, and the developmental data to validate the design. Quench heater development will entail power testing and quench initiation studies. Heater power testing will establish the reliability of the epoxy heater interface. Quench initiation studies will measure the characteristic times required to induce quench in coils at design fields. This paper presents developmental progress on the power testing results, and a discussion of the power testing results on the heater network design for 900 MHz.

We have developed a new computer code that addresses quench simulation and analysis of a magnetically coupled epoxy-impregnated superconducting magnet system. The new computer code contains several new provisions: (1) it includes the effect of AC loss from the field variations in the winding due to field change because of the fast current transfer between the magnetically coupled solenoids; and (2) simultaneous solution of the propagation velocities in all directions in each coil by solving the thermal diffusion equation in the three directions (tangential, radial and axial). In addition to the above new features, the code solves for the currents, voltage, temperature distribution, and resistance of each coil as function of time. Thermal simulation of the protection switch and the quenching heaters is part of the new code. >

The new National High Magnetic Field Laboratory (NHMFL) at Tallahassee, Florida is committed to putting into operation in 1995 a 45-T Hybrid Magnet System to support research in steady, high magnetic fields. This facility will be accessible by qualified users world-wide on the basis of proposal and review. The more prominent components of this system will be a 24-MW resistive insert and a 120-MJ superconducting outsert. But successful achievement of the performance goals for the 45-T Hybrid System will depend on a number of unique, state-of-the-art subsystems and components. This paper describes the requirements and specifications on the individual subsystems and components in the context of the overall performance gears and reviews the plan for putting the whole together. >

The new National High Magnetic Field Laboratory (NHMFL), equipped with a 40 MW DC power supply, will design and construct the next generation of high field resistive magnets and hybrid inserts generating DC fields up to 50 T. We present a study on the required materials and the necessary cooling characteristics, these magnets need. The configuration selected for this study consists of a combination of thin poly-Bitter and thick Bitter coils optimized in dimensions and power under constraint of maximum design stress and heat removal to obtain maximum field. The study shows that each design requires a different optimum ratio of conductor strength to electrical conductivity and that efficient cooling is only advantageous if strong copper alloys are used. For efficient use of the available power the development of new high strength, high conductivity materials will be necessary. Equally important are improvements in the heat transfer characteristics of these high power density magnets. >

The world's first 12 megawatt resistive magnet will be available to users at NHMFL-FSU during the first quarter of 1994. The magnet will generate an on-axis field of 27 T in a 32 mm warm bore. The magnet consists of three concentric Bitter stacks with axial cooling. Optimal geometries, materials, and power distribution were determined by a constrained optimization program written by S. Prestemon. >

A new DC-DC converter to control the output power delivered from a magnetic energy storage magnet or an equivalent current source is discussed. The circuit consists of:(1) highly coupled transformer (air or iron core) with coupling coefficient better than 0.95; (2) low frequency mechanical or superconducting switches (0.1-10 Hz) or high frequency (10-1000 Hz) GTO switches depending on the application; (3) small voltage source (capacitor or battery) to control the output voltage. Two examples illustrating the application of this circuit are discussed. They are a step up dc current converter for use in uninterruptible power supplies and a step down one for use in discharging large current storage coil into a small current load. The efficiency expected to exceed 90 %. >

The authors investigate some options that can improve the design and performance of the Superconducting Super Collider (SSC) collider quadrupole magnet (CQM). They concentrate on the effect of the CQM magnetic material (yoke) on the design. Among these options are reduction of the amount of iron used; transfer function improvement to match that of the collider dipole magnets (CDM); yoke hysteresis effects; and shaping yoke or inserted magnetic material in the CQM collar to correct for some multipoles. PE2D software and FORTRAN codes were used to conduct the analysis. >

A novel vertically rippled flat coil design concept for superconductive magnetic energy storage (SMES) is presented. The coil consists of two or more horizontal layers that are rippled in the vertical direction. The thermal strains of the coil are accommodated by vertical bending and the magnetic forces are taken up by radial bending. The coil is very stiff in the radial direction to transfer magnetic forces to the external warm structure, which causes very small structure bending stresses and results in essentially a strain-free conductor during operation. The vertically rippled coil is very flexible in the vertical direction and accommodates large thermal strains occurring during a cool-down or warm-up process with only small stresses. The impact of this concept upon the SMES design is discussed. >

Large variety of large and small magnetic energy storage systems have been designed and analyzed in the last 20 years. Cryoresistive and superconductive energy storage (SMES) magnets have been considered for applications such as load leveling for electric utilities, pulsed storage for electromagnetic launchers and accelerator devices, and space borne superconductive energy storage systems. Large SMES are supported by a combination of cold and warm structure while small SMES are supported only by cold structure. In this article we provide analytical and numerical tools to estimate the structure requirements as function of the stored energy and configuration. Large and small solenoidal and toroidal geometries are used. Considerations for both warm and cold structure are discussed. Latest design concepts for both large and small units are included.

A complete stability analysis is given for a highly stabilized large current (50–100 kA) conductor cooled by a He II bath. The analysis concentrates on the minimum normalizing energy pulse, the minimum quench energy pulse (transient stability) and the maximum non-propagating current for constant length travelling normal zones (dynamic stability). The minimum normalizing energy pulse is defined as the energy required to raise the strand temperature above the current sharing level. The quench energy pulse is the pulse over which the conductor cannot recover. The dynamic stability is defined as two constant length normal zones travelling at constant velocity in opposite directions and is related to the change in ohmic heat generation following a normalization pulse. The computational model includes thermal conduction in Nb-Ti/Cu strands and the aluminium stabilizer, the thermal and electrical properties of both, heat transfer to helium at the conductor surface and current diffusion.

High-current large composite conductors cooled in He II baths are planned for superconductive magnetic energy storage (SMES) systems. Such conductors have long time constant current diffusion causing high initial I/sup 2/R generation when driven normal. As a result, the front of a normal zone may propagate even though the back of the normal zone is recovering as current diffuses deeper (with less I/sup 2/R) into the stabilizer. Accurate knowledge of I/sup 2/R heat generation in the current sharing region and the time-dependent transient heat transfer to helium is determined for the stability analysis. Analytical and numerical procedures are developed to calculate the maximum nonpropagating currents and propagation velocities. Round and rectangular shaped conductors are considered via the computational model. Numerical results are compared with experimental data.

An emergency internal dump procedure and analysis are presented for the 21-MWh engineering test model (ETM) of a full-scale superconductive magnetic energy storage (SMES) coil. The coil is arranged into four modules which can be connected in parallel using cryogenic switches. The first step in the energy dump procedure is to close all switches. The second step is to expel the liquid helium in about 20 to 40 s. As the liquid helium level drops, the current transfers inductively from the uncovered top modules to the other modules. The conductor and parallel structure pieces tend to warm up uniformly with tolerant voltage levels. Two cases are considered: the case where all turns are connected in series (no parallel switching) and the case of the parallel connection of the four modules. A safety analysis of the consequences of a faulty switch is also presented.

In a conventional radial magnetic bearing, the rotor (soft magnetic material) can only have attraction force from one of the electromagnets in the stator. The stator electromagnets consist of small copper windings with a soft magnetic material iron yoke. The maximum pressure obtainable is about 200 N/sq cm. It is shown that replacing the stator copper winding by a superconducting winding in the above configuration can increase the pressure to about 1000 N/sq cm. It is also shown that replacing the iron in the rotor by a group of superconducting windings in persistent mode and using a group of saddle coils in the stator can produce a pressure in excess of 2000 N/sq cm.

A program has been established to develop a 25T high resolution NMR magnet. An initial design is presented incorporating a HTS inner coil. The technology development program in support of the outer magnet, which constitutes a large bore 900 MHz magnet is described.

The world's first 27 T resistive magnet was delivered 22 June 1994 at the National High Magnetic Field Laboratory in Tallahassee, FL. The magnet consists of three concentric axially cooled Bitter stacks connected in series electrically and consumes 13.5 MW of power. The warm bore has a diameter of 32 mm. The magnet has now accumulated over 1200h of operation. A 30 T resistive magnet is under construction and more and higher field resistive magnets are being developed employing the “poly-Bitter” concept.

This report describes some solenoid design work done for the cooling experiment for the muon collider collaboration. This report describes an analysis section of superconducting solenoids that have a center line induction of 3.0 T. The section is bent in the shape of an S. Each bend in the S bends the muon beam one radian (57.3 degrees). The warm bore diameter of the solenoid bent solenoid is 300 to 320 mm. The radius of the bend at the solenoid center line is 1000 mm. This report shows the results of three dimensional field calculations and presents a solenoid design that will include four TPC detectors that are 240 mm in diameter and 550 mm long as well as a 1300 mm long section of 1300 MHz RF cavities. The TPC sections need a solenoid warm bore diameter of about 300 320 mm while RF cavities require a warm bore diameter of 440 mm. The superconducting solenoid design must take into account the varying warm bore diameter requirements for the magnet string yet meet the stringent solenoidal field uniformity requirements within the active volume of the four TPCs.

Analytic procedures are developed for calculating the ohmic heating loss for various cryoresistive magnetic energy storage coil configurations that are used to deliver periodic short huge bursts of energy to electromagnetic launchers (railguns). Simple geometries such as long solenoids, continuous winding toroids, low aspect ratio dipoles or straight wire are considered as examples. The effect of cabling on reducing eddy current losses is addressed in detail.

An optimization study aimed at minimum weight under certain constraints on module size and weight has been carried out. This study includes a structural material survey of materials with high specific strength and modulus, and an analysis of the effectiveness of coil configuration parameters on the value of E/M, energy stored per unit mass. Some typical structure problems, such as buckling in the bucking cylinder, are also discussed. >