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Some organic additive manufacturing feedstocks can be cohesive and tend to agglomerate in suspensions, which can lead to significant challenges in formulating solids-loaded fluids, like those used in many additive manufacturing processes. By depositing an ultra-thin, layer of a second material conformally with the surface of the feedstock powder, Atomic Layer Deposition (ALD) can be used to uniquely modify the surface and, thereby, cohesion of the powder material without changing the properties of the bulk material. This paper demonstrates low temperature (

Many governments have begun to adopt aggressive targets for electric vehicles. However, studies of the drivers of electric vehicle (EV) adoption are scarce. Social media interactions can provide a new data-driven vantage point to explore such drivers. This study uses data from 36,000 public posts on Facebook to investigate intersectionality in EV-communication as per the Political, Economic, Social, Technological, Legal and Environmental (PESTLE) categories. A computational social science methodology was adopted using a mixed-method application of social network analysis and machine learning-based topic modelling through Latent Dirichlet Allocation algorithm on a 600,000-text corpus extracted from the Facebook posts. Results showed that political, economic, and legal posts had dense clusters around the technology policy of EV, the institutional discourse of electrification of the federal vehicle fleet, and tax and credit framework politics. The environmental and social dimensions had a higher discourse for social justice, clean air, and better health and well-being. A market shift towards EV as a service industry was observed in the technology and economics-related posts. These findings can help policymakers, and planners design contextualised energy policy for influencing EV adoption in the U.S. and other countries.

Nine samples of pure stand alfalfa hay, representative of the compositional variability found in Mediterranean and Intermountain West climates, were collected throughout California and western Nevada during the 2008 growing season. Samples were evaluated in vivo (at either maintenance or ad libitum intakes by lambs), in vitro, in silico, and by near infrared spectrophotometry to determine characteristics of DM and fiber degradation as well as energy metabolizability. Also determined, from these and other routine analyses, were common indices of alfalfa quality including relative feed quality, relative feed value, in vivo TDN and ME. Significant differences (P < 0.05) in observed ME (Mcal/kg) were noted for alfalfa hays depending on source; quality indices were compared with observed ME. None of the indices evaluated were valid predictors of observed ME (P < 0.050), with the exception of near infrared predicted ME at either level of intake. Users of quality indices may expect less than optimal prediction of animal performance from use of indices or calculations based on indices failing to accurately predict ME. Results from this study indicate that ME estimated from near infrared spectrophotometry of pure stand alfalfa hay may improve characterization of alfalfa hay quality in that, depending on the feeding standard, ME input explains the vast majority of variation in animal output. However, given the limited numbers of alfalfa hay samples evaluated in this study, more studies are required.

As is well known, historians' surroundings often influence their scholarly work. The “Life in History” examined in these pages illustrates this point clearly as family, place, colleagues, occupational activities, and contemporary political trends shaped my decisions about higher education and scholarly work.

The ITER Central Solenoid has 36 interpancake joints and 12 bus joints in the magnet. The joints are required to have resistance below 4 nOhm at 45 kA at 4.5 K. The interpancake joints will have to withstand a significant cyclic tensile strain during ITER operation. The joints are located at the OD of the magnet embedded in the winding pack and therefore need to be compliant with the rest of the winding pack to avoid excessive stress. The US ITER Project Office is carrying out a program for joints development in order to establish fabrication process and also characterize electrical and mechanical performance of the joints in a special Joint Test Apparatus. Status of the joint development and test results are presented and discussed in the paper.

Irish and Scottish Encounters with Indigenous Peoples, edited by Graeme Morton and David A. Wilson. Montreal & Kingston, McGill-Queen's University Press, 2013. ix, 389 pp. $34.95 US (paper). Among the many enduring myths that figure in both Aboriginal history and studies of the Irish and Scottish peoples is a notion that Irish and Scots who ventured abroad enjoyed more positive relations with the Indigenous peoples they encountered than did adventurers from other lands. Or, as co-editor David A. Wilson of the University of Toronto poses what he terms "the general question at the heart of this volume: to what extent did Irishness or Scottishness affect attitudes toward Indigenous peoples?" (p. 17). It turns out, as both Wilson and the author of the lead article on European migration and Indigenous populations, Donald Hannon Akenson of Queen's University, put it--not much. Akenson contends that all agents of European expansion were horrible colonizers, apparently without exception. And editor Wilson agrees, even going so far as to cavil that one of his authors' evidence "hardly amount to 'striking Gaelic statements of solidarity'" with Indigenous people as the author contended (p. 13). Nonetheless, the volume does contain a wealth of fascinating information about Indigenous people and the Scots and Irish, even if it does not provide a satisfying explanation of any pattern in the relations that occurred along the frontiers of contact. Irish and Scottish Encounters brings together research results from fourteen scholars in history, literature, folklore, ethnomusicology, anthropology, and Celtic, Irish, and New Zealand Studies. Their approaches are similarly eclectic, resulting in a volume that includes a number of case studies of individuals and broadly comparative analyses in literature, music, and fiddling. The bulk of the studies look at Indigenous-European interactions in North America, principally Canada, but there are also treatments that focus on New Zealand, Australia, Orkney, and the Hebrides. A striking absence, both in the volume in general and in Akenson's overview essay, is any attention to interactions with Indigenous peoples in Asia and Africa, where, presumably, Scots and Irish also ventured. Only one author claims that ethnicity had much influence on relations with Indigenous peoples, with the rest concluding it had none or studiously avoiding "the general question at the heart of this volume" (p. 17). The collection also reveals a broad range of interactions between the Celtic newcomers and Indigenous peoples. Some contributions, such as the otherwise excellent study of nineteenth-century Toronto Bishop Michael Power, do not have much to do with the Irish. Historian Mark McGowan's chapter reveals a Canadian-born Catholic prelate energetically contending with an unsympathetic colonial Indian Department dominated by Anglicans and being forced to rely on French Jesuits for frontline missionary work in the western reaches of his diocese. …

A trap for the collection of bedbugs, Cimex lectularius Linnaeus (Hemiptera: Cimicidae), is described. The trap was baited with CO2 (50-400 mL/min), heat (37.2-42.2 degrees C) and a chemical lure comprised of 33.0 microg proprionic acid, 0.33 microg butyric acid, 0.33 microg valeric acid, 100 microg octenol and 100 microg L-lactic acid, impregnated into a gel. Laboratory studies, conducted in a square arena measuring 183 cm on each side, showed that traps with and without baits captured adult bedbugs, but traps with CO2 emissions of 50-400 mL/min caught significantly (P0.05) more bedbugs than traps without CO2. In an infested unoccupied apartment, traps with heat and with or without the chemical lure were tested without CO2 on 29 trap-days and with CO2 on 9 trap-days. The numbers of bedbugs captured were 656 and 5898 in traps without and with CO2, respectively. The numbers of bedbugs of all development stages captured were significantly greater in traps with CO2 (chi2 = 15 942, d.f. = 1, P10(-9)). A non-parametric two-way analysis of variance evaluation of six different traps with or without CO2, heat or a chemical lure monitored over 19 trap-days in an infested apartment showed that trap type was highly significant (n = 2833 bedbugs collected) (P10(-7)). The trap with CO2, heat and a chemical lure captured more bedbugs than the other traps, but only caught significantly more fourth and fifth instar nymphs than all other traps. Otherwise, the catches in this trap did not differ significantly from those caught by traps that contained CO2 and heat only. The total numbers of bedbugs collected for each trapping date (pooling all six traps) followed an exponential decline over the trapping period. This type of trap, which caught bedbugs in unoccupied apartments with and without furniture, and in an occupied apartment, may have utility in studying the ecology of bedbugs, in detecting bedbug infestations and in reducing numbers of bites by trapping host-seeking bedbugs.

A pair of 3.5 m long ITER TF size straight conductors has been fabricated into a conductor short sample and submitted to the SULTAN facility at CRPP for cold test. The sample used a triplet-based cabling pattern in one leg and a septuplet-based in the other. The legs had different cabling pattern and strand diameters, but the same void fraction. To assure the accuracy in measurement of the conductor current sharing temperature, it is important to have uniform current distribution in the cable, which requires uniformly low interstrand resistivity in the joint. In the present sample, the cable/subcable wraps and the chrome plating on all strands were removed from the cable in the termination, followed by compacting and heat treating the termination in a Glidcop sleeve. To improve current transfer, the sintered termination was further filled with soft solder before it was soldered to the copper profile. To clarify the effectiveness of short sample instrumentation, the sample was equipped with enhanced number of sensors and with sensor mounts penetrating the conductor jacket for the thermometers and voltage taps positioned in the high field zone. This paper presents the experiences in sample fabrication and instrumentation, and outlines the parameters used in the key processes.

The US Domestic Agency is one of six parties supplying TF cable-in-conduit conductors (CICCs) for ITER. Previous tests have shown that measured performance of the TF CICCs can be much lower than expected from the strand properties at the projected uniaxial strain and that the cabling pattern may also be an important factor. Worst of all, voltage signals well below the expected critical surface could not be reliably interpreted or canceled, making test results very suspect. The TFUS1 sample was prepared to achieve multiple goals: 1) to ensure uniform current distribution and to eliminate parasitic voltage signals by improving joints, 2) to explore the potential benefits of a different cabling pattern for better support of strain-sensitive strands, and 3) to explore the source of voltage development in the cable through the use of innovative penetrating diagnostics. Test results of the first US-made samples are presented and discussed.

ITER high J C Nb3Sn wires are designed to compensate for the performance degradation due to transverse electromagnetic force in cable-in-conduit-conductor. J C characterization of these wires, especially as a function of axial strain, is very important. We performed I C irreversibility strain epsivirr-epsivmax measurements and geometry examinations on two types of ITER high J C Nb3Sn wires. epsivirr-epsivmax is measured in a 18 T magnetic field by a straight pull device developed at the NHMFL. Consistent difference in epsivirr between the two types of strands is observed. We found that the epsivirr-epsivmax is ~ 0.3% for the type of strands with higher J C and ~ 0.4% for that with lower J C . This can be correlated to the difference in their geometry.

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.

This paper describes a procedure developed to fabricate air-bridges on coplanar transmission lines using a SU-8 substrate. SU-8 is attractive for micromachined multilayer circuit fabrication because it is photo-polymerizable resin, leading to safe, economical processing. The ability to fabricate air-bridges provides a means of suppressing the coupled slotline mode, thereby enabling single-mode design. The air-bridges also provide ground equalization at coplanar discontinuities. The properties of the air-bridge are investigated and compared to similar structures without air-bridges. As examples of possible device applications of this technology, an asymmetrical slot antenna and coplanar waveguide both operating at 35 GHz are presented. The return loss of both devices is 5 dB lower on structures that contain the air-bridge. This technology is promising for extending the use of SU-8 at millimeter-wave frequencies.

An Nb3Sn planar undulator demonstration magnet is under development at the NHMFL. Key technological aspects include a 15 mm period, a target of 0.8 T on the beam and a beam tube that is thermally isolated from the windings. Two yoke assembly procedures are explored. First, a modular approach in which each racetrack is wound, reacted and impregnated separately before assembly with iron pole pieces and the creation of joints between the racetracks. The second approach is based on the more traditional single-piece yoke on which the conductor is wound on a fully iron yoke, followed by heat treatment and impregnation of the entire assembly. Each approach is used to build a 10-racetrack coil; both coils are tested at 4.2 K in liquid helium. Results of the coil tests are discussed, as well as joint development and testing, leading to a choice of assembly method for the demonstration magnet.

Nb3Sn superconductors are examined to select proper conductors for hybrid magnets outserts (that is a superconductor solenoid wound on the outside of a Bitter magnet) at the National High Magnetic Field Laboratory. The materials are subject to both thermal and mechanical stresses when in service. The stresses are complex due to the thermal contraction of the conduit applying extra stresses to the conductors. The final thermal stress levels can be well beyond the yield stress of some components in the superconductor composite and therefore plastic flow occurs in these components, such as Cu stabilizer and Cu-Sn matrix. If the plastic deformation strain is large, deformation strain in Nb3Sn superconductor filaments can be difficult to estimate. The differences in conductor design also render the estimation of the strain status difficult. It is well documented that the critical current is strongly affected by strain in the Nb3Sn superconductors. Therefore, we have characterized the microstructure and critical current of the superconductors with respect to the strain of various Nb3Sn superconductors. Other relevant properties are also measured and related to the fabrication, design and microstructure of the conductors. This paper reports our efforts in characterization of the Nb3Sn superconductors for hybrid magnets.

An active quench protection system is planned to safely guard the superconducting coils of a 36 T hybrid magnet during a quench. The quench circuit includes a 0.1 Omega external discharge resistor, blocking diodes, and high-current circuit breakers for isolation of the power supplies during a dump. The protection system will rely on redundant hardware encoded circuits for detection of quench voltages. A quench modeling program has been created that incorporates GANDALF as the thermal and hydraulic module. Quench simulations have been performed to model temperatures, pressures, and mass flow rates of the helium and conductor. The response of the system under a protected quench has been analysed and it is shown that the coils would be adequately protected with a quench detection voltage of 1 V. Energy and helium expulsion rates during a quench are computed to determine the capacity and configuration of the cryogenic refrigeration system during off-normal events.

The cooling system design for the superconducting outsert of a 36 T Series-Connected Hybrid (SCH) magnet being developed at the NHMFL is discussed and analyzed. The outsert will be wound with a superconducting cable-in-conduit conductor (CICC) that uses a cable of multi-filamentary Nb3Sn/Cu strands inside a high-strength alloy jacket that confines slowly flowing supercritical helium (under 3-3.5 atm pressure at 4.5 K) in direct contact with the cable strands. The cooling design option with the highest flow to all the winding layers is selected (each layer has an inlet and outlet), aiming to sustain a wide range of duty cycles required by diverse science experiments, conducted with this magnet. Typically, many experiments will need multiple cycles (charging/discharging) with short, albeit variable, waiting time before each one. The charging cycles would have ramp rates of about 30 A/s to relatively high ramp rates, up to 500-600 A/s. The different ramp rate characteristics will result in different patterns of deposition and evacuation of heat due to AC losses in the outsert windings. All of these cases are carefully analyzed and discussed.

A new concept of current leads for a 21 T Fourier Transform Ion Cyclotron Resonance (FT-ICR) superconducting magnet system is presented. The binary current lead, a series combination of a normal conductor in the high-temperature section and an HTS conductor in the low-temperature section, is employed. The HTS section is partly immersed in liquid helium and the joint between the normal metal and HTS conductor is cooled by the contact with a cryocooler. After excitation, the normal metal conductor section is thermally disengaged from the HTS section without disturbance to the insulating vacuum space and without requiring complete removal of the current leads. The present paper describes the so-called semi-retractable current leads for a 21 T FT-ICR magnet system application. The optimized dimensions of the leads are presented in order to minimize the thermal heat load when carrying operational current with some margin.

The measurement of critical current of superconducting conductors under applied tensile strain in high magnetic field [IC(B, isin) is essential for the application of Nb3Sn composite conductor in high field superconducting magnets. The large bore 20 T DC magnet at the NHMFL along with a device designed to apply tensile strain allows the IC(B, isin) measurement of about 100 mm long straight Nb3Sn composite wire. The superconducting wires are soldered to dog-bone shaped backing plates made of different materials. Our results show that the backing plate materials have significant effects on the measured IC(B, isin) behaviors. This paper also reports our recent experimental results on high current density Nb3Sn conductors.

The series connected hybrid (SCH) Magnet developed at the NHMFL will provide high field (36 T), high field quality (1 ppm stability and homogeneity) and a moderately large bore (40 mm inside the resistive shim coils) for users interested in medium resolution NMR studies. The SCH comprises a superconducting outsert built with Nb3Sn cable-in-conduit conductor and a resistive insert using Florida-Bitter technology. The insert and outsert magnets are connected electrically in series, which mitigates many of the engineering challenges for such systems, but mechanical design of the structural components linking these remains critical to the performance of the superconducting outsert. We present detailed design and analysis of these components with an assessment of their ability to meet the functional requirements presented by potentially normal, off normal and fault conditions during operation.

The objective of this descriptive study was to measure the amount of variability in the composition of 12 by-product feedstuffs commonly used in rations for lactating dairy cows in California. This study followed a prior descriptive study that was designed to provide the beginning of a nutrient database of by-product feedstuffs. Eleven of the by-product feedstuffs were from a single manufacturer source, with only soybean samples obtained from multiple sources. Samples of each by-product feedstuff were obtained from various locations in California and several locations outside the state. Variability in chemical composition and digestibility are discussed within each of the by-product feedstuff subgroups. Variation generally tended to be within acceptable ranges, although a wider variability was observed when sample numbers were smaller or the absolute value of the nutrient being measured was low.

A new set of resistive magnets is being installed using technology developed for our 45-T hybrid magnet. Test results will be presented for the two new 20-MW magnets: the first providing 31 T in a 50-mm bore, the second 35 T in a 32-mm bore. Fabrication status is provided for a third high-homogeneity magnet expected to provide 28 T with inhomogeneity of less than 50 ppm over a 10-mm diameter spherical volume in a 32-mm bore. A new 36-T, 40mm bore high-homogeneity series-connected hybrid is also in the Engineering Design Phase and concepts are being developed for a 55-T hybrid magnet

The COHMAG report of the National Academy of Sciences provides an assessment of high field magnet science and technology in the United States, and identifies possible new initiatives for future high field magnets. Regarding NMR, the report identifies high resolution NMR spectrometers in the range of 30 T/1.3 GHz as having great scientific interest. This paper discusses technology issues associated with 30 T superconducting magnets. The enabling technology is HTS conductors and coil technology. Significant issues remain for application of HTS conductors to large coils, including long length quality, heat treatment, anisotropy and strain dependence. The outer LTS coil sections are large, with high stress and stored energy. Structural issues, including high strength conductor and reinforcement, and quench protection issues are significant. The status of technology required for a 30 T NMR magnet is examined. A preliminary conceptual design of the 30 T magnet is presented

An innovative hybrid magnet configuration is being developed at the NHMFL, consisting of a Florida-Bitter resistive magnet nested within a cable-in-conduit conductor (CICC) superconducting magnet to provide high fields for less power than traditional hybrid magnets. The resistive and superconducting magnets, connected in series, will be capable of producing 23.1 T and 13.8 T respectively for a total central field of 36.9 T. The CICC uses a cable of multifilamentary Nb3Sn/Cu strands inside a superalloy jacket that confines flowing supercritical helium in direct contact with the cable strands. The design of the magnet system is presented along with the design criteria used to evaluate the superconducting magnet and its integral components. The results of a structural analysis performed using finite elements for normal operational and fault loads are discussed for the most critical component, the conduit

With the intention to develop a technology suitable for a 2.4 m magnetic length, superconducting undulator with 0.8 T on the beam and a 15 mm period for the IXS beam line at the Advanced Photon Source at the Argonne National Lab, USA, a 0.6-m Nb3Sn undulator demonstration magnet is under development at the NHMFL. The intent is to investigate the applicability of Nb3Sn superconductor, in combination with soft magnetic materials, for a 15 mm period planar superconducting undulator. The demonstration requirements include a peak undulator magnetic field of at least 0.8 T and a vertical stay-clear aperture for the beam of at least 7 mm. In concept, the beam tube will be thermally isolated from the windings and operated at LN2 temperature to promote system reliability. Liquid helium and nitrogen reservoirs provide conduction cooling and the former also acts as a basic structural element. A brief description of a design is presented. A comparative study of fully and partly iron yokes and their effect on the required current density is performed. The results have implications for the yoke assembly procedure. Finally, a new yoke-winding geometry is presented

The National High Magnetic Field Laboratory (NHMFL) has identified as one of its next high-field persistent-magnet targets a 21 T superconducting magnet system to be used in a Fourier Transform Ion Cyclotron Resonance (FT-ICR) Mass Spectrometer. The required fundamental parameters of a 21 T central field and 110 mm warm bore diameter are similar to those already successfully demonstrated in the NHMFL's Ultra-Wide Bore 900 MHz Nuclear Magnetic Resonance magnet system. However, there are several ancillary requirements of the FT-ICR spectrometer that require technical attention such as fringe field restrictions requiring shielding, length of uniformity zone, magnitude of inhomogeneity, horizontal orientation of the magnet axis and a limitation on the length of the cryostat. This paper describes the overall system requirements, features and status of the superconducting magnet conceptual design proposed for meeting these requirements

A tensile test device has been built to investigate the in-field transport properties of research grade Nb/sub 3/Sn internal tin superconducting wires under axial strain. The device is operated by a stepper-motor and worm gear assembly and is rated for maximum loads up to 2.5 kN. Tensile strains of 1% can be easily accommodated. The probe is instrumented with vapor-cooled current leads and high temperature superconducting current lead extensions to allow for high transport currents up to 1.5 kA. The setup was operated in the NHMFL large bore resistive magnet in fields up to 20 T. Preliminary tests on short wire samples were carried out. Results of I/sub c/(B,/spl epsiv/) measurements at 4.2 K and n-values are presented.

The observation of nonuniform current distribution (NUCD) in multi-strand cables, in particular cable-in-conduit conductors (CICC's), has been reported often. NUCD may have important effects on AC loss and stability margin in such conductors; therefore, this phenomenon must be better understood. In this study, we have used numerical simulations to study the magnetic flux changes caused by NUCD's that themselves derive from details of lap-joint construction between cables composed of hundreds of strands and twisted in specific patterns. In the steady state, a NUCD is governed by the distribution and quantitation of contact resistances between individual strands in one cable to individual strands in the other. In an otherwise well-made joint, contact resistances will be lowest between strands that approach each other across the lap-joint-interface, and a strand that has many close encounters with the interface can be expected to carry larger current in the steady-state condition than a strand that has fewer or none. The length of the joint and the cable pattern determine the number of close encounters to the lap-joint-interface by individual strands. We present the results of our simulations using different joint length, we suggest experiments to observe these effects, and we discuss their significance with regard to conductor and magnet performance.

During a planned replacement of one of the three superconducting coils in the outsert magnet of the 45 T Hybrid, there is an opportunity to replace the existing pair of standard helium-vapor-cooled current leads with a pair of leads incorporating high-temperature superconductor (HTS) sections. A conceptual design for these leads has been completed, and various critical components have been modeled and tested. The design includes an integral liquid-nitrogen reservoir at the interface between resistive and HTS sections, automatic liquid-nitrogen level control, a resistive heat-exchanger section cooled by nitrogen vapor, an HTS section with integral stainless-steel shunt for protection, and an interface to the low-temperature superconductor bus. A detailed design is presently underway and fabrication tooling and techniques are being developed. We present design details, projected performance, results of development testing, and plans for manufacturing and acceptance testing.

The National High Magnetic Field Laboratory in Tallahassee, Florida and the National Superconducting Cyclotron Laboratory in East Lansing, Michigan have been collaborating on the design and construction of a large-gap, compact superconducting sweeper magnet for nuclear physics experiments. The magnet consists of two NbTi D-shaped coils and 20 tons of magnet iron in a "C" configuration. The coils were successfully bucket tested in their support structures during the summer of 2002. The design of the cryostat was completed in late 2002 and construction is nearly completed. System testing is expected to occur late in 2003.

The National High Magnetic Field Laboratory (NHMFL) proposes to build a new hybrid magnet system with three specific goals: 1) address the needs of users requiring high homogeneity, high temporal stability, and long residence times at moderately high fields; 2) enhance user service through use of a single 10 MW power supply (allowing simultaneous operation of multiple systems); and 3) make the system attractive in terms of combined capital and operating costs. The basic configuration are series-connected hybrid, wherein resistive insert and superconducting outsert are connected in series and powered by a single 10-MW unit (20 kA and 500 V) of the NHMFL dc power system, a configuration with advantages for handling faults and off-normal operating conditions and with improved temporal stability. Specific design goals are 35 T, 10-ppm uniformity over a 10-mm DSV, and access for 40-mm diameter probes. By powering the superconducting outsert with 20-kA high-temperature-superconductor (HTS) current leads, cryogenic loads are kept small, substantially smaller even than the present 45-T Hybrid. The net result is a magnet design: 1) with capability for both higher field and higher field quality than present resistive-only systems, 2) that permits simultaneous service of two or more users, 3) that is sufficiently compact to fit within the standard resistive-magnet cell, 4) whose ease of operation is comparable to resistive-only systems, and 5) whose lifetime cost (including construction and operation) can be significantly lower than comparable resistive-only systems. We discuss details of the existing conceptual design, the methodology for its creation, the perceived development needs, and the projected program to realize this system.

Several high field magnets using Nb/sub 3/Sn superconductor are under development for future particle accelerators. The high levels of stored energy in these magnets can cause high peak temperatures during a quench. The thermo-mechanical stress generated in the winding during the fast temperature rise can result in a permanent damage of the brittle Nb/sub 3/Sn. Although there are several studies of the critical current degradation of Nb/sub 3/Sn strands due to strain, little is known about how to apply the strain limitations to define a maximum acceptable temperature in the coils during a quench. Therefore, an experimental program was launched, aimed at improving the understanding of the effect of thermo-mechanical stress in coils made from brittle Nb/sub 3/Sn. A first experiment, reported here, was performed on cables. The experimental results were compared to analytical and finite element models. The next step in our experimental program will be to repeat similar measurements in small racetrack coils and later in full size magnets.

A hybrid magnet system, combining superconducting and resistive magnet technologies for the production of 45-T steady field in a 32-mm room-temperature bore, has been operated successfully as a user facility for the past two years at the National High Magnetic Field Laboratory in Tallahassee, Florida. The superconducting outsert is a 710-mm bore magnet with demonstrated capability for 100-MJ stored energy, over 14-T field on axis, and nearly 16-T maximum field at the windings. This system continues to provide to researchers the highest steady field available anywhere in the world, even after degradation of the superconducting outsert, which resulted from an "unprotected" quench in July 2000. This paper reviews the important specifications and design features for the superconducting outsert, its nearly 3-year history of operation, as well as plans for its repair and future upgrades.

Magnetic confinement of positrons has been achieved in small scales, and the key to achieve better confinement is the design of compact and cost-efficient high field superconducting magnets. The paper describes a general algorithm to optimize a magnet design to match a pre-specified magnetic field profile needed to achieve confinement. The numerical model is used to calculate magnetic field, forces, and inductance for the superconducting magnetic bottle (magnetic mirror) based on simple solenoidal configurations. The model incorporates magnet stability and quench constraints in order to arrive at a feasible optimum design. A preliminary design for an experimental facility is presented.