National Magnet Laboratory Research Articles

Benjamin Lax

Benjamin Lax, a pioneering solid-state and plasma physicist, an MIT professor of physics, and the long-time director of the MIT National Magnet Laboratory, died at age 99 on 21 April 2015 in Newton, Massachusetts.Benjamin LaxBACHRACH PHOTOGRAPHYPPT|High resolutionBorn on 29 December 1915 in Miskolc, Hungary, Ben moved with his family in 1926 to the US, where they settled in Brooklyn, New York. After completing Boys High School in Brooklyn, he graduated cum laude from the Cooper Union for the Advancement of Science and Art in 1941 with a degree in mechanical engineering. He wanted to do graduate work in mathematics at Brown University, but he was drafted into the US Army in 1942. Assigned to the famous MIT Radiation Laboratory, he worked on a crash program to develop a new radar system, named Little Abner, which was successfully tested in the field. After World War II ended, Ben went to MIT, where he completed his PhD in physics in 1949 under Sanborn Brown. For his thesis, “The effect of magnetic field on the breakdown of gases at high frequencies,” he utilized cyclotron resonance, a technique that he continued to pursue throughout his career.In 1951 Ben joined the MIT Lincoln Laboratory, where he made significant contributions to the understanding of semiconductors, particularly by using cyclotron resonance to study the semiconductors’ energy band structure. Ben and his coworkers employed cyclotron resonance absorption of microwave radiation to measure the effective mass of electrons, which was determined by the curvature of the energy bands. His studies of germanium and silicon were particularly important to the progress of semiconductor devices. Ben was also a coinventor on an early patent for the semiconductor laser. Because of his scientific advances and his abilities as a leader, Ben was made head of the Lincoln Laboratory’s solid-state division in 1958 and served as associate director of the lab in 1964–65. In 1960 he was recognized by the American Physical Society with the Oliver E. Buckley Condensed Matter Physics Prize “for his fundamental contributions in microwave and infrared spectroscopy of semiconductors.”In the late 1950s, Ben led a group of scientists and engineers in proposing that a high-magnetic-field laboratory be built on the MIT campus to conduct research in solid-state and plasma physics, magnetic resonance spectroscopy, and magnet engineering. The successful proposal led to the 1960 establishment of the National Magnet Laboratory (NML), later renamed the Francis Bitter Magnet Laboratory. Ben served as director for its first 21 years. In 1965 he also accepted a position as a professor in the MIT physics department.Under Ben’s leadership, the NML became known internationally for its wide-ranging research, including in such areas as the physics of solids in high magnetic fields; high-field nuclear magnetic resonance; biomagnetism; magnet technology, including magnetic levitation for trains; laser–plasma interactions in high magnetic fields; and laser–plasma diagnostics. He was also interested in the use of high magnetic fields to achieve better confinement of plasmas for fusion. The first high-magnetic-field tokamak confinement device, Alcator A, was constructed at the NML and successfully demonstrated the benefits of the high-field approach. But the research on fusion energy and plasma physics soon required larger facilities, which led to the creation of what is now the MIT Plasma Science and Fusion Center.Ben supervised 36 PhD students, many of whom went on to highly successful careers in physics and engineering. Ben retired from the NML in 1981 and from the physics faculty in 1986. But he continued working in physics for over 15 more years, including being a consultant at the Lincoln Laboratory. He was coauthor with Kenneth Button of the classic book Microwave Ferrites and Ferrimagnetics (McGraw-Hill, 1962) and author or coauthor of more than 300 journal articles and book chapters.Ben was also a talented athlete; he was a gymnast in his youth and began skiing at the age of 50. He brought to the athletic field the same intensity and enthusiasm he conveyed in the laboratory. He was a wonderful mentor to countless students, young scientists, and colleagues. Ben’s brilliance, his boundless energy, and his enthusiasm for physics will be greatly missed.© 2016 American Institute of Physics.

In Memoriam: Professor Arthur E. Bergles (1935–2014), the Pioneering Advocate of Enhanced Heat Transfer and Energy Conservation

In Memoriam: Professor Arthur E. Bergles (1935–2014), the Pioneering Advocate of Enhanced Heat Transfer and Energy Conservation

Simon Foner

Simon Foner, an experimental physicist in magnetism and superconductivity and their applications, died on 2 October 2007 in Cambridge, Massachusetts. He was active in his laboratory and involved in journal editorial activities until very near the end of his life.Born on 13 August 1925 in Pittsburgh, Pennsylvania, Si remained in the area for his higher education at what is now Carnegie Mellon University; he received his BS in 1947, MS in 1948, and doctorate in 1952 under the direction of Emerson Pugh. From 1944 to 1946, Si served in the US Navy, troubleshooting sonar equipment aboard vessels in the Pacific theater. He took a position in 1953 as a staff physicist at the MIT Lincoln Laboratory, where he served until 1961. It was at the Lincoln Lab that he developed the idea for and eventually patented the vibrating sample magnetometer. His name will forever be associated with that versatile and widely used method for magnetism measurements.In 1961 Si became one of the founding staff members of the MIT high-field laboratory, principally founded by Ben Lax the year before; the lab was named the Francis Bitter National Magnet Laboratory in 1967. Si was a project leader for the FBNML until 1977, when he became its chief scientist; he served for two years (1988–89) as associate director of the lab. After 1982 Si also was affiliated with the MIT physics department as a research scientist. He retired from MIT in 1995.While at the FBNML, Si assumed several positions of influence and authority in the greater condensed-matter physics community. He was chair of the condensed-matter physics division of the American Physical Society (APS) from 1978 to 1981 and was the division’s councillor from 1982 to 1986. He served as an advisory editor from 1975 to 1989 for the Journal of Magnetism and Magnetic Materials . As a consulting editor of the Review of Scientific Instruments from 1979 until a few years before his death, Si was responsible for expanding the scope and increasing the number of the journal’s review articles.A prolific experimentalist, Si published more than 400 refereed papers. He edited four books on the topics of superconductivity and magnetism and their applications. He worked tirelessly on committees, boards, panels, advisory groups, and workshops and was active in many conferences on those subjects. He hosted at least four well-attended Advanced Study Institutes in Europe for the North Atlantic Treaty Organization between 1970 and 1980. In the 1980s Si took an interest in developing high-quality superconducting wire for high-field applications and was responsible for the measurement and understanding of many materials in superconductivity and magnetism. He was chair of the International Cryogenic Materials Conference from 1983 to 1985.Si and his colleagues at the FBNML were pioneers in pulsed high-field magnet technology; his advances underpin much of the current technology in that area. In the mid-1980s Si used a high-strength, metal-matrix copper-niobium microcomposite conductor to wind magnets that generated millisecond-length fields in the 60–70 T range; those magnets were regularly and successfully operated at the FBNML. Even after the lab’s DC high-field facility stopped running in 1995, Si continued to use the magnets for experiments with collaborators such as Yaacov Shapira and one of us (Guertin).His invention of the vibrating sample magnetometer won Si APS’s Joseph F. Keithley Award in 1999. He was chosen as a distinguished lecturer for the IEEE Magnetics Society in 1995–97 and was a recipient of the IEEE Millennium Medal in 2000.A familiar figure at the APS March meetings, Si will be remembered for buttonholing participants at all hours of the day and night, challenging their contentions (and pretensions), and keeping them honest, yet doing it all without rancor.Si was a tireless tinkerer with experimental apparatus, a restless gadfly, and an uncontrollable and incorrigible punster who will be greatly missed by his many friends in the physics and engineering communities. Si’s professional life was dedicated to honest scientific advancement, and he gave every indication that he thoroughly enjoyed the ride.Simon FonerAMERICAN PHYSICAL SOCIETYPPT|High resolution© 2008 American Institute of Physics.

Magnetic ordering of the antiferromagnetCu2MnSnS4from magnetization and neutron-scattering measurements

The work at Tufts University was partially supported by NSF Grant No. DMR-9219727. The research in Zaragoza was supported by CICYT Grant No. MAT94-0043. The work at Brown University was supported by NSF Grant No. DMR-9221141. The Francis Bitter National Magnet Laboratory was supported by NSF.

Structural optimization of the superconducting outsert of a 45-T hybrid magnet

The National High Magnetic Field Laboratory (NHMFL), Tallahassee, Florida, in collaboration with the Francis Bitter National Magnet Laboratory, MIT, is constructing a 45 T hybrid magnet system using cable-in-conduit conductor (CICC) technology for the superconducting coils. In this technology, superconducting wires are cabled and placed in a steel conduit that acts as the principal load-bearing member of the solenoid. In this paper, a structural optimization of the CICC is performed with the aim of reducing the coil mass required to generate the same field strength. The constraints for the optimization are the upper limits values (allowable limits) for the three state variables: the average and peak values of equivalent von Mises stress, and hoop strain. Different geometric and material options were analyzed for optimum performance. Global-local finite element technique was used to conduct the stress analysis. First, a global analysis, using effective material properties, was performed; followed by a local structural analysis. This procedure was iteratively applied until one of the state variables just reached its allowable limit, thus yielding the optimized design. Significant reductions were achieved in mass and stored energy of the magnet as a result of the optimization. © 1997 Elsevier Science Limited

Attracting Funds and Hopes

Tallahassee—This Florida Panhandle city is fast becoming the Mecca of condensed matter physics, thanks to the National High Magnetic Field Laboratory (NHMFL), which opened its doors on the campus of Florida State University (FSU) in 1993. the National Science Foundation stunned many scientists in 1990 when it picked FSU rather than the Massachusetts Institute of Technology, home of the famed Francis Bitter National Magnet Laboratory, to house the new lab. It's still too early to predict what NHMFL will achieve, but its staff recruitments, world-class magnets, and agenda suggest that it is already becoming an important player in areas ranging from high temperature superconductivity to biology.

Final design of a 24 MW radially-cooled insert for a 45 T hybrid system

For the National High Magnetic Field Laboratory the Francis Bitter National Magnet Laboratory has designed and is fabricating a 24 MW radially-cooled insert magnet. It is to add 31 teslas or more to the 14 T of the 616 mm bore superconducting magnet of Hybrid V, a system to generate at least 45 T in a 32 mm bore. The insert embodies many innovations for the sake of housing component commonality, unobstructed access for users quick installation, efficiency, longevity and burnout isolation, while coping with power densities up to 7 W/mm/sup 3/, heat flux densities to 9 W/mm/sup 2/, water pressures to 40 bars, and fault loads to 3.5 MN. The upper surface of the housing is free of all electrical and hydraulic clutter. The compact coil package plugs in from above. Its three coils are electrically and hydraulically in series-parallel, with inward flow through the outer two coils. High water pressure and short passages give water velocities up to 40 m/s, despite depths of only 0.10 to 0.15 mm, thus achieving outstanding cooling efficiency and a peak temperature of only 68/spl deg/C. Conductors, with strengths to match local stresses, are trio thicknesses of copper, three of Be-Cu and two of 24% Ag-Cu. All have excellent combinations of strength and electrical conductivity.

Hybrid magnets: A magnet engineer's experience and a proposal for the next generation of hybrids

Key aspects of the design and operation of hybrid magnets are reviewed. For a hybrid system to become a successful “facility” magnet, the system must have the following operational properties: (1) a “high” central field; (2) good experimental access; (3) can be scheduled for operation on a regular basis; and (4) readily replaceable water-cooled inserts. Because, as in most engineering problems, these requirements result in conflicting options, no solution is straightforward; solutions to one requirement must not dominate solutions to the other requirements. The paper also proposes and discusses design issues for the next generation of hybrids, in which the superconducting magnets would be wound entirely of high-temperature superconductor and operated at ∼ 20 K. Silver-sheathed bismuth-based (Bi-2223) tapes appear to be most promising for this application; new field records of 24.0 and 23.4 T have recently been established by a combination of Hybrid III at the MIT Francis Bitter National Magnet Laboratory and a test coil wound with Bi-2223 tapes operating, respectively, at 4.2 and 27 K. The paper concludes with a number of challenging problems that must be faced and overcome before Bi-2223 tapes can be used in large magnets such as those required for hybrid systems.

Studies of helical magnetohydrodynamic seawater flow in fields up to twelve teslas

This article discusses analytical and experimental studies of a helical magnetohydrodynamic (MHD) seawater thruster (or pump) device using a 12-T superconducting solenoid magnet. This magnet is situated and the experiments are conducted at Francis Bitter National Magnet Laboratory of the Massachusetts Institute of Technology. Analytical models are developed to predict the performance of the helical MHD thruster in a closedloop environment. The analytical results are compared with experimental data and good agreement is obtained. A significant increase in MHD energy conversion efficiency compared to the same thruster at lower magnetic field strengths (6-8 T) is realized. A significant increase in the maximum fluid velocity, from 2.5 m/s at the 8T electromagnet, to 3.7 m/s, is also realized. For the first time in our experimental MHD thruster studies, a gross mechanical efficiency greater than 10% is observed.

Generation of 24.0 T at 4.2 K and 23.4 T at 27 K with a high-temperature superconductor coil in a 22.54 T background field

The 4.2 K and 27 K current-carrying performance of a high-temperature superconducting (HTS) coil was measured in background fields up to 22.54 T generated by a hybrid magnet (Hybrid III) at the MIT Francis Bitter National Magnet Laboratory. The coil, 40 mm winding i.d., 108 mm winding o.d., and 113 mm high, consists of 17 double pancakes, each wound with silver-sheathed BSCCO-2223 tapes. Each pancake is the product of a react-and-wind method. In total, the test coil contains ∼1200 m of BSCCO-2223 conductor weighing ∼7 kg. Prior to the measurements in Hybrid III, the coil was tested in zero background field in the temperature range from 4.2 to 77 K. It was coupled to a Gifford–McMahon type cryocooler and at 15 K generated a peak field of 2.1 T; at 18 K, it generated 1.9 T, operating continuously for ∼50 h. In a 22.54 T background field of Hybrid III, the coil reached critical currents of 116.5 A ([Jc]sc, critical current density based on the BSCCO cross-sectional area only, of 261 A/mm) at 4.2 K and 67 A ([Jc]sc=150 A/mm) at 27 K, establishing record net fields at respective temperatures of 24.0 and 23.4 T for HTS magnets. These currents correspond to overall winding current densities of 47 and 27 A/mm. High-field critical current data for short samples of the tape of the same formulation at 4.2 and 27 K are also presented. Although a [J]sc of 261 A/mm at 24 T and 4.2 K for the test coil is significantly less than ∼600 A/mm for the short samples at the same operating point, if factors such as length, bending, and even differences in defining critical current are considered, the coil and short samples have nearly the same critical current performance. Electromagnetic stresses do not seem to have any negative effects on coil performance. Record fields of 24.0 and 23.4 T were achieved after the test coil had experienced, over a period of 15 months, 20 thermal cycles between room temperature and cryogenic temperatures.

Characterization of multifilamentary Nb/sub 3/Sn superconducting wires for use in the 45-T hybrid magnet

The National High Magnetic Field Laboratory (NHMFL), in collaboration with the Francis Bitter National Magnet Laboratory, is constructing a 45-T hybrid magnet system. Here we report the results of studies to characterize candidate Nb/sub 3/Sn superconductor for use in the superconducting outsert coils. We have determined the effects of strain and magnetic field on the critical current, measured ac losses, and measured residual resistivity ratios (RRR). Critical currents in excess of 1000 A mm/sup -2/ non-Cu have been measured in sample wires at 12 T and 4.2 K combined with a hysteresis loss of less than 500 mJ cm/sup -3/ We also present predicted 1.8 K performance, based on empirical models, and present a methodology for calculating sample holder prestrain.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-field magnets and high-field superconductors

This paper gives a brief historical review of the development of high magnetic fields and high field superconductors including brief summaries of the early developments of high magnetic fields and the Francis Bitter National Magnet Laboratory (FBNML). The start of the first revolution (when large critical currents in Nb/sub 3/Sn were observed in high magnetic fields) and the development of practical superconductors are outlined in parallel with selected applications developed at Lincoln Laboratory, FBNML, and other departments at MIT. Many large scale superconductor applications, supported by governments, are reviewed briefly; although many models and preliminary designs were completed, a number of US initiatives for large superconducting systems were discontinued. This summary of high-field superconducting applications is followed by an outline of the development of the highest field superconducting materials, comments on the false reports of high T/sub c/ superconductors which appeared throughout the 1970s, and the start of the second revolution (when the high T/sub c/ oxides were reported). >

Manufacture and verification testing of low-resistance Nb/sub 3/Sn joints for Cable-in-Conduit Conductors

Two coils using Nb/sub 3/Sn Cable-in-Conduit Conductor (CICC) will be manufactured for assembly into the 45 T Hybrid Magnet at the National High Magnetic Field Laboratory (NHMFL). The design calls for low-resistance joints on the order of 1 nanoohm. Several joints were fabricated at Intermagnetics General Corporation (IGC) and tested at the Francis Bitter tested at the Francis Bitter National Magnet Laboratory (FBNML) to qualify the fabrication procedures and specifications. Two types of joints were tested: praying hands and shorted-loop joints. The joint design, fabrication procedures, modeling and tests are discussed. Test results are compared with the requirements of the 45 T system. >

Ａｇ繊維分散強化Ｃｕ合金とその超強磁場発生技術への応用

Recently, we successfully developed a new Cu-Ag microcomposite alloy with a promising combination of high mechanical strength and high electrical conductivity. When a Cu-16 at% Ag alloy ingot was cold-worked into a wire or a sheet with several times of intermediate annealing at 350-450°C, it shows high conductivity of 75-83% IACS and a high tensile strength of 0.7-1.1GPa at room temperature. These values are superior to those of Cu-Nb microcomposite alloy. The Cu-Ag microcomposite alloy shows excellent mechanical strength with cold work of over 93% areal reduction ratio, while a very heavy cold work of more than 99.97% areal reduction ratio is necessary for realizing such mechanical strength in the Cu-Nb microcomposite. A further advantage of the Cu-Ag microcomposite is easy casting of the alloy ingot, resulting in excellent homogeneity of the microstructure and, therefore, the properties in the alloy wire and sheet. We wound the Cu-Ag microcomposite alloy wire into several pulsed magnets. One of them generated non-destructively 73.4T with duration time of 5msec in a 10mm bore. An other one generated non-destructively 65.3T with duration time of 100msec in a 16mm bore. The feasibility study of the Cu-Ag microcomposite alloy sheet as Bitter magnet sheets is progressing now in collaboration with the Francis Bitter National Magnet Laboratory and the National High Magnetic Field Laboratory. A steady field of 35.2T could be generated by inserting the Cu-Ag microcomposite alloy Bitter sheets into the highest-field region in Hybrid III of FBNML. These pulsed fields and the steady one are world records as of this writing.

The Francis Bitter National Magnet Laboratory.

The Francis Bitter National Magnet Laboratory.

Florida Dedicates National High Magnetic Field Laboratory

On 1 October, four years after the National Science Foundation chose to build a new high‐magnetic‐field laboratory at Florida State University rather than upgrade the existing Francis Bitter National Magnet Laboratory at MIT (see PHYSICS TODAY, January 1991, page 53), the new laboratory was dedicated in Tallahassee.

Australian national pulsed magnet laboratory for condensed matter physics research

The National Pulsed Magnet Laboratory (NPML) provides access to high pulsed and steady magnetic fields, with particular emphasis on combining high fields with temperatures down to the millikelvin regime and a range of physical probes for condensed matter studies. NPML provides both short pulse (≈ 10 ms) fields to 60 T and long duration (1 s) fields to 30 T.

Progress in the manufacture of the cable-in-conduit Nb/sub 3/Sn outsert coils for the 45 Tesla Hybrid Magnet

The 45 Tesla Hybrid Magnet is being built in a collaborative effort between the National High Magnetic Field Laboratory at Florida State University and the Francis Bitter National Magnet Laboratory at the Massachusetts Institute of Technology. The Hybrid Magnet combines a resistive insert magnet with two Nb/sub 3/Sn and one NbTi superconducting cable-in-conduit outsert coil to produce the required field on axis. The Nb/sub 3/Sn outsert coils are being built at Intermagnetics General Corporation under contract with FSU. A design summary for the entire 100 MJ outsert magnet is presented. The design criteria and manufacturing status for the two Nb/sub 3/Sn outsert coils are described. >

Materials Science in High Magnetic Fields

The recent rapid growth in the emerging areas of magnetic and magnet-related materials research and applications has led to worldwide recognition of the increased importance of research and technology using high magnetic fields. New high-field magnet facilities and major upgrades of existing facilities are being planned and implemented by a number of countries, among them Japan, Germany, France, the Netherlands, Belgium, Great Britain, Poland, Australia, and the United States. Over the next ten years, these developments will advance the state of the art in magnet-related materials science and technologies by a significant quantum jump. Support by many of the national agencies and a strong corporate commitment to stimulate rapid growth in the development of capabilities at higher magnetic fields and in related technologies results in part from an awareness of the impact these technologies will have in developing the new emerging industrial technologies of the 21st century.The Francis Bitter National Magnet Laboratory (FBNML) at the Massachusetts Institute of Technology has been one of the pre-eminent facilities in developing and advancing science and technology in high magnetic fields. The new U.S. National High Magnetic Field Laboratory (NHMFL) at Florida State University, at the University of Florida, and at Los Alamos National Laboratory builds on the success of existing facilities. NHMFL will provide the necessary environment to develop the next generation of high magnetic fields: 30–50-tesla continuous fields, 60-tesla quasi-continuous fields, and pulsed fields from 60–1,000 tesla. The ability to develop broad user capabilities at these extreme fields is crucial for the advancement of the frontiers of science and of magnet-related industries.

The monohelix: (1) five years of operation at the FBNML and (2) finite element stress analyses

The FBNML (Francis Bitter National Magnet Laboratory) has built and operated seven partial monohelices employing helices of Be-Cu, Cu-alumina, or Cr-Cu. Fabrication was by conventional lathe, numerically controlled lathe, or wire electric discharge machining. Each monohelix is the innermost coil of a hybrid magnet system which can generate 27 T in a 53-mm bore or 31 T in a 33-mm bore (35 T with holmium poles). Compared to their Bitter coil predecessors, these monohelices have demonstrated comparable performance and superior life. One helix gave 270 hours of service; another is still active after 230 hours. The finite element stress analysis program ABAQUS was used to calculate the stresses and strains in radially cooled Bitter coils and monohelices. At a maximum conductor strain of 0.8% (the approximate empirical limit for acceptable coil life), a perfect monohelix is structurally a third stronger than the Bitter coil analyzed. The strength of the partial monohelix design appears to depend on the relative thicknesses of the helix and cooling plates, and on the friction between them.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>