High Magnetic Field Research Research Articles

Design and experiment of projectile-borne storage testing system with pulsed strong magnetic field

To solve the problem of magnetic field measurement during electromagnetic launch, a projectile-borne storage testing system of low frequency and strong magnetic field is proposed. The commercial linear Hall sensor combined with integrated chip is used to realize small volume and high precision data recovery. The testing system is calibrated in the pulsed magnetic field generator of Wuhan National High Magnetic Field Research Center. Moreover, the shielding effectiveness of conductive and magnetic materials is considered, and the shielding effectiveness of common conductive and magnetism material is completed. The results show that the projectile-borne storage testing system can be used to measure the magnetic flux density distribution of ammunition and fuze during electromagnetic launch, which provides a reference for the electromagnetic adaptability design.

Redesign of the Coils for the 60T Controlled-Waveform Magnet at NHMFL

Driven by the1.4 GW generator, the 60T Controlled Waveform (60 TCW) magnet was the most powerful controlled waveform system in the world and had always been one of most important magnets to the National High Magnetic Field (NHMFL) and high-field research community because of its following unique features: (1) quasi-static field up to 60 T with 100 ms flat-top and total pulse-length of about 2000 ms, (2) variable magnetic field waveforms such as staircase and triangle with flat-top (3) relative large bore (32 mm) and (4) very fast cooling time (20 minutes) between pulses [Boebinger, 2001], [Crooker <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> 2001]. The magnet is composed of nine concentric coils, with each coil consisting of several conductor winding layers reinforced by a high-strength metallic shell. The magnet underwent a catastrophic failure in 2000 and all the coils had to be rebuilt. In late 2014 the second magnet version failed near the mid-plane of coil 7. The simulations afterward that incident indicated that the overall strength of the coil would be increased by replacing a section of the reinforcing shell with Zylon fiber-epoxy composite. This reduces the stress and thus significantly lowers the level of plastic deformation in the windings. The role of the metal and Zylon fiber reinforcing layers in bearing the axial and radial Lorentz forces has been studied to optimize the magnet design. The results of the optimization will be discussed as well as challenges that have been presented in rebuilding the individual coils of the magnet.

New 25 T Cryogen-Free Superconducting Magnet Project at Tohoku University

The new high magnetic field research laboratory network is recognized as one of the Japanese Master Plans of Large Research Project by the Science Council of Japan. Recently, the project of the 25 T cryogen-free superconducting magnet (25 T-CSM), which is operated under a conductive cooling condition by cryocooler, was approved under the high magnetic field research laboratory network. We adopted a high strength CuNb/Nb3Sn Rutherford cable with a prebending treatment for the middle section coils of the 25 T-CSM. The central magnetic field of 14 T is generated by the operational current of 851 A by the Nb3Sn middle section and NbTi outer section coils in a 300 mm bore. The induced maximum hoop stress in the CuNb/Nb3Sn section is about 250 MPa. In addition, the 11.5 T high temperature superconducting insert coil is also designed using Gd123 tapes. Therefore, a total central magnetic field of 25.5 T can be achieved.

2G HTS Coil Technology Development at SuperPower

The second-generation high-temperature superconductor (2G HTS), Re-Ba-Cu-O coated conductors are known for strong mechanical properties and have numerous potential applications in high magnetic field research and electrical power systems. It has been noted in the community that coated conductors can be prone to performance degradation on thermal cycling when used in epoxy impregnated magnet windings. This degradation has been tied to the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</i> -axis peel strength in the wire. SuperPower is addressing this issue with a short term approach of developing novel technologies in conductor post processing and coil winding technology, which allows building high quality coils with current generation conductor, and a longer term approach of improving wire production to build stronger wire with high <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</i> -axis peel strength.

Present Status and Future Plan at High Magnetic Field Laboratory in Osaka University

We report on the development of experimental apparatus and the achievement of our research since 2006 when we reported “the present status and future plan of research in high magnetic fields” at the RHMF 2006 conference, after brief introduction of history and facility of the High Magnetic Field Laboratory at KYOKUGEN in Osaka University. As for our high-field and multi-frequency electron spin resonance (ESR) apparatus, we have expanded the magnetic field range up to 65 T and the frequency range up to 6 THz. In addition, ultra low temperature ESR apparatus down to 0.1 K for static fields and down to 0.6 K for pulsed fields have been fabricated. Furthermore, we have constructed a wide bore pulse magnet with the bore diameter of 48 mmϕ that enables us to perform resistivity measurements, which have been improved with the signal to noise ratio more than 100 times, under high pressure utilizing a diamond anvil pressure cell.

The 9th International Conference on Research in High Magnetic Fields in Retrospective View

The 9th International Conference on Research in High Magnetic Fields (RHMF 2009) was held in the historical center of Dresden during July 22–25, 2009. The conference carried on the tradition of previous meetings in Sendai (2006), Toulouse (2003), Porto (2000), Sydney (1997), Nijmegen (1994), Amsterdam (1991), Leuven (1988), and Osaka (1982) as well. These events have established the RHMF conference series as the most important platform to present latest results of research in high magnetic fields and, as a satellite meeting of the International Conferences on Magnetism (ICM), have linked it to the concert of large international conferences. The number of participants followed the trend of the previous RHMF conferences and has further grown reflecting the increasing demand of high magnetic fields in research. 219 official participants from 27 countries with strongest appearance from Europe, Japan, United States, Russia, China, and Israel have contributed 176 posters and 43 talks within a scientific program of three days. Amongst them, 91 participants contributed papers to the proceedings of RHMF 2009 which are published in this special issue of the Journal of Low Temperature Physics. Each of the articles has been carefully evaluated by two referees before it was accepted for publication. According to the dedication of RHMF conferences to all aspects related to recent advances in solid-state physics, a wide spectrum of contributions in magnetism, the physics of strongly correlated electron systems, superconductivity, semiconductor physics, mesoscopic phenomena, the physics of low-dimensional or organic materials, highfield technology as well as reports on high-field facilities are published here. RHMF 2009 clearly reflected that research in high magnetic fields has become even more a driving factor for solid-state physics, material sciences, and technology in the recent

Present status and future plan of research in high magnetic fields at KYOKUGEN in Osaka University

After brief introduction of history and facility of the High Magnetic Field Laboratory at KYOKUGEN in Osaka University, we describe our high field and multi-frequency electron spin resonance (ESR) apparatus by utilizing pulsed and superconducting magnets for the fields up to about 60 T. For the ESR measurements in pulsed magnetic fields, several Gunn and backward oscillators, and a far infrared laser are used as millimeter and submillimeter wave sources. In steady magnetic fields up to 16 T, we have utilized a vector network analyzer with extensions which covers the frequencies between 8 and 700 GHz almost continuously. The latter ESR apparatus is used not only dense magnetic materials but also weak ones, such as metalloproteins. Therefore, we have developed high sensitive multi-frequency ESR apparatus. To extend ESR studies further, we are now constructing ESR apparatus for much higher fields up to 70 T and the wide frequency range up to 7 THz. Magnetization and transport measurements are also performed in high magnetic fields up to 70 T and 60 T, respectively and magnetization measurements under high pressure up to 1 GPa. We plan to develop a 50 T wide bore pulsed magnet with the diameter of about 50 mm for the use of high sensitive ESR and high pressure measurements above 1 GPa.

Development of 15 T Cryogen-Free Superconducting Magnets

Cryogen-free superconducting magnets are becoming popular due to their simple operation compared with the conventional liquid Helium cooled magnet. However, for higher fields such as those greater than 14 T, the cryogen-free magnet has not become popular yet, because it is difficult to design and manufacture since the critical current is markedly reduced at higher fields and higher temperatures. We have developed two types of 15 T cryogen-free superconducting magnets, which will be among the highest field magnets in operation as cryogen-free with a GM cryocooler. One magnet has a 52 mm room temperature bore with overall dimensions of 820 mm in diameter and 680 mm in height. This magnet is designed so as to be simple in both operation and installation. Therefore, the magnet is cooled with a single 1 W GM cryocooler. Also, all coils are connected in series and charged with a single power supply. The magnet was successfully charged up to 15 T in 30 minutes and then charged slowly to 16 T without quench. The other magnet has a 170 mm room temperature bore with overall dimensions of 980 mm in diameter and 1015 mm in height. This magnet is designed so as to be used with temperature controlled sample cryostats with an outer diameter of 168 mm. The magnet is cooled with four 1 W GM cryocoolers and charged with a single power supply. The magnet was successfully charged up to 15 T in 90 minutes. Both magnets will enable high magnetic field research or application with very easy operation

金属材料研究所における小型冷凍機冷却超伝導マグネットの強磁場化 強磁場超伝導材料研究センターと小型冷凍機冷却超伝導マグネット開発

The High Field Laboratory for Superconducting Materials (HFLSM), Institute for Materials Research, Tohoku University has demonstrated the first practical cryocooled superconducting magnets using a GM-cryocooler and high temperature superconducting current leads. For high magnetic field research, various kinds of easy-to-operate cryocooled superconducting magnets such as wide bore, high field, and new functional magnets have been constructed. Recently, the HFLSM succeeded in developing a cryocooled 18.1 T high temperature superconducting magnet and a cryocooled 27.5 T hybrid magnet. This paper reviews cryocooled superconducting magnet technology and relevant new research areas.

Magnetic flux compression Generators

Magnetic flux compression generators offer the largest pulsed power output per unit size or weight when compared with other more conventional systems. They have found widespread use as pulsed power sources for hydrodynamics programs and high magnetic field research at national laboratories or in commercial applications, including exploration for oil and minerals and mine detection. Also, due to their nature as a true one-time-use device with superior energy density, a large portion of applications is defense related. A variety of basic magnetic flux compression generator designs have been developed and tested during the past four decades. All of them rely on the explosive-driven deformation of a system of conductors having an initial, preferably large, inductance. The most successful basic design is the helical flux compression generator, which is capable of producing a high-energy output into large impedance loads, just as it is needed for a practical pulsed power source. This paper will review the advances and state of the art of primarily helical magnetic flux compression generators mainly developed as pulsed power sources and will offer new insights gained as a result of a recently completed five-year AFOSR/DoD Multidisciplinary University Research Initiative program that studied the basic physics and engineering aspects of helical flux compression generators.

First Operation of the 20 MW Nijmegen High Field Magnet Laboratory

The University of Nijmegen has realized a new installation for high magnetic field research. The user-facility has opened its doors in April 2003. The principal part is an installation for continuous magnetic fields based on a 20 MW power converter, capable of energizing resistive magnets up to 33 T. We discuss the principle of the installation, and the magnets that have been installed and are under development. In addition, there is a pulsed field installation based on 2 MJ stored energy, capable of magnetic field pulses up to 70 T with several milliseconds duration.

The National High Magnetic Field Laboratory Pulsed-Field Facility at Los Alamos National Laboratory

Los Alamos National Laboratory (LANL) is the home institution of the National High Magnetic Field Laboratory Pulsed-Field Facility (NHMFL-PFF). NHMFL-PFF is the only pulsed-field facility in the US (among a few worldwide) to host qualified users whilst running a strong in-house science program on high magnetic field research. State-of-the-art experimental capabilities and pulsed magnets are used to examine the frontiers of condensed matter physics at extremes of high magnetic field, low temperature and high pressure. This paper describes current facilities and science and future developments at NHMFL-PFF.

Research in High Magnetic Fields: The Installation at the University of Nijmegen

For research in the highest continuous and pulsed magnetic fields large, complex and powerful installations are needed. This paper describes the new 20 MW installation for continuous high magnetic fields that has been built at the University of Nijmegen. The ultra-low ripple power converter provides the capability to perform experiments up to 33 T with resistive magnets (up to 40 T with the hybrid magnet system under construction) and will be of great value for investigations in physics, chemistry and biology at the forefront of fundamental and applied research. Typically during experiments, the magnetic field is slowly varied or held constant for a period lasting from a few minutes to an hour. The cooling installation is designed to allow uninterrupted operation at maximum power for 3 hours, and when the magnetic field is being swept between zero and full field the cooling plant does not pose limits to the operation. When much higher fields are required, there is the option to go to pulsed magnetic fields with duration in the tens of milliseconds.

The National High Magnetic Field Laboratory at Los Alamos National Laboratory

Los Alamos National Laboratory (LANL) is the home institution of the Pulsed Field Facility of the National High Magnetic Field Laboratory (NHMFL). The NHMFL laboratories are the only facilities in the US (among a few world-wide) to host qualified users while running strong in-house science programs related to high magnetic field research. At Los Alamos, the NHMFL advances the frontiers of condensed matter physics at extreme conditions of high magnetic field, low temperature and pressure, utilizing start-of-the-art pulsed magnets and unique experimental capabilities. This paper will describe the current and future plans of pulsed magnet technology and science at the NHMFL Pulsed Field Facility at LANL.

The new 20 MW high magnetic field installation at the University of Nijmegen

The University of Nijmegen is setting up a new installation for high magnetic field research, with generous support of the Netherlands Organization for Scientific Research. The user-facility will open its doors in summer 2002. The heart of the new installation will be a low-ripple 20 MW power converter delivering up to 40 kA at 500 V, and a cooling system. The cold water system will use cooling towers with the optional use of two chillers, in combination with a 1400 m 3 buffer, and the inlet-temperature of the cooling water to magnet coils can be kept below 15°C, while allowing uninterrupted experiments at the maximum power for up to 3 h/day. The laboratory will have six resistive-magnet sites, and a pulsed-field-installation with a 2 MJ capacitor bank and three pulsed-magnet cells. The laboratory will operate amongst other two 33 T resistive magnets with 32 mm bore; these will be constructed in close collaboration with the National High Magnetic Field Laboratory in Tallahassee, FL. Design efforts have been started such that in a later phase, using the existing hybrid magnet system Nijmegen-II, even higher fields can be generated with a newly designed high-power insert coil.

The new Nijmegen installation for DC and pulsed high magnetic fields

The University of Nijmegen is setting up a new installation for high magnetic field research. The user-facility will open doors late in 2001 in a new building and with minimal disruption of ongoing research at the present High Field Magnet Laboratory.

Development and research in high magnetic fields at ASIPP

Steady magnetic fields up to 20 T have been generated at the Institute of Plasma Physics, Academia Sinica (ASIPP), by a hybrid magnet consisting of an outer NbTi superconducting (SC) coil and an inner water-cooled (WC) Bitter coil consuming 3.0 MW. The laboratory has also installed WC magnets at two magnet sites with fields up to 14 T and some SC magnets capable of producing 8.0 T in different bores. The research programs in high magnetic fields are in progress and extensive studies on superconductors, magnetic materials, low dimensional organic conductors as well as biological effects of high magnetic fields have been performed. Based on the use of the 40 MW fly-wheel generators the next project for constructing a 45 T, 2 s flat-top quasi-steady magnet has been proposed for creating new scientific opportunities at higher fields.

Magnetically aligned polycrystalline dysprosium as ultimate saturation ferromagnet for high magnetic field polepieces

Magnetic properties of microcrystalline aligned Dysprosium are reported in order to discuss the perspectives for application of this ferromagnetic material in high magnetic field research apparatus. This technology, based on multistage thermal and mechanical treatment of polycrystalline Dysprosium under high-pressure conditions, provides the alignment of microcrystallites' axes along the [1 1 2 0] crystallographic direction, i.e., along the easiest magnetization axis. Such magnetically aligned material could be saturated completely at a relatively low external magnetic field of 5–7 T, and creates magnetization up to 3.5T, which is close to the highest induction of saturation attainable for any known material in nature. To demonstrate applicability of the material for research appratus design, experiments with the help of a 13.5 T standard superconducting solenoid were performed and additional fields up to 5.1 T were obtained by using magnetically aligned Dy polepieces.

Physics in high magnetic fields

The nowadays employed technologies for obtaining high magnetic fields (up to 30 T in DC fields, above 200 T in pulsed fields) are briefly discussed. In the area of condensed-matter physics examples of fundamental research in high magnetic fields are given.

Research in steady high magnetic fields at Sendai

The most powerful facilities of steady high magnetic fields in Japan are at the Institute for Materials Research, Tohoku University, Sendai. The field of 31 T is produced by a hybrid magnet consisting of an outer large-bore superconducting magnet and an inner water-cooled resistive magnet of 8 MW power. The laboratory is open to visiting scientists and engineers for cooperative research prograns. In addition to the research and development of high-field superconductors and permanent magnet materials, basic researches on superconductivity, quantum transport properties, magnetic-field-induced phase transitions and chemical effects of high magnetic fields have been conducted. This paper presents a brief review of these works.