Superhigh Magnetic Field Research Articles

Modified pressure of relativistic electrons in a superhigh magnetic field

Magnetar is a kind of pulsar powered by magnetic field energy. The study of magnetars is an important hotspot in the field of pulsars. In this paper, according to the work of Zhu Cui, et al. (Zhu C, Gao Z F, Li X D, Wang N, Yuan J P, Peng Q H <ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://doi.org/doi.10.1142/S021773231650070X">2016 <i>Mod. Phys. Lett. A</i> <b>31</b> 1650070</ext-link>), we reinvestigate the Landau-level stability of electrons in a superhigh magnetic field (SMF), <inline-formula><tex-math id="Z-20230117140609">\begin{document}$B\gg B_{\rm cr}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_Z-20230117140609.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_Z-20230117140609.png"/></alternatives></inline-formula>(<i>B</i><sub>cr</sub> is a quantum critical magnetic field with a value of 4.414×10<sup>13</sup> G), and its influence on the pressure of electrons in magnetar. First, we briefly review the pressure of electrons in neutron star (NS) with a weak-magnetic field limit (<inline-formula><tex-math id="Z-20230117140625">\begin{document}$ B\ll B $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_Z-20230117140625.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_Z-20230117140625.png"/></alternatives></inline-formula><sub>cr</sub>). Then, we introduce an electron Landau level stability coefficient <i>g</i><sub><i>ν</i></sub> and a Dirac-<i>δ</i> function to deduce a modified pressure formula for the degenerate and relativistic electrons in an SMF in an application range of matter density <i>ρ</i> ≥ 10<sup>7</sup> g·cm<sup>–3</sup> and <i>B</i><sub>cr</sub> <i><inline-formula><tex-math id="Z-20230117140650">\begin{document}$ \ll $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_Z-20230117140650.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_Z-20230117140650.png"/></alternatives></inline-formula>B</i> < 10<sup>17</sup> G. By modifying the phase space of relativistic electrons, the SMF can enhance the electron number density <i>n</i><sub>e</sub>, and reduce the maximum of electron Landau level number<i> ν</i><sub>max</sub>, which results in a redistribution of electrons. As <i>B</i> increases, more and more electrons will occupy higher Landau levels, and the electron Landau level stability coefficient <i>g</i><sub><i>ν</i></sub> will decrease with the augment of Landau energy-level number <i>ν</i>. By modifying the phase space of relativistic electrons, the electron number density <i>n</i><sub>e</sub> increases with the MF strength increasing, leading the electron pressure <i>P</i><sub>e</sub> to increase. Utilizing the modified expression of electron pressure, we discuss the phenomena of Fermion spin polarization and electron magnetization in the SMF, and the modification of the equation of state by the SMF. We calculate the baryon number density, magnetization pressure, and the difference between pressures in the direction parallel to and perpendicular to the magnetic field in the frame of the relativistic mean field model. Moreover, we find that the pressure anisotropy due to the strong magnetic field is very small and can be ignored in the present model. We compare our results with the results from other similar studies, and examine their similarities and dissimilarities. The similarities include 1) the abnormal magnetic moments of electrons and the interaction between them are ignored; 2) the electron pressure relate to magnetic field intensity <i>B</i>, electron number density <i>n</i><sub>e</sub> and electron Fermi energy <inline-formula><tex-math id="M1">\begin{document}$E_{{\rm{F}}}^{{\rm{e}}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_M1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_M1.png"/></alternatives></inline-formula>, and the latter two are complex functions containing <i>B</i>; 3) with <i>n</i><sub>e</sub> and <inline-formula><tex-math id="M2">\begin{document}$E_{{\rm{F}}}^{{\rm{e}}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20220092_M2.png"/></alternatives></inline-formula> fixed, <i>P</i><sub>e</sub> increases with <i>B</i> rising; 4) as <i>B</i> increases, the pressure-density curves fitted by the results from other similar studies have irregular protrusions or fluctuations, which are caused by the transformation of electron energy state from partial filling to complete filling at the<i> ν</i>-level or the transition of electrons from the<i> ν</i> to the (<i>ν</i>+1)-level. This phenomenon is believed to relate to the behavior of electrons near the Fermi surface in a strong magnetic field, which essentially reflects the Landau level instability. Finally, the future research direction is prospected. The present results provide a reference for future studies of the equation of state and emission mechanism of high-<i>B</i> pulsar, magnetar and strongly magnetized white dwarf.

Growth dynamics of the segregated phase in Zn-6 wt%Bi immiscible alloy superheated in super high static magnetic field

Eliminating phase segregation under high temperature at high growth rate remains a long term challenge. Methods such as adding third element, inoculations and nanoparticle bring materials pollution and difficulties for compatibility. This work provides a path to realize a diffusional growth through extremely reducing the size of the segregated phase by highly superheating the system and suppressing their collision and coagulation via magnetohydrodynamic effect in Zn-6 wt%Bi immiscible system. The application of super high static magnetic field (SHSMF) compounded with superheating technique resulted in a homogeneous distribution of phase concentrated to about 3–4 µm when increased the magnetic flux density (MFD) from 0 T to 24 T and the superheating temperature from 600 °C to 900 °C. The undercooling of monotectic reaction was improved about 5–6 times from 0.4 °C to 2.1 °C when increased the super heating temperature from 600 °C to 900 °C with and without SHSMF. Bi-rich droplets grow as a near pure diffusion way when the particle size distribution follows the near LSW theory at 24 T. SHSMF has not only suppressed the mass transport of Bi atom but also decreased the size of Bi-rich clusters and even suppressed the precipitation of Bi-rich phases. The practicality has been proved by the same immiscible system with a critical composition. This novel method overcomes the microstructure refinement limit only through adding the extraneous and contaminated elements and realizes a contactless green way for growth control of phase. It has practical significance and is opening for expanding its scope of applications.

The dissipation of toroidal magnetic fields and spin‐down evolution of young and strongly magnetized pulsars

AbstractMagnetars are a kind of pulsars powered mainly by superhigh magnetic fields. They are popular sources with many unsolved issues in themselves but are also linked to various high‐energy phenomena, such as quasi periodic oscillations (QPOs), giant flares, fast radio bursts, and superluminous supernovae. In this work, we first review our recent works on the dissipation of toroidal magnetic fields in magnetars and rotationally powered pulsars and then review the spin‐down evolution of young and strongly magnetized pulsars, especially of magnetars. We present an interesting and important relation between the magnetization parameter and magnetic field in the magnetar crust. Finally, we introduce our two works in progress: to explain the magnetar “antiglitch” events in the thermal plastic flow model and to revisit the expression of braking index n, which is independent of the second derivative of spin frequency of a pulsar, and give some proposals for our future work.

Solute trapping in Al-Cu alloys caused by a 29 Tesla super high static magnetic field

Solidification of Al-Cu alloys has been investigated using a 29 Tesla super high static magnetic field (SHSMF). The results show that, by imposing a 29 Tesla SHSMF, the size of primary phases and spacing of eutectic structure have been refined through the increase of undercooling which results from the suppression of diffusion coefficient. The diffusion coefficient of atoms in the liquid matrix decreases to be about 1.2 × 10−12 m2/s. The lattice constants are reduced and high dislocation density forms in the primary phase, which induces a solute trapping effects. The spacing of (110) plane in Al2Cu is corrected to be 4.3123 Å and 4.2628 Å for Al-40 wt.%Cu alloys treated without and with a SHSMF. The spacing of (111) plane in Al is corrected to be 2.3351 Å and 2.3258 Å for Al-26 wt.%Cu alloys treated without and with a SHSMF. The compression yield strength has been improved by about 42% from 268 MPa to 462 MPa for Al-26 wt.%Cu and 42.5% from 248 MPa to 431 MPa for Al-40 wt.%Cu. The maximum elastic strain increases from about 2% to 4.3% for Al-26 wt.%Cu and from 2% to 4% for Al-40 wt.%Cu. It is expected that SHSMF is beneficial to process materials with high mechanical properties.

Conductivity of neutron star crust under superhigh magnetic fields and Ohmic decay of toroidal magnetic field of magnetar

<sec>Magnetar is a kind of pulsar powered by magnetic field energy. Part of the X-ray luminosities of magnetars in quiescence have a thermal origin and can be fitted by a blackbody spectrum with temperature <i>kT</i> ～ 0.2－0.6 keV, much higher than the typical values for rotation-powered pulsars. The observation and theoretical study of magnetar are one of hot topics in the field of pulsar research. The activity and emission characteristics of magnetar can be attributed to internal superhigh magnetic field. According to the work of WGW19 and combining with the equation of state, we first calculate the electric conductivity of the crust under a strong magnetic field, and then calculate the toroidal magnetic field decay rate and magnetic energy decay rate by using an eigenvalue equation of toroidal magnetic field decay and considering the effect of general relativity. We reinvestigate the <i>L</i><sub>X</sub>-<i>L</i><sub>rot</sub> relationship of 22 magnetars with persistent soft X-ray luminosities and obtain two new fitting formulas on <i>L</i><sub>X</sub>-<i>L</i><sub>rot</sub>. We find that for the magnetars with <i>L</i><sub>X</sub> < <i>L</i><sub>rot</sub>, the soft X-ray radiations may originate from their rotational energy loss rate, or from magneto-sphere flow and particle wind heating. For the magnetars with <i>L</i><sub>X</sub> > <i>L</i><sub>rot</sub>, the Ohmic decay of crustal toroidal magnetic fields can provide their observed isotropic soft X-ray radiation and maintain higher thermal temperature.</sec><sec>As for the initial dipole magnetic fields of magnetars, we mainly refer to the rersearch by Viganò et al. (Viganò D, Rea N, Pons J A, Perna R, Aguilera D N, Miralles J A 2013 <i>Mon. Not. R. Astron. Soc.</i> <b>434</b> 123), because they first proposed the up-dated neutron star magneto-thermal evolution model, which can successfully explain the X-ray radiation and cooling mechanism of young pulsars including magnetars and high-magnetic field pulsars. Objectively speaking, as to the decay of toroidal magnetic fields, there are some differences between our theoretical calculations of magnetic energy release rates and the actual situation of magnetic field decay in magnetars, this is because the estimate of initial dipolar magnetic field, true age and the thickness of inner crust of a magnetar are somewhat uncertain. In addition, due to the interstellar-medium’s absorptions to soft X-ray and the uncertainties of distance estimations, the observed soft X-ray luminosities of magnetars have certain deviations. With the continuous improvement of observation, equipment and methods, as well as the in-depth development of theoretical research, our model will be further improved, and the theoretical results are better accordant with the high-energy observation of magnetars.</sec><sec>We also discuss other possible anisotropy origins of soft X-ray fluxes of magnetars, such as the formation of magnetic spots and thermoplastic flow wave heating in the polar cap. Although anisotropic heating mechanisms are different from Ohmic decay, all of them require that there exist strong toroidal magnetic fields inside a magnetar. However, the anisotropic heating mechanisms require higher toroidal multipole fields inside a magnetar (such as magnetic octupole field) and are related to complex Hall drift: these may be our research subjects in the future.</sec>

Modified Fermi energy of electrons in a superhigh magnetic field

In this paper, we investigate the electron Landau level stability and its influence on the electron Fermi energy, [Formula: see text], in the circumstance of magnetars, which are powered by magnetic field energy. In a magnetar, the Landau levels of degenerate and relativistic electrons are strongly quantized. A new quantity [Formula: see text], the electron Landau level stability coefficient is introduced. According to the requirement that [Formula: see text] decreases with increasing the magnetic field intensity [Formula: see text], the magnetic field index [Formula: see text] in the expression of [Formula: see text] must be positive. By introducing the Dirac-[Formula: see text] function, we deduce a general formulae for the Fermi energy of degenerate and relativistic electrons, and obtain a particular solution to [Formula: see text] in a superhigh magnetic field (SMF). This solution has a low magnetic field index of [Formula: see text], compared with the previous one, and works when [Formula: see text] and [Formula: see text] Gauss. By modifying the phase space of relativistic electrons, a SMF can enhance the electron number density [Formula: see text], and decrease the maximum of electron Landau level number, which results in a redistribution of electrons. According to Pauli exclusion principle, the degenerate electrons will fill quantum states from the lowest Landau level to the highest Landau level. As [Formula: see text] increases, more and more electrons will occupy higher Landau levels, though [Formula: see text] decreases with the Landau level number [Formula: see text]. The enhanced [Formula: see text] in a SMF means an increase in the electron Fermi energy and an increase in the electron degeneracy pressure. The results are expected to facilitate the study of the weak-interaction processes inside neutron stars and the magnetic-thermal evolution mechanism for magnetars.

The effects of superhigh magnetic fields on the equations of state of neutron stars

AbstractBy introducing Dirac's δ‐function in superhigh magnetic fields, we deduce a general formula for the pressure of degenerate and relativistic electrons, Pe, which is suitable for superhigh magnetic fields, discuss the quantization of Landau levels of electrons, and consider the quantum electrodynamic(QED) effects on the equations of states (EOSs) for different matter systems. The main conclusions are as follows: the stronger the magnetic field strength, the higher the electron pressure becomes; compared with a common radio pulsar, a magnetar could be a more compact oblate spheroid‐like deformed neutron star due to the anisotropic total pressure; and an increase in the maximum mass of a magnetar is expected because of the positive contribution of the magnetic field energy to the EoS of the star. Since this is an original work in which some uncertainties could exist, modifications and improvements of our theory should be considered in our future studies. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Quantitative assessment of atherosclerotic lesion of rabbit aorta by compressed slice analysis of magnetic resonance images ex vivo

The objective of the present study was to evaluate a new compressed slice analysis technique of aortas ex vivo. Atherosclerosis was developed in rabbits by feeding an atherogenic diet containing 2% cholesterol and 6% peanut oil for 8 weeks. At termination, aortas were excised and imaged ex vivo by Magnetic resonance images (MRI). MRI data were acquired on a super high magnetic field vertical bore imaging scanner equipped with a Unity/Inova console, operating at 14.1 T and dedicated to small animal studies. T2-weighted coronal 2-D sections were acquired first to determine a ROI (region of interest) of the thoracic aorta using a Spin-Echo multi slice pulse sequence. Then, T2-weighted images were acquired in transversal sections of ROI slice by slice (2 mm/slice) in the total length of 4 cm. The MRI images of 20 slices were then compressed into a single image, and the resultant compressed single image was used as a quantitative characteristic of atherosclerotic lesions. By utilizing the compressed slices (CS) analysis, the imaging intensity of atherosclerotic lesions was calculated. A significant correlation was found between the quantitative CS-MRI and the aortic cholesterol content (Pearson correlation coefficient r = 0.95). The present findings demonstrate that the compressed slice analysis technique of MRI images could be applied for a quantitative assessment of the progression and/or regression of atherosclerosis.

Operation of a 400 MHz NMR magnet using a (RE:Rare Earth)Ba2Cu3O7−x high-temperature superconducting coil: Towards an ultra-compact super-high field NMR spectrometer operated beyond 1 GHz

High-temperature superconductors (HTS) are the key technology to achieve super-high magnetic field nuclear magnetic resonance (NMR) spectrometers with an operating frequency far beyond 1GHz (23.5T). (RE)Ba2Cu3O7−x (REBCO, RE: rare earth) conductors have an advantage over Bi2Sr2Ca2Cu3O10−x (Bi-2223) and Bi2Sr2CaCu2O8−x (Bi-2212) conductors in that they have very high tensile strengths and tolerate strong electromagnetic hoop stress, thereby having the potential to act as an ultra-compact super-high field NMR magnet. As a first step, we developed the world’s first NMR magnet comprising an inner REBCO coil and outer low-temperature superconducting (LTS) coils. The magnet was successfully charged without degradation and mainly operated at 400MHz (9.39T). Technical problems for the NMR magnet due to screening current in the REBCO coil were clarified and solved as follows: (i) A remarkable temporal drift of the central magnetic field was suppressed by a current sweep reversal method utilizing ∼10% of the peak current. (ii) A Z2 field error harmonic of the main coil cannot be compensated by an outer correction coil and therefore an additional ferromagnetic shim was used. (iii) Large tesseral harmonics emerged that could not be corrected by cryoshim coils. Due to those harmonics, the resolution and sensitivity of NMR spectra are ten-fold lower than those for a conventional LTS NMR magnet. As a result, a HSQC spectrum could be achieved for a protein sample, while a NOESY spectrum could not be obtained. An ultra-compact 1.2GHz NMR magnet could be realized if we effectively take advantage of REBCO conductors, although this will require further research to suppress the effect of the screening current.

PRESSURE OF DEGENERATE AND RELATIVISTIC ELECTRONS IN A SUPERHIGH MAGNETIC FIELD

Based on our previous work, we deduce a general formula for pressure of degenerate and relativistic electrons, Pe, which is suitable for superhigh magnetic fields, discuss the quantization of Landau levels of electrons, and consider the quantum electrodynamic (QED) effects on the equations of states (EOSs) for different matter systems. The main conclusions are as follows: Pe is related to the magnetic field B, matter density ρ, and electron fraction Ye; the stronger the magnetic field, the higher the electron pressure becomes; the high electron pressure could be caused by high Fermi energy of electrons in a superhigh magnetic field; compared with a common radio pulsar, a magnetar could be a more compact oblate spheroid-like deformed neutron star (NS) due to the anisotropic total pressure; and an increase in the maximum mass of a magnetar is expected because of the positive contribution of the magnetic field energy to the EOS of the star.

Magnetic field decay of magnetars in supernova remnants

In this paper, we modify our previous research carefully, and derive a new expression of electron energy density in superhigh magnetic fields. Based on our improved model, we re-compute the electron capture rates and the magnetic fields' evolutionary timescales $t$ of magnetars. According to the calculated results, the superhigh magnetic fields may evolve on timescales $\sim (10^{6}-10^{7})$ yrs for common magnetars, and the maximum timescale of the field decay, $t\approx 2.9507 \times 10^{6}$ yrs, corresponding to an initial internal magnetic field $B_{\rm 0}= 3.0 \times 10^ {15}$ G and an initial inner temperature $T_{\rm 0}= 2.6 \times 10^ {8}$ K. Motivated by the results of the neutron star-supernova remnant(SNR) association of Zhang $\&$ Xie(2011), we calculate the maximum $B_{\rm 0}$ of magnetar progenitors, $B_{\rm max}\sim (2.0\times 10^{14}-2.93 \times 10^{15})$ G when $T_{\rm 0}= 2.6 \times 10^ {8}$ K. When $T_{\rm 0}\sim 2.75 \times 10^ {8}-~1.75 \times 10^ {8}$ K, the maximum $B_{\rm 0}$ will also be in the range of $\sim 10^{14}-10^{15}$ G, not exceeding the upper limit of magnetic field of a magnetar under our magnetar model. We also investigate the relationship between the spin-down ages of magnetars and the ages of their SNRs, and explain why all AXPs associated with SNRs look older than their real ages, whereas all SGRs associated with SNRs appear younger than they are.

Long-term cyclotron dynamics of relativistic wave packets: Spontaneous collapse and revival

In this work we study the effects of collapse and revival as well as {\it Zitterbewegung} (ZB) phenomenon, for the relativistic electron wave packets, which are a superposition of the states with quantum numbers sharply peaked around some level $n_0$ of the order of few tens. The probability densities as well as average velocities of the packet center and the average spin components were calculated analytically and visualized. Our computations demonstrate that due to dephasing of the states for times larger than the cyclotron period the initial wave packet (which includes the states with the positive energy only) loses the spatial localization so that the evolution can no longer be described classically. However, at the half-revival time $t=T_R/2$ its reshaping takes place firstly. The behavior of the wave packet containing the states of both energy bands (with $E_n>0$ and $E_n<0$) is more complicated. At short times of a few classical periods such packet splits into two parts which rotate with cyclotron frequency in the opposite directions and meet each other every one-half of the cyclotron period. At these moments their wave functions have significant overlap that leads to ZB. At the time of fractional revival each of two sub-packets is decomposed into few packets-fractions. However, at $t=T_R$ each of the two sub-packets (with positive or negative energy) restores at various points of the cyclotron orbit, that makes it impossible reshaping of initial wave packet entirely unlike the wave packet which consists of states with energies $E_n>0$ only. Obtained results can be useful for the description of electromagnetic radiation and absorption in relativistic plasma on astrophysics objects, where super high magnetic field has the value of the order $10^8-10^9$T, as well as for interpretation of experiments with trapped ions.

Super-High Magnetic Fields in Spatially Inhomogeneous Plasma

Super-High Magnetic Fields in Spatially Inhomogeneous Plasma

Evolution of superhigh magnetic fields of magnetars

In this paper, we consider the effect of Landau levels on the decay of superhigh magnetic fields of magnetars. Applying ${}^3P_2$ anisotropic neutron superfluid theory yield a second-order differential equation for a superhigh magnetic field $B$ and its evolutionary timescale $t$. The superhigh magnetic fields may evolve on timescales $\sim (10^{6}-10^{7})$ yrs for common magnetars. According to our model, the activity of a magnetar may originate from instability caused by the high electron Fermi energy.

Numerical simulation of the electron capture process in a magnetar interior

In a superhigh magnetic field, direct Urca reactions can proceed for an arbitrary proton concentration. Since only the electrons with high energy $E$ ($E > Q$, $Q$ is the threshold energy of inverse $\beta-$decay) at large Landau levels can be captured, we introduce the Landau level effect coefficient $q$ and the effective electron capture rate $\Gamma_{\rm eff}$. By using $\Gamma_{\rm eff}$, the values of $L_{\rm X}$ and $L_{\rm \nu}$ are calculated, where and $L_{\rm \nu}$, $L_{\rm X}$ are the average neutrino luminosity of Anomalous X-ray Pulsars (AXPs) and the average X-ray luminosity of AXPs, respectively. The complete process of electron capture inside a magnetar is simulated numerically.

Control of Ceramic Material Microstructure with Super High Magnetic Field

A new control method of the particle orientation structure with super high magnetic field is studied for Al2O3 ceramics. Al2O3 slurry was made with two types of Al2O3 particles, which one was spherical shape of, and the other one was elongated shape of. The Al2O3 ceramics of orientation structure was fabricated by drying the Al2O3 slurry under the super high magnetic field, cold isostatic pressing (CIP) and sintering. Effects of particle shape, particle size, the solid loading, slurry viscosity, dispersant content and the magnetic field strength on the particle orientation structure were examined in detail. The experimental results indicate that even the spherical Al2O3 particles can align under the magnetic field; the particle orientation degree changes with the particle shape and the solid loading under same magnetic field strength conditions, and the elongated particle system is easier to align than the spherical particle system; the particle orientation degree of the Al2O3 ceramics can be controlled by adjusting the particle shape, particle size, solid loading, slurry viscosity, dispersant content and magnetic field strength.

Crystallization Behavior of Zr-Based Bulk Metallic Glass under Super High Magnetic Field

Crystallization Behavior of Zr-Based Bulk Metallic Glass under Super High Magnetic Field

Research in Super-High Pulsed Magnetic Fields at the Megagauss Laboratory of the University of Tokyo

We present in this paper a brief review of the facilities of the Megagauss Laboratory (MGL) of the University of Tokyo, and an overview of the highlights of solid state physics in megagauss fields at MGL. The Megagauss Laboratory has a long history since the first prototype was established in 1972 in order to pursue new phenomena which may occur in the extreme high magnetic field limit. Since then, it has achieved successful development in the last three decades, and very recently in 1999, it was enlarged and renewed at the Kashiwa new campus. At the MGL, pulsed high magnetic fields are produced by three different techniques: electromagnetic flux compression (EMFC), the single-turn coil (STC) technique, and non-destructive long pulse magnets. The highest magnetic fields of 622 T has been obtained by EMFC. By the STC technique, very high fields exceeding 300 T have been obtained depending on the coil bore, in two systems with horizontal and vertical coil axes. These fields are applied in many different kinds of experiments, such as optical spectroscopy, cyclotron and electron spin resonance, magnetization and transport measurements. Non-destructive long pulse fields up to nearly 70 T from wire-wound coils are also available.

Quantum transitions and magnetization of the magnetic V15 cluster in strong magnetic fields

The process of rearrangement of the magnetic structure of the low-spin cluster V15 in superhigh magnetic fields is investigated. At low temperatures, this process is shown to manifest itself as three quantum jumps, each of which is a transition causing the spin of the complex to increase by two unities. The nature of these quantum jumps is discussed. The magnetization curve and the magnetic susceptibility are calculated.

A new cultivation system operated under a super high magnetic field

A new cultivation system which operates under a super high magnetic field in the range of 0.5 to 7 Tesla was developed. In this reactor system, the effects of a high magnetic field on various biological reactions could be investigated not only under a homogeneous high magnetic field, but also under a gradient magnetic field. The maximum magnetic field gradient is 23 Tesla/m. Since the superconductive magnet was designed so as to significantly reduce the evaporation rates of liquid helium and nitrogen, operation is virtually maintenance-free compared with that in conventional superconductive magnets. The temperature of the reactor is controllable within the range of 10 to 70°C (deviations of ±0.1°C). When Escherichia coli B cells were grown at 37°C, total cell number during the stationary phase was 70% higher under homogeneous 7 Tesla conditions than in the geomagnetic field. A three fold larger cell number was detected in a gradient magnetic fields between 5 and 6 Tesla.