scholarly journals Medicean Moons Sailing Through Plasma Seas: Challenges in Establishing Magnetic Properties

2010 ◽  
Vol 6 (S269) ◽  
pp. 58-70
Author(s):  
Margaret G. Kivelson ◽  
Xianzhe Jia ◽  
Krishan K. Khurana
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Fields ◽  
Boundary Conditions ◽  
Computer Simulations ◽  
Internal Field ◽  
Internal Magnetic Field ◽  
Complex Behavior ◽  
Flowing Plasma ◽  
Linear Interactions

AbstractJupiter's moons, embedded in the magnetized, flowing plasma of Jupiter's magnetosphere, the plasma seas of the title, are fluids whose highly non-linear interactions imply complex behavior. In a plasma, magnetic fields couple widely separated regions; consequently plasma interactions are exceptionally sensitive to boundary conditions (often ill-specified). Perturbation fields arising from plasma currents greatly limit our ability to establish more than the dominant internal magnetic field of a moon. With a focus on Ganymede and a nod to Io, this paper discusses the complexity of plasma-moon interactions, explains how computer simulations have helped characterize the system and presents improved fits to Ganymede's internal field.

Local Magnetic Fields in some Bismuth Compounds. A Survey of Experimental Evidences

1994 ◽  
Vol 49 (1-2) ◽  
pp. 418-424 ◽  
Author(s):  
E. A. Kravchenko ◽  
V. G. Orlov
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Fields ◽  
Unpaired Electron ◽  
Internal Magnetic Field ◽  
Zero Magnetic Field ◽  
Typical Pattern ◽  
Bismuth Compounds ◽  
Local Magnetic Fields ◽  
Nuclear Quadrupole

Abstract The splittings observed in the 209Bi nuclear quadrupole resonances of α-Bi2O3, in zero magnetic field, follow the typical pattern of a Zeeman perturbed NQR spectrum. The lineshapes in Bi3O4Br also indicate a poorly resolved splitting that points to the presence of an internal magnetic field in the order of 200 G. This exceeds notably the dipole nuclear magnetic fields (about several G), but is orders of magnitude smaller than paramagnetic fields produced by unpaired electron spins. The results obtained using a SQUID and μSR-technique can also be interpreted as indicative of magnetic properties not conventionally expected in such compounds.

scholarly journals Sensitivity of PS/CoPd Janus particles to an external magnetic field

RSC Advances ◽  
2021 ◽  
Vol 11 (28) ◽  
pp. 17051-17057
Author(s):  
Anna Eichler-Volf ◽  
Yara Alsaadawi ◽  
Fernando Vazquez Luna ◽  
Qaiser Ali Khan ◽  
Simon Stierle ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Janus Particles ◽  
Weak Magnetic Fields

PS/CoPd Janus particles respond very sensitively to application of low external magnetic fields. Owing to the magnetic properties, the PS/CoPd particles may be used, for example, to sense the presence of weak magnetic fields as micro-magnetometers.

scholarly journals Controlled electrochemical growth and magnetic properties of CoFe2O4 nanowires with high internal magnetic field

2021 ◽  
pp. 159196
Author(s):  
Nabil Labchir ◽  
Abdelkrim Hannour ◽  
Abderrahim Ait Hssi ◽  
Didier Vincent ◽  
Patrick Ganster ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Internal Magnetic Field ◽  
Electrochemical Growth

scholarly journals The study of the magnetic properties of matter in strong magnetic fields. Part III.—Magnetostriction

1932 ◽  
Vol 135 (828) ◽  
pp. 537-554 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Fields ◽  
Crystal Lattice ◽  
The Body ◽  
Considerable Part ◽  
Strong Magnetic Fields ◽  
Theoretical Investigations ◽  
General Aspects

Magnetostriction may be defined in general as the change of shape of a substance when it is magnetised. The phenomenon may originate from various causes, but there is one which appears to us to be of major importance. From our present conceptions of the origin of cohesion between the atoms forming a crystal lattice it appears that a considerable part of this cohesion is due to forces of electrodynamical origin; we may therefore expect to influence these forces by means of a magnetic field, and thus produce a change of shape of the body. In ferromagnetic substances magnetostriction is easily observed in ordinary magnetic fields and a number of theoretical investigations have been carried out to explain the general aspects of the phenomenon. With para- and diamagnetic substances, however, no magnetostriction has been observed.

scholarly journals Computing nonlinear force free coronal magnetic fields

2003 ◽  
Vol 10 (4/5) ◽  
pp. 313-322 ◽  
Author(s):  
T. Wiegelmann ◽  
T. Neukirch
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Boundary Conditions ◽  
Random Noise ◽  
Coronal Magnetic Field ◽  
Optimization Method ◽  
Numerical Code ◽  
Coronal Magnetic Fields ◽  
Nonlinear Force ◽  
Free Fields

Abstract. Knowledge of the structure of the coronal magnetic field is important for our understanding of many solar activity phenomena, e.g. flares and CMEs. However, the direct measurement of coronal magnetic fields is not possible with present methods, and therefore the coronal field has to be extrapolated from photospheric measurements. Due to the low plasma beta the coronal magnetic field can usually be assumed to be approximately force free, with electric currents flowing along the magnetic field lines. There are both observational and theoretical reasons which suggest that at least prior to an eruption the coronal magnetic field is in a nonlinear force free state. Unfortunately the computation of nonlinear force free fields is way more difficult than potential or linear force free fields and analytic solutions are not generally available. We discuss several methods which have been proposed to compute nonlinear force free fields and focus particularly on an optimization method which has been suggested recently. We compare the numerical performance of a newly developed numerical code based on the optimization method with the performance of another code based on an MHD relaxation method if both codes are applied to the reconstruction of a semi-analytic nonlinear force-free solution. The optimization method has also been tested for cases where we add random noise to the perfect boundary conditions of the analytic solution, in this way mimicking the more realistic case where the boundary conditions are given by vector magnetogram data. We find that the convergence properties of the optimization method are affected by adding noise to the boundary data and we discuss possibilities to overcome this difficulty.

Magnetic phenomena

2004 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Flux Density ◽  
Magnetic Dipole ◽  
Electric Charge ◽  
Dipole Moments ◽  
Magnetic Flux Density

In this chapter we deal with a number of magnetic properties and their directional dependence: pyromagnetism, magnetic susceptibility, magnetoelectricity, and piezomagnetism. In the course of dealing with these properties, two new ideas are introduced: magnetic symmetry and axial tensors. Moving electric charge generates magnetic fields and magnetization. Macroscopically, an electric current i flowing in a coil of n turns per meter produces a magnetic field H = ni amperes/meter [A/m]. On the atomic scale, magnetization arises from unpaired electron spins and unbalanced electronic orbital motion. The weber [Wb] is the basic unit of magnetic charge m. The force between two magnetic charges m1 and m2 is where r is the separation distance and μ0 (=4π×10−7 H/m) is the permeability of vacuum. In a magnetic field H, magnetic charge experiences a force F = mH [N]. North and south poles (magnetic charges) separated by a distance r create magnetic dipole moments mr [Wb m]. Magnetic dipole moments provide a convenient way of picturing the atomistic origins arising from moving electric charge. Magnetization (I) is the magnetic dipole moment per unit volume and is expressed in units of Wb m/m3 = Wb/m2. The magnetic flux density (B = I + μ0H) is also in Wb/m2 and is analogous to the electric displacement D. All materials respond to magnetic fields, producing a magnetization I = χH, and a magnetic flux density B = μH where χ is the magnetic susceptibility and μ is the magnetic permeability. Both χ and μ are in henries/m (H/m). The permeability μ = χ + μ0 and is analogous to electric permittivity. χ and μ are sometimes expressed as dimensionless quantities (x ̅ and μ ̅ and ) like the dielectric constant, where = x ̅/μ0 and = μ ̅/μ0. Other magnetic properties will be defined later in the chapter. A schematic view of the submicroscopic origins of magnetic phenomena is presented in Fig. 14.1. Most materials are diamagnetic with only a weak magnetic response induced by an applied magnetic field.

Linear Buckling and Vibration Behavior of Piezoelectric/Piezomagnetic Beam under Uniform Magnetic Field

2014 ◽  
Vol 592-594 ◽  
pp. 2071-2075 ◽  
Author(s):  
A. Kumaravel ◽  
J. Jones Praveen ◽  
Raju Sethuraman ◽  
A. Arockiarajan
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Finite Element ◽  
Magnetic Fields ◽  
Boundary Conditions ◽  
Constitutive Equations ◽  
Uniform Magnetic Field ◽  
Vibration Behavior ◽  
Linear Buckling ◽  
Piezoelectric Coupling

The constitutive equations of MEE materials are used to derive the finite element equations involving the coupling between mechanical, electrical and magnetic fields. The candidate materials for this study are piezoelectric (BaTiO3) and magnetostrictive (CoFe2O4) material. The linear buckling and vibration behavior of layered MEE beam under uniform magnetic field is carried out using finite element method. The present study is limited to clamped-clamped boundary conditions. The influence of stacking sequences and piezoelectric coupling on critical buckling magnetic field and vibration behaviour is investigated.

3. Spots and magnetic fields

2020 ◽  
pp. 65-99
Author(s):  
Philip Judge
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Fields ◽  
Solar Interior ◽  
Solar Dynamo ◽  
The Sun ◽  
Electrically Conducting ◽  
New Science ◽  
The 1960S ◽  
Conducting Fluids

‘Spots and magnetic fields’ explores sunspot behaviour. We have known since 1908 that sunspots are magnetic, but why does the Sun form them at all? Is the Sun extraordinary in this, or is its behaviour in line with other stars? The Sun’s magnetic field is generated by a solar dynamo, which can be partly explained by magnetohydrodynamics (MHD)—the study of the magnetic properties and behaviour of electrically conducting fluids—however, there is no full consensus on the solar dynamo. In the 1960s the new science of helioseismology gave us insights into the Sun’s interior rotation, but we are unable to make truly critical observations in the solar interior.

scholarly journals Magnetic Field Reconstruction in a Solar Active Region

2001 ◽  
Vol 203 ◽  
pp. 328-330
Author(s):  
H. Wang ◽  
Y. Yan ◽  
T. Sakurai
Keyword(s):  
Magnetic Field ◽  
Integral Equation ◽  
Active Region ◽  
Magnetic Fields ◽  
Boundary Conditions ◽  
Numerical Technique ◽  
Boundary Integral ◽  
Field Reconstruction ◽  
Coronal Magnetic Fields ◽  
Function Vector

Supposing coronal magnetic fields are in a force-free state from the chromosphere to the height of two solar radii, we reconstruct 3D force-free magnetic fields by making use of a new numerical technique, in which the fields are represented by a boundary integral equation based on a specific Green's function. Vector magnetic fields observed on the photospheric surface can be taken as the boundary conditions of this equation. Magnetic fields in AR8270 on 14 July 1998 were employed as an example to exhibit the capability of this numerical technique.

scholarly journals Evaluation of Magnetic Parameters and Kinetics of the Magnetic Nanoparticles in High Magnetic Fields and its Potential Applications

2020 ◽  
Vol 8 (A) ◽  
pp. 24-36
Author(s):  
Mark Christopher Arokiaraj ◽  
Aleksandr Liubimtcev
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Nanoparticles ◽  
Magnetic Fields ◽  
Flux Density ◽  
7 Tesla ◽  
High Magnetic Fields ◽  
Drag Forces ◽  
Magnetic Strength ◽  
Motion Characteristics

BACKGROUND: Multifunctional nanoparticles are known for their wide range of biomedical applications. Controlling the magnetic properties of these nanoparticles is imperative for various applications, including therapeutic angiogenesis. AIM: The study was performed to evaluate the magnetic properties and their control mechanisms by the external magnetic field. METHODS: A100 nm magnetic nanoparticle was placed in the magnetic field, and parametrically, the magnet field strength and distance were evaluated. Various models of magnetic strength and disposition were evaluated. Magnetic flux density, force/weight, and magnetic gradient strength were the parameters evaluated in the electromagnetic computational software. RESULTS: The seven-coil method with three centrally placed coils as Halbach array, and each coil with a flux density of 7 Tesla, and with a coil dimension of 20 cm × 20 cm (square model) of each coil showed a good magnetic strength and force/weight parameters in a distance of 15 cm from the centrally placed coil. The particles were then evaluated for their motion characteristics in saline. It showed good displacement and acceleration properties. After that, the particles were theoretically assessed in a similar mathematical model after parametrically correcting the drag force. After the application of high drag forces, the particles showed adequate motion characteristics. When the particle size was reduced further, the motion characteristics were preserved even with high drag forces. CONCLUSION: There is potential for a novel method of controlling multifunctional magnetic nanoparticles using high magnetic fields. Further studies are required to evaluate the motion characteristics of these particles in vivo and in vitro.

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