A new furnace for improving thermal demagnetization in paleomagnetism

2020 ◽  
Author(s):  
Huafeng Qin ◽  
Xiang Zhao ◽  
Shuangchi Liu ◽  
Greig Paterson ◽  
Zhaoxia Jiang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Curie Temperature ◽  
High Performance ◽  
Thermal Treatments ◽  
Thermal Demagnetization ◽  
Heating Wire ◽  
Low Magnetic Field ◽  
Detrimental Impact ◽  
The Magnetic Field ◽  
The Ideal

<p>Thermal demagnetization furnaces are routine facilities for paleomagnetic studies. The ideal thermal demagnetizer should maintain “zero” magnetic field during thermal treatments. However, magnetic field noises, including residual magnetic fields of material and induced fields caused by the heating current in the furnace are always present. The key to making high-performance demagnetization furnace is to reduce the magnetic field noises. By combining efficient demagnetization of shielding and a new structure of heating wire, we have developed a new demagnetization furnace with low magnetic field noises. Repeated progressive thermal demagnetization experiments using specimens that were previously completely thermal demagnetized above their Curie temperature were carry out to explore the effects of field within various types of furnace during demagnetization. These experiment confirm that magnetic field noises in the furnace can have an observable and detrimental impact on demagnetization behavior. Comparison between commercial furnaces and our new design show a notable reduction in the impacts of on thermal demagnetization behavior. The new heating element design and procedure for reducing magnetic field noises represent a significant improvement in the design of thermal demagnetizers and allows for extremely weak specimens to be successfully measured.</p>

The Influence of the Soaking Process on Magnetization Saturation and Coercivity Field of the Classic Amorphous Alloy Fe61Co10Y8Nb1B20.

2018 ◽  
Vol 69 (10) ◽  
pp. 2819-2822
Author(s):  
Marcin Nabialek
Keyword(s):  
Magnetic Field ◽  
Saturation Magnetization ◽  
Coercive Field ◽  
Thermal Treatments ◽  
Solid Samples ◽  
Magnetization Saturation ◽  
Transmission Geometry ◽  
Negative Effect ◽  
Coercivity Field ◽  
The Magnetic Field

This study presents the results of Mossbauer research and magnetic properties. The tests were carried out for amorphous Fe61Co10Y8Nb1B20 alloys produced in the form of strips with a thickness of approximately 35 mm. Mossbauer spectra were measured in transmission geometry for solid samples. Measurements were taken for samples in solidified state and after two heating processes. The first process was carried out at 700K and 60 minutes, the second at 720K and 210 minutes. For the samples prepared in this way, magnetization tests were performed as a function of the magnetic field strength. The values of saturation magnetization and the value of the coercive field were determined from these matrices. It was found that the performed thermal treatments had a negative effect on the value of saturation magnetization and change in the value of the coercive field.

scholarly journals Simulation study of the plasma-brake effect

2014 ◽  
Vol 32 (10) ◽  
pp. 1207-1216 ◽  
Author(s):  
P. Janhunen
Keyword(s):  
Magnetic Field ◽  
High Performance ◽  
Ionospheric Plasma ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Breaking Force ◽  
Field Orientation ◽  
Particle In Cell ◽  
Leo Satellite ◽  
The Magnetic Field

Abstract. Plasma brake is a thin, negatively biased tether that has been proposed as an efficient concept for deorbiting satellites and debris objects from low Earth orbit. We simulate the interaction with the ionospheric plasma ram flow with the plasma-brake tether by a high-performance electrostatic particle in cell code to evaluate the thrust. The tether is assumed to be perpendicular to the flow. We perform runs for different tether voltage, magnetic-field orientation and plasma-ion mass. We show that a simple analytical thrust formula reproduces most of the simulation results well. The interaction with the tether and the plasma flow is laminar (i.e. smooth and not turbulent) when the magnetic field is perpendicular to the tether and the flow. If the magnetic field is parallel to the tether, the behaviour is unstable and thrust is reduced by a modest factor. The case in which the magnetic field is aligned with the flow can also be unstable, but does not result in notable thrust reduction. We also correct an error in an earlier reference. According to the simulations, the predicted thrust of the plasma brake is large enough to make the method promising for low-Earth-orbit (LEO) satellite deorbiting. As a numerical example, we estimate that a 5 km long plasma-brake tether weighing 0.055 kg could produce 0.43 mN breaking force, which is enough to reduce the orbital altitude of a 260 kg object mass by 100 km over 1 year.

HALL AND MAGNETORESISTANCE EFFECTS OBTAINED FROM SIMULTANEOUS MEASUREMENTS OF LIQUID METALS AND SEMICONDUCTORS

2004 ◽  
Vol 18 (27n29) ◽  
pp. 3625-3628
Author(s):  
M. OGITA ◽  
T. ITO ◽  
M. ISAI ◽  
I. MOGI ◽  
S. AWAJI ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Liquid Metals ◽  
Simultaneous Methods ◽  
Hall Measurements ◽  
Hall Effects ◽  
Galvanomagnetic Effects ◽  
Liquid States ◽  
Low Magnetic Field ◽  
The Magnetic Field ◽  
Solid And Liquid States

Hall measurements of liquid metals, using two-frequency, ac-dc and simultaneous methods are described. The Hall effect has been measured in Hg and Ga metals, in both solid and liquid states. The magnetoresistance and Hall effects have also been measured in an InSb single crystal, which exhibited magnetoresistance even in low magnetic field, and in Si , which did not exhibit magnetoresistance in low magnetic field. In order to investigate the magnetic field dependence of the observed galvanomagnetic effects for solid and liquid state metals, and for semiconductors, Hall measurements in high magnetic field, up to ±9 T, were also performed.

scholarly journals Tunable Magnetocaloric Properties of Gd-Based Alloys by Adding Tb and Doping Fe Elements

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2877 ◽  
Author(s):  
Lingfeng Xu ◽  
Chengyuan Qian ◽  
Yongchang Ai ◽  
Tong Su ◽  
Xueling Hou
Keyword(s):  
Magnetic Field ◽  
Curie Temperature ◽  
Temperature Change ◽  
Indirect Measurement ◽  
Adiabatic Temperature ◽  
Doping Content ◽  
Adiabatic Temperature Change ◽  
Magnetocaloric Properties ◽  
Capacity Calculation ◽  
Low Magnetic Field

In this paper, the magnetocaloric properties of Gd1−xTbx alloys were studied and the optimum composition was determined to be Gd0.73Tb0.27. On the basis of Gd0.73Tb0.27, the influence of different Fe-doping content was discussed and the effect of heat treatment was also investigated. The adiabatic temperature change (ΔTad) obtained by the direct measurement method (under a low magnetic field of 1.2 T) and specific heat capacity calculation method (indirect measurement) was used to characterize the magnetocaloric properties of Gd1−xTbx (x = 0~0.4) and (Gd0.73Tb0.27)1−yFey (y = 0~0.15), and the isothermal magnetic entropy (ΔSM) was also used as a reference parameter for evaluating the magnetocaloric properties of samples together with ΔTad. In Gd1−xTbx alloys, the Curie temperature (Tc) decreased from 293 K (x = 0) to 257 K (x = 0.4) with increasing Tb content, and the Gd0.73Tb0.27 alloy obtained the best adiabatic temperature change, which was ~3.5 K in a magnetic field up to 1.2 T (Tc = 276 K). When the doping content of Fe increased from y = 0 to y = 0.15, the Tc of (Gd0.73Tb0.27)1−yFey (y = 0~0.15) alloys increased significantly from 276 K (y = 0) to 281 K (y = 0.15), and a good magnetocaloric effect was maintained. The annealing of alloys (Gd0.73Tb0.27)1−yFey (y = 0~0.15) at 1073 K for 10 h resulted in an average increase of 0.3 K in the maximum adiabatic temperature change and a slight increase in Tc. This study is of great significance for the study of magnetic refrigeration materials with adjustable Curie temperature in a low magnetic field.

scholarly journals DYNAMO EFFECTS IN MAGNETIZED IDEAL PLASMA COSMOLOGIES

2008 ◽  
Vol 23 (11) ◽  
pp. 1697-1710 ◽  
Author(s):  
KOSTAS KLEIDIS ◽  
APOSTOLOS KUIROUKIDIS ◽  
DEMETRIOS PAPADOPOULOS ◽  
LOUKAS VLAHOS
Keyword(s):  
Magnetic Field ◽  
Cosmological Model ◽  
Homogeneous Magnetic Field ◽  
Mhd Equations ◽  
Cosmological Perturbations ◽  
Gravitational Instabilities ◽  
Ideal Magnetohydrodynamic ◽  
The Magnetic Field ◽  
Ideal Plasma ◽  
The Ideal

The excitation of cosmological perturbations in an anisotropic cosmological model and in the presence of a homogeneous magnetic field has been studied, using the ideal magnetohydrodynamic (MHD) equations. In this case, the system of partial differential equations which governs the evolution of the magnetized cosmological perturbations can be solved analytically. Our results verify that fast-magnetosonic modes propagating normal to the magnetic field, are excited. But, what is most important, is that, at late times, the magnetic-induction contrast(δB/B) grows, resulting in the enhancement of the ambient magnetic field. This process can be particularly favored by condensations, formed within the plasma fluid due to gravitational instabilities.

Glass-Coated Cu-Mn-Ga Microwires Produced by Taylor-Ulitovsky Technique

2009 ◽  
Vol 152-153 ◽  
pp. 79-84 ◽  
Author(s):  
Joan Josep Suñol ◽  
L. Escoda ◽  
C. García ◽  
V.M. Prida ◽  
Victor Vega ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solid Solution ◽  
Curie Temperature ◽  
Energy Dispersive Spectroscopy ◽  
Room Temperature ◽  
Alloy Composition ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Magnetic Field

Glass-coated Cu-Mn-Ga microwires were fabricated by Taylor-Ulitovsky technique. By means of energy dispersive spectroscopy microanalysis, an average alloy composition of Cu56Ga28Mn16 was determined. The temperature dependence of magnetization measured at a low magnetic field showed the coexistence of two ferromagnetic phases. The Curie temperature of one phase is 125 K and above room temperature for the other one. X-ray diffraction at room temperature and at 100 K reflects the presence of the same three crystalline phases corresponding to the cubic B2 Cu-Mn-Ga structure as a main phase and the minor phases of fcc Cu rich solid solution with Mn and Ga and the monoclinic CuO.

scholarly journals An ultra-low magnetic field thermal demagnetizer for high-precision paleomagnetism

2020 ◽  
Author(s):  
Huafeng Qin ◽  
Xiang Zhao ◽  
Shuangch Liu ◽  
Greig Paterson ◽  
Zhaoxia Jiang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Elevated Temperatures ◽  
Construction Material ◽  
New Technology ◽  
Low Noise ◽  
Zero Magnetic Field ◽  
Thermal Demagnetization ◽  
Sample Chamber ◽  
Weakly Magnetic ◽  
Low Magnetic Field

Abstract Thermal demagnetization furnaces are widely used paleomagnetic facilities for progressive removal of naturally acquired magnetic remanence or the imparting of well controlled laboratory magnetization. An ideal thermal demagnetizer should maintain “zero” magnetic field in the sample chamber during thermal treatments. However, magnetic field noises, including the residual magnetic fields of the construction material and the induced fields caused by the alternating current (AC) in the heating element are always present, which often greatly contaminate the paleoamgnetic results at the elevated temperatures or for the magnetically weak samples. Here, we designed a new structure of heating wire named named straight core solenoid to develop a new demagnetization furnace with ultra-low magnetic field noise. Simulation and practical measurement show that the heating current magnetic field can be greatly reduced by using the new technology. Thermal demagnetization experiments demonstrate that the new demagnetizer can yield low noise results even for weakly magnetic samples.

scholarly journals An Ultra-low Magnetic Field Thermal Demagnetizer for High-precision Paleomagnetism

2020 ◽  
Author(s):  
Huafeng Qin ◽  
Xiang Zhao ◽  
Shuangchi Liu ◽  
Greig Paterson ◽  
Zhaoxia Jiang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Elevated Temperatures ◽  
Construction Material ◽  
New Technology ◽  
Low Noise ◽  
Zero Magnetic Field ◽  
Thermal Demagnetization ◽  
Sample Chamber ◽  
Weakly Magnetic ◽  
Low Magnetic Field

Abstract Thermal demagnetization furnaces are widely used paleomagnetic facilities for progressive removal of naturally acquired magnetic remanence or the imparting of well controlled laboratory magnetization. An ideal thermal demagnetizer should maintain “zero” magnetic field in the sample chamber during thermal treatments. However, magnetic field noises, including the residual magnetic fields of the construction material and the induced fields caused by the alternating current (AC) in the heating element are always present, which often greatly contaminate the paleoamgnetic results at the elevated temperatures or for the magnetically weak samples. Here, we designed a new structure of heating wire named named straight core solenoid to develop a new demagnetization furnace with ultra-low magnetic field noise. Simulation and practical measurement show that the heating current magnetic field can be greatly reduced by using the new technology. Thermal demagnetization experiments demonstrate that the new demagnetizer can yield low noise results even for weakly magnetic samples.

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