The Unique Property in Magnetic Noise of Spin Modulated Atomic Magnetometer

2018 ◽  
Vol 787 ◽  
pp. 75-80
Author(s):  
Xiao Fei Wang ◽  
Ji Min Li
Keyword(s):  
Magnetic Field ◽  
Conversion Coefficient ◽  
Transverse Relaxation Time ◽  
Unique Property ◽  
Magnetic Noise ◽  
Transverse Relaxation ◽  
Polarization Signal ◽  
Measurement Experiment ◽  
The Magnetic Field ◽  
Higher Sensitivity

This paper presents a spin modulated atomic magnetometer, different from other kinds of atomic magnetometers, the conversion coefficient between the polarization signal and the magnetic field to be measured is independent of the transverse relaxation time, which means that the higher sensitivity can be achieved when polarization is kept constant. For better understanding, the magnetic noise of spin modulated magnetometer is demonstrated and compared to SERF magnetometer. The magnetic noise measurement experiment is designed, the experimental results are consistent with the theoretical prediction. This paper validate the unique property of spin modulated magnetometer and this property will play an important role in guiding the optimization of future experiments.

Linear conversion in a magnetized plasma with density gradient parallel to the magnetic field

1983 ◽  
Vol 30 (2) ◽  
pp. 179-192 ◽  
Author(s):  
E. Mjølhus
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Wave ◽  
Density Gradient ◽  
Conversion Coefficient ◽  
Magnetized Plasma ◽  
Angle Of Incidence ◽  
Linear Conversion ◽  
The Magnetic Field

The problem of linear conversion of an ordinary polarized electromagnetic wave in a magnetized plasma with density gradient parallel to the magnetic field is considered. An expression for the conversion coefficient as a function of angle of incidence, WKB parameter and magnetic field is obtained. The magnetic field leads to a narrowing of the range of angles of incidence leading to linear conversion, compared with the unmagnetized case.

scholarly journals Effect of Mineral Composition on Transverse Relaxation Time Distributions and MR Imaging of Tight Rocks from Offshore Ireland

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 232
Author(s):  
Stian Almenningen ◽  
Srikumar Roy ◽  
Arif Hussain ◽  
John Georg Seland ◽  
Geir Ersland
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Mr Imaging ◽  
Field Strength ◽  
High Field ◽  
Transverse Relaxation Time ◽  
Transverse Relaxation ◽  
The Core ◽  
Low Field ◽  
Field Strengths

In this paper, we investigate the effect of magnetic field strength on the transverse relaxation time constant (T2) in six distinct core plugs from four different rock types (three sandstones, one basalt, one volcanic tuff and one siltstone), retrieved from offshore Ireland. The CPMG pulse-sequence was used at two different magnetic field strengths: high-field at 4.70 T and low-field at 0.28 T. Axial images of the core plugs were also acquired with the RAREst sequence at high magnetic field strength. Thin-sections of the core plugs were prepared for optical imaging and SEM analysis, and provided qualitative information on the porosity and quantification of the elemental composition of the rock material. The content of iron varied from 4 wt. % to close to zero in the rock samples. Nevertheless, the effective T2 distributions obtained at low-field were used to successfully predict the porosity of the core plugs. Severe signal attenuations from internal magnetic gradients resulted in an underestimation of the porosity at high-field. No definitive trend was identified on the evolution of discrete relaxation time components between magnetic field strengths. The low-field measurements demonstrate that NMR is a powerful quantitative tool for petrophysical rock analysis as compared to thin-section analysis. The results of this study are of interest to the research community who characterizes natural gas hydrates in tight heterogeneous core plugs, and who typically relies on MR imaging to distinguish between solid hydrates and fluid phases. It further exemplifies the importance of selecting appropriate magnetic field strengths when employing NMR/MRI for porosity calculation in tight rock.

Research and Design for Three-Axis Electromagnetic Leakage Detector

2012 ◽  
Vol 241-244 ◽  
pp. 223-226
Author(s):  
Jiang Shan Qian ◽  
Zhong Ran Zhou ◽  
Yu Wang ◽  
Tong Guang Shao ◽  
Jin Bo Zhang
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Coupling ◽  
Low Frequency ◽  
Electrical Equipment ◽  
Electronic Products ◽  
Total Magnetic Field ◽  
Leakage Magnetic Field ◽  
Measurement Experiment ◽  
Research And Design ◽  
The Magnetic Field

In order to measure the magnetic field around electronic products, household appliances and industrial electrical equipment, this paper puts forward a new method which makes use of electromagnetic coupling design based on three-axis electromagnetic leakage. This method can overcome the disadvantage of traditional single-axis measurement which needs to get the total magnetic field after several times’ measurement. This paper designs three-axis electromagnetic leakage detector for circuit measurement, which is proved to be correct after circuit measurement experiment. It can easily detect 30-2K Hz leakage magnetic field of low frequency generated from electrical appliances products.Introduction.

scholarly journals The Influence of Incident Power on the Magnetic Fluid Sensor Sensitivity Based on Optical Transmission Properties

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Yongqian Li ◽  
Hao Zhang ◽  
Zhi Yang ◽  
Baoyi Yuan ◽  
Ze Yuan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fluid ◽  
Optical Transmission ◽  
Incident Power ◽  
Field Range ◽  
Film Sensor ◽  
Transmission Properties ◽  
Fluid Sensor ◽  
The Magnetic Field ◽  
Higher Sensitivity

Sensitivity is a critical characteristic of sensors, and increasing the sensitivity of the sensor is valuable for measurement study. Incident power has an important influence on the sensitivity of magnetic fluid sensors based on optical transmission properties. Variation in the magnetic field sensitivity at different incident powers was investigated by the measurement of transmitted power through the magnetic fluid sensors. As the magnetic field strength increases, the sensitivity variation of the magnetic fluid film sensor can be divided into four stages: first decreasing sharply, secondly increasing, then decreasing gradually, and finally tending toward a small stable value. The magnitudes of the change in the sensor sensitivity are influenced by the incident power, because the structural pattern of the nano-magnetic particles in the magnetic fluid sensor changes, the Soret effect and the Photonic Hall effect co-define the sensing system. In the weak magnetic field range, when a higher sensitivity is required, it is appropriate to select a larger incident power; however, in a large magnetic field range, when a higher sensitivity is required, a small incident power should be selected. Therefore, the magnetic fluid film sensor exhibits different sensitivity characteristics if different incident power values are chosen. The appropriate incident power can be selected according to the range of the magnetic field to be measured to improve the sensitivity in the magnetic field measurement study.

Observing the galactic magnetic field

1967 ◽  
Vol 31 ◽  
pp. 375-380
Author(s):  
H. C. van de Hulst
Keyword(s):  
Magnetic Field ◽  
Fair Agreement ◽  
Solar Neighbourhood ◽  
Galactic Magnetic Field ◽  
The Magnetic Field

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

On the Configuration of the Magnetic Field of β CrB

1976 ◽  
Vol 32 ◽  
pp. 613-622
Author(s):  
I.A. Aslanov ◽  
Yu.S. Rustamov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radial Velocity ◽  
Magnetic Field Strength ◽  
Complex Shape ◽  
Rotation Period ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Secular Variations ◽  
The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

Sign in / Sign up

Export Citation Format

Share Document