On the relationship between quadrupolar magnetic field and collisionless reconnection

2014 ◽  
Vol 21 (6) ◽  
pp. 062111 ◽  
Author(s):  
R. Smets ◽  
N. Aunai ◽  
G. Belmont ◽  
C. Boniface ◽  
J. Fuchs
Keyword(s):  
Magnetic Field ◽  
Collisionless Reconnection ◽  
The Relationship

scholarly journals High-Resolution Observations of Emerging Magnetic Fields and Flux Tubes in Active Region Photosphere

1990 ◽  
Vol 138 ◽  
pp. 147-152 ◽  
Author(s):  
T. Tarbell ◽  
S. Ferguson ◽  
Z. Frank ◽  
R. Shine ◽  
A. Title ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Solar Observatory ◽  
Disk Center ◽  
Line Center ◽  
Solar Photosphere ◽  
Flux Tubes ◽  
National Solar Observatory ◽  
La Palma ◽  
The Relationship

On 29 September 1988, filtergrams of the solar photosphere with excellent resolution (0.3 to 0.5 arcsecond) were obtained at the Swedish Solar Observatory on La Palma, Canary Islands. An outstanding 2.5 hour run of digital filtergram observations was obtained, looking at a small area within an active region near disk center. On 6 August 1987, an 80 minute run of similar observations was obtained at the Vacuum Tower Telescope of the National Solar Observatory at Sacramento Peak. Digital and video movies have been made of Dopplergrams, magnetograms, line center, continuum, and white light images. Several examples of magnetic field emergence and formation of flux tubes can be studied in detail in the movies. The relationship between photospheric bright points, “filigree”, the line center brightness, and the magnetic field has been established for individual images in analysis to date.

scholarly journals Observations of magnetic and kinetic helicity proxies

2012 ◽  
Vol 8 (S294) ◽  
pp. 13-24
Author(s):  
Hongqi Zhang
Keyword(s):  
Magnetic Field ◽  
Velocity Field ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
Active Regions ◽  
Solar Dynamo ◽  
Magnetic Helicity ◽  
Vector Magnetograms ◽  
Topological Configuration ◽  
The Relationship

AbstractThe helicity is important to present the basic topological configuration of magnetic field in solar atmosphere. The distribution of magnetic helicity in solar atmosphere is presented by means of the observational (vector) magnetograms. As the kinetic helicity in the solar subatmosphere can be inferred from the velocity field based on the technique of the helioseismology and used to compare with the magnetic helicity in the solar atmosphere, the observational helicities provide the important chance for the confirmation on the generation of magnetic fields in the subatmosphere and solar dynamo models also. In this paper, we present the observational magnetic and kinetic helicity in solar active regions and corresponding questions, except the relationship with solar eruptive phenomena.

scholarly journals Recording brain activities in unshielded Earth’s field with optically pumped atomic magnetometers

2020 ◽  
Vol 6 (24) ◽  
pp. eaba8792 ◽  
Author(s):  
Rui Zhang ◽  
Wei Xiao ◽  
Yudong Ding ◽  
Yulong Feng ◽  
Xiang Peng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Medical Diagnosis ◽  
Alpha Rhythm ◽  
Brain Activity ◽  
High Sensitivity ◽  
Noninvasive Method ◽  
Optically Pumped ◽  
Field Noise ◽  
The Relationship ◽  
The Brain

Understanding the relationship between brain activity and specific mental function is important for medical diagnosis of brain symptoms, such as epilepsy. Magnetoencephalography (MEG), which uses an array of high-sensitivity magnetometers to record magnetic field signals generated from neural currents occurring naturally in the brain, is a noninvasive method for locating the brain activities. The MEG is normally performed in a magnetically shielded room. Here, we introduce an unshielded MEG system based on optically pumped atomic magnetometers. We build an atomic magnetic gradiometer, together with feedback methods, to reduce the environment magnetic field noise. We successfully observe the alpha rhythm signals related to closed eyes and clear auditory evoked field signals in unshielded Earth’s field. Combined with improvements in the miniaturization of the atomic magnetometer, our method is promising to realize a practical wearable and movable unshielded MEG system and bring new insights into medical diagnosis of brain symptoms.

scholarly journals RANCANG BANGUN EXTERNAL ELECTROMAGNETIC RETARDERS SYSTEM PADA MOTOR 1 PHASA

2016 ◽  
Vol 18 (4) ◽  
pp. 1
Author(s):  
Bima Dicky Anugrah Dewantara ◽  
Saiful Manan
Keyword(s):  
Magnetic Field ◽  
New York ◽  
Eddy Currents ◽  
Focal Point ◽  
Metal Plate ◽  
Rotating Shaft ◽  
Braking System ◽  
Motor Current ◽  
Safety Systems ◽  
The Relationship

Bima Dicky Anugrah Dewantara, Saiful Manan, in this paper explain that Electromagnetic retarders are generally known as electromagnetic inhibitors or brakes, the braking system eliminates most braking mechanics, thereby reducing conventional braking systems. Safety requirements and safety systems are developed and become a focal point of an equipment. Electromagnetic brakes are a safety component with a control system that is easy to control. With this electromagnetic brake, it will reduce maintenance costs, because it only requires a factor of electricity to be able to move it. The braking system uses electromagnetic forces to slow down a movement, which is generally a shaft motion. A dish with non-ferromagnetic metal material is attached to a rotating shaft. The disk is flanked by the side of the stator in the form of an electromagnetic coil system that can generate a magnetic field from electricity. Electric current generates a magnetic field in the coil. And the metal plate that cuts the magnetic field will cause eddy currents on the disk itself. This eddy current will generate a magnetic field whose direction is opposite to the previous magnetic field, thus inhibiting the rotary motion of the shaft. In designing, experimenting and making an External Electromagnetic Retarders System Design on 1 Phase Motor, use the NE 555 IC as the control duty cycle. So that the relationship between braking current and braking time is inversely proportional if the higher the current, the shorter the time it takes for the rotor to stop. And the relationship between braking current and motor current is directly proportional, by increasing the braking current will increase the load on the motor causing the motor current to increase. Keywords: Electromagnetic Retarders, Electromagnetic Brakes, Eddy Flow EffectReferencesTipler, P. 2008. Physics for Scientist volume 2. New York : WH Freeman and Company..Ishaq, M. 2007. Fisika Dasar Elektisitas dan Magnetisme. Yogyakarta: Graha Ilmu.Millman, Halkias, M.Barmawi, dan M.O.Tjia. 1971. Integrated Electronics:Analog and Digital Circuits and Systems. Jakarta : Erlangga.Ramdhani, Mohamad. 2008. Rangkaian Listrik. Jakarta : Erlangga.Bishop, Owen. 2004. Dasar-Dasar Elektronika. Jakarta : Erlangga.Halliday, David. Robert Resnick. 1978. Fisika Jilid II Edisi Ketiga. Jakarta : Erlangga

scholarly journals Particle Acceleration in Collisionless Magnetic Reconnection

2001 ◽  
Vol 203 ◽  
pp. 555-557
Author(s):  
P. K. Browning ◽  
G. E. Vekstein
Keyword(s):  
Magnetic Field ◽  
Field Component ◽  
Charged Particles ◽  
Energy Spectra ◽  
Uniform Field ◽  
Two Dimensional ◽  
Point Field ◽  
Field Geometry ◽  
Collisionless Reconnection ◽  
Accelerated Particles

We investigate the acceleration of charged particles in the framework of collisionless reconnection. A steady reconnection scenario is considered, with a two dimensional X-point magnetic field geometry having also a uniform field component transverse to the plane of the X-point field, and an inductive electric field generating an inflow of particles. Test particle trajectories are studied, and the energy spectra of the accelerated particles are determined.

scholarly journals Interhemispheric comparison of average substorm onset locations: evidence for deviation from conjugacy

2007 ◽  
Vol 25 (4) ◽  
pp. 989-999 ◽  
Author(s):  
H. Wang ◽  
H. Lühr ◽  
S. Y. Ma ◽  
H. U. Frey
Keyword(s):  
Magnetic Field ◽  
Significant Influence ◽  
Solar Zenith Angle ◽  
Statistical Study ◽  
Substorm Onset ◽  
Seasonal Effects ◽  
Linear Relationships ◽  
Substorm Onsets ◽  
Relationship Of ◽  
The Relationship

Abstract. Based on 2760 well-defined substorm onsets in the Northern Hemisphere and 1432 in the Southern Hemisphere observed by the FUV Imager on board the IMAGE spacecraft, a detailed statistical study is performed including both auroral regions. This study focuses on the hemispheric comparisons. Southward pointing interplanetary magnetic field (IMF) is favorable for substorm to occur, but still 30% of the events are preceded by northward IMF. The magnetic latitude (MLat) of substorm onset depends mainly on the merging electric field (Em) with a relationship of |dMLat|= −5.2 Em0.5, where dMLat is the deviation from onset MLat. In addition, seasonal effects on onset MLat are also detected, with about 2 degrees higher latitudes during solstices than equinoxes. Both IMF By and solar illumination have a significant influence on the magnetic local time (MLT) of onsets. An average relation, dMLT=0.25 By between IMF By and the deviation from onset MLT, was found. The By dependence varies slightly with the onset latitude. At lower latitudes (higher activity) it is reduced. After removal of the relationship with IMF By a linear relationships remains between the solar zenith angle and onset MLT with dMLT=1 min/deg. Therefore, both solar illumination and IMF By can contribute to hemispheric longitudinal displacements of substorm onset locations from conjugacy. No indications for systematic latitudinal displacements between the hemispheres have been found.

The Effect of Magnetic Field Strength on the Oscillatory Characteristics of Multimode Magnetoconvection

1993 ◽  
Vol 10 (4) ◽  
pp. 275-277
Author(s):  
J.O. Murphy ◽  
J.M. Lopez ◽  
C.P. Dyt
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
The Relationship ◽  
The Magnetic Field ◽  
Period Of Oscillation

AbstractThe effect of varying magnetic field strength on the frequency of oscillatory motions for cellular multimode magnetoconvection has been investigated. In addition the influence of the thermal, viscous and magnetic diffusivities have been taken into account and the range of preferred horizontal scales established. The relationship between the period of oscillation and the magnetic field strength is determined.

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