scholarly journals Simulations of Switchback, Fragmentation and Sunspot Pair in δ-Sunspots during Magnetic Flux Emergence

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 586
Author(s):  
Che-Jui Chang ◽  
Jean-Fu Kiang
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Field Strength ◽  
Magnetic Flux ◽  
Initial Conditions ◽  
Observation Data ◽  
Flux Emergence ◽  
Polarity Inversion ◽  
Simulation Results ◽  
Spot Type

Strong flares and coronal mass ejections (CMEs), launched from δ-sunspots, are the most catastrophic energy-releasing events in the solar system. The formations of δ-sunspots and relevant polarity inversion lines (PILs) are crucial for the understanding of flare eruptions and CMEs. In this work, the kink-stable, spot-spot-type δ-sunspots induced by flux emergence are simulated, under different subphotospheric initial conditions of magnetic field strength, radius, twist, and depth. The time evolution of various plasma variables of the δ-sunspots are simulated and compared with the observation data, including magnetic bipolar structures, relevant PILs, and temperature. The simulation results show that magnetic polarities display switchbacks at a certain stage and then split into numerous fragments. The simulated fragmentation phenomenon in some δ-sunspots may provide leads for future observations in the field.

scholarly journals Energetics of magnetic transients in a solar active region plage

2019 ◽  
Vol 623 ◽  
pp. A176 ◽  
Author(s):  
L. P. Chitta ◽  
A. R. C. Sukarmadji ◽  
L. Rouppe van der Voort ◽  
H. Peter
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Flux ◽  
Numerical Simulations ◽  
Extreme Ultraviolet ◽  
Spatial Scales ◽  
Coronal Loops ◽  
The Sun ◽  
Flux Emergence ◽  
Transient Events

Context. Densely packed coronal loops are rooted in photospheric plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plage areas are patches of mostly unidirectional magnetic field extending several arcsec on the solar surface. Aims. We aim to explore the transient nature of the magnetic field, its mixed-polarity characteristics, and the associated energetics in the active region plage using high spatial resolution observations and numerical simulations. Methods. We used photospheric Fe I 6173 Å spectropolarimetric observations of a decaying active region obtained from the Swedish 1-m Solar Telescope (SST). These data were inverted to retrieve the photospheric magnetic field underlying the plage as identified in the extreme-ultraviolet emission maps obtained from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). To obtain better insight into the evolution of extended unidirectional magnetic field patches on the Sun, we performed 3D radiation magnetohydrodynamic simulations of magnetoconvection using the MURaM code. Results. The observations show transient magnetic flux emergence and cancellation events within the extended predominantly unipolar patch on timescales of a few 100 s and on spatial scales comparable to granules. These transient events occur at the footpoints of active region plage loops. In one case the coronal response at the footpoints of these loops is clearly associated with the underlying transient. The numerical simulations also reveal similar magnetic flux emergence and cancellation events that extend to even smaller spatial and temporal scales. Individual simulated transient events transfer an energy flux in excess of 1 MW m−2 through the photosphere. Conclusions. We suggest that the magnetic transients could play an important role in the energetics of active region plage. Both in observations and simulations, the opposite-polarity magnetic field brought up by transient flux emergence cancels with the surrounding plage field. Magnetic reconnection associated with such transient events likely conduits magnetic energy to power the overlying chromosphere and coronal loops.

scholarly journals First clear detection of the CCS Zeeman splitting toward the pre-stellar core, Taurus Molecular Cloud 1

2019 ◽  
Author(s):  
Fumitaka Nakamura ◽  
Seiji Kameno ◽  
Takayoshi Kusune ◽  
Izumi Mizuno ◽  
Kazuhito Dobashi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Radiative Transfer ◽  
Field Strength ◽  
Magnetic Flux ◽  
Molecular Cloud ◽  
Sound Speed ◽  
Flux Ratio ◽  
Zeeman Splitting ◽  
Line Of Sight ◽  
Taurus Molecular Cloud

Abstract We report the first clear detection of the Zeeman splitting of a CCS emission line at 45 GHz toward the nearby pre-stellar dense filament, Taurus Molecular Cloud 1 (TMC-1). We observed HC$_3$N non-Zeeman lines simultaneously with the CCS line, and did not detect any significant splitting of the HC$_3$N lines. Thus, we conclude that our detection of CCS Zeeman splitting is robust. The derived line-of-sight magnetic field strength is about $117 \pm 21 \, \mu$G, which corresponds to a normalized mass-to-magnetic flux ratio of 2.2 if we adopt an inclination angle of 45$^\circ$. Thus, we conclude that the TMC-1 filament is magnetically supercritical. Recent radiative transfer calculations of the CCS and HC$_3$N lines along the line of sight suggest that the filament is collapsing with a speed of $\sim$0.6 km s$^{-1}$, which is comparable to three times the isothermal sound speed. This infall velocity appears to be consistent with the evolution of a gravitationally infalling core.

scholarly journals Modelling coronal electron density and temperature profiles of the Active Region NOAA 11855

2016 ◽  
Vol 12 (S328) ◽  
pp. 149-151
Author(s):  
J. M. Rodríguez Gómez ◽  
L. E. Antunes Vieira ◽  
A. Dal Lago ◽  
J. Palacios ◽  
L. A. Balmaceda ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Physical Mechanism ◽  
Magnetic Energy ◽  
Plasma Temperature ◽  
Coronal Magnetic Field ◽  
Flux Emergence ◽  
Vector Magnetic Field ◽  
Atmospheric Phenomena ◽  
Coronal Electron

AbstractThe magnetic flux emergence can help understand the physical mechanism responsible for solar atmospheric phenomena. Emerging magnetic flux is frequently related to eruptive events, because when emerging they can reconnected with the ambient field and release magnetic energy. We will use a physic-based model to reconstruct the evolution of the solar emission based on the configuration of the photospheric magnetic field. The structure of the coronal magnetic field is estimated by employing force-free extrapolation NLFFF based on vector magnetic field products (SHARPS) observed by HMI instrument aboard SDO spacecraft from Sept. 29 (2013) to Oct. 07 (2013). The coronal plasma temperature and density are described and the emission is estimated using the CHIANTI atomic database 8.0. The performance of the our model is compared to the integrated emission from the AIA instrument aboard SDO spacecraft in the specific wavelengths 171Å and 304Å.

Transport of Magnetic Particles Under a Uniform Magnetic Field in Microchannels

2013 ◽  
Author(s):  
Gui-Ping Zhu ◽  
Nam-Trung Nguyen
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Flux ◽  
Flux Density ◽  
Uniform Magnetic Field ◽  
Magnetic Particles ◽  
Independent Solution ◽  
Magnetic Flux Density ◽  
Mixing Efficiency ◽  
Water Mixture

This paper reports the numerical and experimental investigation on magnetic particle concentration in a uniform magnetic field. The flow system consists of water-based ferrofluid and glycerol/DI water mixture streams. Two regimes were observed with spreading and mixing phenomena. With a low magnetic field strength, the spread of magnetic particles is caused by improved diffusion migration. With a relatively high field strength, instability at the interface would occur due to the mismatch in magnetization of the fluid streams. The transport of magnetic particles is induced by chaotic mixing of the fluids caused by a secondary flow. The mixing phenomena are characterized by magnetic flux density. For configuration with flow rate and viscosity ratio (between diamagnetic and magnetic streams) being set at 1 and 0.5, the mixing efficiency analyzed based on magnetic particles concentration increases approximately by 0.3 at around 3.5 mT. This value of magnetic flux density indicates the requirement on instability inception. The mixing efficiency increases with magnetic flux density increases further. Complete mixing can be achieved with a magnetic flux density at around 10 mT. The magnetic approach offers a wireless, heat-free and pH-independent solution for a lab-on-a-chip system.

scholarly journals Observations of solar small-scale magnetic flux-sheet emergence

2019 ◽  
Vol 622 ◽  
pp. L12 ◽  
Author(s):  
C. E. Fischer ◽  
J. M. Borrero ◽  
N. Bello González ◽  
A. J. Kaithakkal
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Large Scale ◽  
Magnetic Loop ◽  
Field Vector ◽  
Magnetic Flux Density ◽  
Small Scale ◽  
Flux Emergence ◽  
Vector Information

Aims. Two types of flux emergence were recently discovered in numerical simulations: magnetic loops and magnetic sheet emergence. While magnetic loop emergence has been documented well in recent years using high-resolution full Stokes data from ground-based telescopes as well as satellites, magnetic sheet emergence is still an understudied process. We report here on the first clear observational evidence of a magnetic sheet emergence and characterise its development. Methods. Full Stokes spectra from the Hinode spectropolarimeter were inverted with the Stokes Inversion based on Response functions (SIR) code to obtain solar atmospheric parameters such as temperature, line-of-sight velocities, and full magnetic field vector information. Results. We analyse a magnetic flux emergence event observed in the quiet-Sun internetwork. After a large-scale appearance of linear polarisation, a magnetic sheet with horizontal magnetic flux density of up to 194 Mx cm−2 hovers in the low photosphere spanning a region of 2–3 arcsec. The magnetic field azimuth obtained through Stokes inversions clearly shows an organised structure of transversal magnetic flux density emerging. The granule below the magnetic flux sheet tears the structure apart leaving the emerged flux to form several magnetic loops at the edges of the granule. Conclusions. A large amount of flux with strong horizontal magnetic fields surfaces through the interplay of buried magnetic flux and convective motions. The magnetic flux emerges within 10 minutes and we find a longitudinal magnetic flux at the foot points of the order of ∼1018 Mx. This is one to two orders of magnitude larger than what has been reported for small-scale magnetic loops. The convective flows feed the newly emerged flux into the pre-existing magnetic population on a granular scale.

A New Concept of Multimode Magnetorheological Brake Design

2014 ◽  
Vol 605 ◽  
pp. 271-274 ◽  
Author(s):  
L.H. Hamdan ◽  
Saiful Amri Mazlan ◽  
S. Sarip ◽  
Hairi Zamzuri
Keyword(s):  
Magnetic Field ◽  
Magnetic Material ◽  
Field Strength ◽  
Outer Diameter ◽  
Disc Brake ◽  
Electromagnetic Coil ◽  
Mr Fluids ◽  
Simulation Results ◽  
The Magnetic Field ◽  
Rotational Shear

This paper presents a magnetorheological (MR) brake design by using additional squeeze working mode to an existing conventional rotational shear. The MR brake was designed with consideration given to a new concept of braking mechanism with the help of magnetic simulation. Important parameters such as disc brake dimensions, clearance gap and electromagnetic coil configuration were taken into account when constructed the MR brake. Simulation results showed that the magnetic field strength was at best by having the magnetic coil beside the non-magnetic material, which was located at the end of the outer diameter. Meanwhile, the value of magnetic field was greater than when a small squeeze gap was applied. Eventually, the design will provide an opportunity to study and consequently understand on how the MR fluids react to such operating condition in order to be realized in the MR brake.

ANSYS Simulation Analysis of the Tri-Axial Pipeline Magnetic Flux Leakage In-Line Inspection

2012 ◽  
Vol 490-495 ◽  
pp. 2086-2090
Author(s):  
Li Jian Yang ◽  
Yan Xiu Su ◽  
Song Wei Gao
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Magnetic Flux ◽  
Simulation Analysis ◽  
Magnetic Flux Leakage ◽  
Ansys Simulation ◽  
Leakage Magnetic Field ◽  
Simulation Results ◽  
Flux Leakage ◽  
Three Components

In order to improve the detect performance of the traditional pipeline magnetic flux leakage(MFL) in-line inspection tools, the method of tri-axial pipeline MFL in-line inspection is advanced. By the three leakage magnetic field components: axial, radial and circumferential, the pipeline defects are recognized. Applying finite element method to build the simulation model of pipeline MFL in-line inspection, then proceeding 3-D simulation analysis. The three components of leakage magnetic field (axial, radial and circumferential) can be obtained by using ANSYS 3-D simulation, and the pipeline defects’ existence as well as the change of the defect’s size can be estimated by the three components’ graph. The simulation results indicate: By the ANSYS 3-D simulation, it proves that the tri-axial pipeline MFL in-line inspection can be achieved and the inspection can be used to improve the level of traditional pipeline MFL in-line inspection.

scholarly journals On the Stability of Magnetic Flux Tubes in the Equator of a Star

1993 ◽  
Vol 157 ◽  
pp. 45-48
Author(s):  
A. Ferriz-Mas ◽  
M. Schüssler
Keyword(s):  
Magnetic Field ◽  
Angular Velocity ◽  
Field Strength ◽  
Magnetic Flux ◽  
Magnetic Field Strength ◽  
Equatorial Plane ◽  
Flux Tubes ◽  
Magnetic Flux Tubes ◽  
Rotating Star ◽  
The Stability

We consider the linear stability of a toroidal flux tube lying in the equatorial plane of a differentially rotating star and investigate its dependence on superadiabaticity, magnetic field strength, and gradient of angular velocity.

scholarly journals Effect of Pole Shoe Design on Inclination Angle of Different Magnetic Fields in Permanent Magnet Machines

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2437
Author(s):  
Jonathan Sjölund ◽  
Sandra Eriksson
Keyword(s):  
Magnetic Field ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Field Strength ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Magnetic Circuit ◽  
Magnetic Flux Density ◽  
Element Analysis ◽  
Inclination Angles

Electromagnetic modelling of electrical machines through finite element analysis is an important design tool for detailed studies of high resolution. Through the usage of finite element analysis, one can study the electromagnetic fields for information that is often difficult to acquire in an experimental test bench. The requirement for accurate result is that the magnetic circuit is modelled in a correct way, which may be more difficult to maintain for rare earth free permanent magnets with an operating range that is more likely to be close to non-linear regions for the relation between magnetic flux density and magnetic field strength. In this paper, the inclination angles of the magnetic flux density, magnetic field strength and magnetization are studied and means to reduce the inclination angles are investigated. Both rotating and linear machines are investigated in this paper, with different current densities induced in the stator windings. By proper design of the pole shoes, one can reduce the inclination angles of the fields in the permanent magnet. By controlling the inclination angles, one can both enhance the performance of the magnetic circuit and increase the accuracy of simpler models for permanent magnet modelling.

Sign in / Sign up

Export Citation Format

Share Document