scholarly journals Spiky electric and magnetic field structures in flux rope experiments

2018 ◽  
Vol 116 (37) ◽  
pp. 18239-18244 ◽  
Author(s):  
W. Gekelman ◽  
S. W. Tang ◽  
T. DeHaas ◽  
S. Vincena ◽  
P. Pribyl ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Laboratory Experiments ◽  
Magnetic Energy ◽  
Flux Rope ◽  
Building Blocks ◽  
Counting Method ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Corona Of The Sun ◽  
Probability Density Function Pdf

Magnetic flux ropes are structures that are common in the corona of the sun and presumably all stars. They can be thought of as the building blocks of solar structures. They have been observed in Earth’s magnetotail and near Mars and Venus. When multiple flux ropes are present magnetic field line reconnection, which converts magnetic energy to other forms, can occur when they collide. The structure of multiple magnetic ropes, the interactions between multiple ropes, and their topological properties such as helicity and writhing have been studied theoretically and in laboratory experiments. Here, we report on spiky potential and magnetic fields associated with the ropes. We show that the potential structures are chaotic for a range of their temporal half-widths and the probability density function (PDF) of their widths resembles the statistical distribution of crumpled paper. The spatial structure of the magnetic spikes is revealed using a correlation counting method. Computer simulation suggests that the potential structures are the nonlinear end result of an instability involving relative drift between ions and electrons.

scholarly journals Evolution of Plasma Composition in an Eruptive Flux Rope

2022 ◽  
Vol 924 (1) ◽  
pp. 17
Author(s):  
D. Baker ◽  
L. M. Green ◽  
D. H. Brooks ◽  
P. Démoulin ◽  
L. van Driel-Gesztelyi ◽  
...  
Keyword(s):  
Magnetic Energy ◽  
Flux Rope ◽  
Plasma Composition ◽  
Imaging Spectrometer ◽  
Polarity Inversion ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Free Magnetic Energy ◽  
Polarity Inversion Line ◽  
Euv Imaging

Abstract Magnetic flux ropes are bundles of twisted magnetic field enveloping a central axis. They harbor free magnetic energy and can be progenitors of coronal mass ejections (CMEs). However, identifying flux ropes on the Sun can be challenging. One of the key coronal observables that has been shown to indicate the presence of a flux rope is a peculiar bright coronal structure called a sigmoid. In this work, we show Hinode EUV Imaging Spectrometer observations of sigmoidal active region (AR) 10977. We analyze the coronal plasma composition in the AR and its evolution as a sigmoid (flux rope) forms and erupts as a CME. Plasma with photospheric composition was observed in coronal loops close to the main polarity inversion line during episodes of significant flux cancellation, suggestive of the injection of photospheric plasma into these loops driven by photospheric flux cancellation. Concurrently, the increasingly sheared core field contained plasma with coronal composition. As flux cancellation decreased and a sigmoid/flux rope formed, the plasma evolved to an intermediate composition in between photospheric and typical AR coronal compositions. Finally, the flux rope contained predominantly photospheric plasma during and after a failed eruption preceding the CME. Hence, plasma composition observations of AR 10977 strongly support models of flux rope formation by photospheric flux cancellation forcing magnetic reconnection first at the photospheric level then at the coronal level.

The evolution of magnetic flux ropes in sheared plasma flows

2000 ◽  
Vol 64 (1) ◽  
pp. 41-55 ◽  
Author(s):  
J. M. SCHMIDT ◽  
P. J. CARGILL
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Shear Layer ◽  
Cross Section ◽  
Circular Cross Section ◽  
Flux Rope ◽  
Plasma Pressure ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
The Magnetic Field

The evolution of magnetic flux ropes in a sheared plasma flow is investigated. When the magnetic field outside the flux rope lies parallel to the axis of the flux rope, a flux rope of circular cross-section, whose centre is located at the midpoint of the shear layer, has its shape distorted, but remains in the shear layer. Small displacements of the flux-rope centre above or below the midpoint of the shear layer lead to the flux-rope being expelled from the shear layer. This motion arises because small asymmetries in the plasma pressure around the flux-rope boundary leads to a force that forces the flux rope into a region of uniform flow. When the magnetic field outside the flux rope lies in a plane perpendicular to the flux-rope axis, the flux rope and external magnetic field reconnect with each other, leading to the destruction of the flux rope.

scholarly journals Non-Gaussianity and cross-scale coupling in interplanetary magnetic field turbulence during a rope–rope magnetic reconnection event

2018 ◽  
Vol 36 (2) ◽  
pp. 497-507 ◽  
Author(s):  
Rodrigo A. Miranda ◽  
Adriane B. Schelin ◽  
Abraham C.-L. Chian ◽  
José L. Ferreira
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Coherent Structures ◽  
Flux Rope ◽  
Inertial Subrange ◽  
Order Moment ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Non Gaussian

Abstract. In a recent paper (Chian et al., 2016) it was shown that magnetic reconnection at the interface region between two magnetic flux ropes is responsible for the genesis of interplanetary intermittent turbulence. The normalized third-order moment (skewness) and the normalized fourth-order moment (kurtosis) display a quadratic relation with a parabolic shape that is commonly observed in observational data from turbulence in fluids and plasmas, and is linked to non-Gaussian fluctuations due to coherent structures. In this paper we perform a detailed study of the relation between the skewness and the kurtosis of the modulus of the magnetic field |B| during a triple interplanetary magnetic flux rope event. In addition, we investigate the skewness–kurtosis relation of two-point differences of |B| for the same event. The parabolic relation displays scale dependence and is found to be enhanced during magnetic reconnection, rendering support for the generation of non-Gaussian coherent structures via rope–rope magnetic reconnection. Our results also indicate that a direct coupling between the scales of magnetic flux ropes and the scales within the inertial subrange occurs in the solar wind. Keywords. Space plasma physics (turbulence)

Direct evidence of secondary reconnection inside filamentary currents of magnetic flux ropes in magnetic reconnection

2020 ◽  
Author(s):  
Shimou Wang ◽  
Quanming Lu
Keyword(s):  
Energy Dissipation ◽  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Magnetic Energy ◽  
Flux Rope ◽  
Plasma Jets ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Reconnecting Current Sheet

<p>Magnetic reconnection is a fundamental plasma process, by which magnetic energy is explosively released in the current sheet to energize charged particles and to create bi-directional Alfvénic plasma jets. A long-outstanding issue is how the stored magnetic energy is rapidly released in the process. Numerical simulations and observations show that formation and interaction of magnetic flux ropes dominate the evolution of the reconnecting current sheet. Accordingly, most volume of the reconnecting current sheet is occupied by the flux ropes and energy dissipation primarily occurs along their edges via the flux rope coalescence. Here, for the first time, we present in-situ evidence of magnetic reconnection inside the filamentary currents which was driven possibly by electron vortices inside the flux ropes. Our results reveal an important new way for energy dissipation in magnetic reconnection.</p>

scholarly journals The structure of flux transfer events recovered from Cluster data

2006 ◽  
Vol 24 (2) ◽  
pp. 603-618 ◽  
Author(s):  
H. Hasegawa ◽  
B. U. Ö. Sonnerup ◽  
C. J. Owen ◽  
B. Klecker ◽  
G. Paschmann ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Rope ◽  
Time Interval ◽  
Reconstruction Technique ◽  
Magnetic Flux Ropes ◽  
Flux Transfer Events ◽  
Cluster Data ◽  
Flux Ropes ◽  
Flux Transfer

Abstract. The structure and formation mechanism of a total of five Flux Transfer Events (FTEs), encountered on the equatorward side of the northern cusp by the Cluster spacecraft, with separation of ~5000 km, are studied by applying the Grad-Shafranov (GS) reconstruction technique to the events. The technique generates a magnetic field/plasma map of the FTE cross section, using combined magnetic field and plasma data from all four spacecraft, under the assumption that the structure is two-dimensional (2-D) and time-independent. The reconstructed FTEs consist of one or more magnetic flux ropes embedded in the magnetopause, suggesting that multiple X-line reconnection was involved in generating the observed FTEs. The dimension of the flux ropes in the direction normal to the magnetopause ranges from about 2000 km to more than 1 RE. The orientation of the flux rope axis can be determined through optimization of the GS map, the result being consistent with those from various single-spacecraft methods. Thanks to this, the unambiguous presence of a strong core field is confirmed, providing evidence for component merging. The amount of magnetic flux contained within each flux rope is calculated from the map and, by dividing it by the time interval between the preceding FTE and the one reconstructed, a lower limit of the reconnection electric field during the creation of the flux rope can be estimated; the estimated value ranges from ~0.11 to ~0.26 mV m-1, with an average of 0.19 mV m-1. This can be translated to the reconnection rate of 0.038 to 0.074, with an average of 0.056. Based on the success of the 2-D model in recovering the observed FTEs, the length of the X-lines is estimated to be at least a few RE.

Study of flux-rope characteristics at sub-astronomical-unit distances using the Helios 1 and 2 spacecraft

2020 ◽  
Vol 495 (2) ◽  
pp. 1566-1576
Author(s):  
Anil Raghav ◽  
Sandesh Gaikwad ◽  
Yuming Wang ◽  
Zubair I Shaikh ◽  
Wageesh Mishra ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Magnetic Energy ◽  
Ambient Medium ◽  
Flux Rope ◽  
Magnetic Clouds ◽  
Astronomical Unit ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
External Conditions ◽  
Internal Properties

ABSTRACT Magnetic flux ropes observed as magnetic clouds near 1 au have been extensively studied in the literature and their distinct features are derived using numerous models. These studies summarize the general characteristics of flux ropes at 1 au without providing an understanding of the continuous evolution of the flux ropes from near the Sun to 1 au. In the present study, we investigate 26 flux ropes observed by the Helios 1 and 2 spacecraft (from 0.3 to 1 au) using the velocity-modified Gold–Hoyle model. The correlation and regression analyses suggest that the expansion speed, poloidal speed, total magnetic helicity and twist per au of the flux rope are independent of heliospheric distance. The study implies that the aforementioned features are more strongly influenced by their internal properties compared with external conditions in the ambient medium. Moreover, the poloidal magnetic flux and magnetic energy of the studied flux ropes exhibit power-law dependence on heliospheric distance. A better understanding of the underlying physics and corroboration of these results is expected from the Parker Solar Probe measurements in the near future.

scholarly journals Confined and Eruptive Catastrophes of Solar Magnetic Flux Ropes Caused by Mass Loading and Unloading

2021 ◽  
Vol 921 (2) ◽  
pp. 172
Author(s):  
Quanhao Zhang ◽  
Rui Liu ◽  
Yuming Wang ◽  
Xiaolei Li ◽  
Shaoyu Lyu
Keyword(s):  
Magnetic Flux ◽  
Total Mass ◽  
Large Scale ◽  
Magnetic Energy ◽  
Flux Rope ◽  
Mass Loading ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Loading And Unloading ◽  
Rope System

Abstract It is widely accepted that coronal magnetic flux ropes are the core structures of large-scale solar eruptive activities, which have a dramatic impact on the solar-terrestrial system. Previous studies have demonstrated that varying magnetic properties of a coronal flux rope system could result in a catastrophe of the rope, which may trigger solar eruptive activities. Since the total mass of a flux rope also plays an important role in stabilizing the rope, we use 2.5 dimensional magnetohydrodynamic numerical simulations in this article to investigate how a flux rope evolves as its total mass varies. It is found that an unloading process that decreases the total mass of the rope could result in an upward (eruptive) catastrophe in the flux rope system, during which the rope jumps upward and the magnetic energy is released. This indicates that mass unloading processes could initiate the eruption of the flux rope. Moreover, when the system is not too diffusive, there is also a downward (confined) catastrophe that could be caused by mass loading processes via which the total mass accumulates. The magnetic energy, however, is increased during the downward catastrophe, indicating that mass loading processes could cause confined activities that may contribute to the storage of energy before the onset of coronal eruptions.

scholarly journals Small-scale Magnetic Flux Ropes with Field-aligned Flows via the PSP In-situ Observations

2021 ◽  
Author(s):  
Yu Chen ◽  
Qiang Hu ◽  
Lingling Zhao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Rope ◽  
Local Magnetic Field ◽  
Small Scale ◽  
Magnetic Flux Rope ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Field Lines

<p>Magnetic flux rope, formed by the helical magnetic field lines, can sometimes remain its shape while carrying significant plasma flow that is aligned with the local magnetic field. We report the existence of such structures and static flux ropes by applying the Grad-Shafranov-based algorithm to the Parker Solar Probe (PSP) in-situ measurements in the first five encounters. These structures are detected at heliocentric distances, ranging from 0.13 to 0.66 au, in a total of 4-month time period. We find that flux ropes with field-aligned flows have certain properties similar to those of static flux ropes, such as the decaying relations of the magnetic fields within structures with respect to heliocentric distances. Moreover, these events are more likely with magnetic pressure dominating over the thermal pressure and occurring more frequently in the relatively fast-speed solar wind. Taking into account the high Alfvenicity, we also compare these events with switchbacks and present the cross-section maps via the new Grad-Shafranov type reconstruction. Finally, the possible evolution and relaxation of the magnetic flux rope structures are discussed.</p>

Parker Solar Probe Observations of Alfvénic Waves and Ion-cyclotron Waves in a Small-scale Flux Rope

2021 ◽  
Author(s):  
Chen Shi ◽  
Jinsong Zhao ◽  
Jia Huang ◽  
Tieyan Wang ◽  
Dejin Wu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Flux Rope ◽  
Small Scale ◽  
Power Law Distribution ◽  
Magnetic Flux Ropes ◽  
Ion Cyclotron Waves ◽  
Ion Cyclotron ◽  
Flux Ropes ◽  
The Magnetic Field

<p>Magnetic flux ropes can play important roles in transferring the mass, momentum, and energy in the interplanetary environment and in affecting space weather. Small-scale flux ropes (SFRs) are common in the interplanetary environment. However, SFRs with medium and high Alfvénicity are generally discarded in previous identification procedures. Using Parker Solar Probe measurements, we identify an SFR event with medium Alfvénicity in the inner heliosphere (at ~ 0.2 au). Based on high correlations between the magnetic field and velocity fluctuations, we show Alfvénic waves arising inside such SFR. We also show occurrence of quasi-monochromatic electromagnetic waves at the leading and trailing edges of this SFR. These waves are well explained by the outward-propagating ion-cyclotron waves, which have wave frequencies ~ 0.03 - 0.3 Hz and wavelengths ~ 60 - 2000 km in the plasma frame. Furthermore, we show that the power spectral density of the magnetic field in SFR middle region follows the power-law distribution, where the spectral index changes from -1.5 (f <~ 1 Hz) to -3.3 (f >~ 1 Hz). These findings would motivate developing an automated program to identify SFRs with medium and high Alfvénicity from Alfvénic waves structures.</p>

Dayside Magnetopause Reconnection and Flux Transfer Events: BepiColombo Earth-Flyby

2021 ◽  
Author(s):  
Wei-Jie Sun ◽  
James Slavin ◽  
Rumi Nakamura ◽  
Daniel Heyner ◽  
Johannes Mieth
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
European Space Agency ◽  
Flux Rope ◽  
Transfer Event ◽  
Flux Transfer Events ◽  
Space Agency ◽  
Flux Ropes ◽  
Flux Transfer ◽  
Magnetospheric Multiscale Mission

<p>BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. The BepiColombo mission consists of two spacecraft, which are the Mercury Planetary Orbiter (MPO) and Mercury Magnetospheric Orbiter (Mio). The mission made its first planetary flyby, which is the only Earth flyby, on 10 April 2020, during which several instruments collected measurements. In this study, we analyze MPO magnetometer (MAG) observations of Flux Transfer Events (FTEs) in the magnetosheath and the structure of the subsolar magnetopause near the  flow stagnation point. The magnetosheath plasma beta was high with a value of ~ 8 and the interplanetary magnetic field (IMF) was southward with a clock angle that decreased from ~ 100 degrees to ~ 150 degrees.  As the draped IMF became increasingly southward several of the flux transfer event (FTE)-type flux ropes were observed. These FTEs traveled southward indicating that the magnetopause X-line was located northward of the spacecraft, which is consistent with a dawnward tilt of the IMF. Most of the FTE-type flux ropes were in ion-scale, <10 s duration, suggesting that they were newly formed. Only one large-scale FTE-type flux rope, ~ 20 s, was observed. It was made up of two successive bipolar signatures in the normal magnetic field component, which is evidence of coalescence at a secondary reconnection site. Further analysis demonstrated that the dimensionless reconnection rate of the re-reconnection associated with the coalescence site was ~ 0.14. While this investigation was limited to the MPO MAG observations, it strongly supports a key feature of dayside reconnection discovered in the Magnetospheric Multiscale mission, the growth of FTE-type flux ropes through coalescence at secondary reconnection sites.</p>

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