scholarly journals Magnetic Flux Ropes of Venus: A Paradigm for Helical Magnetic Structures in Astrophysical Systems

1985 ◽  
Vol 107 ◽  
pp. 43-46
Author(s):  
R. C. Elphic
Keyword(s):  
Magnetic Flux ◽  
Small Scale ◽  
Magnetic Structures ◽  
Magnetic Flux Ropes ◽  
Kink Mode ◽  
Cylindrically Symmetric ◽  
Direct Measurements ◽  
Flux Ropes ◽  
Symmetric Structures

The magnetic flux ropes of Venus are small scale (ion gyroradius) cylindrically symmetric structures observed in situ by the Pioneer Venus orbiter in the largely magnetic field-free ionosphere of the planet. They are so named because of their helical magnetic structure, which in turn is due to primarily field-aligned currents within the rope. Empirical models can be used to examine the current structure in detail, and these models indicate that flux ropes may be unstable to the helical kink mode. Statistics of rope distribution and orientation also support this instability picture. The results of investigations into the direct measurements of Venus flux ropes may be relevant to certain astrophysical phenomena that must be observed remotely.

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

2021 ◽  
Vol 914 (2) ◽  
pp. 108
Author(s):  
Yu Chen ◽  
Qiang Hu ◽  
Lingling Zhao ◽  
Justin C. Kasper ◽  
Jia Huang
Keyword(s):  
Magnetic Flux ◽  
Small Scale ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
In Situ Observations

scholarly journals Small-scale Magnetic Flux Ropes and Their Properties Based on In Situ Measurements from the Parker Solar Probe

2022 ◽  
Vol 924 (2) ◽  
pp. 43
Author(s):  
Yu Chen ◽  
Qiang Hu
Keyword(s):  
Magnetic Flux ◽  
Flux Rope ◽  
Residual Energy ◽  
In Situ Measurements ◽  
Small Scale ◽  
Flux Function ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Field Lines

Abstract We report small-scale magnetic flux ropes via the in situ measurements from the Parker Solar Probe during the first six encounters, and present additional analyses to supplement our prior work in Chen et al. These flux ropes are detected by the Grad–Shafranov-based algorithm, with their durations and scale sizes ranging from 10 s to ≲1 hr and from a few hundred kilometers to 10−3 au, respectively. They include both static structures and those with significant field-aligned plasma flows. Most structures tend to possess large cross helicity, while the residual energy is distributed over wide ranges. We find that these dynamic flux ropes mostly propagate in the antisunward direction relative to the background solar wind, with no preferential signs of magnetic helicity. The magnetic flux function follows a power law and is proportional to scale size. We also present case studies showing reconstructed two-dimensional (2D) configurations, which confirm that both the static and dynamic flux ropes have a common configuration of spiral magnetic field lines (also streamlines). Moreover, the existence of such events hints at interchange reconnection as a possible mechanism for generating flux rope-like structures near the Sun. Lastly, we summarize the major findings, and discuss the possible correlation between these flux rope-like structures and turbulence due to the process of local Alfvénic alignment.

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>

scholarly journals Statistical Study of Small-Scale Interplanetary Magnetic Flux Ropes in the Vicinity of the Heliospheric Current Sheet

2021 ◽  
Vol 9 ◽  
Author(s):  
Qiang Liu ◽  
Yan Zhao ◽  
Guoqing Zhao
Keyword(s):  
Magnetic Flux ◽  
Current Sheet ◽  
Interplanetary Space ◽  
Axial Direction ◽  
Heliospheric Current Sheet ◽  
Normal Direction ◽  
Small Scale ◽  
Magnetic Structures ◽  
Magnetic Flux Ropes ◽  
Flux Ropes

The small-scale interplanetary magnetic flux ropes (SIMFRs) are common magnetic structures in the interplanetary space, yet their origination is still an open question. In this article, we surveyed 63 SIMFRs found within 6-day window around the heliospheric current sheet (HCS) and investigated their axial direction, as well as the local normal direction of the HCS. Results showed that the majority (48/63) of the SIMFRs were quasi-parallel to the associated HCS (i.e., the axial direction of SIMFRs was quasi-perpendicular to the normal direction of the associated HCS). They also showed that the SIMFRs quasi-parallel to the associated HCS statistically had shorter duration than the cases quasi-perpendicular. The results indicate that most of these SIMFRs may be generated in the nearby HCSs.

scholarly journals Investigating 1st and 2nd order Fermi acceleration of energetic particles by small-scale magnetic flux ropes at 1AU

2020 ◽  
Vol 1620 ◽  
pp. 012008
Author(s):  
J A le Roux ◽  
G M Webb ◽  
O V Khabarova ◽  
K T Van Eck ◽  
L-L Zhao ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Energetic Particles ◽  
Small Scale ◽  
Fermi Acceleration ◽  
Magnetic Flux Ropes ◽  
Flux Ropes
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