Small-scale Magnetic Flux Ropes in the First two Parker Solar Probe Encounters. (arXiv:2007.04551v1 [physics.space-ph])

Small-scale Magnetic Flux Ropes in the First two Parker Solar Probe Encounters. (arXiv:2007.04551v1 [physics.space-ph])
<a href="http://arxiv.org/find/physics/1/au:+Chen_Y/0/1/0/all/0/1">Yu Chen</a>, <a href="http://arxiv.org/find/physics/1/au:+Hu_Q/0/1/0/all/0/1">Qiang Hu</a>, <a href="http://arxiv.org/find/physics/1/au:+Zhao_L/0/1/0/all/0/1">Lingling Zhao</a>, <a href="http://arxiv.org/find/physics/1/au:+Kasper_J/0/1/0/all/0/1">Justin C. Kasper</a>, <a href="http://arxiv.org/find/physics/1/au:+Bale_S/0/1/0/all/0/1">Stuart D. Bale</a>, <a href="http://arxiv.org/find/physics/1/au:+Korreck_K/0/1/0/all/0/1">Kelly E. Korreck</a>, <a href="http://arxiv.org/find/physics/1/au:+Case_A/0/1/0/all/0/1">Anthony W. Case</a>, <a href="http://arxiv.org/find/physics/1/au:+Stevens_M/0/1/0/all/0/1">Michael L. Stevens</a>, <a href="http://arxiv.org/find/physics/1/au:+Bonnell_J/0/1/0/all/0/1">John W. Bonnell</a>, <a href="http://arxiv.org/find/physics/1/au:+Goetz_K/0/1/0/all/0/1">Keith Goetz</a>, <a href="http://arxiv.org/find/physics/1/au:+Harvey_P/0/1/0/all/0/1">Peter R. Harvey</a>, <a href="http://arxiv.org/find/physics/1/au:+Klein_K/0/1/0/all/0/1">Kristopher G. Klein</a>, <a href="http://arxiv.org/find/physics/1/au:+Larson_D/0/1/0/all/0/1">Davin E. Larson</a>, <a href="http://arxiv.org/find/physics/1/au:+Livi_R/0/1/0/all/0/1">Roberto Livi</a>, <a href="http://arxiv.org/find/physics/1/au:+MacDowall_R/0/1/0/all/0/1">Robert J. MacDowall</a>, <a href="http://arxiv.org/find/physics/1/au:+Malaspina_D/0/1/0/all/0/1">David M. Malaspina</a>, <a href="http://arxiv.org/find/physics/1/au:+Pulupa_M/0/1/0/all/0/1">Marc Pulupa</a>, <a href="http://arxiv.org/find/physics/1/au:+Whittlesey_P/0/1/0/all/0/1">Phyllis L. Whittlesey</a>

Small-scale magnetic flux ropes (SFRs) are a type of structures in the solar
wind that possess helical magnetic field lines. In a recent report (Chen & Hu
2020), we presented the radial variations of the properties of SFR from 0.29 to
8 au using in situ measurements from the Helios, ACE/Wind, Ulysses, and Voyager
spacecraft. With the launch of the Parker Solar Probe (PSP), we extend our
previous investigation further into the inner heliosphere. We apply a
Grad-Shafranov-based algorithm to identify SFRs during the first two PSP
encounters. We find that the number of SFRs detected near the Sun is much less
than that at larger radial distances, where magnetohydrodynamic (MHD)
turbulence may act as the local source to produce these structures. The
prevalence of Alfvenic structures significantly suppresses the detection of
SFRs at closer distances. We compare the SFR event list with other event
identification methods, yielding a dozen well-matched events. The cross-section
maps of two selected events confirm the cylindrical magnetic flux rope
configuration. The power-law relation between the SFR magnetic field and
heliocentric distances seems to hold down to 0.16 au.

Small-scale magnetic flux ropes (SFRs) are a type of structures in the solar
wind that possess helical magnetic field lines. In a recent report (Chen & Hu
2020), we presented the radial variations of the properties of SFR from 0.29 to
8 au using in situ measurements from the Helios, ACE/Wind, Ulysses, and Voyager
spacecraft. With the launch of the Parker Solar Probe (PSP), we extend our
previous investigation further into the inner heliosphere. We apply a
Grad-Shafranov-based algorithm to identify SFRs during the first two PSP
encounters. We find that the number of SFRs detected near the Sun is much less
than that at larger radial distances, where magnetohydrodynamic (MHD)
turbulence may act as the local source to produce these structures. The
prevalence of Alfvenic structures significantly suppresses the detection of
SFRs at closer distances. We compare the SFR event list with other event
identification methods, yielding a dozen well-matched events. The cross-section
maps of two selected events confirm the cylindrical magnetic flux rope
configuration. The power-law relation between the SFR magnetic field and
heliocentric distances seems to hold down to 0.16 au.

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