The characteristics of sharp (small-scale) boundaries of solar wind plasma and magnetic field structures

Parker Solar Probe (PSP) routinely observes magnetic field deflections in the solar wind at distances less than 0.3 au from the Sun. These deflections are related to structures commonly called 'switchbacks' (SBs), whose origins and characteristic properties are currently debated. Here, we use a database of visually selected SB intervals - and regions of solar wind plasma measured just before and after each SB - to examine plasma parameters, turbulent spectra from inertial to dissipation scales, and intermittency effects in these intervals. We find that many features, such as perpendicular stochastic heating rates and turbulence spectral slopes are fairly similar inside and outside of SBs. However, important kinetic properties, such as the characteristic break scale between the inertial to dissipation ranges differ inside and outside these intervals, as does the level of intermittency, which is notably enhanced inside SBs and in their close proximity, most likely due to magnetic field and velocity shears observed at the edges. We conclude that the plasma inside and outside of a SB, in most of the observed cases, belongs to the same stream, and that the evolution of these structures is most likely regulated by kinetic processes, which dominate small scale structures at the SB edges.&#160;

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The small spacecraft with a magnetic sail on high-temperature superconductors

Space engineering and technology ◽

10.33950/spacetech-2308-7625-2021-2-51-61 ◽

2021 ◽

pp. 51-61

Author(s):

Timur Sh. KOMBAEV ◽

Mikhail K. ARTEMOV ◽

Valentin K. SYSOEV ◽

Dmitry S. DEZHIN

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

High Temperature ◽

Shape Memory ◽

New Technologies ◽

High Temperature Superconductors ◽

Solar Wind Plasma ◽

Large Area ◽

Small Spacecraft ◽

Shape Memory Materials

It is proposed to develop a small spacecraft for an experiment using high-temperature superconductors (HTS) and shape memory materials. The purpose of the experiment is to test a technological capability of creating a strong magnetic field on the small spacecraft using HTS and shape memory materials for deployed large-area structures, and study the magnetic field interaction with the solar wind plasma and the resulting force impact on the small spacecraft. This article is of a polemical character and makes it possible to take a fresh look at the applicability of new technologies in space-system engineering. Key words: high-temperature superconductors, shape memory materials, solar wind, spacecraft.

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HelioSwarm: The Nature of Turbulence in Space Plasmas

10.5194/egusphere-egu21-12092 ◽

2021 ◽

Author(s):

Harlan Spence ◽

Kristopher Klein ◽

HelioSwarm Science Team

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Large Scale ◽

Solar Wind Plasma ◽

Turbulent Energy ◽

Space Plasmas ◽

Plasma Parameters ◽

Astrophysical Plasmas ◽

Ion Distributions ◽

Background Magnetic Field

Recently selected for phase A study for NASA&#8217;s Heliophysics MidEx Announcement of Opportunity, the HelioSwarm Observatory proposes to transform our understanding of the physics of turbulence in space and astrophysical plasmas by deploying nine spacecraft to measure the local plasma and magnetic field conditions at many points, with separations between the spacecraft spanning MHD and ion scales.&#160;&#160;HelioSwarm resolves the transfer and dissipation of turbulent energy in weakly-collisional magnetized plasmas with a novel configuration of spacecraft in the solar wind. These simultaneous multi-point, multi-scale measurements of space plasmas allow us to reach closure on two science goals comprised of six science objectives: (1) reveal how turbulent energy is transferred in the most probable, undisturbed solar wind plasma and distributed as a function of scale and time; (2) reveal how this turbulent cascade of energy varies with the background magnetic field and plasma parameters in more extreme solar wind environments; (3) quantify the transfer of turbulent energy between fields, flows, and ion heat; (4) identify thermodynamic impacts of intermittent structures on ion distributions; (5) determine how solar wind turbulence affects and is affected by large-scale solar wind structures; and (6) determine how strongly driven turbulence differs from that in the undisturbed solar wind.&#160;

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Plasma and Magnetic Field Turbulence in the Earth’s Magnetosheath at Ion Scales

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2020.616635 ◽

2021 ◽

Vol 7 ◽

Author(s):

Liudmila Rakhmanova ◽

Maria Riazantseva ◽

Georgy Zastenker

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Wind Plasma ◽

Bow Shock ◽

Present Review ◽

Wind Effects ◽

Earth’S Bow Shock ◽

Magnetic Field Turbulence ◽

Plasma Measurements ◽

Turbulent Cascade

Crossing the Earth’s bow shock is known to crucially affect solar wind plasma including changes in turbulent cascade. The present review summarizes results of more than 15 years of experimental exploration into magnetosheath turbulence. Great contributions to understanding turbulence development inside the magnetosheath was made by means of recent multi-spacecraft missions. We introduce the main results provided by them together with first observations of the turbulent cascade based on direct plasma measurements by the Spektr-R spacecraft in the magnetosheath. Recent results on solar wind effects on turbulence in the magnetosheath are also discussed.

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Statistical relations between in-situ measured Bz component and thermospheric density variations

10.5194/egusphere-egu21-4773 ◽

2021 ◽

Author(s):

Sofia Kroisz ◽

Lukas Drescher ◽

Manuela Temmer ◽

Sandro Krauss ◽

Barbara Süsser-Rechberger ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Measurements ◽

Satellite Orbit ◽

Solar Wind Plasma ◽

Statistical Investigation ◽

Neutral Density ◽

Special Focus ◽

Short Term

Through advanced statistical investigation and evaluation of solar wind plasma and magnetic field data, we investigate the statistical relation between the magnetic field Bz component, measured at L1, and Earth&#8217;s thermospheric neutral density. We will present preliminary results of the time series analyzes using in-situ plasma and magnetic field measurements from different spacecraft in near Earth space (e.g., ACE, Wind, DSCOVR) and relate those to derived thermospheric densities from various satellites (e.g., GRACE, CHAMP). The long and short term variations and dependencies in the solar wind data are related to variations in the neutral density of the thermosphere and geomagnetic indices. Special focus is put on the specific signatures that stem from coronal mass ejections and stream or corotating interaction regions.&#160; The results are used to develop a novel short-term forecasting model called SODA (Satellite Orbit DecAy). This is a joint study between TU Graz and University of Graz funded by the FFG Austria (project &#8220;SWEETS&#8221;).

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MHD and Ion Kinetic Waves in Field-aligned Flows Observed by Parker Solar Probe

The Astrophysical Journal ◽

10.3847/1538-4357/ac28fb ◽

2021 ◽

Vol 922 (2) ◽

pp. 188

Author(s):

L.-L. Zhao ◽

G. P. Zank ◽

J. S. He ◽

D. Telloni ◽

L. Adhikari ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Whistler Wave ◽

Spectral Energy ◽

Small Scale ◽

The Sun ◽

Fast Mode ◽

Magnetic Fluctuations ◽

Background Magnetic Field ◽

Ion Cyclotron

Abstract Parker Solar Probe (PSP) observed predominately Alfvénic fluctuations in the solar wind near the Sun where the magnetic field tends to be radially aligned. In this paper, two magnetic-field-aligned solar wind flow intervals during PSP’s first two orbits are analyzed. Observations of these intervals indicate strong signatures of parallel/antiparallel-propagating waves. We utilize multiple analysis techniques to extract the properties of the observed waves in both magnetohydrodynamic (MHD) and kinetic scales. At the MHD scale, outward-propagating Alfvén waves dominate both intervals, and outward-propagating fast magnetosonic waves present the second-largest contribution in the spectral energy density. At kinetic scales, we identify the circularly polarized plasma waves propagating near the proton gyrofrequency in both intervals. However, the sense of magnetic polarization in the spacecraft frame is observed to be opposite in the two intervals, although they both possess a sunward background magnetic field. The ion-scale plasma wave observed in the first interval can be either an inward-propagating ion cyclotron wave (ICW) or an outward-propagating fast-mode/whistler wave in the plasma frame, while in the second interval it can be explained as an outward ICW or inward fast-mode/whistler wave. The identification of the exact kinetic wave mode is more difficult to confirm owing to the limited plasma data resolution. The presence of ion-scale waves near the Sun suggests that ion cyclotron resonance may be one of the ubiquitous kinetic physical processes associated with small-scale magnetic fluctuations and kinetic instabilities in the inner heliosphere.

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On the probability distribution function of small-scale interplanetary magnetic field fluctuations

Annales Geophysicae ◽

10.5194/angeo-22-3751-2004 ◽

2004 ◽

Vol 22 (10) ◽

pp. 3751-3769 ◽

Cited By ~ 38

Author(s):

R. Bruno ◽

V. Carbone ◽

L. Primavera ◽

F. Malara ◽

L. Sorriso-Valvo ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Robust Statistics ◽

Interplanetary Space ◽

Parametric Instability ◽

Field Vector ◽

Small Scale ◽

Magnetic Fluctuations ◽

Mhd Turbulence ◽

The One

Abstract. In spite of a large number of papers dedicated to the study of MHD turbulence in the solar wind there are still some simple questions which have never been sufficiently addressed, such as: a) Do we really know how the magnetic field vector orientation fluctuates in space? b) What are the statistics followed by the orientation of the vector itself? c) Do the statistics change as the wind expands into the interplanetary space? A better understanding of these points can help us to better characterize the nature of interplanetary fluctuations and can provide useful hints to investigators who try to numerically simulate MHD turbulence. This work follows a recent paper presented by some of the authors which shows that these fluctuations might resemble a sort of random walk governed by Truncated Lévy Flight statistics. However, the limited statistics used in that paper did not allow for final conclusions but only speculative hypotheses. In this work we aim to address the same problem using more robust statistics which, on the one hand, forces us not to consider velocity fluctuations but, on the other hand, allows us to establish the nature of the governing statistics of magnetic fluctuations with more confidence. In addition, we show how features similar to those found in the present statistical analysis for the fast speed streams of solar wind are qualitatively recovered in numerical simulations of the parametric instability. This might offer an alternative viewpoint for interpreting the questions raised above.

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Impact of solar wind depression on the dayside magnetosphere under northward interplanetary magnetic field

Annales Geophysicae ◽

10.5194/angeo-29-31-2011 ◽

2011 ◽

Vol 29 (1) ◽

pp. 31-46 ◽

Cited By ~ 2

Author(s):

S. Baraka ◽

L. Ben-Jaffel

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Interplanetary Magnetic Field ◽

Cell Model ◽

Dynamic Pressure ◽

Outer Boundary ◽

Solar Wind Plasma ◽

Tail Region ◽

Dayside Magnetopause

Abstract. We present a follow up study of the sensitivity of the Earth's magnetosphere to solar wind activity using a particles-in-cell model (Baraka and Ben Jaffel, 2007), but here during northward Interplanetary Magnetic Field (IMF). The formation of the magnetospheric cavity and its elongation around the planet is obtained with the classical structure of a magnetosphere with parallel lobes. An impulsive disturbance is then applied to the system by changing the bulk velocity of the solar wind to simulate a decrease in the solar wind dynamic pressure followed by its recovery. In response to the imposed drop in the solar wind velocity, a gap (abrupt depression) in the incoming solar wind plasma appears moving toward the Earth. The gap's size is a ~15 RE and is comparable to the sizes previously obtained for both Bz<0 and Bz=0. During the initial phase of the disturbance along the x-axis, the dayside magnetopause (MP) expands slower than the previous cases of IMF orientations as a result of the abrupt depression. The size of the MP expands nonlinearly due to strengthening of its outer boundary by the northward IMF. Also, during the initial 100 Δt, the MP shrank down from 13.3 RE to ~9.2 RE before it started expanding, a phenomenon that was also observed for southern IMF conditions but not during the no IMF case. As soon as they felt the solar wind depression, cusps widened at high altitude while dragged in an upright position. For the field's topology, the reconnection between magnetospheric and magnetosheath fields is clearly observed in both the northward and southward cusps areas. Also, the tail region in the northward IMF condition is more confined, in contrast to the fishtail-shape obtained in the southward IMF case. An X-point is formed in the tail at ~110 RE compared to ~103 RE and ~80 RE for Bz=0 and Bz<0, respectively. Our findings are consistent with existing reports from many space observatories (Cluster, Geotail, Themis, etc.) for which predictions are proposed to test furthermore our simulation technique.

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Predictions of local ground geomagnetic field fluctuations during the 7-10 November 2004 events studied with solar wind driven models

Annales Geophysicae ◽

10.5194/angeo-23-3095-2005 ◽

2005 ◽

Vol 23 (9) ◽

pp. 3095-3101 ◽

Cited By ~ 12

Author(s):

P. Wintoft ◽

M. Wik ◽

H. Lundstedt ◽

L. Eliasson

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Flow Direction ◽

Strong Dependence ◽

Solar Wind Plasma ◽

Magnetic Field Data ◽

Solar Wind Magnetic Field ◽

Solar Wind Flow ◽

Field Fluctuations ◽

Ground Magnetic

Abstract. The 7-10 November 2004 period contains two events for which the local ground magnetic field was severely disturbed and simultaneously, the solar wind displayed several shocks and negative Bz periods. Using empirical models the 10-min RMS and at Brorfelde (BFE, 11.67° E, 55.63° N), Denmark, are predicted. The models are recurrent neural networks with 10-min solar wind plasma and magnetic field data as inputs. The predictions show a good agreement during 7 November, up until around noon on 8 November, after which the predictions become significantly poorer. The correlations between observed and predicted log RMS is 0.77 during 7-8 November but drops to 0.38 during 9-10 November. For RMS the correlations for the two periods are 0.71 and 0.41, respectively. Studying the solar wind data for other L1-spacecraft (WIND and SOHO) it seems that the ACE data have a better agreement to the near-Earth solar wind during the first two days as compared to the last two days. Thus, the accuracy of the predictions depends on the location of the spacecraft and the solar wind flow direction. Another finding, for the events studied here, is that the and models showed a very different dependence on Bz. The model is almost independent of the solar wind magnetic field Bz, except at times when Bz is exceptionally large or when the overall activity is low. On the contrary, the model shows a strong dependence on Bz at all times.

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Dynamical evolution of the inner heliosphere approaching solar activity maximum: interpreting Ulysses observations using a global MHD model

Annales Geophysicae ◽

10.5194/angeo-21-1347-2003 ◽

2003 ◽

Vol 21 (6) ◽

pp. 1347-1357 ◽

Cited By ~ 17

Author(s):

P. Riley ◽

Z. Mikić ◽

J. A. Linker

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Maximum ◽

Dynamical Evolution ◽

Solar Wind Plasma ◽

Polar Regions ◽

Activity Maximum ◽

Interplanetary Magnetic Fields ◽

Interplanetary Physics ◽

Interaction Regions

Abstract. In this study we describe a series of MHD simulations covering the time period from 12 January 1999 to 19 September 2001 (Carrington Rotation 1945 to 1980). This interval coincided with: (1) the Sun’s approach toward solar maximum; and (2) Ulysses’ second descent to the southern polar regions, rapid latitude scan, and arrival into the northern polar regions. We focus on the evolution of several key parameters during this time, including the photospheric magnetic field, the computed coronal hole boundaries, the computed velocity profile near the Sun, and the plasma and magnetic field parameters at the location of Ulysses. The model results provide a global context for interpreting the often complex in situ measurements. We also present a heuristic explanation of stream dynamics to describe the morphology of interaction regions at solar maximum and contrast it with the picture that resulted from Ulysses’ first orbit, which occurred during more quiescent solar conditions. The simulation results described here are available at: http://sun.saic.com.Key words. Interplanetary physics (Interplanetary magnetic fields; solar wind plasma; sources of the solar wind)

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