scholarly journals Dynamics of He++ ions at interplanetary shocks

2020 ◽  
Author(s):  
Olga V. Sapunova ◽  
Natalia L. Borodkova ◽  
Georgii N. Zastenker ◽  
Yuri I. Yermolaev
Keyword(s):  
Solar Wind ◽  
Solar Wind Plasma ◽  
Interplanetary Shock ◽  
Helium Abundance ◽  
Interplanetary Shocks ◽  
Helium Ions ◽  
Wind Instrument ◽  
Absolute Density ◽  
Calculated Velocity ◽  
Α Particles

Abstract. Variations of parameters of twice-ionized helium ions – He++ ions or α-particles – in the solar wind plasma during the interplanetary shock front passage are investigated. We used the data measured by the BMSW (Bright Monitor of Solar Wind) instrument installed on the SPEKTR-R satellite, which operated since August 2011 to 2019 and registered 57 interplanetary shocks. According to received data, the parameters of He++ ions were calculated: velocity Vα, temperature Tα, absolute density Nα and relative density (helium abundance) Nα/Np. The correlation of changes in helium abundance Nα/Np with the parameters βi, θBn and MMS were investigated.

scholarly journals In situ local shock speed and transit shock speed

1998 ◽  
Vol 16 (4) ◽  
pp. 370-375 ◽  
Author(s):  
S. Watari ◽  
T. Detman
Keyword(s):  
Solar Wind ◽  
Solar Wind Plasma ◽  
Interplanetary Shock ◽  
Propagation Model ◽  
Interplanetary Shocks ◽  
Shock Speed ◽  
Interplanetary Physics ◽  
Speed Solar Wind ◽  
Transit Speed

Abstract. A useful index for estimating the transit speeds was derived by analyzing interplanetary shock observations. This index is the ratio of the in situ local shock speed and the transit speed; it is 0.6–0.9 for most observed shocks. The local shock speed and the transit speed calculated for the results of the magnetohydrodynamic simulation show good agreement with the observations. The relation expressed by the index is well explained by a simplified propagation model assuming a blast wave. For several shocks the ratio is approximately 1.2, implying that these shocks accelerated during propagation in slow-speed solar wind. This ratio is similar to that for the background solar wind acceleration.Keywords. Interplanetary physics (Flare and stream dynamics; Interplanetary shocks; Solar wind plasma)

scholarly journals Cluster observations of sudden impulses in the magnetotail caused by interplanetary shocks and pressure increases

2005 ◽  
Vol 23 (2) ◽  
pp. 609-624 ◽  
Author(s):  
K. E. J. Huttunen ◽  
J. Slavin ◽  
M. Collier ◽  
H. E. J. Koskinen ◽  
A. Szabo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Dynamic Pressure ◽  
Solar Wind Speed ◽  
Interplanetary Shock ◽  
Wind Pressure ◽  
Shock Propagation ◽  
Interplanetary Shocks ◽  
Maximum Variance ◽  
The Magnetic Field

Abstract. Sudden impulses (SI) in the tail lobe magnetic field associated with solar wind pressure enhancements are investigated using measurements from Cluster. The magnetic field components during the SIs change in a manner consistent with the assumption that an antisunward moving lateral pressure enhancement compresses the magnetotail axisymmetrically. We found that the maximum variance SI unit vectors were nearly aligned with the associated interplanetary shock normals. For two of the tail lobe SI events during which Cluster was located close to the tail boundary, Cluster observed the inward moving magnetopause. During both events, the spacecraft location changed from the lobe to the magnetospheric boundary layer. During the event on 6 November 2001 the magnetopause was compressed past Cluster. We applied the 2-D Cartesian model developed by collier98 in which a vacuum uniform tail lobe magnetic field is compressed by a step-like pressure increase. The model underestimates the compression of the magnetic field, but it fits the magnetic field maximum variance component well. For events for which we could determine the shock normal orientation, the differences between the observed and calculated shock propagation times from the location of WIND/Geotail to the location of Cluster were small. The propagation speeds of the SIs between the Cluster spacecraft were comparable to the solar wind speed. Our results suggest that the observed tail lobe SIs are due to lateral increases in solar wind dynamic pressure outside the magnetotail boundary.

scholarly journals Theoretical Interpretation of Traveling Interplanetary Phenomena and Their Solar Origins

1980 ◽  
Vol 91 ◽  
pp. 443-458 ◽  
Author(s):  
S. T. Wu
Keyword(s):  
Solar Wind ◽  
Wave Propagation ◽  
Interplanetary Shock ◽  
Theoretical Interpretation ◽  
Theoretical Studies ◽  
Interplanetary Shocks ◽  
Physical Processes ◽  
Mathematical Methods ◽  
Microscopic Approach ◽  
Alternative Approaches

Recent theoretical studies on Traveling Interplanetary Phenomena (TIP) and their relation or presumed relation to their solar origins will be reviewed. An attempt is made to outline the theoretical studies in the context of mathematical methods and physical processes. The following alternative approaches are examined: analytical vs. numerical methods; magnetohydrodynamics vs. hydrodynamics; processes with or without dissipation; continuum (macroscopic) vs. the kinetic (microscopic) approach. In particular, the flare-generated interplanetary shocks are used as examples to illustrate these theoretical studies within the context of TIP. Some emphasis will be placed on MHD wave propagation through the inner corona and its maturity to a fully-developed interplanetary shock. Further, their propagation and the disturbing effects on the solar wind will be considered. Cases concerning the classification and characteristics of blast-produced shocks and long-lasting ejecta are also discussed in the context of numerical simulations.

Interplanetary Shock-driven Magnetopause Compressions in Gorgon Global-MHD Simulations

2021 ◽  
Author(s):  
Ravindra Desai ◽  
Jonathan Eastwood ◽  
Joseph Eggington ◽  
Mervyn Freeman ◽  
Martin Archer ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Interplanetary Shock ◽  
Interplanetary Shocks ◽  
Pressure Balance ◽  
Interplanetary Coronal Mass Ejections ◽  
Corotating Interaction Regions ◽  
Mhd Simulations ◽  
Interaction Regions ◽  
Space Weather Event

<p>Fast-forward interplanetary interplanetary shocks, as occur at the forefront of interplanetary coronal mass ejections and at corotating interaction regions, can rapidly compress the magnetopause inside the drift paths of electrons and protons, and expose geosynchonous satellites directly to the solar wind.  Here, we use Gorgon Global-MHD simulations to study the response of the magnetopause to different fast-forward interplanetary shocks, with strengths extending from the median shocks observed during solar minimum up to that representing an extreme space weather event. The subsequent magnetopause response can be characterised by three distinct phases; an initial acceleration as inertial forces are overcome, a rapid compression well-represented by a power law, and large-scale damped oscillatory motion of the order of an Earth radius, prior to reaching pressure-balance equilibrium. The subsolar magnetopause is found to oscillate with notable frequencies in the range of 2–13 mHz over several periods of diminishing amplitudes.  These results provide an explanation for similar large-scale magnetopause oscillations observed previously during the extreme events of August 1972 and March 1991 and highlight why static magnetopause models break down during periods of strong solar wind driving.</p>

Interplanetary shocks at 5 AU and their effects on Jupiter's decametric radio emissions

2020 ◽  
Author(s):  
Ezequiel Echer
Keyword(s):  
Magnetic Field ◽  
Field Data ◽  
Heliocentric Distance ◽  
Solar Wind Plasma ◽  
Interplanetary Shock ◽  
Interplanetary Shocks ◽  
Magnetic Field Data ◽  
Radio Emissions ◽  
Abrupt Changes

<p>Interplanetary shocks cause large and abrupt changes in solar wind plasma and magnetic field parameters. Shock occurrence and strength are dependent on the heliocentric distance. Further, shocks have important effects on planetary magnetospheres, such as causing large magnetospheric compressions or expansions, and triggering auroral activity emissions. In this work recent results regarding interplanetary shock parameters determined from analysis of in-situ spacecraft plasma and magnetic field data measured near Jupiter’s orbit are presented. The distribution of parameters for both fast forward and fast reverse shocks is analysed and compared with interplanetary shocks detected at other heliocentric distances, Further, an analysis of  interplanetary shock effects on Jupiter decametric auroral radio emissions independent of Io (non-Io DAM) is presented. </p>

Small-scale variations of helium abundance in different large-scale solar wind structures

2020 ◽  
Author(s):  
Alexander Khokhlachev ◽  
Maria Riazantseva ◽  
Liudmila Rakhmanova ◽  
Yuri Yermolaev ◽  
Irina Lodkina ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Solar Wind Plasma ◽  
Magnetic Clouds ◽  
Slow Solar Wind ◽  
Small Scale ◽  
Plasma Stream ◽  
Helium Abundance ◽  
Russian Science ◽  
Plasma Parameters

<p>The boundaries between large-scale solar wind streams are often accompanied by sharp changes in helium abundance.  Wherein the high value of relative helium abundance is known as a sign of some large-scale solar wind structures ( for example magnetic clouds). Unlike the steady slow solar wind where the helium abundance is rather stable and equals ~5%, in magnetic clouds its value can grow significantly up to 20% and more, and at the same time helium component becomes more variable.  In this paper we analyze the small-scale variations of solar wind plasma parameters, including the helium abundance variations in different large-scale solar wind streams, especially in magnetic clouds and Sheath regions before them. We use rather long intervals of simultaneous measurements at Spektr-R (spectrometer BMSW) and Wind (spectrometer 3DP) spacecrafts.  We choose the intervals with rather high correlation  level of plasma parameters as a whole to be sure that we are deal with the same plasma stream.  The intervals associated with different large scale-solar wind structures are selected by using of our catalog ftp://ftp.iki.rssi.ru/pub/omni/catalog/. For selected intervals we examine cross-correlation function for Spektr-R and Wind measurements  to reveal the local spatial inhomogeneities by helium abundance which can be observed only at one of spacecrafts, and we determine properties of ones. Such inhomogeneities can be generate by turbulence, which is typically getting more intense in the considered disturbed intervals in the solar wind. The work is supported by Russian Science Foundation grant 16-12-10062.</p>

Automatic Detection and Classification of Boundary Crossings in Spacecraft in situ Data

2021 ◽  
Author(s):  
Hannah Ruedisser ◽  
Andreas Windisch ◽  
Ute V. Amerstorfer ◽  
David Píša ◽  
Jan Soucek
Keyword(s):  
Solar Wind ◽  
Solar Wind Plasma ◽  
Interplanetary Shocks ◽  
Boundary Crossings ◽  
In Situ Data ◽  
Planetary Missions ◽  
High Frequency Waves ◽  
Magnetospheric Boundaries

<p>Planetary magnetospheres create multiple sharp boundaries, such as the bow shock, where the solar wind plasma is decelerated and compressed, or the magnetopause, a transition between solar wind field and planetary field.<br />We attempt to use convolutional neural networks (CNNs) to identify magnetospheric boundaries, i.e.  planetary and interplanetary shocks crossings and magnetopause crossings in spacecraft in situ data. The boundaries are identified by a discontinuity in a magnetic field, plasma density, and in the spectrum of high-frequency waves. These measurements are available on many planetary missions. Data from Earth's missions Cluster and THEMIS are used for CNN training. We ultimately strive for successful classification of boundaries (shock, magnetopause, inbound, outbound) and the correct handling of multiple crossings.</p>

scholarly journals Influence of He++ and shock geometry on interplanetary shocks in the solar wind: 2D Hybrid simulations

2020 ◽  
Author(s):  
Luis Preisser ◽  
Xochitl Blanco-Cano ◽  
Domenico Trotta ◽  
David Burgess ◽  
Primoz Kajdic
Keyword(s):  
Solar Wind ◽  
Velocity Distribution Function ◽  
Interplanetary Shock ◽  
Alpha Particles ◽  
Upstream Region ◽  
Interplanetary Shocks ◽  
Temperature Anisotropy ◽  
Ion Species ◽  
The Magnetic Field ◽  
Hybrid Simulations

<p>Alpha particles (He<sup>++</sup>) are the most important minor ion species in the solar wind, constituting typically about 5% of the total ion number density. When crossing an interplanetary shock protons and He<sup>++</sup> particles are accelerated differently due to their different charge-to-mass ratio. This behavior can produce changes in the velocity distribution function (VDF) for both species in the immediate downstream region generating anisotropy in the temperature which is considered to be the energy source for various phenomena such as ion cyclotron and mirror mode waves for example. How these changes in temperature anisotropy and shock structure depend on the percentage of He<sup>++</sup> particles and the geometry of the shock is not completely understood. In this work we perform various 2D local hybrid simulations (particle ions, massless fluid electrons) with similar characteristics (e.g., Mach number) to observed interplanetary shocks for both quasi-parallel and quasi-perpendicular geometries including self-consistently different percentages of He<sup>++</sup> particles. We find that the change of the initial θ<sub>Bn</sub> leads to variations of the efficiency with which particles can escape to the upstream region facilitating or not the formation of compressive structures in the magnetic field that will produce increments in perpendicular temperature. The regions where both temperature anisotropy and compressive fluctuations appear tend to be more extended and reach higher values as the He<sup>++</sup> content in the simulations increase.</p>

Sign in / Sign up

Export Citation Format

Share Document