scholarly journals Energetic particle sounding of the magnetospheric cusp with ISEE-1

2007 ◽  
Vol 25 (5) ◽  
pp. 1175-1182 ◽  
Author(s):  
K. E. Whitaker ◽  
T. A. Fritz ◽  
J. Chen ◽  
M. Klida
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Pitch Angle ◽  
Energetic Particle ◽  
Bow Shock ◽  
Local Magnetic Field ◽  
Slow Solar Wind ◽  
Energetic Ions ◽  
Cusp Region ◽  
Magnetospheric Cusp

Abstract. Observations on 30 October 1978 show the ISEE-1 spacecraft passing though the high-altitude dayside northern magnetospheric cusp region from roughly 16:00 to 18:30 UT, during a slow solar wind period (~380 km/s). More than two orders of magnitude enhancements of the cusp energetic particle (CEP) fluxes were observed along with a depressed and turbulent local magnetic field. The observed variations of the pitch angle distributions (PAD) provide a unique opportunity to determine the structure of the cusp and the origin of the CEP. Through a boundary sounding technique, the location and orientation of the cusp poleward (or backside) boundary was observed for almost 10 min during which time it appeared initially to be stationary in the GSM/GSE X-direction and then moved sunward about 0.12 Earth radii (RE). The orientation remained approximately perpendicular to the GSM/GSE X-axis until it was observed to rotate by 60 degrees in ~3 min before ISEE-1 was fully inside the cusp cavity. The cavity itself was filled with CEP fluxes displaying large anisotropies, indicative of their source being located below (Earthward) of the satellite location. The spacecraft entered from the backside of the cusp, then traveled ~4 RE through the cavity, and exited through the "top" of the cavity leaving a region of energetic ions below. The PADs demonstrate that the bow shock cannot be the main source of the observed CEPs. The CEP fluxes were measured at about 8.5 h MLT when the IMF had both an 8–10 nT duskward and southward component.

scholarly journals Energetic particles observed by ISEE-1 and ISEE-2 in a cusp diamagnetic cavity on 29 September 1978

2007 ◽  
Vol 25 (12) ◽  
pp. 2633-2640 ◽  
Author(s):  
B. M. Walsh ◽  
T. A. Fritz ◽  
N. M. Lender ◽  
J. Chen ◽  
K. E. Whitaker
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Pitch Angle ◽  
Energetic Particle ◽  
Electron Flux ◽  
Energetic Particles ◽  
Local Magnetic Field ◽  
Local Source ◽  
Magnetospheric Cusp ◽  
The Magnetic Field

Abstract. Observations by the ISEE-1 and ISEE-2 spacecraft on 29 September 1978 show large CEP (Cusp Energetic Particle) fluxes while passing through the dayside magnetospheric cusp in near coincident orbits. The event was observed around 11:00 MLT between roughly 12:30 and 13:00 UT by ISEE-1 and 12:00 and 13:00 UT by ISEE-2. During these periods, both electron and ion fluxes increased by more than two orders of magnitude, with the electron flux showing a strong peak at a pitch angle of 90°. The solar wind was ~710 km s−1 and the Dst was ~−200 nT, suggesting the occurrence of a strong geomagnetic storm. The ISEE-1 and ISEE-2 observations, however, show no time-energy dispersion of the CEPs, leading us to believe that these particles could not be the result of substorm processes in the magnetotail. The local magnetic field was depressed and extremely turbulent. Changes in the magnitude of the magnetic field anticorrelate closely to variations of the electron flux. The observations in electron flux peaking at 90° and the close anticorrelation between the local magnetic field strength and electron flux are unique and provide evidence of a potential local source for these energetic particles.

scholarly journals Statistics of counter-streaming solar wind suprathermal electrons at solar minimum: STEREO observations

2010 ◽  
Vol 28 (1) ◽  
pp. 233-246 ◽  
Author(s):  
B. Lavraud ◽  
A. Opitz ◽  
J. T. Gosling ◽  
A. P. Rouillard ◽  
K. Meziane ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Pitch Angle ◽  
Solar Minimum ◽  
Local Magnetic Field ◽  
Occurrence Rate ◽  
Slow Solar Wind ◽  
Closed Field ◽  
Magnetic Field Topology ◽  
Suprathermal Electrons

Abstract. Previous work has shown that solar wind suprathermal electrons can display a number of features in terms of their anisotropy. Of importance is the occurrence of counter-streaming electron patterns, i.e., with "beams" both parallel and anti-parallel to the local magnetic field, which is believed to shed light on the heliospheric magnetic field topology. In the present study, we use STEREO data to obtain the statistical properties of counter-streaming suprathermal electrons (CSEs) in the vicinity of corotating interaction regions (CIRs) during the period March–December 2007. Because this period corresponds to a minimum of solar activity, the results are unrelated to the sampling of large-scale coronal mass ejections, which can lead to CSE owing to their closed magnetic field topology. The present study statistically confirms that CSEs are primarily the result of suprathermal electron leakage from the compressed CIR into the upstream regions with the combined occurrence of halo depletion at 90° pitch angle. The occurrence rate of CSE is found to be about 15–20% on average during the period analyzed (depending on the criteria used), but superposed epoch analysis demonstrates that CSEs are preferentially observed both before and after the passage of the stream interface (with peak occurrence rate >35% in the trailing high speed stream), as well as both inside and outside CIRs. The results quantitatively show that CSEs are common in the solar wind during solar minimum, but yet they suggest that such distributions would be much more common if pitch angle scattering were absent. We further argue that (1) the formation of shocks contributes to the occurrence of enhanced counter-streaming sunward-directed fluxes, but does not appear to be a necessary condition, and (2) that the presence of small-scale transients with closed-field topologies likely also contributes to the occurrence of counter-streaming patterns, but only in the slow solar wind prior to CIRs.

scholarly journals Radial dependence of foreshock cavities: a case study

2004 ◽  
Vol 22 (12) ◽  
pp. 4143-4151 ◽  
Author(s):  
D. G. Sibeck ◽  
K. Kudela ◽  
T. Mukai ◽  
Z. Nemecek ◽  
J. Safrankova
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Bow Shock ◽  
Radial Dependence ◽  
Energetic Ions ◽  
Interplanetary Physics ◽  
Bow Shocks

Abstract. We present a case study of Geotail, Interball-1, IMP-8, and Wind observations of density and magnetic field strength cavities excavated by the enhanced pressures associated with bursts of energetic ions in the foreshock. Consistent with theoretical predictions, the pressure of the energetic ions diminishes rapidly with upstream distance due to a decrease in the flux of energetic ions and a transition from near-isotropic to streaming pitch angle distributions. Consequently, the cavities can only be observed immediately upstream from the bow shock. A comparison of conditions upstream from the pre- and post-noon bow shock demonstrates that foreshock cavities introduce perturbations into the oncoming solar wind flow with dimensions smaller than those of the magnetosphere. Dayside geosynchronous magnetic field strength variations observed by GOES-8 do not track the density variations seen by any of the spacecraft upstream from the bow shock in a one-to-one manner, indicating that none of these spacecraft observed the precise sequence of density variations that actually struck the subsolar magnetopause. Key words. Interplanetary physics (energetic particles; planetary bow shocks) – Magnetospheric physics (solar wind-magnetosphere interactions)

scholarly journals Energetic protons at Mars: interpretation of SLED/Phobos-2 observations by a kinetic model

2012 ◽  
Vol 30 (11) ◽  
pp. 1595-1609 ◽  
Author(s):  
E. Kallio ◽  
S. McKenna-Lawlor ◽  
M. Alho ◽  
R. Jarvinen ◽  
S. Dyadechkin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Kinetic Model ◽  
Energetic Particle ◽  
Particle Energy ◽  
Bow Shock ◽  
Solar Wind Interaction ◽  
Flux Enhancement ◽  
Field Environment ◽  
Electric And Magnetic Fields

Abstract. Mars has neither a significant global intrinsic magnetic field nor a dense atmosphere. Therefore, solar energetic particles (SEPs) from the Sun can penetrate close to the planet (under some circumstances reaching the surface). On 13 March 1989 the SLED instrument aboard the Phobos-2 spacecraft recorded the presence of SEPs near Mars while traversing a circular orbit (at 2.8 RM). In the present study the response of the Martian plasma environment to SEP impingement on 13 March was simulated using a kinetic model. The electric and magnetic fields were derived using a 3-D self-consistent hybrid model (HYB-Mars) where ions are modelled as particles while electrons form a massless charge neutralizing fluid. The case study shows that the model successfully reproduced several of the observed features of the in situ observations: (1) a flux enhancement near the inbound bow shock, (2) the formation of a magnetic shadow where the energetic particle flux was decreased relative to its solar wind values, (3) the energy dependency of the flux enhancement near the bow shock and (4) how the size of the magnetic shadow depends on the incident particle energy. Overall, it is demonstrated that the Martian magnetic field environment resulting from the Mars–solar wind interaction significantly modulated the Martian energetic particle environment.

scholarly journals Highly Alfvénic slow solar wind at 0.3 au during a solar minimum: Helios insights for Parker Solar Probe and Solar Orbiter

2020 ◽  
Vol 633 ◽  
pp. A166 ◽  
Author(s):  
D. Perrone ◽  
R. D’Amicis ◽  
R. De Marco ◽  
L. Matteini ◽  
D. Stansby ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Low Frequency ◽  
Intrinsic Property ◽  
Flow Speed ◽  
Local Magnetic Field ◽  
Slow Solar Wind ◽  
Magnetic Fluctuations ◽  
Origin And Evolution ◽  
Slow Wind

Alfvénic fluctuations in solar wind are an intrinsic property of fast streams, while slow intervals typically have a very low degree of Alfvénicity, with much more variable parameters. However, sometimes a slow wind can be highly Alfvénic. Here we compare three different regimes of solar wind, in terms of Alfvénic content and spectral properties, during a minimum phase of the solar activity and at 0.3 au. We show that fast and Alfvénic slow intervals share some common characteristics. This would suggest a similar solar origin, with the latter coming from over-expanded magnetic field lines, in agreement with observations at 1 au and at the maximum of the solar cycle. Due to the Alfvénic nature of the fluctuations in both fast and Alfvénic slow winds, we observe a well-defined correlation between the flow speed and the angle between magnetic field vector and radial direction. The high level of Alfvénicity is also responsible of intermittent enhancements (i.e. spikes), in plasma speed. Moreover, only for the Alfvénic intervals do we observe a break between the inertial range and large scales, on about the timescale typical of the Alfvénic fluctuations and where the magnetic fluctuations saturate, limited by the magnitude of the local magnetic field. In agreement with this, we recover a characteristic low-frequency 1/f scaling, as expected for fluctuations that are scale-independent. This work is directly relevant for the next solar missions, Parker Solar Probe and Solar Orbiter. One of the goals of these two missions is to study the origin and evolution of slow solar wind. In particular, Parker Solar Probe will give information about the Alfvénic slow wind in the unexplored region much closer to the Sun and Solar Orbiter will allow us to connect the observed physics to the source of the plasma.

scholarly journals Experimental and numerical investigation of plasma parameters in the magnetosheath

2018 ◽  
Vol 145 ◽  
pp. 03003
Author(s):  
Polya Dobreva ◽  
Monio Kartalev ◽  
Olga Nitcheva ◽  
Natalia Borodkova ◽  
Georgy Zastenker
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Numerical Investigation ◽  
Euler Equations ◽  
Ideal Gas ◽  
Bow Shock ◽  
Plasma Parameters ◽  
Wind Spacecraft ◽  
The Magnetic Field ◽  
Good Agreement

We investigate the behaviour of the plasma parameters in the magnetosheath in a case when Interball-1 satellite stayed in the magnetosheath, crossing the tail magnetopause. In our analysis we apply the numerical magnetosheath-magnetosphere model as a theoretical tool. The bow shock and the magnetopause are self-consistently determined in the process of the solution. The flow in the magnetosheath is governed by the Euler equations of compressible ideal gas. The magnetic field in the magnetosphere is calculated by a variant of the Tsyganenko model, modified to account for an asymmetric magnetopause. Also, the magnetopause currents in Tsyganenko model are replaced by numericaly calulated ones. Measurements from WIND spacecraft are used as a solar wind monitor. The results demonstrate a good agreement between the model-calculated and measured values of the parameters under investigation.

scholarly journals Calibration of QM-MOURA three-axis magnetometer and gradiometer

2015 ◽  
Vol 4 (1) ◽  
pp. 1-18 ◽  
Author(s):  
M. Díaz-Michelena ◽  
R. Sanz ◽  
M. F. Cerdán ◽  
A. B. Fernández
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Geomagnetic Storm ◽  
Remanent Magnetization ◽  
Local Magnetic Field ◽  
Daily Variations ◽  
Scientific Goal ◽  
Solar Events

Abstract. MOURA instrument is a three-axis magnetometer and gradiometer designed and developed for Mars MetNet Precursor mission. The initial scientific goal of the instrument is to measure the local magnetic field in the surroundings of the lander i.e. to characterize the magnetic environment generated by the remanent magnetization of the crust and the superimposed daily variations of the field produced either by the solar wind incidence or by the thermomagnetic variations. Therefore, the qualification model (QM) will be tested in representative scenarios like magnetic surveys on terrestrial analogues of Mars and monitoring solar events, with the aim to achieve some experience prior to the arrival to Mars. In this work, we present a practical first approach for calibration of the instrument in the laboratory; a finer correction after the comparison of MOURA data with those of a reference magnetometer located in San Pablo de los Montes (SPT) INTERMAGNET Observatory; and a comparative recording of a geomagnetic storm as a demonstration of the compliance of the instrument capabilities with the scientific objectives.

scholarly journals Scattering of field-aligned beam ions upstream of Earth's bow shock

2007 ◽  
Vol 25 (3) ◽  
pp. 785-799 ◽  
Author(s):  
A. Kis ◽  
M. Scholer ◽  
B. Klecker ◽  
H. Kucharek ◽  
E. A. Lucek ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Bow Shock ◽  
Ion Distribution ◽  
Parallel Side ◽  
Earth’S Bow Shock ◽  
High Mach ◽  
The Magnetic Field

Abstract. Field-aligned beams are known to originate from the quasi-perpendicular side of the Earth's bow shock, while the diffuse ion population consists of accelerated ions at the quasi-parallel side of the bow shock. The two distinct ion populations show typical characteristics in their velocity space distributions. By using particle and magnetic field measurements from one Cluster spacecraft we present a case study when the two ion populations are observed simultaneously in the foreshock region during a high Mach number, high solar wind velocity event. We present the spatial-temporal evolution of the field-aligned beam ion distribution in front of the Earth's bow shock, focusing on the processes in the deep foreshock region, i.e. on the quasi-parallel side. Our analysis demonstrates that the scattering of field-aligned beam (FAB) ions combined with convection by the solar wind results in the presence of lower-energy, toroidal gyrating ions at positions deeper in the foreshock region which are magnetically connected to the quasi-parallel bow shock. The gyrating ions are superposed onto a higher energy diffuse ion population. It is suggested that the toroidal gyrating ion population observed deep in the foreshock region has its origins in the FAB and that its characteristics are correlated with its distance from the FAB, but is independent on distance to the bow shock along the magnetic field.

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

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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