scholarly journals Ion distributions upstream and downstream of the Earth's bow shock: first results from Vlasiator

2013 ◽  
Vol 31 (12) ◽  
pp. 2207-2212 ◽  
Author(s):  
D. Pokhotelov ◽  
S. von Alfthan ◽  
Y. Kempf ◽  
R. Vainio ◽  
H. E. J. Koskinen ◽  
...  
Keyword(s):  
Distribution Functions ◽  
Bow Shock ◽  
Three Dimensions ◽  
Ion Distribution ◽  
Plasma Kinetics ◽  
Ion Distributions ◽  
Spatial Dimensions ◽  
First Results ◽  
Earth’S Bow Shock

Abstract. A novel hybrid-Vlasov code, Vlasiator, is developed for global simulations of magnetospheric plasma kinetics. The code is applied to model the collisionless bow shock on scales of the Earth's magnetosphere in two spatial dimensions and three dimensions in velocity space retrieving ion distribution functions over the entire foreshock and magnetosheath regions with unprecedented detail. The hybrid-Vlasov approach produces noise-free uniformly discretized ion distribution functions comparable to those measured in situ by spacecraft. Vlasiator can reproduce features of the ion foreshock and magnetosheath well known from spacecraft observations, such as compressional magnetosonic waves generated by backstreaming ion populations in the foreshock and mirror modes in the magnetosheath. An overview of ion distributions from various regions of the bow shock is presented, demonstrating the great opportunities for comparison with multi-spacecraft observations.

WIND observation of gyrating-like ion distributions and low frequency waves upstream from the Earth's bow shock

1997 ◽  
Vol 20 (4-5) ◽  
pp. 703-706 ◽  
Author(s):  
K. Meziane ◽  
C. Mazelle ◽  
C. d'Uston ◽  
H. Rème ◽  
R.P. Lin ◽  
...  
Keyword(s):  
Low Frequency ◽  
Bow Shock ◽  
Wind Observation ◽  
Ion Distributions ◽  
Earth’S Bow Shock ◽  
Low Frequency Waves

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 An experiment to study and control the Langmuir sheath around INTERBALL-2

1998 ◽  
Vol 16 (9) ◽  
pp. 1086-1096 ◽  
Author(s):  
K. Torkar ◽  
M. V. Veselov ◽  
V. V. Afonin ◽  
H. Arends ◽  
M. Fehringer ◽  
...  
Keyword(s):  
Ion Beam ◽  
Distribution Functions ◽  
Ion Distribution ◽  
Space Plasma Physics ◽  
Ambient Plasma ◽  
Spacecraft Potential ◽  
First Results ◽  
Instruments And Techniques ◽  
And Control ◽  
Eventual Control

Abstract. The satellite INTERBALL-2 has an orbit with high inclination (62.8°), covering the altitude range between a few hundred and about 20000 km. The ambient plasma conditions along this orbit are highly variable, and the interactions of this plasma with the spacecraft body as well as the photo-electron sheath around it are considered to be interesting topics for detailed studies. The electric potential of the spacecraft with respect to the ambient plasma that develops as a result of the current equilibrium reacts sensitively to variations of the boundary conditions. The measurement and eventual control of this potential is a prerequisite for accurate measurements of the thermal plasma. We describe the purpose and technical implementation of an ion emitter instrument on-board INTERBALL-2 utilising ion beams at energies of several thousand electron volts in order to reduce and stabilise the positive spacecraft potential. First results of the active ion beam experiments, and other measures taken on INTERBALL-2 to reduce charging are presented. Furthermore, the approach and initial steps of modelling efforts of the sheath in the vicinity of the INTERBALL-2 spacecraft are described together with some estimates on the resulting spacecraft potential, and effects on thermal ion measurements. It is concluded that even moderate spacecraft potentials as are commonly observed on-board INTERBALL-2 can significantly distort the measurements of ion distribution functions, especially in the presence of strongly anisotropic distributions.Key words. Space plasma physics (active perturbation experiments; spacecraft sheaths · wakes · charging; instruments and techniques).

scholarly journals Electron energization in quasi-parallel shocks

2020 ◽  
Vol 642 ◽  
pp. A47
Author(s):  
Adrian Hanusch ◽  
Tatyana V. Liseykina ◽  
Mikhail A. Malkov
Keyword(s):  
Supernova Remnants ◽  
Cosmic Ray ◽  
Bow Shock ◽  
Shock Acceleration ◽  
Diffusive Shock Acceleration ◽  
Proton Temperature ◽  
Earth’S Bow Shock ◽  
Long Time ◽  
Spatial Dimensionality

Context. In situ observations of energetic particles at the Earth’s bow-shock that are attainable by the satellite missions have fostered the opinion for a long time that electrons are most efficiently accelerated in a quasi-perpendicular shock geometry. However, shocks that are deemed to be responsible for the production of cosmic ray electrons and their radiation from sources such as supernova remnants are much more powerful and larger than the Earth’s bow-shock. Their remote observations and also in situ measurements at Saturn’s bow shock, that is, the strongest shock in the Solar System, suggest that electrons are accelerated very efficiently in the quasi-parallel shocks as well. Aims. In this paper we investigate the possibility that protons that are accelerated to high energies create sufficient wave turbulence, which is necessary for the electron preheating and subsequent injection into the diffusive shock acceleration in a quasi-parallel shock geometry. Methods. An additional test-particle-electron population, which is meant to be a low-density addition to the electron core-distribution on which the hybrid simulation operates, is introduced. Our purpose is to investigate how these electrons are energized by the “hybrid” electromagnetic field. The reduced spatial dimensionality allowed us to dramatically increase the number of macro-ions per numerical cell and achieve the converged results for the velocity distributions of test electrons. Results. We discuss the electron preheating mechanisms, which can make a significant part of thermal electrons accessible to the ion-driven waves observed in hybrid simulations. We find that the precursor wave field supplied by ions has a considerable potential to preheat the electrons before they are shocked at the subshock. Our results indicate that a downstream thermal equilibration of the hot test electrons and protons does not occur. Instead, the resulting electron-to-proton temperature ratio is a decreasing function of the shock Mach number, MA, which has a tendency for a saturation at high MA.

scholarly journals Ion distribution dynamics near the Earth's bow shock: first measurements with the 2D ion energy spectrometer CORALL on the INTERBALL/Tail-probe satellite

1997 ◽  
Vol 15 (5) ◽  
pp. 533 ◽  
Author(s):  
Yu. I. Yermolaev ◽  
A. O. Fedorov ◽  
O. L. Vaisberg ◽  
V. M. Balebanov ◽  
Yu. A. Obod ◽  
...  
Keyword(s):  
Bow Shock ◽  
Ion Distribution ◽  
Distribution Dynamics ◽  
Ion Energy ◽  
Earth’S Bow Shock ◽  
Energy Spectrometer ◽  
Tail Probe

scholarly journals Relativistic electrons generated at Earth’s quasi-parallel bow shock

2019 ◽  
Vol 5 (7) ◽  
pp. eaaw1368 ◽  
Author(s):  
Terry Z. Liu ◽  
Vassilis Angelopoulos ◽  
San Lu
Keyword(s):  
Cosmic Ray ◽  
Bow Shock ◽  
Relativistic Electrons ◽  
Nonlinear Structure ◽  
Earth’S Bow Shock ◽  
Primary Means ◽  
Order Of Magnitude ◽  
In Situ Observations ◽  
The Universe

Plasma shocks are the primary means of accelerating electrons in planetary and astrophysical settings throughout the universe. Which category of shocks, quasi-perpendicular or quasi-parallel, accelerates electrons more efficiently is debated. Although quasi-perpendicular shocks are thought to be more efficient electron accelerators, relativistic electron energies recently observed at quasi-parallel shocks exceed theoretical expectations. Using in situ observations at Earth’s bow shock, we show that such relativistic electrons are generated by the interaction between the quasi-parallel shock and a related nonlinear structure, a foreshock transient, through two betatron accelerations. Our observations show that foreshock transients, overlooked previously, can increase electron acceleration efficiency at a quasi-parallel shock by an order of magnitude. Thus, quasi-parallel shocks could be more important in generating relativistic electrons, such as cosmic ray electrons, than previously thought.

Numerical simulation of ion reflection by lunar crustal magnetic fields

2020 ◽  
Author(s):  
Andrey Divin ◽  
Jan Deca ◽  
Charles Lue ◽  
Roman Beliaev
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Large Scale ◽  
Field Measurements ◽  
Distribution Functions ◽  
Three Dimensions ◽  
Lunar Crust ◽  
Ion Distribution ◽  
Particle In Cell ◽  
Reflection Model

<p>We investigate the dynamics of solar wind - Moon interaction by means of large-scale Particle-in-Cell (PIC) simulations in this study. Implicit moment PIC method and open boundaries are implemented in the code (iPIC3D) allowing to use large-scale domains in three dimensions. Even though the Moon has no global dipolar magnetic field, satellite magnetic field measurements at low-altitude (8-80 km) orbits discovered the presence of patches of intense remanent magnetization of the lunar crust. In order to simulate the scattering effect of the lunar remanent magnetic field we implemented an empirical proton reflection model based on low-attitude survey by the Chandrayaan-1 spacecraft [Lue, 2011]. In this study we focus on the day side effects only and thus do not resolve wake and limb effects. Reflected ions are found to create an energized population of particles in the solar wind and are responsible for sub-ion scale instabilities over the strongest anomalies with non-Maxwellian ion distribution functions.</p>

scholarly journals Revisiting the theory of the evolution of pick-up ion distributions: magnetic or adiabatic cooling?

2007 ◽  
Vol 25 (12) ◽  
pp. 2649-2659 ◽  
Author(s):  
H. J. Fahr
Keyword(s):  
Solar Wind ◽  
Particle Interaction ◽  
Distribution Functions ◽  
Particle Interactions ◽  
Ion Distribution ◽  
Ion Distributions ◽  
Magnetic Cooling ◽  
Adiabatic Cooling ◽  
Diffusive Acceleration ◽  
Nonlinear Energy

Abstract. We study the phasespace behaviour of heliospheric pick-up ions after the time of their injection as newly created ions into the solar wind bulk flow from either charge exchange or photoionization of interplanetary neutral atoms. As interaction with the ambient MHD wave fields we allow for rapid pitch angle diffusion, but for the beginning of this paper we shall neglect the effect of quasilinear or nonlinear energy diffusion (Fermi-2 acceleration) induced by counterflowing ambient waves. In the up-to-now literature connected with the convection of pick-up ions by the solar wind only adiabatic cooling of these ions is considered which in the solar wind frame takes care of filling the gap between the injection energy and energies of the thermal bulk of solar wind ions. Here we reinvestigate the basics of the theory behind this assumption of adiabatic pick-up ion reactions and correlated predictions derived from it. We then compare it with the new assumption of a pure magnetic cooling of pick-up ions simply resulting from their being convected in an interplanetary magnetic field which decreases in magnitude with increase of solar distance. We compare the results for pick-up ion distribution functions derived along both ways and can point out essential differences of observational and diagnostic relevance. Furthermore we then include stochastic acceleration processes by wave-particle interactions. As we can show, magnetic cooling in conjunction with diffusive acceleration by wave-particle interaction allows for an unbroken power law with the unique power index γ=−5 beginning from lowest velocities up to highest energy particles of about 100 KeV which just marginally can be in resonance with magnetoacoustic turbulences. Consequences for the resulting pick-up ion pressures are also analysed.

scholarly journals Spatial distribution of upstream magnetospheric ≥50 keV ions

2000 ◽  
Vol 18 (1) ◽  
pp. 42-46 ◽  
Author(s):  
G. C. Anagnostopoulos ◽  
G. Argyropoulos ◽  
G. Kaliabetsos
Keyword(s):  
Solar Wind ◽  
Statistical Analysis ◽  
Wind Speed ◽  
Solar Wind Speed ◽  
Bow Shock ◽  
Occurrence Frequency ◽  
Ion Distributions ◽  
Interplanetary Physics ◽  
Earth’S Bow Shock ◽  
Bow Shocks

Abstract. We present for the first time a statistical study of \\geq50 keV ion events of a magnetospheric origin upstream from Earth's bow shock. The statistical analysis of the 50-220 keV ion events observed by the IMP-8 spacecraft shows: (1) a dawn-dusk asymmetry in ion distributions, with most events and lower intensities upstream from the quasi-parallel pre-dawn side (4 LT-6 LT) of the bow shock, (2) highest ion fluxes upstream from the nose/dusk side of the bow shock under an almost radial interplanetary magnetic field (IMF) configuration, and (3) a positive correlation of the ion intensities with the solar wind speed and the index of geomagnetic index Kp, with an average solar wind speed as high as 620 km s-1 and values of the index Kp > 2. The statistical results are consistent with (1) preferential leakage of ~50 keV magnetospheric ions from the dusk magnetopause, (2) nearly scatter free motion of ~50 keV ions within the magnetosheath, and (3) final escape of magnetospheric ions from the quasi-parallel dawn side of the bow shock. An additional statistical analysis of higher energy (290-500 keV) upstream ion events also shows a dawn-dusk asymmetry in the occurrence frequency of these events, with the occurrence frequency ranging between ~16%-~34% in the upstream region.Key words. Interplanetary physics (energetic particles; planetary bow shocks)

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