scholarly journals The spectral scalings of magnetic fluctuations upstream and downstream of the Venusian bow shock

2020 ◽  
Author(s):  
S. D. XIAO ◽  
M. Y. Wu ◽  
G. Q. Wang ◽  
Y. Q. Chen ◽  
T. L. Zhang
Keyword(s):  
Solar Wind ◽  
Bow Shock ◽  
Energy Cascade ◽  
Kinetic Regime ◽  
Magnetic Fluctuations ◽  
Solar Wind Interaction ◽  
Large Dispersion ◽  
Key Factor ◽  
Bow Shocks ◽  
Statistical Results

Abstract We statistically investigate the spectral scalings of magnetic fluctuations at the upstream and downstream regions near the Venusian bow shock and perform a differentiation by shock geometry. Based on the Venus Express data, 115 quasi-parallel (Q∥) bow shock crossings and 303 quasi-perpendicular (Q⊥) bow shock crossings are selected. The statistical results suggest that the bow shock tends to modify the upstream spectra flatter to 1/f noise in the magnetohydrodynamics (MHD) regime and steeper to turbulence in the kinetic regime after the magnetic fluctuations crossing the bow shock, and this modification for the Q∥ and Q⊥ bow shock is basically consistent. While the upstream spectral scalings are associated with the shock geometry. The changes of the spectral scalings of magnetic fluctuations near the Q∥ bow shocks are not as significant as near the Q⊥ bow shock crossings. That might result from the fluctuations generated by the backstreaming ions which can escape across the Q∥ bow shock into the foreshock. Our results suggest that the energy cascade and dissipation near Venus can be modified by the Venusian bow shock, and the Q∥ bow shock plays an important role on the energy injection and dissipation in the solar wind interaction with Venus. The large dispersion of spectral scalings indicates that this fluctuation environment is complicated, and the shock geometry is not the only key factor in the fluctuations across the Venusian bow shock. Other possible factors in the shock modification to the upstream fluctuations will be explored in future.

scholarly journals The spectral scalings of magnetic fluctuations upstream and downstream of the Venusian bow shock

2020 ◽  
Author(s):  
S. D. XIAO ◽  
M. Y. Wu ◽  
G. Q. Wang ◽  
Y. Q. Chen ◽  
T. L. Zhang
Keyword(s):  
Solar Wind ◽  
Bow Shock ◽  
Energy Cascade ◽  
Kinetic Regime ◽  
Magnetic Fluctuations ◽  
Solar Wind Interaction ◽  
Large Dispersion ◽  
Key Factor ◽  
Bow Shocks ◽  
Statistical Results

Abstract We statistically investigate the spectral scalings of magnetic fluctuations at the upstream and downstream regions near the Venusian bow shock and perform a differentiation by shock geometry. Based on the Venus Express data, 115 quasi-parallel (Q ∥ ) bow shock crossings and 303 quasi-perpendicular (Q ⊥ ) bow shock crossings are selected. The statistical results suggest that the bow shock tends to modify the upstream spectra flatter to 1/f noise in the magnetohydrodynamics (MHD) regime and steeper to turbulence in the kinetic regime after the magnetic fluctuations crossing the bow shock, and this modification for the Q ∥ and Q ⊥ bow shock is basically consistent. While the upstream spectral scalings are associated with the shock geometry. The changes of the spectral scalings of magnetic fluctuations near the Q ∥ bow shocks are not as significant as near the Q ⊥ bow shock crossings. That might result from the fluctuations generated by the backstreaming ions which can escape across the Q ∥ bow shock into the foreshock. Our results suggest that the energy cascade and dissipation near Venus can be modified by the Venusian bow shock, and the Q ∥ bow shock plays an important role on the energy injection and dissipation in the solar wind interaction with Venus. The large dispersion of spectral scalings indicates that this fluctuation environment is complicated, and the shock geometry is not the only key factor in the fluctuations across the Venusian bow shock. Other possible factors in the shock modification to the upstream fluctuations will be explored in future.

scholarly journals The spectral scalings of magnetic fluctuations upstream and downstream of the Venusian bow shock

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
S. D. Xiao ◽  
M. Y. Wu ◽  
G. Q. Wang ◽  
Y. Q. Chen ◽  
T. L. Zhang
Keyword(s):  
Solar Wind ◽  
Bow Shock ◽  
Energy Cascade ◽  
Kinetic Regime ◽  
Magnetic Fluctuations ◽  
Solar Wind Interaction ◽  
Large Dispersion ◽  
Key Factor ◽  
Bow Shocks ◽  
Statistical Results

AbstractWe statistically investigate the spectral scalings of magnetic fluctuations at the upstream and downstream regions near the Venusian bow shock and perform a differentiation by shock geometry. Based on the Venus Express data, 115 quasi-parallel ($$Q_{\parallel }$$ Q ‖ ) bow shock crossings and 303 quasi-perpendicular ($$Q_{ \bot }$$ Q ⊥ ) bow shock crossings are selected. The statistical results suggest that the bow shock tends to modify the upstream spectra flatter to 1/f noise in the magnetohydrodynamics (MHD) regime and steeper to turbulence in the kinetic regime after the magnetic fluctuations crossing the bow shock, and this modification for the $$Q_{\parallel }$$ Q ‖ and $$Q_{ \bot }$$ Q ⊥ bow shocks is basically consistent. However, the upstream spectral scalings are associated with the shock geometry. The changes of the spectral scalings of magnetic fluctuations near the $$Q_{\parallel }$$ Q ‖ bow shocks are not as significant as near the $$Q_{ \bot }$$ Q ⊥ bow shock crossings. That might result from the fluctuations generated by the backstreaming ions which can escape across the $$Q_{\parallel }$$ Q ‖ bow shock into the foreshock. Our results suggest that the energy cascade and dissipation near Venus can be modified by the Venusian bow shock, and the $$Q_{\parallel }$$ Q ‖ bow shock plays an important role on the energy injection and dissipation in the solar wind interaction with Venus. The large dispersion of spectral scalings indicates that this fluctuation environment is complicated, and the shock geometry is not the only key factor in the fluctuations across the Venusian bow shock. Other possible factors in the shock modification to the upstream fluctuations will be explored in future.

scholarly journals The spectral scalings of magnetic fluctuations upstream and downstream of the Venusian bow shock

2020 ◽  
Author(s):  
S. D. XIAO ◽  
M. Y. Wu ◽  
G. Q. Wang ◽  
Y. Q. Chen ◽  
T. L. Zhang
Keyword(s):  
Solar Wind ◽  
Bow Shock ◽  
Energy Cascade ◽  
Kinetic Regime ◽  
Magnetic Fluctuations ◽  
Solar Wind Interaction ◽  
Bow Shocks ◽  
Venus Express ◽  
Statistical Results

Abstract We statistically investigate the spectral scalings of magnetic fluctuations at the upstream and downstream regions near the Venusian bow shock and perform a differentiation by shock geometry. Based on the Venus Express data, 115 quasi-parallel ( {Q}_{\parallel } ) bow shock crossings and 303 quasi-perpendicular ( {Q}_{\perp } ) bow shock crossings are selected. The statistical results suggest that the bow shock tends to modify the upstream spectra flatter to 1/f noise in the magnetohydrodynamics (MHD) regime and steeper to turbulence in the kinetic regime after the magnetic fluctuations crossing the bow shock, and this modification for the {Q}_{\parallel } and {Q}_{\perp } bow shock is basically consistent. While the upstream spectral scalings are associated with the shock geometry. The changes of the spectral scalings of magnetic fluctuations near the {Q}_{\parallel } bow shocks are not as significant as near the {Q}_{\perp } bow shock crossings. That might result from the fluctuations generated by the backstreaming ions which can escape across the {Q}_{\parallel } bow shock into the foreshock. Our results suggest that the energy cascade and dissipation near Venus can be modified by the Venusian bow shock, and the {Q}_{\parallel } bow shock plays an important role on the energy injection and dissipation in the solar wind interaction with Venus.

scholarly journals Injection and acceleration of H<sup>+</sup> and He<sup>2+</sup> at Earth's bow shock

1999 ◽  
Vol 17 (5) ◽  
pp. 583-594 ◽  
Author(s):  
M. Scholer ◽  
H. Kucharek ◽  
K.-H. Trattner
Keyword(s):  
Solar Wind ◽  
Ion Beam ◽  
Background Field ◽  
Bow Shock ◽  
Acceleration Process ◽  
Magnetic Fluctuations ◽  
Folding Energy ◽  
Interplanetary Physics ◽  
Earth’S Bow Shock ◽  
Bow Shocks

Abstract. We have performed a number of one-dimensional hybrid simulations (particle ions, massless electron fluid) of quasi-parallel collisionless shocks in order to investigate the injection and subsequent acceleration of part of the solar wind ions at the Earth's bow shock. The shocks propagate into a medium containing magnetic fluctuations, which are initially superimposed on the background field, as well as generated or enhanced by the electromagnetic ion/ion beam instability between the solar wind and backstreaming ions. In order to study the mass (M) and charge (Q) dependence of the acceleration process He2+ is included self-consistently. The upstream differential intensity spectra of H+ and He2+ can be well represented by exponentials in energy. The e-folding energy Ec is a function of time: Ec increases with time. Furthermore the e-folding energy (normalized to the shock ramming energy Ep) increases with increasing Alfvén Mach number of the shock and with increasing fluctuation level of the initially superimposed turbulence. When backstreaming ions leave the shock after their first encounter they exhibit already a spectrum which extends to more than ten times the shock ramming energy and which is ordered in energy per charge. From the injection spectrum it is concluded that leakage of heated downstream particles does not contribute to ion injection. Acceleration models that permit thermal particles to scatter like the non-thermal population do not describe the correct physics.Key words. Interplanetary physics (planetary bow shocks) · Space plasma physics (charged particle motion and acceleration; numerical simulation studies)

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 Variations and Effects of the Venusian Bow Shock from VEX Mission

2012 ◽  
Vol 8 (S293) ◽  
pp. 329-332
Author(s):  
Yansong Xue ◽  
Shuanggen Jin
Keyword(s):  
Solar Wind ◽  
Solar Maximum ◽  
Direct Interaction ◽  
Magnetic Pressure ◽  
Bow Shock ◽  
Bow Shocks ◽  
Venus Express ◽  
Inner Region ◽  
Planetary Magnetic Field ◽  
Atmosphere Of Venus

AbstractThe upper atmosphere of Venus is not shielded by planetary magnetic field from direct interaction with the solar wind. The interaction of shocked solar wind and the ionosphere results in ionopause. Magnetic barrier, the inner region of dayside magnetosheath with the dominated magnetic pressure deflects the solar wind instead of the ionopause at solar maximum. Therefore, the structure and interaction of venusian ionosphere is very complex. Although the Venus Express (VEX) arrived at Venus in April 2006 provides more knowledge on the Venusian ionosphere and plasma environment, compared to Pioneer Venus Orbiter (PVO) with about 14 years of observations, some important details are still unknown (e.g., long Venusian bow shock variations and effects). In this paper, the bow shock positions of Venus are determined and analyzed from magnetometer (MAG) and ASPERA-4 of the Venus Express mission from May 28, 2006 to August 17, 2010. Results show that the altitude of BS was mainly affected by SZA (solar zenith angle) and Venus bow shocks inbound and outbound are asymmetry.

Modulation of the solar wind driven ion escape from unmagnetized planets by ultra-low-frequency foreshock waves in a global hybrid simulation

2020 ◽  
Author(s):  
Riku Jarvinen ◽  
Esa Kallio ◽  
Tuija Pulkkinen
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Low Frequency ◽  
Hybrid Simulation ◽  
Bow Shock ◽  
Upstream Region ◽  
Ulf Waves ◽  
Solar Wind Interaction ◽  
Ion Escape ◽  
A Charge

&lt;p&gt;We study the solar wind interaction with Venus in a 3-dimensional global hybrid model where ions are treated as particles and electrons are a charge-neutralizing fluid. We concentrate on large-scale ultra-low frequency (ULF) waves in the ion foreshock and how they affect the energization and escape of planetary ions. The ion foreshock forms in the upstream region ahead of the quasi-parallel bow shock, where the angle between the shock normal and the magnetic field is smaller than about 45 degrees. The magnetic connection with the bow shock allows backstreaming of the solar wind ions leading to the formation of the ion foreshock. This kind of beam-plasma configuration is a source of free energy for the excitation of plasma waves. The foreshock ULF waves convect downstream with the solar wind flow and encounter the bow shock and transmit in the downstream region. We analyze the coupling of the ULF waves with the planetary ion acceleration and compare Venus and Mars in a global hybrid simulation.&lt;/p&gt;

Solar wind interaction with the Earth's magnetic field: 2. Magnetohydrodynamic bow shock

1973 ◽  
Vol 78 (19) ◽  
pp. 3731-3744 ◽  
Author(s):  
V. Formisano ◽  
P. C. Hedgecock ◽  
G. Moreno ◽  
F. Palmiotto ◽  
J. K. Chao
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Bow Shock ◽  
Earth’S Magnetic Field ◽  
Solar Wind Interaction ◽  
Earth's Magnetic Field

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.

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