Foreshock waves as observed in energetic ion flux

Petrukovich, A. A.; Chugunova, O. M.; Inamori, Takaya; Kudela, K.; Stetiarova, J.

doi:10.1002/2016ja023693

Cited by 3 publications

(5 citation statements)

References 53 publications

(74 reference statements)

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“…The modulation was visible both in the distribution core and in fluxes of suprathermal reflected ions. Such oscillations of enhanced energetic ion fluxes in foreshock observations were also reported by Petrukovich et al (),Petrukovich et al (). The authors discussed the coupling of magnetic field and particle oscillations and suggested that it may be caused by the foreshock ULF waves.…”

Section: Discussionsupporting

confidence: 83%

Solar Wind Deflection in the Foreshock: Model‐Data Comparison

et al. 2020

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We present the results of a 2.5‐D (2‐D in space and 3‐D in currents and electromagnetic fields) electromagnetic hybrid simulation run for foreshock wave activity during an interval of a radial interplanetary magnetic field (IMF). The simulation predicts nonlinear waves and foreshock expansion in connection with the development of cavitons and the formation of the foreshock compressional boundary. Fluctuations of the ion velocity VY component are associated with wave fronts corresponding to small wave normal angles and oscillate around 0 in the far upstream region. At distances closer to the bow shock, these fluctuations become asymmetric with duskward flow perturbations dominating at dusk and dawnward flow perturbations at dawn. We compare this simulation with THEMIS observations of large‐amplitude quasi‐monochromatic variations of ion velocity in the foreshock under radial IMF. A case study of simultaneous dual observations of unipolar VY fluctuations is followed by a statistical study of similar solar wind deflections in the foreshock. The observations that confirm the simulation predictions indicate that, in addition to ion heating, ultralow‐frequency waves participate in the magnetosheath‐like plasma flow deflection in the foreshock during periods of small IMF cone angles.

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Section: Discussionsupporting

confidence: 83%

Solar Wind Deflection in the Foreshock: Model‐Data Comparison

et al. 2020

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“…Enhanced fluxes of energetic ions are observed at large solar wind speeds (see, e.g., Kudela et al, ; Trattner et al, ), suggesting that acceleration at the bow shock is more efficient under these conditions. Moreover, recent studies have shown that the 30‐s waves in the magnetic field are accompanied by oscillations of the energetic ion fluxes when the solar wind velocity is above 400 km/s (Petrukovich et al, ).…”

Section: Introductionmentioning

confidence: 99%

Foreshock Properties at Typical and Enhanced Interplanetary Magnetic Field Strengths: Results From Hybrid‐Vlasov Simulations

et al. 2018

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In this paper, we present a detailed study of the effects of the interplanetary magnetic field (IMF) strength on the foreshock properties at small and large scales. Two simulation runs performed with the hybrid‐Vlasov code Vlasiator with identical setup but with different IMF strengths, namely, 5 and 10 nT, are compared. We find that the bow shock position and shape are roughly identical in both runs, due to the quasi‐radial IMF orientation, in agreement with previous magnetohydrodynamic simulations and theory. Foreshock waves develop in a broader region in the higher IMF strength run, which we attribute to the larger growth rate of the waves. The velocity of field‐aligned beams remains essentially the same, but their density is generally lower when the IMF strength increases, due to the lower Mach number. Also, we identify in the regular IMF strength run ridges of suprathermal ions which disappear at higher IMF strength. These structures may be a new signature of the foreshock compressional boundary. The foreshock wave field is structured over smaller scales in higher IMF conditions, due to both the period of the foreshock waves and the transverse extent of the wave fronts being smaller. While the foreshock is mostly permeated by monochromatic waves at typical IMF strength, we find that magnetosonic waves at different frequencies coexist in the other run. They are generated by multiple beams of suprathermal ions, while only a single beam is observed at typical IMF strength. The consequences of these differences for solar wind‐magnetosphere coupling are discussed.

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“…A decrease in the SW density causes a lower ULF wave activity (Francia et al, 2012;Regi et al, 2014), and changes of plasma can affect wave modes or frequencies (Hobara et al, 2007;. Recent studies (Petrukovich et al, 2017) have shown that the 30-s waves are accompanied with oscillations of the energetic ion fluxes when the SW velocity is above 400 km/s. Recent studies (Petrukovich et al, 2017) have shown that the 30-s waves are accompanied with oscillations of the energetic ion fluxes when the SW velocity is above 400 km/s.…”

Section: Introductionmentioning

confidence: 99%

“…Enhanced fluxes of energetic ions are observed at large SW speeds (Kudela et al, 2005) probably due to a more efficient acceleration at the BS under these conditions. Recent studies (Petrukovich et al, 2017) have shown that the 30-s waves are accompanied with oscillations of the energetic ion fluxes when the SW velocity is above 400 km/s. A detailed description of wave modes in the ion FS is out of a scope of this paper, but it can be found in the review papers by Eastwood et al (2005) and Wilson (2016).…”

Section: Introductionmentioning

confidence: 99%

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Solar Wind Proton Deceleration in Front of the Terrestrial Bow Shock

et al. 2019

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The terrestrial foreshock as a region permeated by different types of plasma waves, various particle populations, and strong wave activity is a subject of intensive investigations. Our statistical study of the solar wind proton velocity deceleration in the foreshock uses multipoint observations of the THEMIS mission and compare them with the Wind solar wind monitor with a motivation to estimate the factors influencing evolution/modification of the solar wind speed. In order to follow changes of the solar wind proton speed, our moment calculations do not include the reflected particles as well as heavier ions. We have found a systematic deceleration of the solar wind protons with a decreasing distance to the bow shock that is correlated with the flux of reflected and accelerated particles, with the level of magnetic field fluctuations in the ultralow frequency range, and with their compressibility. We can conclude that the reflected particles excite waves of large amplitudes and, as a consequence, modify median values of the velocity measured in an unperturbed solar wind. The deceleration is as high as 3% in front of the quasi‐parallel bow shock and decreases with the distance being observable up to 50 RE. We found similar effects in front of the Moon and attributed them to an influence of the solar wind ions reflected from the lunar surface.

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Foreshock waves as observed in energetic ion flux

Cited by 3 publications

References 53 publications

Solar Wind Deflection in the Foreshock: Model‐Data Comparison

Solar Wind Deflection in the Foreshock: Model‐Data Comparison

Foreshock Properties at Typical and Enhanced Interplanetary Magnetic Field Strengths: Results From Hybrid‐Vlasov Simulations

Solar Wind Proton Deceleration in Front of the Terrestrial Bow Shock

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