Nonstationarity and reformation of high‐Mach‐number quasiperpendicular shocks: Cluster observations

Lobzin, V. V.; Krasnoselskikh, V.; Bosqued, J. M.; Pinçon, Jean Louis; Schwartz, S. J.; Dunlop, M. W.

doi:10.1029/2006gl029095

Cited by 91 publications

(100 citation statements)

References 25 publications

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“…This process is periodic, and is named self-reformation. Nonstationary characteristic of the shock front is later confirmed by an individual case study of Cluster observation at the terrestrial bow shock (Lobzin et al 2007). Mazelle et al (2010) statistically confirms this robust characteristic.…”

Section: Introductionmentioning

confidence: 76%

Contributions to the cross shock electric field at supercritical perpendicular shocks: impact of the pickup ions

Yang¹,

Han²,

Yang³

et al. 2012

Astrophys Space Sci

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A particle-in-cell code is used to examine contributions of the pickup ions (PIs) and the solar wind ions (SWs) to the cross shock electric field at the supercritical, perpendicular shocks. The code treats the pickup ions self-consistently as a third component. Herein, two different runs with relative pickup ion density of 25% and 55% are presented in this paper. Present preliminary results show that: (1) in the low percentage (25%) pickup ion case, the shock front is nonstationary. During the evolution of this perpendicular shock, a nonstationary foot resulting from the reflected solar wind ions is formed in front of the old ramp, and its amplitude becomes larger and larger. At last, the nonstationary foot grows up into a new ramp and exceeds the old one. Such a nonstationary process can be formed periodically. When the new ramp begins to be formed in front of the old ramp, the Hall term mainly contributed by the solar wind ions becomes more and more important. The electric field E x is dominated by the Hall term when the new ramp exceeds the old one. Furthermore, an extended and stationary foot in pickup ion gyro-scale is located upstream of the nonstationary/self-reforming region within the shock front, and is always dominated by the Lorentz term contributed by the pickup ions; (2) in the high percentage (55%) pickup ion case, the amplitude of the stationary foot is increased as expected. One striking point is that the nonstationary region of the shock front evidenced by the self-reformation disappears. Instead, a stationary extended foot dominated by Lorentz term contributed by the pickup ions, and a stationary ramp dominated by Hall term contributed by the solar wind ions are clearly evidenced. The significance of the cross electric field on ion dynamics is also discussed.

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Section: Introductionmentioning

confidence: 76%

Contributions to the cross shock electric field at supercritical perpendicular shocks: impact of the pickup ions

Yang¹,

Han²,

Yang³

et al. 2012

Astrophys Space Sci

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“…However, although this problem was raised in the very beginning of collisionless shock physics, after more than four decades of research it is far from being well understood, most probably due to formidable difficulties of the experimental and theoretical analysis. A brief summary of the state of art can be found in the papers by Krasnoselskikh et al (2002) and Lobzin et al (2007), as well as in recent reviews (Hellinger, 2003;Lembege et al, 2004;Bale et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Horbury et al (2001) argue that these fluctuations stop before the ramp and do not appear to disrupt the shock structure; on the other hand, they don't reject the possibility that the fluctuations may be signatures of the unsteady shock reformation. The first convincing experimental evidence in favor of shock front reformation was presented by Lobzin et al (2007). Moullard et al (2006) were the first who probably observed another aspect of shock front nonstationarity -rippling.…”

Section: Introductionmentioning

confidence: 99%

On nonstationarity and rippling of the quasiperpendicular zone of the Earth bow shock: Cluster observations

et al. 2008

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Abstract. A new method for remote sensing of the quasiperpendicular part of the bow shock surface is presented. The method is based on analysis of high frequency electric field fluctuations corresponding to Langmuir, upshifted, and downshifted oscillations in the electron foreshock. Langmuir waves usually have maximum intensity at the upstream boundary of this region. All these waves are generated by energetic electrons accelerated by quasiperpendicular zone of the shock front. Nonstationary behavior of the shock, in particular due to rippling, should result in modulation of energetic electron fluxes, thereby giving rise to variations of Langmuir waves intensity. For upshifted and downshifted oscillations, the variations of both intensity and central frequency can be observed. For the present study, WHISPER measurements of electric field spectra obtained aboard Cluster spacecraft are used to choose 48 crossings of the electron foreshock boundary with dominating Langmuir waves and to perform for the first time a statistical analysis of nonstationary behavior of quasiperpendicular zone of the Earth's bow shock. Analysis of hidden periodicities in plasma wave energy reveals shock front nonstationarity in the frequency range 0.33 f Bi

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“…This is mainly due to most studies of shock crossings being near the Earth where the Mach numbers typically range from low to modest (M A = 2-8). While some observations have been reported at Earth's bow shock [Lobzin et al, 2007], they remain open to interpretation [Comisel et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

The Near-Saturn Magnetic Field Environment

Sulaiman

2017

Springer Theses

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Shock waves exist throughout the universe and are fundamental to understanding the nature of collisionless plasmas. The complex coupling between charged particles and electromagnetic fields in plasmas give rise to a whole host of mechanisms for dissipation and heating across shock waves, particularly at high Mach numbers. While ongoing studies have investigated these process extensively both theoretically and via simulations, their observations remain few and far between. This thesis presents a study of very high Mach number shocks in a parameter space that has been poorly explored and identifies reformation using in situ magnetic field observations from the This non-axisymmetry is revealed to have an impact in the rotation of the magnetic field and is significant enough to influence the magnetic shear at the magnetopause.

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Nonstationarity and reformation of high‐Mach‐number quasiperpendicular shocks: Cluster observations

Cited by 91 publications

References 25 publications

Contributions to the cross shock electric field at supercritical perpendicular shocks: impact of the pickup ions

Contributions to the cross shock electric field at supercritical perpendicular shocks: impact of the pickup ions

On nonstationarity and rippling of the quasiperpendicular zone of the Earth bow shock: Cluster observations

The Near-Saturn Magnetic Field Environment

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