Shock front nonstationarity and ion acceleration in supercritical perpendicular shocks

Yang, Zhongwei; Lu, Quanming; Lembège, Bertrand; Wang, S.

doi:10.1029/2008ja013785

Cited by 69 publications

(87 citation statements)

References 46 publications

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“…At that time, the electric field E x is obviously larger that at other times. As pointed previously by Yang et al (2009a) the shock surfing acceleration (SSA), where the particles are reflected mainly due to the electric field E x , ion Lorentz term become negligible at that time. The characteristics mentioned above is nearly the same as that obtained at the nonstationary perpendicular shock in the absence of pickup ions (Yang et al 2009b).…”

Section: Discussionmentioning

confidence: 81%

“…During the conversion process, the interaction between the electromagnetic fields and particles replaces the role played by collisions in a normal hydrodynamics. In quasi-perpendicular shocks (θ Bn > 45 • , θ Bn is the angle between the upstream magnetic field and shock normal), the normal/cross shock electric field/potential plays an key role in both acceleration (Zank et al 1996;Shapiro andÜçer 2003;Yang et al 2009a) and thermalization (Burgess et al 1989;Lembège and Savoini 1992) of the incident particles. In-situ observations of the electric field at Earth's bow shock provide important and unique experimental data that can be used to understand the details of plasma thermalization and energetic particle production in more general circumstances.…”

Section: Introductionmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

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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“…At a quasi-perpendicular shock, the reflected upstream ions return to the shock immediately due to the gyromotion of the particles in the magnetic field. So the excited waves by energetic particles are not generated in situ, thus limiting particle scattering (Wilkinson & Schwartz 1990;Gordon et al 1999;Yang et al 2009). These particles escape the shock rapidly.…”

Section: Introductionmentioning

confidence: 99%

The Interaction of Alfvén Waves With Perpendicular Shocks

Zank

2009

ApJ

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Two-dimensional hybrid simulations are performed to investigate the interaction of Alfvén waves with a perpendicular shock self-consistently. The perpendicular shock is formed by reflecting the particles in the right boundary, and it propagates to the left. The Alfvén waves are injected from the left boundary, and they are convected toward the right. The results show that the injected Alfvén waves have no obvious effects on the propagation speed of the shock. However, after the upstream Alfvén waves are transmitted into the downstream, their amplitude is enhanced about 10-30 times. The transmitted waves can be separated into two parts, and both of them are left-hand polarized Alfvén waves: one propagates along the +y direction and the other along the −y direction. Obvious ripples in the shock front are also found due to the interaction of the Alfvén waves with the shock. The great enhancement of the amplitude of the Alfvén waves by the shock is verified by the satellite observations. The implications of the simulation results to the influences on the diffusive shock acceleration are also discussed in this paper.

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“…From the observation of SNRs, structures of collisionless MHD shock and particle acceleration at the shock front have been studied [28][29][30][31][32][33]. Numerical simulation has revealed a lot of interesting physics on collisionless MHD shock, such as supercritical shock structure [34] and reflection/acceleration of ions at shock [35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Collisionless electrostatic shock generation using high-energy laser systems

Sakawa

Morita

Kuramitsu

et al. 2016

Advances in Physics: X

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Collisionless shock is ubiquitous in space and astrophysical plasmas, and is believed to be a source of cosmic rays. In this review article, historical achievements of three different types of collisionless shocks, i.e. magnetohydrodynamic, electromagnetic, and electrostatic (ES) shocks, in theory/simulation, observation in space and astrophysical plasmas, and laboratory experiments are shown. An overview is given on recent progress of collisionless ES shock experiments using high-energy laser systems for two schemes. One is an interaction between laser-produced highdensity ablating plasma and a low-density ambient plasma, and the other is an interaction between laser-ablated counterstreaming plasmas using double-plane target. For the former scheme, detailed measurements of structures of collisionless ES shock and ion-acoustic soliton, and the transition from double-layer to collisionless ES shock are conducted by proton radiography. For the latter scheme, optical diagnostics are used to observe global structures of plasmas and shocks; collective laser Thomson scattering method is applied to clarify local plasma parameters, such as electron and ion temperatures, flow velocity, and electron density; and proton radiography is employed to measure a shock electric field. The measured large density-jump, steepening of self-emission profile, plasma parameters in the upand down-stream regions of a shock, and the narrow width of the shock electric field compared with the ion-ion Coulomb meanfree-path reveal the evidence for the formation of collisionless ES shock. ARTICLE HISTORY

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Shock front nonstationarity and ion acceleration in supercritical perpendicular shocks

Cited by 69 publications

References 46 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

The Interaction of Alfvén Waves With Perpendicular Shocks

Collisionless electrostatic shock generation using high-energy laser systems

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