Pickup protons at quasi-perpendicular shocks: full particle electrodynamic simulations

Matsukiyo, Shuichi; Scholer, M.; Burgess, David

doi:10.5194/angeo-25-283-2007

Cited by 19 publications

(36 citation statements)

References 28 publications

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“…We see that the solar wind ion dynamics proceed essentially as in the absence of the pickup ions, whereas the pickup ions form an stationary extended foot starting ∼ 4(c/Ω ci ) upstream. This phenomenon has already been demonstrated by a good deal of hybrid and PIC simulations Liewer et al 1993;Lipatov and Zank 1999;Chapman et al 2005; Lee et al 2005;Matsukiyo et al 2007;Wu et al 2009;Matsukiyo and Scholer 2011). In this subsection, we will clarify why the low percentage pickup ions can not suppress the self-reformation of the shock front by analyzing the cross shock electric field which play a key role in the reflection of incident ions.…”

Section: Effect Of Low Percentage Pickup Ions On the Cross Shock Elecmentioning

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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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: Effect Of Low Percentage Pickup Ions On the Cross Shock Elecmentioning

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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“…Herein, the shock is produced by the injection method as in previous PIC simulations ( Lee et al 2005;Matsukiyo et al 2007;Yang et al 2012a). In order to reproduce self-consistently the impacts of PUIs, three particlespecies are introduced within our PIC code: electrons, SWIs, and PUIs.…”

Section: Simulation Modelmentioning

confidence: 99%

“…In contrast to hybrid simulations, both electron and ion populations are taken into account as individual particles in PIC simulations, and the electrostatic potential jump at the ramp with awidth ofa few electron inertial lengths has been self-consistently reproduced (Matsukiyo et al 2007). Matsukiyo & Scholer (2011) have investigated the impact of PUIs on the TS by using a 1D PIC code.…”

Section: Introductionmentioning

confidence: 99%

Physical Roles of Interstellar-Origin Pickup Ions at the Heliospheric Termination Shock: Impact on the Shock Front Microstructures and Nonstationarity

Lembège

Yang

2016

ApJ

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The nonstationary dynamics of the heliospheric termination shock in the presence of pickup ions (PUI) is analyzed by using a one-dimensional particle-in-cell simulation code. This work initially stimulated by Voyager 2 data focusses on this nonstationarity for different percentages of PUIs and for different Alfvén Mach numbers M A . Solar wind ions (SWIs) and PUIs are described, respectively, as Maxwellian and shell distributions (with a zero/finite thickness). For a moderate M A , present results show that(1) the shock front is still nonstationary even in the presence of 25% of PUIs; its instantaneous velocity varies, which is in favor for shock multicrossing; (2) the presence of PUIs tends to smooth out the time fluctuations of fieldamplitude and of microstructurewidths at the front and overshoot; (3) the shock has a multiple overshoot, which is analyzed by identifying the contributions of SWIs and the PUIs; (4) as the PUI percentage increases, the shock moves faster and the downstream compression becomes weaker, which is explained by a Rankine-Hugoniot model; (5) the reflection rate of SWIs and PUIs decreases as the PUI percentage increases; (6) the shock structure is almost insensitive to the shell thickness;and (7) for the PUIs dominated shock case (PUI=55%), the shock becomes stationary. However, for higher M A regime, the front nonstationarity persists even in the PUI=55% case. In summary, high M A regime allows to compensate the smoothing of the microstructures and the time fluctuations of the shock front brought by the presence of PUIs.

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“…Wu et al [2009] developed a modified Rankine-Hugoniot model that included pickup ions to interpret the hybrid simulations. Wu et al [2010] showed that specular reflection of ions [Zank et al, 1996] by the electric field normal to such a shock is not necessary for an initial energy gain of pickup ions; rather, the large gyroradius of these ions enables some of them to return upstream where they gain substantial energy from the motional electric field as they gyrate in the foot Chapman et al, 2005;Matsukiyo et al, 2007]. Further, Wu et al [2010] demonstrated that faster solar wind flows lead to increased fluxes of ions in the tails of their velocity distributions, consistent with energetic neutral atom observations from IBEX [Funsten et al, 2009].…”

Section: Previous Simulationsmentioning

confidence: 99%

“…Although onedimensional PIC simulations have been applied to the termination shock Chapman et al, 2005;Matsukiyo et al, 2007], such computations require that the electron dynamics be followed in detail. This restricts such calculations to relatively short times and, typically, to one spatial dimension.…”

Section: Previous Simulationsmentioning

confidence: 99%

Heliosheath fluctuations near the perpendicular termination shock: Two‐dimensional hybrid simulations

2010

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[1] The two-dimensional Los Alamos hybrid simulation code is used to study the excitation of fluctuations and the associated ion dynamics at the high Alfvén-Mach heliospheric termination shock and in the near-shock heliosheath. This simulation represents the electrons as a zero-mass fluid, addresses only a perpendicular shock, and considers the upstream ions to consist of a cool solar wind component and a more energetic pickup component. The shock yields two strongly heated downstream components: the more dense thermals and the more tenuous suprathermals, each with strong T ? > T k anisotropies. In the downstream, relatively homogeneous sheath plasma, linear dispersion theory predicts that each component anisotropy drives both the Alfvén-cyclotron instability and the proton mirror instability. The simulation demonstrates that Alfvén-cyclotron modes dominate mirror-like modes in the downstream, in contrast to earlier two-dimensional hybrid simulations of high-Mach quasi-perpendicular shocks without pickup ions, in which the Alfvén-cyclotron and mirror modes were excited to comparable intensities. A hypothesis is presented that the presence of pickup ions implies a relatively low magnetosonic Mach number at termination shocks, thereby favoring the excitation of the Alfvén-cyclotron instability. The primary consequence of wave-particle interactions from this instability is pitch angle scattering, so the energetic part of the ion perpendicular velocity distribution in the heliosheath is depleted by comparison with the distribution computed from a comparable one-dimensional hybrid simulation.

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Pickup protons at quasi-perpendicular shocks: full particle electrodynamic simulations

Cited by 19 publications

References 28 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

Physical Roles of Interstellar-Origin Pickup Ions at the Heliospheric Termination Shock: Impact on the Shock Front Microstructures and Nonstationarity

Heliosheath fluctuations near the perpendicular termination shock: Two‐dimensional hybrid simulations

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