Abstract:Collisionless shocks efficiently convert the energy of the directed ion flow into their thermal energy. Ion distributions change drastically at the magnetized shock crossing. Even in the absence of collisions, ion dynamics within the shock front is non-integrable and gyrophase dependent. The downstream distributions just behind the shock are not gyrotropic but become so quickly due to the kinematic gyrophase mixing even in laminar shocks. During the gyrotropization all information about gyrophases is lost. Her… Show more
“…This means that the reflection is due to the combined effect of the deceleration by the cross-shock electric field and deflection by the increasing magnetic field (Gedalin et al. 2023). Figure 3.Black: vs for the reflected ions only.…”
Section: Resultsmentioning
confidence: 99%
“…Note that the ions are reflected after the ramp but before the maximum of the overshoot. This means that the reflection is due to the combined effect of the deceleration by the cross-shock electric field and deflection by the increasing magnetic field (Gedalin et al 2023).…”
Section: Resultsmentioning
confidence: 99%
“…If, for example, an overshoot increases at some site, ion reflection is enhanced at this site (Gedalin et al. 2023). A larger number of reflected ions enter the shock at a certain distance from the perturbed site.…”
Section: Discussionmentioning
confidence: 99%
“…In sufficiently low-Mach-number shocks, all or almost all ions cross the shock from the upstream region to the downstream region and proceed further without return (directly transmitted ions). In these shocks ion heating is due to the gyration of directly transmitted ions (Gedalin 1997(Gedalin , 2021 and the downstream magnetic structure, including moderate overshoot, is due to the non-gyrotropy of the downstream ion distributions. This non-gyrotropy causes spatially quasi-periodic variations of the total, dynamic and kinetic, pressure of ions, and corresponding variations of the magnetic pressure in the opposite phase (Balikhin et al 2008;Gedalin, Friedman & Balikhin 2015).…”
In typical heliospheric collisionless shocks most of the mass, momentum and energy are carried by ions. Therefore, the shock structure should be most affected by ions. With the increase of the Mach number, ion reflection becomes more and more important, and reflected ions participate in shaping the shock profile. Ion reflection at the collisionless shock is a non-local process: the reflected–transmitted ions re-enter the shock front far from the reflection point. The direction and the magnitude of this shift depend on the shock angle. The distance between the reflection point and the re-entry point is of the order of the upstream ion convective gyroradius and exceeds the shock width. The non-locality of ion reflection may have implications for shock rippling since reflected ions may carry perturbations along the shock front.
“…This means that the reflection is due to the combined effect of the deceleration by the cross-shock electric field and deflection by the increasing magnetic field (Gedalin et al. 2023). Figure 3.Black: vs for the reflected ions only.…”
Section: Resultsmentioning
confidence: 99%
“…Note that the ions are reflected after the ramp but before the maximum of the overshoot. This means that the reflection is due to the combined effect of the deceleration by the cross-shock electric field and deflection by the increasing magnetic field (Gedalin et al 2023).…”
Section: Resultsmentioning
confidence: 99%
“…If, for example, an overshoot increases at some site, ion reflection is enhanced at this site (Gedalin et al. 2023). A larger number of reflected ions enter the shock at a certain distance from the perturbed site.…”
Section: Discussionmentioning
confidence: 99%
“…In sufficiently low-Mach-number shocks, all or almost all ions cross the shock from the upstream region to the downstream region and proceed further without return (directly transmitted ions). In these shocks ion heating is due to the gyration of directly transmitted ions (Gedalin 1997(Gedalin , 2021 and the downstream magnetic structure, including moderate overshoot, is due to the non-gyrotropy of the downstream ion distributions. This non-gyrotropy causes spatially quasi-periodic variations of the total, dynamic and kinetic, pressure of ions, and corresponding variations of the magnetic pressure in the opposite phase (Balikhin et al 2008;Gedalin, Friedman & Balikhin 2015).…”
In typical heliospheric collisionless shocks most of the mass, momentum and energy are carried by ions. Therefore, the shock structure should be most affected by ions. With the increase of the Mach number, ion reflection becomes more and more important, and reflected ions participate in shaping the shock profile. Ion reflection at the collisionless shock is a non-local process: the reflected–transmitted ions re-enter the shock front far from the reflection point. The direction and the magnitude of this shift depend on the shock angle. The distance between the reflection point and the re-entry point is of the order of the upstream ion convective gyroradius and exceeds the shock width. The non-locality of ion reflection may have implications for shock rippling since reflected ions may carry perturbations along the shock front.
“…With the increase of the Mach number the downstream magnetic field increases, which causes a stronger drop of the ion pressure and a larger overshoot (Mellott & Livesey 1987; Gedalin et al. 2023). In supercritical shocks (the high Mach number), with an increase in the Mach number, ion reflection becomes crucial for ion heating (Chodura 1975; Sckopke et al.…”
The structure of a collisionless shock affects ion motion in the shock front and is affected by the formed ion distribution. In high-Mach-number shocks, a significant fraction of incident ions are reflected by the macroscopic electric and magnetic fields in the shock front. Ions are non-specularly reflected by the combined electric deceleration and magnetic deflection. Here, a first analytical description of the non-specular reflection is presented. The contribution of the increasing magnetic field is evaluated and shown to enhance reflection. The distribution of non-specularly reflected ions ahead of the ramp is calculated and their velocities at the re-entry to the shock are found numerically. Dependence on the angle between the shock normal and the upstream magnetic field vector is illustrated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
