相关论文: Effects of Leakage Neutral Particles on Shocks
A collisionless shock may be strongly modified by the presence of neutral atoms through the processes of charge exchange between ions and neutrals and ionization of the latter. These two processes lead to exchange of energy and momentum…
Perpendicular collisionless shocks propagating into partially ionized plasmas are investigated by two-dimensional hybrid particle simulations. It is shown that some neutral particles leak into the upstream region from the downstream region,…
Recent studies about collisionless shocks in partially ionized plasmas showed that some of neutral particles leak into the shock upstream region from the downstream region. In this paper, we perform a linear analysis and show that acoustic…
In this paper, we study shock structures of collisionless shocks in partially ionized plasmas by means of two-dimensional hybrid simulations, where the shock is a perpendicular shock with shock velocity Vsh ~ 40 Va ~ 1333 km/s and the…
We present a three-dimensional hybrid simulation of a collisionless perpendicular shock in a partially ionized plasma for the first time. In this simulation, the shock velocity and the upstream ionization fraction are Vsh ~ 1333 km/s and fi…
The presence of neutral hydrogen in the shock proximity changes the structure of the shock and affects the spectra of particles accelerated through the first-order Fermi mechanism. This phenomenon has profound implications for the…
A simplified model of particle transport at a quasiparallel one-dimensional collisionless shock is suggested. In this model the MHD-turbulence behind the shock is dominated by a circularly polarized, large amplitude Alfv\'en wave originated…
Models of steady-state plane-parallel shock waves propagating through the unperturbed hydrogen gas of temperature T=6000K and density rho = 1e-10 gm/cm^3 are computed for upstream velocities from 15 km/s to 70 km/s. The shock wave structure…
The momentum distribution of particles accelerated at strong non-relativistic shocks may be influenced by the spatial distribution of the flow speed around the shock. This phenomenon becomes evident in the cosmic-ray modified shock, where…
H-alpha emission from supernova remnants (SNRs) implies the existence of neutral hydrogens in the ambient medium. In the precursor of an SNR shock modified by cosmic rays (CRs), upstream plasmas are pushed by the CR pressure, but neutral…
Aims: Ultraviolet (UV) lines of neutral carbon observed in absorption in the local diffuse interstellar medium (ISM) have long revealed that a substantial fraction of the mass of the gas lies at a thermal pressure one to three orders of…
We investigate effects of upstream density fluctuations on the diffusive shock acceleration by Monte Carlo simulations. The simulations show that particles are reaccelerated in the shock downstream region by a sound wave generated at the…
We determine the spectrum of particles accelerated at shocks with arbitrary speed and arbitrary scattering properties for different choices of the equation of state of the downstream plasma. More specifically we consider the effect of…
The limits imposed on diffusive shock acceleration by upstream ion-neutral Alfven wave damping, and by ionisation and Coulomb losses of low energy particles, are calculated. Analytic solutions are given for the steady upstream wave…
Stationary solutions to the problem of particle acceleration at shock waves in the non-linear regime, when the dynamical reaction of the accelerated particles on the shock cannot be neglected, are known to show a prominent energy flux…
Energetic particles spectra at interplanetary shocks often exhibit a power law within a narrow momentum range softening at higher energy. We introduce a transport equation accounting for particle acceleration and escape with diffusion…
The grid of the models of radiative shock waves propagating through partially ionized hydrogen gas with temperature 3000K <= T_1 <= 8000K and density 10^{-12} gm/cm^3 <= \rho_1 <= 10^{-9}gm/cm^3 is computed for shock velocities 20 km/s <=…
We present here a semi-analytical solution of the problem of particle acceleration at non-linear shock waves with a free escape boundary at some location upstream. This solution, besides allowing us to determine the spectrum of particles…
In this paper, two-dimensional (2-D) hybrid simulations are performed to investigate ion dynamics at a rippled quasi-parallel shock. The results show that the ripples around the shock front are inherent structures of a quasi-parallel shock,…
Shocks in astrophysical transients are key sites of particle acceleration. If the shock upstream is optically thick, radiation smoothens the velocity discontinuity at the shock (radiation-mediated shocks). However, in mildly magnetized…