Pavel M Trávníček

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We investigate the effect of slow expansion on a magnetosheath plasma and low-frequency waves using a two-dimensional hybrid expanding box simulation. We start our simulation with a homogeneous high beta plasma, which is marginally stable to the mirror and proton cyclotron instabilities. The expansion is imposed as an external force: the physical size of(More)
We show that in one-dimensional hybrid simulations supercrit-ical perpendicular shocks have a well-defined, slightly oscillating structure (including foot, ramp, overshoot, and undershoot) for hot upstream protons and low Mach numbers. In this case the reflected protons are able to stop the shock steepening at proton scales. However , for colder upstream(More)
Mercury's regolith, derived from the crustal bedrock, has been altered by a set of space weathering processes. Before we can interpret crustal composition, it is necessary to understand the nature of these surface alterations. The processes that space weather the surface are the same as those that form Mercury's exosphere (micrometeoroid flux and solar wind(More)
We present a comparison between WIND/SWE observations [Kasper et al., 2006] of β p and T ⊥p /T p (where β p is the proton parallel beta and T ⊥p and T p are the perpendicular and parallel proton temperatures, respectively; here parallel and perpendicular indicate directions with respect to the ambient magnetic field) and predictions of the Vlasov linear(More)
Hybrid expanding box (HEB) is used to study a slow compression of the magnetosheath plasma. The HEB simulations confirm the previous results of Hellinger et al. [2003b]: the slowly compressed plasma follows a marginal stability path of the proton cyclotron instability in a low-beta plasma whereas in a high-beta plasma the mirror instability becomes(More)
Polyploidization is one of the leading forces in the evolution of land plants, providing opportunities for instant speciation and rapid gain of evolutionary novelties. Highly selective conditions of serpentine environments act as an important evolutionary trigger that can be involved in various speciation processes. Whereas the significance of both edaphic(More)
This paper reports a two-dimensional hybrid simulation study which utilizes an expanding box model to represent the slow compression of the plasma as it flows through the magnetosheath. In the code we model the compression as an external force: The physical sizes of the simulation box decrease with time. We present results of a simulation which starts in a(More)
We study the evolution of the expanding solar wind using a one-dimensional and a two-dimensional expanding box model [Grap-pin et al., 1993] implemented here within a hybrid code [Liewer et al., 2001]. We first consider a plasma with protons and 5 % of alpha particles, without drift between the protons and alphas, considering successively the low-beta and(More)
Using 5 years of Cluster data, we present a detailed statistical analysis of magnetic fluctuations associated with mirror structures in the magnetosheath. We especially focus on the shape of these fluctuations which, in addition to quasi-sinusoidal forms, also display deep holes and high peaks. The occurrence frequency and the most probable location of the(More)
With the aim to understand the origin of the pressure-balanced magnetic structures in the form of holes and humps commonly observed in the solar wind and planetary mag-netosheaths, high-resolution hybrid numerical simulations of the Vlasov-Maxwell (VM) equations using both Lagrangian (particle in cells) and Eulerian integration schemes are presented and(More)