636 research outputs found
Self-similar solutions of the G-equation - analytic description of the flame surface
The main feature of the flame kinematics can be desribed with the G-equation.
We investigate the solutions of the G-equation with the well-known self-similar
Ansatz. The results are discussed and the method how to get self-similar
solutions is briefly mentioned.Comment: just a short paper 5 pages, 5 figure
Self-similar shock wave solutions of the non-linear Maxwell equations
In our study we consider nonlinear, power-law field-dependent electrical
permitivity and magnetic permeability and investigate the time-dependent
Maxwell equations with the self-similar Ansatz. This is a first-order
hyperbolic PDE system which can conserve non-continuous initial conditions
describing electromagnetic shock-waves. Besides shock-waves other interesting
solutions (e.g. with localized compact support) can be found with delicate
physical properties. Such phenomena may happen in complex materials induced by
the planned powerful Extreme Light Infrastructure(ELI) laser pulses.Comment: 6 pages, 2 figures published in Laser Phys. 24 (2014) 08600
Laser assisted proton collision on light nuclei at moderate energies
We present analytic angular differential cross section model for laser
assisted proton nucleon scattering on a Woods-Saxon optical potential where the
nth-order photon absorption is taken into account simultaneously. As a physical
example we calculate cross sections for proton - C collision at 49 MeV
in the laboratory frame where the laser intensity is in the range of W/cm at optical frequencies. The upper intensity limit is slightly
below the relativistic regime.Comment: 6 pages, 4 figures, will be submitted to Phys. Rev.
Analytic self-similar solutions of the Oberbeck-Boussinesq equations
In this article we will present pure two-dimensional analytic solutions for
the coupled non-compressible Newtoniain Navier-Stokes
--- with Boussinesq approximation --- and the heat conduction equation. The
system was investigated from E.N. Lorenz half a century ago with Fourier series
and pioneered the way to the paradigm of chaos. We present a novel analysis of
the same system where the key idea is the two-dimensional generalization of the
well-known self-similar Ansatz of Barenblatt which will be interpreted in a
geometrical way. The results, the pressure, temperature and velocity fields are
all analytic and can be expressed with the help of the error functions. The
temperature field has a strongly damped oscillating behavior which is an
interesting feature.Comment: 13 pages, 4 figure
Proton scattering on carbon nuclei in bichromatic laser field at moderate energies
We present the general theory for proton nuclei scattering in a bichromatic
laser field. As a physical example we consider proton collision on carbon
twelve at 49 MeV/amu moderate energies in the field of a titan sapphire laser
with its second harmonic.Comment: 6 pages 5 figures, submitted to NIMB. arXiv admin note: text overlap
with arXiv:1406.631
Analytic solutions of a two-fluid hydrodynamic model
We investigate a one dimensional flow described with the non-compressible
coupled Euler and non-compressible Navier-Stokes equations in Cartesian
coordinate systems. We couple the two fluids through the continuity equation
where different void fractions can be considered. The well-known self-similar
Ansatz was applied and analytic solutions were derived for both velocity and
pressure field as well. The solutions can be expressed with the error
functions.Comment: 11 pages, 4 figure
The influence of a strong infrared radiation field on the conductance properties of doped semiconductors
This work presents an analytic angular differential cross section formula for
the electromagnetic radiation field assisted electron scattering by %% was on
impurities in semiconductors. These impurities are approximated with various
model potentials. The scattered electrons are described by the well-known
Volkov wave function, which has been used describe strong laser field matter
interaction for more than half a century, %% I would remove this time reference
for clarity which exactly describes the interaction of the electron with the
external oscillating field. These calculations show that the electron
conductance in a semiconductor could be enhanced by an order of magnitude if an
infrared electromagnetic field is present with
W/cm intensity.Comment: 11 pages, 5 figure
Homogeneous bubble nucleation limit of mercury under the normal working conditions of the planned European Spallation Source
In spallation neutron sources, liquid mercury is the subject of big thermal
and pressure shocks, upon adsorbing the proton beam. These changes can cause
unstable bubbles in the liquid, which can damage the structural material. While
there are methods to deal with the pressure shock, the local temperature shock
cannot be avoided. In our paper we calculated the work of the critical cluster
formation (i.e. for mercury micro-bubbles) together with the rate of their
formation (nucleation rate). It is shown that the homogeneous nucleation rates
are very low even after adsorbing several proton pulses, therefore the
probability of temperature induced homogeneous bubble nucleation is negligible.Comment: 22 Pages, 11 figures, one of them is colour, we plan to publish it in
Eur. Phys. J.
Pre-Excitation Studies for Rubidium-Plasma Generation
The key element in the Proton-Driven-Plasma-Wake-Field-Accelerator (AWAKE)
project is the generation of highly uniform plasma from Rubidium vapor. The
standard way to achieve full ionization is to use high power laser which can
assure the over-barrier-ionization (OBI) along the 10 meters long active
region. The Wigner-team in Budapest is investigating an alternative way of
uniform plasma generation. The proposed Resonance Enhanced Multi Photon
Ionization (REMPI) scheme probably can be realized by much less laser power. In
the following the resonant pre-excitations of the Rb atoms are investigated,
theoretically and the status report about the preparatory work on the
experiment are presented.Comment: 8 pages, 6 figures, submitted to Nucl. Inst. and Meth. in Phys. Res.
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