Analytic solutions for the one-dimensional compressible Euler equation with heat conduction closed with different kind of equation of states

We present analytic self-similar or traveling wave solutions for a one-dimensional coupled system of continuity, compressible Euler and heat conduction equations. Different kind of equation of states are investigated. In certain forms of the equation of state one can arrive to a picture regarding the long time behavior of density and pressure. The impact of these quantities on the evolution of temperature is also discussed.Comment: 3 figures, will be submitted to Physics of Fluid

Nemradiális pulzációk tanulmányozása fedési kettős csillagrendszerekben = The study of nonradial pulsations in eclipsing binary systems

A kutatási projekt célja olyan módszerek kidolgozása volt, amelyek segítségével a fedési kettőscsillagok pulzáló tagjainak pulzációs móduszai a fedés jelenségének felhasználásával feltérképezhetők, beazonosíthatók, és ezáltal lehetővé teszik a csillagbelsők asztroszeizmológiai vizsgálatát. Az ilyen rendszerek egyedülálló fontossággal bírnak, mert a pulzációk azonosítása egyedülálló csillagokban nehézkes, bonyolult csillagmodelleket és részletes spektroszkópiai méréseket igényel. A kidolgozott Dinamikai Eclipse Mapping módszer a fedések effektív felszíni mintavételezését kihasználva képszerű információt szolgáltat a csillagfelszíni pulzációs mintázatokról. Ez közvetlen és a csillagmodellektől maximálisan független móduszazonosítást tesz lehetővé; mindez pedig egyszerű fotometriai mérési sorozat alapján lehetséges. A módszer továbbfejlesztésével az ismeretlen forgástengely, valamint a forgás (de nem árapály) által eltorzított pulzációk esete is vizsgálható. Első sikeres alkalmazásként egy, a Kepler űrtávcső által mért objektum domináns pulzációit tudtam azonosítani. További eredmények az alkalmas objektumok megfelelő adatainak megjelenése ütemében várhatók. | The main goal of the project was the development of analysis methods suitable to map and identify the pulsation pattenrs on non-radial pulsation components of eclipsing binary star systems, using the binarity and the eclipses. A successful mode identification makes it potentially possible -- via asteroseismic inversion -- to peek into stellar interiors. Pulsations in eclipsing systems are unique, in that the mode identification is extremely awkward in single stars, requiring detailed stellar models and exhaustive measurements. The constructed method of Dynamic Eclipse Mapping is an indirect imaging method that uses the effective surface sampling of the eclipses to reconstruct images of the surface pulsation patterns. Such images allow a direct and maximally model-independent identification of the pulsation modes, using photometric time series only. An extension of the method allows the treatment of more complicated cases, like the simultaneous fitting of the pulsation axis, and the mapping of rotationally (but not tidally) distorted pulsations. As a first successful application, the first few dominant modes of a Kepler asteroseismic target could be identified. More applications are expected, at the rate at which appropriate data of other candidate systems are being collected and analysed

Laser induced distortion of band structure in solids: an analytic model

We consider a spatially periodic (cosine) potential as a model for a crystalline solid that interacts with a harmonically oscillating external electric field. This problem is periodic both in space and time and can be solved analytically using the Kramers-Henneberger co-moving frame. By analyzing the stability of the closely related Mathieu-type differential equation, the electronic band structure can be obtained. We demonstrate that by changing the field intensity, the width of the zero-field band gaps can be drastically modified, including the special case when the external field causes the band gaps to disappearComment: 8 pages, 3 figure

Interaction of antiproton with helium based on ab-initio calculations

We present ionization cross sections for antiproton and helium collisions based on ab-initio time-dependent coupled channel method. In our calculations a finite basis set of regular helium Coulomb wave packets and Slater function were used. The semiclassical approximation was applied with the time-dependent Coulomb potential to describe the antiproton electron interaction. Three different projectile energies were considered as 10, 50 and 100 keV. We found clear evidence for the formation of the anti-cusp in the differential distributions.Comment: 17 pages and 3*3 figure

Electron Acceleration in Underdense Plasmas Described with a Classical Effective Theory

An effective theory of laser--plasma based particle acceleration is presented. Here we treated the plasma as a continuous medium with an index of refraction $n_{m}$ in which a single electron propagates. Because of the simplicity of this model, we did not need to perform PIC simulations in order to study the properties of the electron acceleration. We studied the properties of the electron motion due to the Lorentz force and the relativistic equations of motion were numerically solved and analysed. We compared our results to PIC simulations and experimental data. Keywords: Underdense plasma; Electron acceleration; Classical electrodynamics; Relativistic equation of motion; Ultrashort laser pulsesComment: 14 pages, 7 figures. Proceedings to the ECLIM 2014 Conference (Paris). Submitted to Laser and Particle Beams (Cambridge Journals