Physics Commons^™

All-Optical Control Of Nonlinear Self-Focusing In Plasmas Using Non-Resonantly Driven Plasma Wave, Serguei Y. Kalmykov, Bradley A. Shadwick, Michael C. Downer

Serge Youri Kalmykov

Excitation of plasma density perturbations by an initially bi-color laser pulse helps to control nonlinear refraction in the plasma and enables various types of laser self-guiding. In this report we consider a setup that not only makes possible the transport of laser energy over cm-long relatively dense plasmas (n_0 = 10^{18} cm^{−3}) but also transforms the pulse into the unique format inaccessible to the conventional amplification techniques (relativistically intense periodic trains of few-cycle spikes). This well focusable pulse train is a novel light source interesting for ultra-fast high-field science applications. The opposite case of suppression of nonlinear self-focusing and dynamical …

Electron Self-Injection Into An Evolving Plasma Bubble: The Way To A Dark Current Free Gev-Scale Laser Accelerator, Serguei Y. Kalmykov, Arnaud Beck, Sunghwan A. Yi, Vladimir N. Khudik, Bradley A. Shadwick, Erik Lefebvre, Michael C. Downer

Serge Youri Kalmykov

A time-varying electron density bubble created by the radiation pressure of a tightly focused petawatt laser pulse traps electrons of ambient rarefied plasma and accelerates them to a GeV energy over a few-cm distance. Expansion of the bubble caused by the shape variation of the self-guided pulse is the primary cause of electron self-injection in strongly rarefied plasmas (n_0 ~ 10^{17} cm^{−3}). Stabilization and contraction of the bubble extinguishes the injection. After the bubble stabilization, longitudinal non-uniformity of the accelerating gradient results in a rapid phase space rotation that produces a quasi-monoenergetic bunch well before the de-phasing limit. Combination of …

Energetyka Niskoemisyjna, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.

Multirelational Organization Of Large-Scale Social Networks In An Online World, Renaud Lambiotte

Renaud Lambiotte

The capacity to collect fingerprints of individuals in online media has revolutionized the way researchers explore human society. Social systems can be seen as a nonlinear superposition of a multitude of complex social networks, where nodes represent individuals and links capture a variety of different social relations. Much emphasis has been put on the network topology of social interactions, however, the multidimensional nature of these interactions has largely been ignored, mostly because of lack of data. Here, for the first time, we analyze a complete, multirelational, large social network of a society consisting of the 300,000 odd players of a …

Numerical Modelling Of A 10-Cm-Long Multi-Gev Laser Wakefield Accelerator Driven By A Self-Guided Petawatt Pulse, Serguei Y. Kalmykov, Sunghwan A. Yi, Arnaud Beck, Agustin F. Lifschitz, Xavier Davoine, Erik Lefebvre, Alexander Pukhov, Vladimir N. Khudik, Gennady Shvets, Steven A. Reed, Peng Dong, Xiaoming Wang, Dongsu Du, Stefan Bedacht, Rafal B. Zgadzaj, Watson Henderson, Aaron Bernstein, Gilliss Dyer, Mikael Martinez, Erhard Gaul, Todd Ditmire, Michael C. Downer

Serge Youri Kalmykov

Holographic Visualization Of Laser Wakefields, Peng Dong, Steven A. Reed, Sunghwan A. Yi, Serguei Y. Kalmykov, Zhengyan Y. Li, Gennady Shvets, Nicholas H. Matlis, Christopher Mcguffey, Stepan S. Bulanov, Vladimir Chvykov, Galina Kalintchenko, Karl Krushelnick, Anatoly Maksimchuk, Takeshi Matsuoka, Alexander G. R. Thomas, Victor Yanovsky, Michael C. Downer

Serge Youri Kalmykov

We report ‘snapshots’ of laser-generated plasma accelerator structures acquired by frequency domain holography (FDH) and frequency domain shadowgraphy (FDS), techniques for visualizing quasi-static objects propagating near the speed of light. FDH captures images of sinusoidal wakes in mm-length plasmas of density 1 < n_{e} < 5 x 10^{18} cm^{−3} from phase modulations they imprint on co-propagating probe pulses. Changes in the wake structure (such as the curvature of the wavefront), caused by the laser and plasma parameter variations from shot to shot, were observed. FDS visualizes lasergenerated electron density bubbles in mm-length plasmas of density n_{e} > 10^{19} cm^{−3} using amplitude modulations they imprint on co-propagating probe pulses. Variations in the spatio-temporal structure of bubbles are inferred from corresponding variations in the shape of ‘bullets’ of probe light trapped inside them and correlated with mono-energetic electron generation. Both FDH and FDS average over structural variations that occur during propagation through the plasma medium. We explore …

Formation Of Optical Bullets In Laser-Driven Plasma Bubble Accelerators, Peng Dong, Steven A. Reed, Sunghwan A. Yi, Serguei Y. Kalmykov, Gennady Shvets, Michael C. Downer, Nicholas H. Matlis, Wim P. Leemans, Christopher Mcguffey, Stepan S. Bulanov, Vladimir Chvykov, Galina Kalintchenko, Karl Krushelnick, Anatoly Maksimchuk, Takeshi Matsuoka, Alexander G. R. Thomas, Victor Yanovsky

Serge Youri Kalmykov

Electron density bubbles—wake structures generated in plasma of density n_{e} ~ 10^{19} cm^{-3} by the light pressure of intense ultrashort laser pulses—are shown to reshape weak copropagating probe pulses into optical ‘‘bullets.’’ The bullets are reconstructed using frequency-domain interferometric techniques in order to visualize bubble formation. Bullets are confined in three dimensions to plasma-wavelength size, and exhibit higher intensity, broader spectrum and flatter temporal phase than surrounding probe light, evidence of their compression by the bubble. Bullets observed at 0.8 < n_{e} < 1.2 x 10^{19} cm^{-3} provide the first observation of bubble formation below the electron capture threshold. At higher n_{e}, bullets appear with high shot-to-shot stability together with relativistic electrons that vary widely in spectrum, and help relate bubble formation to fast electron generation.

Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner

Mikhail Khenner

An introduction to mathematical modeling of ultrathin solid films and the role of such modeling in nanotechnologies: Educational/Research presentation for senior physics majors

Time Is Not A Vector: Corrections To The Article “Vectorial Relativity Versus Special Or General Relativity?”, Jorge A. Franco

Jorge A Franco

In this work the main conceptual errors that sequentially were introduced in the development of the Special Theory of Relativity (SR) are explained. A simple presentation of the Lorentz Transformations (LT) is given, within where it is emphasized that, by using an incomplete configuration, repeated by more than one hundred years, it leads to a first error of a chain of them, when it is assumed that the cross sectional components, in the movable inertial reference system, are invariant or not affected by its relative movement respect a fixed inertial system, on the basis of a presumed “postulate of isotropy“ …

Local Fractional Fourier’S Transform Based On The Local Fractional Calculus, Yang Xiao-Jun

Xiao-Jun Yang

A new modeling for the local fractional Fourier’s transform containing the local fractional calculus is investigated in fractional space. The properties of the local fractional Fourier’s transform are obtained and two examples for the local fractional systems are investigated in detail.

Grafika Inżynierska Ćw., Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.

Projektowanie Procesów Biotechnologicznych Proj., Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.

Projektowanie I Optymalizacja Procesów Proj., Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.

Metody Numeryczne Lab., Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.

Odnawialne Źródła Energii W., Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.

Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mikhail Khenner

We study long-wave Marangoni convection in a layer heated from below. Using the scaling k=OBi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.

On The Accuracy Of Explicit Finite-Volume Schemes For Fluctuating Hydrodynamics, Aleksandar Donev, Eric Vanden-Eijnden, Alejandro Garcia, John B. Bell

Alejandro Garcia

This paper describes the development and analysis of finite-volume methods for the Landau–Lifshitz Navier–Stokes (LLNS) equations and related stochastic partial differential equations in fluid dynamics. The LLNS equations incorporate thermal fluctuations into macroscopic hydrodynamics by the addition of white noise fluxes whose magnitudes are set by a fluctuation-dissipation relation. Originally derived for equilibrium fluctuations, the LLNS equations have also been shown to be accurate for nonequilibrium systems. Previous studies of numerical methods for the LLNS equations focused primarily on measuring variances and correlations computed at equilibrium and for selected nonequilibrium flows. In this paper, we introduce a more systematic approach …

Evolution Of Solitary Waves For A Perturbed Nonlinear Schrodinger Equation, Tim Marchant

Tim Marchant

Soliton perturbation theory is used to determine the evolution of a solitary wave described by a perturbed nonlinear Schrödinger equation. Perturbation terms, which model wide classes of physically relevant perturbations, are considered. An analytical solution is found for the first-order correction of the evolving solitary wave. This solution for the solitary wave tail is in integral form and an explicit expression is found, for large time. Singularity theory, usually used for combustion problems, is applied to the large time expression for the solitary wave tail. Analytical results are obtained, such as the parameter regions in which qualitatively different types of …

The Tangled Tale Of Phase Space, David D. Nolte

David D Nolte