WorldWideScience

Sample records for collisional astrophysical plasmas

  1. Weakly Collisional and Collisionless Astrophysical Plasmas

    DEFF Research Database (Denmark)

    Berlok, Thomas

    investigate helium mixing in the weakly collisional intracluster medium of galaxy clusters using Braginskii MHD. Secondly, we present a newly developed Vlasov-fluid code which can be used for studying fully collisionless plasmas such as the solar wind and hot accretions flows. The equations of Braginskii MHD...... are used to study weakly collisional, stratified atmospheres which offer a useful model of the intracluster medium of galaxy clusters. Using linear theory and computer simulations, we study instabilities that feed off thermal and compositional gradients. We find that these instabilities lead to vigorous...... mixing of the composition and discuss the potential consequences for X-ray observations of galaxy clusters. Collisionless plasmas can be subject to microscale velocity-space instabilities which are not well-described by Braginskii MHD. In contrast, Vlasov-fluid theory captures all the kinetic phenomena...

  2. Astrophysical Gyrokinetics: Kinetic and Fluid Turbulent Cascades In Magentized Weakly Collisional Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Schekochihin, A. A.; Cowley, S. C.; Dorland, W.; Hammett, G. W.; Howes, G. G.; Quataert, E.; Tatsuno, T.

    2009-04-23

    This paper presents a theoretical framework for understanding plasma turbulence in astrophysical plasmas. It is motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks. All of these plasmas and many others have turbulentmotions at weakly collisional and collisionless scales. The paper focuses on turbulence in a strong mean magnetic field. The key assumptions are that the turbulent fluctuations are small compared to the mean field, spatially anisotropic with respect to it and that their frequency is low compared to the ion cyclotron frequency. The turbulence is assumed to be forced at some system-specific outer scale. The energy injected at this scale has to be dissipated into heat, which ultimately cannot be accomplished without collisions. A kinetic cascade develops that brings the energy to collisional scales both in space and velocity. The nature of the kinetic cascade in various scale ranges depends on the physics of plasma fluctuations that exist there. There are four special scales that separate physically distinct regimes: the electron and ion gyroscales, the mean free path and the electron diffusion scale. In each of the scale ranges separated by these scales, the fully kinetic problem is systematically reduced to a more physically transparent and computationally tractable system of equations, which are derived in a rigorous way. In the "inertial range" above the ion gyroscale, the kinetic cascade separates into two parts: a cascade of Alfvenic fluctuations and a passive cascade of density and magnetic-fieldstrength fluctuations. The former are governed by the Reduced Magnetohydrodynamic (RMHD) equations at both the collisional and collisionless scales; the latter obey a linear kinetic equation along the (moving) field lines associated with the Alfvenic component (in the collisional limit, these compressive fluctuations

  3. Plasma astrophysics

    CERN Document Server

    Kaplan, S A; ter Haar, D

    2013-01-01

    Plasma Astrophysics is a translation from the Russian language; the topics discussed are based on lectures given by V.N. Tsytovich at several universities. The book describes the physics of the various phenomena and their mathematical formulation connected with plasma astrophysics. This book also explains the theory of the interaction of fast particles plasma, their radiation activities, as well as the plasma behavior when exposed to a very strong magnetic field. The text describes the nature of collective plasma processes and of plasma turbulence. One author explains the method of elementary

  4. Collisionless plasmas in astrophysics

    CERN Document Server

    Belmont, Gerard; Mottez, Fabrice; Pantellini, Filippo; Pelletier, Guy

    2013-01-01

    Collisionless Plasmas in Astrophysics examines the unique properties of media without collisions in plasma physics. Experts in this field, the authors present the first book to concentrate on collisionless conditions in plasmas, whether close or not to thermal equilibrium. Filling a void in scientific literature, Collisionless Plasmas in Astrophysics explains the possibilities of modeling such plasmas, using a fluid or a kinetic framework. It also addresses common misconceptions that even professionals may possess, on phenomena such as "collisionless (Landau) damping". Abundant illustrations

  5. Microphysics in Astrophysical Plasmas

    Science.gov (United States)

    Schwartz, Steven J.; Zweibel, Ellen G.; Goldman, Martin

    Although macroscale features dominate astrophysical images and energetics, the physics is controlled through microscale transport processes (conduction, diffusion) that mediate the flow of mass, momentum, energy, and charge. These microphysical processes manifest themselves in key (all) boundary layers and also operate within the body of the plasma. Crucially, most plasmas of interest are rarefied to the extent that classical particle collision length- and time-scales are long. Collective plasma kinetic phenomena then serve to scatter or otherwise modify the particle distribution functions and in so-doing govern the transport at the microscale level. Thus collisionless plasmas are capable of supporting thin shocks, current sheets which may be prone to magnetic reconnection, and the dissipation of turbulence cascades at kinetic scales. This paper lays the foundation for the accompanying collection that explores the current state of knowledge in this subject. The richness of plasma kinetic phenomena brings with it a rich diversity of microphysics that does not always, if ever, simply mimic classical collision-dominated transport. This can couple the macro- and microscale physics in profound ways, and in ways which thus depend on the astrophysical context.

  6. Collisionality dependent transport in TCV SOL plasmas

    DEFF Research Database (Denmark)

    Garcia, Odd Erik; Pitts, R.A.; Horacek, J.

    2007-01-01

    and radial transport increase with plasma collisionality. Such a collisionality dependence is consistent with a recent theory for radial blob motion, which suggests that filamentary structures become electrically disconnected from the target sheaths at large collisionality and thus experience less sheath......Results are presented from probe measurements in the low field side scrape-off layer (SOL) region of TCV during plasma current scan experiments. It is shown that with decreasing plasma current the radial particle density profile becomes broader and the fluctuation levels and turbulence driven...... radial particle flux increase. In the far SOL the fluctuations exhibit a high degree of statistical similarity and the particle density and flux at the wall radius scale inversely with the plasma current. Together with previous TCV density scan experiments, this indicates that plasma fluctuations...

  7. LAD Dissertation Prize Talk: Molecular Collisional Excitation in Astrophysical Environments

    Science.gov (United States)

    Walker, Kyle M.

    2017-06-01

    While molecular excitation calculations are vital in determining particle velocity distributions, internal state distributions, abundances, and ionization balance in gaseous environments, both theoretical calculations and experimental data for these processes are lacking. Reliable molecular collisional data with the most abundant species - H2, H, He, and electrons - are needed to probe material in astrophysical environments such as nebulae, molecular clouds, comets, and planetary atmospheres. However, excitation calculations with the main collider, H2, are computationally expensive and therefore various approximations are used to obtain unknown rate coefficients. The widely-accepted collider-mass scaling approach is flawed, and alternate scaling techniques based on physical and mathematical principles are presented here. The most up-to-date excitation data are used to model the chemical evolution of primordial species in the Recombination Era and produce accurate non-thermal spectra of the molecules H2+, HD, and H2 in a primordial cloud as it collapses into a first generation star.

  8. Modern methods in collisional-radiative modeling of plasmas

    CERN Document Server

    2016-01-01

    This book provides a compact yet comprehensive overview of recent developments in collisional-radiative (CR) modeling of laboratory and astrophysical plasmas. It describes advances across the entire field, from basic considerations of model completeness to validation and verification of CR models to calculation of plasma kinetic characteristics and spectra in diverse plasmas. Various approaches to CR modeling are presented, together with numerous examples of applications. A number of important topics, such as atomic models for CR modeling, atomic data and its availability and quality, radiation transport, non-Maxwellian effects on plasma emission, ionization potential lowering, and verification and validation of CR models, are thoroughly addressed. Strong emphasis is placed on the most recent developments in the field, such as XFEL spectroscopy. Written by leading international research scientists from a number of key laboratories, the book offers a timely summary of the most recent progress in this area. It ...

  9. Heat flux viscosity in collisional magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C., E-mail: cliu@pppl.gov [Princeton University, Princeton, New Jersey 08544 (United States); Fox, W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Bhattacharjee, A. [Princeton University, Princeton, New Jersey 08544 (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2015-05-15

    Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a “heat flux viscosity,” is demonstrated. Even though no net particle flux is associated with a heat flux, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-flux viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic field in plasmas through the generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux viscosity is calculated directly using the finite-difference method of Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and confirmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.

  10. Nonlinear magnetic reconnection in low collisionality plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ottaviani, M. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Porcelli, F. [Politecnico di Torino, Turin (Italy)

    1994-07-01

    The magnetic reconnection in collisionless regimes, where electron inertia is responsible for the decoupling of the plasma motion from that of the field lines, is discussed. Since the linear theory of m=1 modes breaks down for very small magnetic island widths, a non linear analysis is called for. Thus, the behaviour of a collisionless, 2-D fluid slab model in the limit {rho}/d -> 0, is analyzed. The main result is that, when the island size is larger than the linear layer but smaller than the equilibrium scale length, the reconnection rate exhibits a quasi-explosive time behaviour, during which a current density sub-layer narrower than the skin depth is formed. It is believed that the inclusion of the electron initial term in Ohm`s law opens the possibility to understand the rapidity of relaxation process observed in low collisionality plasmas. 7 refs., 6 figs.

  11. Introduction to plasma physics with space, laboratory and astrophysical applications

    CERN Document Server

    Gurnett, Donald A

    2017-01-01

    Introducing basic principles of plasma physics and their applications to space, laboratory and astrophysical plasmas, this new edition provides updated material throughout. Topics covered include single-particle motions, kinetic theory, magnetohydrodynamics, small amplitude waves in hot and cold plasmas, and collisional effects. New additions include the ponderomotive force, tearing instabilities in resistive plasmas and the magnetorotational instability in accretion disks, charged particle acceleration by shocks, and a more in-depth look at nonlinear phenomena. A broad range of applications are explored: planetary magnetospheres and radiation belts, the confinement and stability of plasmas in fusion devices, the propagation of discontinuities and shock waves in the solar wind, and analysis of various types of plasma waves and instabilities that can occur in planetary magnetospheres and laboratory plasma devices. With step-by-step derivations and self-contained introductions to mathematical methods, this book...

  12. Weakly nonlinear electron plasma waves in collisional plasmas

    DEFF Research Database (Denmark)

    Pecseli, H. L.; Rasmussen, J. Juul; Tagare, S. G.

    1986-01-01

    The nonlinear evolution of a high frequency plasma wave in a weakly magnetized, collisional plasma is considered. In addition to the ponderomotive-force-nonlinearity the nonlinearity due to the heating of the electrons is taken into account. A set of nonlinear equations including the effect...... of a constantly maintained pump wave is derived and a general dispersion relation describing the modulation of the high frequency wave due to different low frequency responses is obtained. Particular attention is devoted to a purely growing modulation. The relative importance of the ponderomotive force...

  13. Magnetic field generation via parametric instabilities in collisional plasmas

    Science.gov (United States)

    Katoh, K.

    1982-06-01

    A formalism for the parametric instability with low-frequency magnetic field generation in a collisional plasma is developed. The spontaneous low-frequency magnetic field results from a resonant decay instability of an intense pump wave into a magneto-static wave which appears only in a collisional plasma. The growth rate for a resonant decay instability of an intense electromagnetic wave into a Langmuir wave and a magneto-static wave is obtained.

  14. Magnetic susceptibility and Landau diamagnetism of quantum collisional plasma

    Science.gov (United States)

    Latyshev, A. V.; Yushkanov, A. A.

    2017-04-01

    Quantum collisional plasma with an arbitrary degree of degeneracy of the electron gas is considered. Using the exact expression for the transverse electric conductivity of quantum collisional plasma, the magnetic susceptibility is described using the kinetic approach and a formula for calculating Landau diamagnetism is derived. Quantum Maxwellian plasma is considered as a special case. To this end, in the formulas derived, the limit is taken for the chemical potential tending to minus infinity. The properties of the magnetic susceptibility of quantum plasma are compared to those of degenerate and Maxwellian plasmas.

  15. Impurity Transport in a Mixed-Collisionality Stellarator Plasma.

    Science.gov (United States)

    Helander, P; Newton, S L; Mollén, A; Smith, H M

    2017-04-14

    A potential threat to the performance of magnetically confined fusion plasmas is the problem of impurity accumulation, which causes the concentration of highly charged impurity ions to rise uncontrollably in the center of the plasma and spoil the energy confinement by excessive radiation. It has long been thought that the collisional transport of impurities in stellarators always leads to such an accumulation (if the electric field points inwards, which is usually the case), whereas tokamaks, being axisymmetric, can benefit from "temperature screening," i.e., an outward flux of impurities driven by the temperature gradient. Here it is shown, using analytical techniques supported by results from a new numerical code, that such screening can arise in stellarator plasmas, too, and indeed does so in one of the most relevant operating regimes, where the impurities are highly collisional while the bulk plasma is at low collisionality.

  16. Theory of sheath in a collisional multi-component plasma

    Indian Academy of Sciences (India)

    Abstract. The aim of this brief report is to study the behaviour of sheath structure in a multi- component plasma with dust-neutral collisions. The plasma consists of electrons, ions, micron size negatively charged dust particles and neutrals. The sheath-edge potential and sheath width are cal- culated for collisionally ...

  17. Theory of sheath in a collisional multi-component plasma

    Indian Academy of Sciences (India)

    The aim of this brief report is to study the behaviour of sheath structure in a multicomponent plasma with dust-neutral collisions. The plasma consists of electrons, ions, micron size negatively charged dust particles and neutrals. The sheath-edge potential and sheath width are calculated for collisionally dominated sheath.

  18. Physics of Collisional Plasmas Introduction to High-Frequency Discharges

    CERN Document Server

    Moisan, Michel

    2012-01-01

    The Physics of Collisional Plasmas deals with the plasma physics of interest to laboratory research and industrial applications, such as lighting, fabrication of microelectronics, destruction of greenhouse gases. Its emphasis is on explaining the physical mechanisms, rather than the detailed mathematical description and theoretical analysis. At the introductory level, it is important to convey the characteristic physical phenomena of plasmas, before addressing the ultimate formalism of kinetic theory, with its microscopic, statistical mechanics approach. To this aim, this text translates the physical phenomena into more tractable equations, using the hydrodynamic model; this considers the plasma as a fluid, in which the macroscopic physical parameters are the statistical averages of the microscopic (individual) parameters. This book is an introduction to the physics of collisional plasmas, as opposed to plasmas in space. It is intended for graduate students in physics and engineering . The first chapter intr...

  19. Coulomb collisional relaxation process of ion beams in magnetized plasmas

    OpenAIRE

    Nishimura, Y.

    2010-01-01

    An orbit following code is developed to calculate ion beam trajectories in magnetized plasmas. The equation of motion (the Newton's equation) is solved including the Lorentz force term and Coulomb collisional relaxation term. Furthermore, a new algorithm is introduced by applying perturbation method regarding the collision term as a small term. The reduction of computation time is suggested.

  20. Collisional Effect On Magnetosonic Solitons In A Dusty Plasma Slab ...

    African Journals Online (AJOL)

    An analytical investigation of collisional effect on magnetosonic solitons in a dusty plasma slab is presented. We have derived and presented solutions of nonlinear magetohydrodynamic equations for a warm dusty magnetoplasma. It is observed that, our work could be considered a general case for magnetosonic solutions ...

  1. Collisional effects in weakly collisional plasmas: nonlinear electrostatic waves and recurrence phenomena

    Science.gov (United States)

    Camporeale, E.; Pezzi, O.; Valentini, F.

    2015-12-01

    The longstanding problem of collisions in plasmas is a very fascinating and huge topic in plasma physics. The 'natural' operator that describes the Coulombian interactions between charged particles is the Landau (LAN) integral operator. The LAN operator is a nonlinear, integro-differential and Fokker-Planck type operator which satisfies the H theorem for the entropy growth. Due to its nonlinear nature and multi-dimensionality, any approach to the solution of the Landau integral is almost prohibitive. Therefore collisions are usually modeled by simplified collisional operators. Here collisional effects are modeled by i) the one-dimensional Lenard-Bernstein (LB) operator and ii) the three-dimensional Dougherty (DG) operator. In the first case i), by focusing on a 1D-1V phase space, we study recurrence effects in a weakly collisional plasma, being collisions modeled by the LB operator. By decomposing the linear Vlasov-Poisson system in the Fourier-Hermite space, the recurrence problem is investigated in the linear regime of the damping of a Langmuir wave and of the onset of the bump-on-tail instability. The analysis is then confirmed and extended to the nonlinear regime through a Eulerian collisional Vlasov-Poisson code. Despite being routinely used, an artificial collisionality is not in general a viable way of preventing recurrence in numerical simulations. Moreover, recursive phenomena affect both the linear exponential growth and the nonlinear saturation of a linear instability by producing a fake growth in the electric field, thus showing that, although the filamentation is usually associated with low amplitude fluctuations contexts, it can occur also in nonlinear phenomena. On the other hand ii), the effects of electron-electron collisions on the propagation of nonlinear electrostatic waves are shown by means of Eulerian simulations in a 1D-3V (one dimension in physical space, three dimensions in velocity space) phase space. The nonlinear regime of the symmetric

  2. Kinetic model for the collisionless sheath of a collisional plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Xian-Zhu, E-mail: xtang@lanl.gov; Guo, Zehua, E-mail: guo@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2016-08-15

    Collisional plasmas typically have mean-free-path still much greater than the Debye length, so the sheath is mostly collisionless. Once the plasma density, temperature, and flow are specified at the sheath entrance, the profile variation of electron and ion density, temperature, flow speed, and conductive heat fluxes inside the sheath is set by collisionless dynamics, and can be predicted by an analytical kinetic model distribution. These predictions are contrasted here with direct kinetic simulations, showing good agreement.

  3. Plasma Astrophysics, Part I Fundamentals and Practice

    CERN Document Server

    Somov, Boris V

    2006-01-01

    This well-illustrated monograph is devoted to classic fundamentals, current practice, and perspectives of modern plasma astrophysics. The first part is unique in covering all the basic principles and practical tools required for understanding and working in plasma astrophysics. The second part presents the physics of magnetic reconnection and flares of electromagnetic origin in space plasmas within the solar system; single and double stars, relativistic objects, accretion disks, and their coronae are also covered. This book is designed mainly for professional researchers in astrophysics. However, it will also be interesting and useful to graduate students in space sciences, geophysics, as well as advanced students in applied physics and mathematics seeking a unified view of plasma physics and fluid mechanics.

  4. Plasma Astrophysics, part II Reconnection and Flares

    CERN Document Server

    Somov, Boris V

    2007-01-01

    This well-illustrated monograph is devoted to classic fundamentals, current practice, and perspectives of modern plasma astrophysics. The first part is unique in covering all the basic principles and practical tools required for understanding and working in plasma astrophysics. The second part presents the physics of magnetic reconnection and flares of electromagnetic origin in space plasmas within the solar system; single and double stars, relativistic objects, accretion disks, and their coronae are also covered. This book is designed mainly for professional researchers in astrophysics. However, it will also be interesting and useful to graduate students in space sciences, geophysics, as well as advanced students in applied physics and mathematics seeking a unified view of plasma physics and fluid mechanics.

  5. Thermalization via collisional and non-collisional mechanisms in ultracold neutral plasmas

    Science.gov (United States)

    Witte, Craig; Roberts, Jacob

    2016-10-01

    Many ultracold neutral plasmas (UCPs) are formed with non-uniform electron and ion densities. They are also formed in a way that the initial electron velocity distribution is not in thermal equilibrium. We present the results of a numerical simulation that compares the electron velocity distribution evolution after UCP formation between uniform and non-uniform density UCPs. We find three distinct thermalization time periods for the electron velocity: a rapid thermalization on the order of the electron plasma frequency timescale where position variations lead to velocity randomization; a slower second phase where non-collisional effects play a role in thermalization as evidenced by differences between thermalization rates in uniform density and non-uniform density plasmas; and an even slower third phase where the highest velocity portion of the electron thermal distribution equilibrates primarily via collisional mechanisms. These mechanisms are relevant for understanding the establishment of equilibrium in the electron component of UCPs in experimentally relevant conditions. This work supported by the AFOSR.

  6. Inverse Bremsstrahlung in Astrophysical Plasmas: The Absorption ...

    Indian Academy of Sciences (India)

    The electron–ion inverse Bremsstrahlung is considered here as a factor of the influence on the opacity of the different stellar atmospheres and other astrophysical plasmas. It is shown that this process can be successfully described in the frames of cut-off Coulomb potential model within the regions of the electron densities ...

  7. Final Scientific/Technical Report: Correlations and Fluctuations in Weakly Collisional Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Skiff, Frederick [Univ. of Iowa, Iowa City, IA (United States)

    2017-11-15

    Plasma is a state of matter that exhibits a very rich range of phenomena. To begin with, plasma is both electrical and mechanical - bringing together theories of particle motion and the electromagnetic field. Furthermore, and especially important for this project, a weakly-collisional plasma, such as is found in high-temperature (fusion energy) experiments on earth and the majority of contexts in space and astrophysics, has many moving parts. For example, sitting in earth’s atmosphere we are immersed in a mechanical wave field (sound), a possibly turbulent fluid motion (wind), and an electromagnetic vector wave field with two polarizations (light). This is already enough to produce a rich range of possibilities. In plasma, the electromagnetic field is coupled to the mechanical motion of the medium because it is ionized. Furthermore, a weakly-collisional plasma supports an infinite number of mechanically independent fluids. Thus, plasmas support an infinite number of independent electromechanical waves. Much has been done to describe plasmas with "reduced models" of various kinds. The goal of this project was to both explore the validity of reduced plasma models that are in use, and to propose and validate new models of plasma motion. The primary means to his end was laboratory experiments employing both electrical probes and laser spectroscopy. Laser spectroscopy enables many techniques which can separate the spectrum of independent fluid motions in the ion phase-space. The choice was to focus on low frequency electrostatic waves because the electron motion is relatively simple, the experiments can be on a spatial scale of a few meters, and all the relevant parameters can be measured with a few lasers systems. No study of this kind had previously been undertaken for the study of plasmas. The validation of theories required that the experimental descriptions be compared with theory and simulation in detail. It was found that even multi-fluid theories leave out a

  8. Signal Propagation in Collisional Plasma with Negative Ions

    Energy Technology Data Exchange (ETDEWEB)

    I. Kaganovich; S.V. Berezhnoi; C.B. Shin

    2000-12-18

    The transport of charged species in collisional currentless plasmas is traditionally thought of as a diffusion-like process. In this paper, it is demonstrated that, in contrast to two-component plasma, containing electrons and positive ions, the transport of additional ions in multi-species plasmas is not governed by diffusion, rather described by nonlinear convection. As a particular example, plasmas with the presence of negative ions have been studied. The velocity of a small perturbation of negative ions was found analytically and validated by numerical simulation. As a result of nonlinear convection, initially smooth ion density profiles break and form strongly inhomogeneous shock-like fronts. These fronts are different from collisionless shocks and shocks in fully ionized plasma. The structure of the fronts has been found analytically and numerically.

  9. Fully implicit kinetic modelling of collisional plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mousseau, Vincent Andrew [Univ. of Idaho, Moscow, ID (United States)

    1996-05-01

    This dissertation describes a numerical technique, Matrix-Free Newton Krylov, for solving a simplified Vlasov-Fokker-Planck equation. This method is both deterministic and fully implicit, and may not have been a viable option before current developments in numerical methods. Results are presented that indicate the efficiency of the Matrix-Free Newton Krylov method for these fully-coupled, nonlinear integro-differential equations. The use and requirement for advanced differencing is also shown. To this end, implementations of Chang-Cooper differencing and flux limited Quadratic Upstream Interpolation for Convective Kinematics (QUICK) are presented. Results are given for a fully kinetic ion-electron problem with a self consistent electric field calculated from the ion and electron distribution functions. This numerical method, including advanced differencing, provides accurate solutions, which quickly converge on workstation class machines. It is demonstrated that efficient steady-state solutions can be achieved to the non-linear integro-differential equation, obtaining quadratic convergence, without incurring the large memory requirements of an integral operator. Model problems are presented which simulate plasma impinging on a plate with both high and low neutral particle recycling typical of a divertor in a Tokamak device. These model problems demonstrate the performance of the new solution method.

  10. Plasma Astrophysics, Part II Reconnection and Flares

    CERN Document Server

    Somov, Boris V

    2013-01-01

    This two-part book is devoted to classic fundamentals and current practices and perspectives of modern plasma astrophysics. This second part discusses the physics of magnetic reconnection and flares of electromagnetic origin in space plasmas in the solar system, single and double stars, relativistic objects, accretion disks and their coronae. More than 25% of the text is updated from the first edition, including the additions of new figures, equations and entire sections on topics such as topological triggers for solar flares and the magnetospheric physics problem. This book is aimed at professional researchers in astrophysics, but it will also be useful to graduate students in space sciences, geophysics, applied physics and mathematics, especially those seeking a unified view of plasma physics and fluid mechanics.

  11. Plasma physics of extreme astrophysical environments.

    Science.gov (United States)

    Uzdensky, Dmitri A; Rightley, Shane

    2014-03-01

    Among the incredibly diverse variety of astrophysical objects, there are some that are characterized by very extreme physical conditions not encountered anywhere else in the Universe. Of special interest are ultra-magnetized systems that possess magnetic fields exceeding the critical quantum field of about 44 TG. There are basically only two classes of such objects: magnetars, whose magnetic activity is manifested, e.g., via their very short but intense gamma-ray flares, and central engines of supernovae (SNe) and gamma-ray bursts (GRBs)--the most powerful explosions in the modern Universe. Figuring out how these complex systems work necessarily requires understanding various plasma processes, both small-scale kinetic and large-scale magnetohydrodynamic (MHD), that govern their behavior. However, the presence of an ultra-strong magnetic field modifies the underlying basic physics to such a great extent that relying on conventional, classical plasma physics is often not justified. Instead, plasma-physical problems relevant to these extreme astrophysical environments call for constructing relativistic quantum plasma (RQP) physics based on quantum electrodynamics (QED). In this review, after briefly describing the astrophysical systems of interest and identifying some of the key plasma-physical problems important to them, we survey the recent progress in the development of such a theory. We first discuss the ways in which the presence of a super-critical field modifies the properties of vacuum and matter and then outline the basic theoretical framework for describing both non-relativistic and RQPs. We then turn to some specific astrophysical applications of relativistic QED plasma physics relevant to magnetar magnetospheres and to central engines of core-collapse SNe and long GRBs. Specifically, we discuss the propagation of light through a magnetar magnetosphere; large-scale MHD processes driving magnetar activity and responsible for jet launching and propagation in

  12. Collisional-radiative model: a plasma spectroscopy theory for experimentalists

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Takashi [Kyoto Univ. (Japan); Sawada, Keiji

    1997-01-01

    The rate equation describing the population n(p) of an excited (and the ground state) level p of ions immersed in plasma is shown. In 1962, the method of quasi-steady state solution (collisional-radiative model) was proposed. Its idea is explained. The coupled differential equations reduce to a set of coupled linear equations for excited levels. The solution of these coupled equations is presented. The equations giving the ionization and recombination of this system of ions under consideration are described in terms of the effective rate coefficients. The collisional-radiative ionization and recombination rate coefficients are expressed in terms of the population coefficients for p > 1. As for ionizing plasma, the excited level populations, the populations, the population distribution among the excited levels, two regimes of the excited levels, the dominant flows of electrons among the levels and so on are shown. As for recombining plasma, the excited level populations, the population distribution among the excited levels, the dominant flows of electrons and so on are shown. Ionization balance plasma may be considered. (K.I.)

  13. Doppler tomography in fusion plasmas and astrophysics

    DEFF Research Database (Denmark)

    Salewski, Mirko; Geiger, B.; Heidbrink, W. W.

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion Dα (FIDA) spectroscopy measurements in magnetically confined plasma......, the Dα-photons are likewise Doppler-shifted ultimately due to gyration of the fast ions. In either case, spectra of Doppler-shifted line emission are sensitive to the velocity distribution of the emitters. Astrophysical Doppler tomography has lead to images of accretion discs of binaries revealing bright...... spots, spiral structures and flow patterns. Fusion plasma Doppler tomography has led to an image of the fast-ion velocity distribution function in the tokamak ASDEX Upgrade. This image matched numerical simulations very well. Here we discuss achievements of the Doppler tomography approach, its promise...

  14. Reduction of collisional-radiative models for transient, atomic plasmas

    Science.gov (United States)

    Abrantes, Richard June; Karagozian, Ann; Bilyeu, David; Le, Hai

    2017-10-01

    Interactions between plasmas and any radiation field, whether by lasers or plasma emissions, introduce many computational challenges. One of these computational challenges involves resolving the atomic physics, which can influence other physical phenomena in the radiated system. In this work, a collisional-radiative (CR) model with reduction capabilities is developed to capture the atomic physics at a reduced computational cost. Although the model is made with any element in mind, the model is currently supplemented by LANL's argon database, which includes the relevant collisional and radiative processes for all of the ionic stages. Using the detailed data set as the true solution, reduction mechanisms in the form of Boltzmann grouping, uniform grouping, and quasi-steady-state (QSS), are implemented to compare against the true solution. Effects on the transient plasma stemming from the grouping methods are compared. Distribution A: Approved for public release; unlimited distribution, PA (Public Affairs) Clearance Number 17449. This work was supported by the Air Force Office of Scientific Research (AFOSR), Grant Number 17RQCOR463 (Dr. Jason Marshall).

  15. Collisional damping rates for electron plasma waves reassessed

    Science.gov (United States)

    Banks, J. W.; Brunner, S.; Berger, R. L.; Arrighi, W. J.; Tran, T. M.

    2017-10-01

    Collisional damping of electron plasma waves, the primary damping for high phase velocity waves, is proportional to the electron-ion collision rate, νei ,th. Here, it is shown that the damping rate normalized to νei ,th depends on the charge state, Z , on the magnitude of νei ,th and the wave number k in contrast with the commonly used damping rate in plasma wave research. Only for weak collision rates in low-Z plasmas for which the electron self-collision rate is comparable to the electron-ion collision rate is the damping rate given by the commonly accepted value. The result presented here corrects the result presented in textbooks at least as early as 1973. The complete linear theory requires the inclusion of both electron-ion pitch-angle and electron-electron scattering, which itself contains contributions to both pitch-angle scattering and thermalization.

  16. Simulations of a molecular plasma in collisional-radiative nonequilibrium

    Science.gov (United States)

    Cambier, Jean-Luc; Moreau, Stephane

    1993-01-01

    A code for the simulation of nonequilibrium plasmas is being developed, with the capability to couple the plasma fluid-dynamics for a single fluid with a collisional-radiative model, where electronic states are treated as separate species. The model allows for non-Boltzmann distribution of the electronic states. Deviations from the Boltzmann distributions are expected to occur in the rapidly ionizing regime behind a strong shock or in the recombining regime during a fast expansion. This additional step in modeling complexity is expected to yield more accurate predictions of the nonequilibrium state and the radiation spectrum and intensity. An attempt at extending the code to molecular plasma flows is presented. The numerical techniques used, the thermochemical model, and the results of some numerical tests are described.

  17. Electrostatic thermal noise in a weakly ionized collisional plasma

    Science.gov (United States)

    Martinović, M. M.; Zaslavsky, A.; Maksimović, M.; Å egan, S.

    2017-01-01

    Quasi-thermal noise (QTN) spectroscopy is a plasma diagnostic technique which enables precise measurements of local electron velocity distribution function moments. This technique is based on measurements and analysis of voltage fluctuations at the antenna terminals, induced by thermal motion of charged particles. In this work, we accommodate, for the first time, this technique to weakly ionized collisional plasmas. It turns out that the QTN spectrum is modified both at low frequencies, increasing the level of power spectrum, and around the plasma frequency, where collisions damp the plasma oscillations and therefore broaden and reduce the amplitude of so called "plasma peak," while the spectrum at high frequencies is nearly unmodified compared to the collisionless case. Based on these results, we show that QTN spectroscopy enables independent measurements of the collision frequency, electron density, and temperature, provided the ratio of collision frequency to plasma frequency is ν/ωp˜0.1. The method presented here can be used for precise estimation of plasma parameters in laboratory devices and unmagnetized ionospheres, while application in the ionosphere of Earth is possible but limited to small, low-frequency range due to magnetic field influence.

  18. Modeling Non-Equilibrium Collisional Plasmas with AtomDB

    Science.gov (United States)

    Foster, Adam; Yamaguchi, H.; Smith, R. K.; Brickhouse, N. S.; Ji, L.; Kallman, T.; Wilms, J.

    2013-04-01

    Collisionally ionized plasmas that are in non-equilibrium ionization (NEI) show distinctly different emission from those in equilibrium. Recombining, or overionized, plasmas show significant recombination-driven continuum features, while ionizing plasmas show strong inner-shell emission lines, such as the Iron Kα line at 6.4-6.7keV. Existing models in analysis tools such as XSPEC treat only the equilibrium case and part of the ionizing plasma case due to a significant lack of atomic data. We present major updates to the AtomDB database, and new models for use XSPEC, which allow all types of these non-equilibrium plasmas to be modeled in a simple yet accurate fashion. This model has been created using a large amount of data obtained from published sources, supplemented by data we have calculated using the Flexible Atomic Code where required. We identify the spectral features that have been seen and can now be modeled using this data for existing missions as well as Astro-H. We also revisit archival data where recombining plasma emission has previously been identified.

  19. Astrophysical Plasmas: Codes, Models, and Observations

    Science.gov (United States)

    Canto, Jorge; Rodriguez, Luis F.

    2000-05-01

    The conference Astrophysical Plasmas: Codes, Models, and Observations was aimed at discussing the most recent advances, arid some of the avenues for future work, in the field of cosmical plasmas. It was held (hiring the week of October 25th to 29th 1999, at the Centro Nacional de las Artes (CNA) in Mexico City, Mexico it modern and impressive center of theaters and schools devoted to the performing arts. This was an excellent setting, for reviewing the present status of observational (both on earth and in space) arid theoretical research. as well as some of the recent advances of laboratory research that are relevant, to astrophysics. The demography of the meeting was impressive: 128 participants from 12 countries in 4 continents, a large fraction of them, 29% were women and most of them were young persons (either recent Ph.Ds. or graduate students). This created it very lively and friendly atmosphere that made it easy to move from the ionization of the Universe and high-redshift absorbers, to Active Galactic Nucleotides (AGN)s and X-rays from galaxies, to the gas in the Magellanic Clouds and our Galaxy, to the evolution of H II regions and Planetary Nebulae (PNe), and to the details of plasmas in the Solar System and the lab. All these topics were well covered with 23 invited talks, 43 contributed talks. and 22 posters. Most of them are contained in these proceedings, in the same order of the presentations.

  20. Magnetosonic shock wave in collisional pair-ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Adak, Ashish, E-mail: ashish-adak@yahoo.com; Khan, Manoranjan, E-mail: mkhan.ju@gmail.com [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Sikdar, Arnab, E-mail: arnabs.ju@gmail.com [Department of Mathematics, Calcutta Institute of Engineering and Management, 24/1A Chandi Ghosh Road, Kolkata 700040 (India); Ghosh, Samiran, E-mail: sran-g@yahoo.com [Department of Applied Mathematics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700 009 (India)

    2016-06-15

    Nonlinear propagation of magnetosonic shock wave has been studied in collisional magnetized pair-ion plasma. The masses of both ions are same but the temperatures are slightly different. Two fluid model has been taken to describe the model. Two different modes of the magnetosonic wave have been obtained. The dynamics of the nonlinear magnetosonic wave is governed by the Korteweg-de Vries Burgers' equation. It has been shown that the ion-ion collision is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The numerical investigations reveal that the magnetosonic wave exhibits both oscillatory and monotonic shock structures depending on the strength of the dissipation. The nonlinear wave exhibited the oscillatory shock wave for strong magnetic field (weak dissipation) and monotonic shock wave for weak magnetic field (strong dissipation). The results have been discussed in the context of the fullerene pair-ion plasma experiments.

  1. (Quasi-)collisional Magneto-optic Effects in Collisionless Plasmas with sub-Larmor-scale Electromagnetic Fluctuations

    CERN Document Server

    Keenan, Brett D; Medvedev, Mikhail V

    2015-01-01

    High-amplitude, chaotic/turbulent electromagnetic fluctuations are ubiquitous in high-energy-density laboratory and astrophysical plasmas, where they can be excited by various kinetic-streaming and/or anisotropy-driven instabilities, such as the Weibel instability. These fields typically exist on "sub-Larmor scales" -- scales smaller than the electron Larmor radius. Electrons moving through such magnetic fields undergo small-angle stochastic deflections of their pitch-angles, thus establishing diffusive transport on long time-scales. We show that this behavior, under certain conditions, is equivalent to Coulomb collisions in collisional plasmas. The magnetic pitch-angle diffusion coefficient, which acts as an effective "collision" frequency, may be substantial in these, otherwise, collisionless environments. We show that this effect, colloquially referred to as the plasma "quasicollisionality", may radically alter the expected radiative transport properties of candidate plasmas. We argue that the modified mag...

  2. Plasma-statistical models of the atom in the theory of some collisional and radiative processes

    NARCIS (Netherlands)

    Astapenko, VA

    2002-01-01

    A plasma-statistical model was used to describe collisional and radiative processes involving target ionization, namely, collisional ionization of atoms and incoherent polarization bremsstrahlung. The cross sections of these processes were expressed through the Compton profile of X-ray scattering,

  3. Effect of polarization force on the Jeans instability in collisional dusty plasmas

    Science.gov (United States)

    A, ABBASI; M, R. RASHIDIAN VAZIRI

    2018-03-01

    The Jeans instability in collisional dusty plasmas has been analytically investigated by considering the polarization force effect. Instabilities due to dust-neutral and ion-neutral drags can occur in electrostatic waves of collisional dusty plasmas with self-gravitating particles. In this study, the effect of gravitational force on heavy dust particles is considered in tandem with both the polarization and electrostatic forces. The theoretical framework has been developed and the dispersion relation and instability growth rate have been derived, assuming the plane wave approximation. The derived instability growth rate shows that, in collisional dusty plasmas, the Jeans instability strongly depends on the magnitude of the polarization force.

  4. Experimental studies of collisional plasma shocks and plasma interpenetration via merging supersonic plasma jets

    Science.gov (United States)

    Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.

    2015-11-01

    Over the past 4 years on the Plasma Liner Experiment (PLX) at LANL, we have studied obliquely and head-on-merging supersonic plasma jets of an argon/impurity or hydrogen/impurity mixture. The jets are formed/launched by pulsed-power-driven railguns. In successive experimental campaigns, we characterized the (a) evolution of plasma parameters of a single plasma jet as it propagated up to ~ 1 m away from the railgun nozzle, (b) density profiles and 2D morphology of the stagnation layer and oblique shocks that formed between obliquely merging jets, and (c) collisionless interpenetration transitioning to collisional stagnation between head-on-merging jets. Key plasma diagnostics included a fast-framing CCD camera, an 8-chord visible interferometer, a survey spectrometer, and a photodiode array. This talk summarizes the primary results mentioned above, and highlights analyses of inferred post-shock temperatures based on observations of density gradients that we attribute to shock-layer thickness. We also briefly describe more recent PLX experiments on Rayleigh-Taylor-instability evolution with magnetic and viscous effects, and potential future collisionless shock experiments enabled by low-impurity, higher-velocity plasma jets formed by contoured-gap coaxial guns. Supported by DOE Fusion Energy Sciences and LANL LDRD.

  5. Coherent emission mechanisms in astrophysical plasmas

    Science.gov (United States)

    Melrose, D. B.

    2017-12-01

    Three known examples of coherent emission in radio astronomical sources are reviewed: plasma emission, electron cyclotron maser emission (ECME) and pulsar radio emission. Plasma emission is a multi-stage mechanism with the first stage being generation of Langmuir waves through a streaming instability, and subsequent stages involving partial conversion of the Langmuir turbulence into escaping radiation at the fundamental (F) and second harmonic (H) of the plasma frequency. The early development and subsequent refinements of the theory, motivated by application to solar radio bursts, are reviewed. The driver of the instability is faster electrons outpacing slower electrons, resulting in a positive gradient ({d}f(v_allel )/{d}v_allel >0) at the front of the beam. Despite many successes of the theory, there is no widely accepted explanation for type I bursts and various radio continua. The earliest models for ECME were purely theoretical, and the theory was later adapted and applied to Jupiter (DAM), the Earth (AKR), solar spike bursts and flare stars. ECME strongly favors the x mode, whereas plasma emission favors the o mode. Two drivers for ECME are a ring feature (implying {d}f(v)/{d}v>0) and a loss-cone feature. Loss-cone-driven ECME was initially favored for all applications. The now favored driver for AKR is the ring-feature in a horseshoe distribution, which results from acceleration by a parallel electric on converging magnetic field lines. The driver in DAM and solar and stellar applications is uncertain. The pulsar radio emission mechanism remains an enigma. Ingredients needed in discussing possible mechanisms are reviewed: general properties of pulsars, pulsar electrodynamics, the properties of pulsar plasma and wave dispersion in such plasma. Four specific emission mechanisms (curvature emission, linear acceleration emission, relativistic plasma emission and anomalous Doppler emission) are discussed and it is argued that all encounter difficulties. Coherent

  6. Impurity transport and bulk ion flow in a mixed collisionality stellarator plasma

    Science.gov (United States)

    Newton, S. L.; Helander, P.; Mollén, A.; Smith, H. M.

    2017-10-01

    The accumulation of impurities in the core of magnetically confined plasmas, resulting from standard collisional transport mechanisms, is a known threat to their performance as fusion energy sources. Whilst the axisymmetric tokamak systems have been shown to benefit from the effect of temperature screening, that is an outward flux of impurities driven by the temperature gradient, impurity accumulation in stellarators was thought to be inevitable, driven robustly by the inward pointing electric field characteristic of hot fusion plasmas. We have shown in Helander et al. (Phys. Rev. Lett., vol. 118, 2017a, 155002) that such screening can in principle also appear in stellarators, in the experimentally relevant mixed collisionality regime, where a highly collisional impurity species is present in a low collisionality bulk plasma. Details of the analytic calculation are presented here, along with the effect of the impurity on the bulk ion flow, which will ultimately affect the bulk contribution to the bootstrap current.

  7. A Hybrid Model for Multiscale Laser Plasma Simulations with Detailed Collisional Physics

    Science.gov (United States)

    2017-06-15

    important physical process as possible with as little computational cost as possible. • To that end, we are in the early processes of characterizing...Detailed Collisional Physics David Bilyeu, Carl Lederman, Richard Abrantes Air Force Research Laboratory (AFMC) AFRL/RQRS 1 Ara Drive Edwards AFB, CA...for Public Release; Distribution is Unlimited. PA# 17383 A Hybrid Model for Multiscale Laser Plasma Simulations with Detailed Collisional Physics

  8. Electrostatic sheath at the boundary of a collisional dusty plasma

    Indian Academy of Sciences (India)

    Moreover, the collisions of the dust charged grains with the neutrals are ex- pected to exhibit novel features. Keywords. ... of continuity and motion. On the inertial time scale of the cold but .... However, in a highly collisional atmosphere the drag force on the dust charged grains due to collisions becomes sufficiently large and ...

  9. A plasma formulary for physics, technology, and astrophysics

    CERN Document Server

    Diver, Declan

    2011-01-01

    Plasma physics has matured rapidly as a discipline, and now touches on many different research areas, including manufacturing processes. This collection of fundamental formulae and definitions in plasma physics is vital to anyone with an interest in plasmas or ionized gases, whether in physics, astronomy or engineering.Both theorists and experimentalists will find this book useful, as it incorporates the latest results and findings.The text treats astrophysical plasmas, fusion plasmas, industrial plasmas and low temperature plasmas as aspects of the same discipline - a unique approach made pos

  10. Mini-conference and Related Sessions on Laboratory Plasma Astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Hantao Ji

    2004-02-27

    This paper provides a summary of some major physics issues and future perspectives discussed in the Mini-Conference on Laboratory Plasma Astrophysics. This Mini-conference, sponsored by the Topical Group on Plasma Astrophysics, was held as part of the American Physical Society's Division of Plasma Physics 2003 Annual Meeting (October 27-31, 2003). Also included are brief summaries of selected talks on the same topic presented at two invited paper sessions (including a tutorial) and two contributed focus oral sessions, which were organized in coordination with the Mini-Conference by the same organizers.

  11. Multi-scale Dynamical Processes in Space and Astrophysical Plasmas

    CERN Document Server

    Vörös, Zoltán; IAFA 2011 - International Astrophysics Forum 2011 : Frontiers in Space Environment Research

    2012-01-01

    Magnetized plasmas in the universe exhibit complex dynamical behavior over a huge range of scales. The fundamental mechanisms of energy transport, redistribution and conversion occur at multiple scales. The driving mechanisms often include energy accumulation, free-energy-excited relaxation processes, dissipation and self-organization. The plasma processes associated with energy conversion, transport and self-organization, such as magnetic reconnection, instabilities, linear and nonlinear waves, wave-particle interactions, dynamo processes, turbulence, heating, diffusion and convection represent fundamental physical effects. They demonstrate similar dynamical behavior in near-Earth space, on the Sun, in the heliosphere and in astrophysical environments. 'Multi-scale Dynamical Processes in Space and Astrophysical Plasmas' presents the proceedings of the International Astrophysics Forum Alpbach 2011. The contributions discuss the latest advances in the exploration of dynamical behavior in space plasmas environm...

  12. FOREWORD: Workshop on "Very Hot Astrophysical Plasmas"

    Science.gov (United States)

    Koch-Miramond, Lydie; Montemerie, Thierry

    1984-01-01

    A Workshop on "Very Hot Astrophysical Plasmas" was held in Nice, France, on 8-10 November 1982. Dedicated mostly to theoretical, observational, and experimental aspects of X-ray astronomy and related atomic physics, it was the first of its kind to be held in France. The Workshop was "European" in the sense that one of its goals (apart from pure science) was to gather the European astronomical community in view of the forthcoming presentation of the "X-80" project for final selection to be the next scientific satellite of the European Space Agency. We now know that the Infrared Space Observatory has been chosen instead, but the recent successful launch of EXOSAT still keeps X-ray astronomy alive, and should be able to transfer, at least for a time, the leadership in this field from the U.S. to Europe, keeping in mind the competitive level of our Japanese colleagues. (With respect to the selection of ISO, one should also keep in mind that observations in the infrared often bring material relevant to the study of X-ray sources!) On a longer time scale, the Workshop also put emphasis on several interesting projects for the late eighties-early nineties, showing the vitality of the field in Europe. Some proposals have already taken a good start, like XMM, the X-ray Multi-Mirror project, selected by ESA last December for an assessment study in 1983. The present proceedings contain most of the papers that were presented at the Workshop. Only the invited papers were presented orally, contributed papers being presented in the form of posters but summarized orally by rapporteurs. To make up this volume, the written versions of these papers were either cross-reviewed by the Invited Speakers, or refereed by the Rapporteurs (for contributed papers) and edited by us, when necessary. Note, however, that the conclusions of the Workshop, which were kindly presented by Richard McCray, have already appeared in the "News and Views" section of Nature (301, 372, 1983). Altogether, the

  13. Collisional effect on the Weibel instability in the limit of high plasma ...

    Indian Academy of Sciences (India)

    Abstract. The Weibel instability (WI) of relativistic electron beam (REB) penetrating an infinite collisional plasma was studied in the following models: (i) REB model, where the total equilibrium distribution function f0(p ) is approximated by nonrelativistic back- ground electron and REB distribution functions and (ii) relativistic ...

  14. Photon pair production in astrophysical transrelativistic plasmas

    Science.gov (United States)

    Stoeger, W. R.

    1977-01-01

    Photon pair-production processes in marginally relativistic (transrelativistic) accretion plasmas are investigated in both Planckian and non-Planckian cases. Pair production in a plasma with an equilibrium (Planck) spectrum is reviewed, and pair-concentration calculations are performed for three general non-Planckian situations most relevant to black-hole accretion scenarios: steady-state transrelativistic plasmas of relatively high density characterized by a pure bremsstrahlung spectrum, a comptonized bremsstrahlung spectrum, and an unsaturated Compton scattering spectrum. The results obtained indicate that for transrelativistic temperatures (600 million to 6 billion K) photon pair production is not generally a dominant process for a plasma with a pure bremsstrahlung spectrum, but becomes dominant for plasmas where comptonization is important. It is also shown that photon pair-creation processes in a transrelativistic bremsstrahlung-radiating plasma that is more than marginally optically thick to Compton scattering significantly alter the plasma's spectrum by forcing it to become black-body before it reaches relativistic temperatures. Pair production and instabilities in unsteady-state plasmas are briefly considered

  15. Collisional entanglement fidelities in quantum plasmas including strong quantum recoil and oscillation effects

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-10-01

    The quantum recoil and oscillation effects on the entanglement fidelity and the electron-exchange function for the electron-ion collision are investigated in a semiconductor plasma by using the partial wave analysis and effective interaction potential in strong quantum recoil regime. The magnitude of the electron-exchange function is found to increase as the collision energy increases, but it decreases with an increase in the exchange parameter. It is also found that the collisional entanglement fidelity in strong quantum recoil plasmas is enhanced by the quantum-mechanical and shielding effects. The collisional entanglement fidelity in a semiconductor plasma is also enhanced by the collective plasmon oscillation and electron-exchange effect. However, the electron-exchange effect on the fidelity ratio function is reduced as the plasmon energy increases. Moreover, the electron-exchange influence on the fidelity ratio function is found to increase as the Fermi energy in the semiconductor plasma increases.

  16. A Hybrid Model for Multiscale Laser Plasma Simulations with Detailed Collisional Physics

    Science.gov (United States)

    2017-06-23

    the effects of inelastic collisions on the Multi-Fluid description of plasmas. 15. SUBJECT TERMS Electric propulsion; plasma; collisional...inverse Bremsstrahlung. One key physical process not in- cluded is radiation transfer; instead an optical escape factor is used to model the loss of...the Monte Carlo integration had excellent agreement with the full transfer integral[6]. A key finding during this investigation was the effect that the

  17. Collisional electron broadening of Stark sublevels of an atom of hydrogen in a plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sholin, G.V.; Demura, A.V.; Lisitsa, V.S.

    1972-12-31

    A theoretical examination was made of the contours of the hydrogen lines in plasma, excited as a result of the static interaction of ions and collisional electrons with consideration of the special characteristics connected with the presence of supplementary degeneration in the Coulomb field. General expressions were obtained for the half-width of the Stark component of every line of the hydrogen spectrum in parabolic coordinates. A subsequent analysis was carried out of the transition from the overlapping of the Stark component to the isolated lines. It was found that such a transition is accompanied by annulment of the nondiagornl matrix elements of the operator of the collisional electron broadening. The form of the interference member in the operator of the collisional electron broadening is corrected with consideration of the perturbation of the upper and lower levels. The calculations carried out made it possible to improve the agreement between theory and experiment for lines with strong central components. (tr-auth)

  18. Space and astrophysical plasmas: Pervasive problems

    Indian Academy of Sciences (India)

    probes, sub-orbital systems and orbiting astronomical observatories point out that there are impor- tant physical ... earth orbiting satellites, deep space probes like Pioneer series and sub-orbital systems. Space plasma ... plorer I and subsequent discovery of Van Allen belts which brought the scientific research in space ...

  19. Longitudinal and transversal current in collisional plasma, generated by two transversal electromagnetic waves

    CERN Document Server

    Latyshev, A V

    2015-01-01

    From kinetic Vlasov equation for collisional plasmas distribution function in square-law approximation on sizes of intensivities of electric fields is received. The known integral of collisions of relaxation type, so-called BGK (Bhatnagar, Gross, Krook) integral of collisions is considered. The formula for calculation electric current at any temperature (any degree of degeneration of electronic gas) is deduced. This formula contains an one-dimensional quadrature. It is shown, that the nonlinearity account leads to occurrence the longitudinal electric current directed along a wave vector. This longitudinal current is orthogonal to a known transversal classical current, received at the linear analysis. When frequency of collisions tends to the zero, all received results for collisional plasmas pass in corresponding formulas for collisionless plasmas. The case of small values of wave number is considered. It is shown, that the received quantity of longitudinal current at aspiration of frequency of collisions to ...

  20. Reduction of collisional-radiative models for laser-produced argon plasmas

    Science.gov (United States)

    Abrantes, Richard June; Karagozian, Ann; Le, Hai

    2016-10-01

    The formation of a laser-induced plasma involves a variety of physical phenomena stemming from the laser-plasma interaction. A thorough understanding of these processes encourages improvement and innovation for many applications. In this work, we aim to computationally reduce a previously-developed collisional-radiative (CR) model constructed from the LANL database, which includes all of the relevant collisional and radiative processes for all the ionic stages of argon. The laser is coupled to the plasma via multiphoton ionization and inverse Bremsstrahlung, processes important for electron production and heating. The use of the CR model allows us to identify dominant mechanisms responsible for initial breakdown of the gas and thermal equilibriation processes. The results are compared with experimental data from laser-induced breakdown experiments. Research supported by the AFOSR.

  1. Cosmic ray transport in astrophysical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Schlickeiser, R. [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- & Astrophysik, Ruhr-Universität, Bochum (Germany)

    2015-09-15

    Since the development of satellite space technology about 50 years ago the solar heliosphere is explored almost routinely by several spacecrafts carrying detectors for measuring the properties of the interplanetary medium including energetic charged particles (cosmic rays), solar wind particle densities, and electromagnetic fields. In 2012, the Voyager 1 spacecraft has even left what could be described as the heliospheric modulation region, as indicated by the sudden disappearance of low energy heliospheric cosmic ray particles. With the available in-situ measurements of interplanetary turbulent electromagnetic fields and of the momentum spectra of different cosmic ray species in different interplanetary environments, the heliosphere is the best cosmic laboratory to test our understanding of the transport and acceleration of cosmic rays in space plasmas. I review both the historical development and the current state of various cosmic ray transport equations. Similarities and differences to transport theories for terrestrial fusion plasmas are highlighted. Any progress in cosmic ray transport requires a detailed understanding of the electromagnetic turbulence that is responsible for the scattering and acceleration of these particles.

  2. Effect of gas mixing on physical properties of warm collisional helicon plasmas

    Science.gov (United States)

    Kabir, M.; Niknam, A. R.

    2017-10-01

    The effect of inert gas mixing on the physical properties of a helicon plasma source with a Nagoya type III antenna is analytically investigated by taking into account the thermal and collisional effects. The dielectric permittivity tensor of this mixed gas plasma is obtained by using the Bhatnagar-Gross- Krook kinetic theory. Considering the dielectric tensor of mixed gas plasma and solving the electromagnetic field equations, the profiles of electromagnetic fields and plasma resistance are plotted and discussed. The results show that the plasma resistance peaks decrease with increasing Xe fraction in Ar-Xe plasma, and increase with the He fraction in Ar-He plasma. It is also shown that by increasing the xenon filling fraction, the electromagnetic field amplitudes are lowered, and by increasing the helium filling fraction, they are increased.

  3. Nonlinear Interaction of Elliptical Laser Beam with Collisional Plasma: Effect of Linear Absorption

    Science.gov (United States)

    Walia, Keshav; Kaur, Sarabjit

    2016-01-01

    In the present work, nonlinear interaction of elliptical laser beam with collisional plasma is studied by using paraxial ray approximation. Nonlinear differential equations for the beam width parameters of semi-major axis and semi-minor axis of elliptical laser beam have been set up and solved numerically to study the variation of beam width parameters with normalized distance of propagation. Effects of variation in absorption coefficient and plasma density on the beam width parameters are also analyzed. It is observed from the analysis that extent of self-focusing of beam increases with increase/decrease in plasma density/absorption coefficient.

  4. Laboratory Plasma Source as an MHD Model for Astrophysical Jets

    Science.gov (United States)

    Mayo, Robert M.

    1997-01-01

    The significance of the work described herein lies in the demonstration of Magnetized Coaxial Plasma Gun (MCG) devices like CPS-1 to produce energetic laboratory magneto-flows with embedded magnetic fields that can be used as a simulation tool to study flow interaction dynamic of jet flows, to demonstrate the magnetic acceleration and collimation of flows with primarily toroidal fields, and study cross field transport in turbulent accreting flows. Since plasma produced in MCG devices have magnetic topology and MHD flow regime similarity to stellar and extragalactic jets, we expect that careful investigation of these flows in the laboratory will reveal fundamental physical mechanisms influencing astrophysical flows. Discussion in the next section (sec.2) focuses on recent results describing collimation, leading flow surface interaction layers, and turbulent accretion. The primary objectives for a new three year effort would involve the development and deployment of novel electrostatic, magnetic, and visible plasma diagnostic techniques to measure plasma and flow parameters of the CPS-1 device in the flow chamber downstream of the plasma source to study, (1) mass ejection, morphology, and collimation and stability of energetic outflows, (2) the effects of external magnetization on collimation and stability, (3) the interaction of such flows with background neutral gas, the generation of visible emission in such interaction, and effect of neutral clouds on jet flow dynamics, and (4) the cross magnetic field transport of turbulent accreting flows. The applicability of existing laboratory plasma facilities to the study of stellar and extragalactic plasma should be exploited to elucidate underlying physical mechanisms that cannot be ascertained though astrophysical observation, and provide baseline to a wide variety of proposed models, MHD and otherwise. The work proposed herin represents a continued effort on a novel approach in relating laboratory experiments to

  5. A collisional-radiative model of iron vapour in a thermal arc plasma

    Science.gov (United States)

    Baeva, M.; Uhrlandt, D.; Murphy, A. B.

    2017-06-01

    A collisional-radiative model for the ground state and fifty effective excited levels of atomic iron, and one level for singly-ionized iron, is set up for technological plasmas. Attention is focused on the population of excited states of atomic iron as a result of excitation, de-excitation, ionization, recombination and spontaneous emission. Effective rate coefficients for ionization and recombination, required in non-equilibrium plasma transport models, are also obtained. The collisional-radiative model is applied to a thermal arc plasma. Input parameters for the collisional-radiative model are provided by a magnetohydrodynamic simulation of a gas-metal welding arc, in which local thermodynamic equilibrium is assumed and the treatment of the transport of metal vapour is based on combined diffusion coefficients. The results clearly identify the conditions in the arc, under which the atomic state distribution satisfies the Boltzmann distribution, with an excitation temperature equal to the plasma temperature. These conditions are met in the central part of the arc, even though a local temperature minimum occurs here. This provides assurance that diagnostic methods based on local thermodynamic equilibrium, in particular those of optical emission spectroscopy, are reliable here. In contrast, deviations from the equilibrium atomic-state distribution are obtained in the near-electrode and arc fringe regions. As a consequence, the temperatures determined from the ratio of line intensities and number densities obtained from the emission coefficient in these regions are questionable. In this situation, the collisional-radiative model can be used as a diagnostic tool to assist in the interpretation of spectroscopic measurements.

  6. Astrophysical Aspects of Neutrino Dynamics in Ultradegenerate Quark Gluon Plasma

    Directory of Open Access Journals (Sweden)

    Souvik Priyam Adhya

    2017-01-01

    Full Text Available The cardinal focus of the present review is to explore the role of neutrinos originating from the ultradense core of neutron stars composed of quark gluon plasma in the astrophysical scenario. The collective excitations of the quarks involving the neutrinos through the different kinematical processes have been studied. The cooling of the neutron stars as well as pulsar kicks due to asymmetric neutrino emission has been discussed in detail. Results involving calculation of relevant physical quantities like neutrino mean free path and emissivity have been presented in the framework of non-Fermi liquid behavior as applicable to ultradegenerate plasma.

  7. Extension of high-beta plasma operation to low-collisionality regime

    Science.gov (United States)

    Sakakibara, S.; Watanabe, K. Y.; Funaba, H.; Suzuki, Y.; Ohdachi, S.; Ida, K.; Tanaka, K.; Tokuzawa, T.; Morisaki, T.; Osakabe, M.; Takeiri, Y.; LHD Experiment Group

    2017-06-01

    In the large helical device, plasma with more than 4% average beta was successfully produced by multi-pellet injections in a regime with a collisionality one order of magnitude lower than that in previous high-beta operations. An improvement in particle confinement was observed during a high-beta discharge produced by a gas puff, and particle flux to the divertor was reduced by more than 40%. High instabilities at the plasma edge occurred and suppressed the increment of the average beta to 3.4%. A spontaneous change in the magnetic topology contributes to an increase in the average beta value while triggering the excitation of edge MHD instabilities.

  8. Revealing an intermediate region between the collisional radiofrequency plasma bulk and its sheath.

    Science.gov (United States)

    Beckers, J; Trienekens, D J M; Kroesen, G M W

    2015-03-01

    Experimental evidence of the existence of an intermediate region between a capacitively coupled plasma and the collisional space-charge region at its borders is presented. This proof is generated by monitoring-in an airplane carrying out parabolic flights-the trajectory of plasma-confined microparticles. Based on only primary data and without the need for a sophisticated model, our analysis concludes a sharply marked transition from the sheath region into another region with a significantly lower-yet nonzero-space-charge density, i.e., a region which is often called the presheath.

  9. A study of the propagation of ulf electromagnetic fields in collisional, inhomogeneous, magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Borovsky, J.E.

    1987-02-01

    The propagation of ultralow-frequency (ulf) electromagnetic signals (Alfven and magnetosonic waves) in collisional, inhomogeneous, magnetized plasmas is analyzed by numerical simulation. The problem is formulated from a Maxwell-equation orbit-theory approach rather than from a magnetohydrodynamic point of view, and the problem is numerically treated in a fully time-dependent manner. Boundary-value-problem behavior is distinguished from initial-value-problem behavior. The propagation of two-dimensional small-amplitude electromagnetic disturbances in plasmas with spatially dependent densities and in plasmas with spatially dependent conductivities is numerically simulated, and when possible, the simulations are compared with theory. Changes in the plasma density lead to changes in the signal speed and to reflections; collisions lead to changes in the signal speed, to reflections, and to attenuations. Theoretical descriptions based upon discontinuities in the media are generally incorrect in predicting the amplitudes of signals reflected from plasma inhomogeneities. 19 refs., 16 figs.

  10. FIRST KODAI-TRIESTE WORKSHOP ON PLASMA ASTROPHYSICS

    CERN Document Server

    Hasan, S. S; Krishan, V; TURBULENCE, DYNAMOS, ACCRETION DISKS, PULSARS AND COLLECTIVE PLASMA PROCESSES

    2008-01-01

    It is well established and appreciated by now that more than 99% of the baryonic matter in the universe is in the plasma state. Most astrophysical systems could be approximated as conducting fluids in a gravitational field. It is the combined effect of these two that gives rise to the mind boggling variety of configurations in the form of filaments, loops , jets and arches. The plasma structures that cannot last for more than a second or less in a laboratory remain intact for astronomical time and spatial scales in an astrophysical setting. The case in point is the well known extragalactic jets whose collimation and stability has remained an enigma inspite of the efforts of many for many long years. The high energy radiation sources such as the active galactic nuclei again summon the coherent plasma radiation processes for their exceptionally large output from regions of relatively small physical sizes. The generation of magnetic field, anomalous transport of angular momentum with decisive bearing on star for...

  11. Jet energy loss in quark-gluon plasma. Kinetic theory with a Bhatnagar-Gross-Krook collisional kernel

    Energy Technology Data Exchange (ETDEWEB)

    Han, Cheng; Hou, De-fu; Li, Jia-rong [Central China Normal University, Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Wuhan, Hubei (China); Jiang, Bing-feng [Hubei University for Nationalities, Center for Theoretical Physics and School of Sciences, Enshi, Hubei (China)

    2017-10-15

    The dielectric functions ε{sub L}, ε{sub T} of the quark-gluon plasma (QGP) are derived within the framework of the kinetic theory with BGK-type collisional kernel. The collision effect manifested by the collision rate is encoded in the dielectric functions. Based on the derived dielectric functions we study the collisional energy loss suffered by a fast parton traveling through the QGP. The numerical results show that the collision rate increases the energy loss. (orig.)

  12. Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas

    Science.gov (United States)

    Mikkelsen, D. R.; Bitter, M.; Delgado-Aparicio, L.; Hill, K. W.; Greenwald, M.; Howard, N. T.; Hughes, J. W.; Rice, J. E.; Reinke, M. L.; Podpaly, Y.; Ma, Y.; Candy, J.; Waltz, R. E.

    2015-06-01

    Peaked density profiles in low-collisionality AUG and JET H-mode plasmas are probably caused by a turbulently driven particle pinch, and Alcator C-Mod experiments confirmed that collisionality is a critical parameter. Density peaking in reactors could produce a number of important effects, some beneficial, such as enhanced fusion power and transport of fuel ions from the edge to the core, while others are undesirable, such as lower beta limits, reduced radiation from the plasma edge, and consequently higher divertor heat loads. Fundamental understanding of the pinch will enable planning to optimize these impacts. We show that density peaking is predicted by nonlinear gyrokinetic turbulence simulations based on measured profile data from low collisionality H-mode plasma in Alcator C-Mod. Multiple ion species are included to determine whether hydrogenic density peaking has an isotope dependence or is influenced by typical levels of low-Z impurities, and whether impurity density peaking depends on the species. We find that the deuterium density profile is slightly more peaked than that of hydrogen, and that experimentally relevant levels of boron have no appreciable effect on hydrogenic density peaking. The ratio of density at r/a = 0.44 to that at r/a = 0.74 is 1.2 for the majority D and minority H ions (and for electrons), and increases with impurity Z: 1.1 for helium, 1.15 for boron, 1.3 for neon, 1.4 for argon, and 1.5 for molybdenum. The ion temperature profile is varied to match better the predicted heat flux with the experimental transport analysis, but the resulting factor of two change in heat transport has only a weak effect on the predicted density peaking.

  13. Collisional Rayleigh-Taylor instability and shear-flow in equatorial Spread-F plasma

    Directory of Open Access Journals (Sweden)

    N. Chakrabarti

    2003-05-01

    Full Text Available Collisional Rayleigh-Taylor (RT instability is considered in the bottom side of the equatorial F-region. By a novel nonmodal calculation it is shown that for an applied shear flow in equilibrium, the growth of the instability is considerably reduced. Finite but small amounts of diffusion enhances the stabilization process. The results may be relevant to the observations of long-lived irregularities at the bottom-side of the F-layer.Key words. Ionosphere (ionospheric irregularities, equatorial ionosphere, plasma waves and instabilities

  14. Collisional Rayleigh-Taylor instability and shear-flow in equatorial Spread-F plasma

    Directory of Open Access Journals (Sweden)

    N. Chakrabarti

    Full Text Available Collisional Rayleigh-Taylor (RT instability is considered in the bottom side of the equatorial F-region. By a novel nonmodal calculation it is shown that for an applied shear flow in equilibrium, the growth of the instability is considerably reduced. Finite but small amounts of diffusion enhances the stabilization process. The results may be relevant to the observations of long-lived irregularities at the bottom-side of the F-layer.

    Key words. Ionosphere (ionospheric irregularities, equatorial ionosphere, plasma waves and instabilities

  15. Negative drag force on finite-size charged dust grain in strongly collisional plasma

    Science.gov (United States)

    Momot, A. I.

    2017-10-01

    The drag force on finite-size charged conductive spherical dust grain stationary moving in strongly collisional weakly ionized plasmas is studied numerically within the drift-diffusion approximation. It is assumed that the grain surface collects all encountered electrons and ions, i.e., the grain is at a floating potential. The velocity dependencies of the drag, stationary charging current and grain charge are obtained for various grain sizes for both isothermal and nonisothermal plasmas. The plasma density profiles were calculated and compared with those obtained earlier in a kinetic approach. The numerical results of the drag force are compared with known analytical expressions. A more simple expression is proposed, and its applicability is examined. Natural drag described by the Stokes' force is taken into consideration.

  16. Fully kinetic simulations of magnetic reconnction in semi-collisional plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Daughton, William S [Los Alamos National Laboratory; Roytershteyn, Vadim S [Los Alamos National Laboratory; Albright, Brian J [Los Alamos National Laboratory; Yin, Lin [Los Alamos National Laboratory; Bowers, Kevin J [Los Alamos National Laboratory; Karimabadi, Homa [UCSD

    2009-01-01

    The influence of Coulomb collisions on the dynamics of magnetic reconnection is examined using fully kinetic simulations with a Monte-Carlo treatment of the Fokker-Planck collision operator. This powerful first-principles approach offers a bridge between kinetic and fluid regimes, which may prove useful for understanding the applicability of various fluid models. In order to lay the necessary groundwork, the collision algorithm is first carefully bench marked for a homogeneous plasma against theoretical predictions for beam-plasma interactions and electrical resistivity. Next, the collisional decay of a current layer is examined as a function of guide field, allowing direct comparisons with transport theory for the parallel and perpendicular resistivity as well as the thermoelectric force. Finally, the transition between collisional and collision less reconnection is examined in neutral sheet geometry. For modest Lundquist numbers S {approx}< 1000, a distinct transition is observed when the thickness of the Sweet-Parker layers falls below the ion inertia length {delta}{sub sp} {approx}< d,. At higher Lundquist number, deviations from the Sweet-Parker scaling are observed due to the growth of plasmoids (secondary-islands) within the elongated resistive layer. In certain cases, this instability leads to the onset of fast reconnection sooner than expected from {delta}{sub sp} {approx} d, condition. After the transition to fast reconnection, elongated electron current layers are formed which are unstable to the formation of new plasmoids. The structure and time-dependence of the electron diffusion region in these semi-collisional regimes is profoundly different than reported in two-fluid simulations.

  17. High density plasmas formation in Inertial Confinement Fusion and Astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Val, J. M.; Minguez, E.; Velarde, P.; Perlado, J. M.; Velarde, G.; Bravo, E.; Eliezer, S.; Florido, R.; Garcia Rubiano, J.; Garcia-Senz, D.; Gil de la Fe, J. M.; Leon, P. T.; Martel, P.; Ogando, F.; Piera, M.; Relano, A.; Rodriguez, R.; Garcia, C.; Gonzalez, E.; Lachaise, M.; Oliva, E.

    2005-07-01

    In inertially confined fusion (ICF), high densities are required to obtain high gains. In Fast Ignition, a high density, low temperature plasma can be obtained during the compression. If the final temperature reached is low enough, the electrons of the plasma can be degenerate. In degenerate plasmas. Bremsstrahlung emission is strongly suppressed an ignition temperature becomes lower than in classical plasmas, which offers a new design window for ICF. The main difficulty of degenerate plasmas in the compression energy needed for high densities. Besides that, the low specific heat of degenerate electrons (as compared to classical values) is also a problem because of the rapid heating of the plasma. Fluid dynamic evolution of supernovae remnants is a very interesting problem in order to predict the thermodynamical conditions achieved in their collision regions. Those conditions have a strong influence in the emission of light and therefore the detection of such events. A laboratory scale system has been designed reproducing the fluid dynamic field in high energy experiments. The evolution of the laboratory system has been calculated with ARWEN code, 2D Radiation CFD that works with Adaptive Mesh Refinement. Results are compared with simulations on the original system obtained with a 3D SPH astrophysical code. New phenomena at the collision plane and scaling of the laboratory magnitudes will be described. Atomic physics for high density plasmas has been studied with participation in experiments to obtain laser produced high density plasmas under NLTE conditions, carried out at LULI. A code, ATOM3R, has been developed which solves rate equations for optically thin plasmas as well as for homogeneous optically thick plasmas making use of escape factors. New improvements in ATOM3R are been done to calculate level populations and opacities for non homogeneous thick plasmas in NLTE, with emphasis in He and H lines for high density plasma diagnosis. Analytical expression

  18. First Test of Long-Range Collisional Drag via Plasma Wave Damping

    Science.gov (United States)

    Affolter, Matthew

    2017-10-01

    In magnetized plasmas, the rate of particle collisions is enhanced over classical predictions when the cyclotron radius rc is less than the Debye length λD. Classical theories describe local velocity scattering collisions with impact parameters ρ theory have shown that these long-range collisions enhance cross-field diffusion, heat transport, and viscosity by orders of magnitude over classical predictions. Here, we present the first experimental confirmation of a new theory, which predicts enhanced parallel velocity slowing due to these long-range collisions. These experiments measure the damping of Trivelpiece-Gould waves in a multispecies pure ion plasma. The damping is dominated by interspecies collisional drag when Landau damping is weak. In this ``drag damping'' regime, the measured damping rates exceed classical predictions of collisional drag damping by as much as an order of magnitude, but agree with the new long-range enhanced collision theory. The enhanced slowing is most significant for strong magnetization and low temperatures. For example, the slowing of anti-protons at a density of 107 cm-3 and a temperature of 10 K in a 6 T trap is enhanced by a factor of 30. Supported by NSF Grant PHY-1414570 and DOE Grant DE-SC0002451. In collaboration with F. Anderegg, D.H.E. Dubin, and C.F. Driscoll.

  19. Laser plasma physics in shock ignition – transition from collisional to collisionless absorption

    Directory of Open Access Journals (Sweden)

    Klimo O.

    2013-11-01

    Full Text Available Shock Ignition is considered as a relatively robust and efficient approach to inertial confinement fusion. A strong converging shock, which is used to ignite the fuel, is launched by a high power laser pulse with intensity in the range of 1015 − 1016 W/cm2 (at the wavelength of 351 nm. In the lower end of this intensity range the interaction is dominated by collisions while the parametric instabilities are playing a secondary role. This is manifested in a relatively weak reflectivity and efficient electron heating. The interaction is dominated by collective effects at the upper edge of the intensity range. The stimulated Brillouin and Raman scattering (SBS and SRS respectively take place in a less dense plasma and cavitation provides an efficient collisionless absorption mechanism. The transition from collisional to collisionless absorption in laser plasma interactions at higher intensities is studied here with the help of large scale one-dimensional Particle-in-Cell (PIC simulations. The relation between the collisional and collisionless processes is manifested in the energy spectrum of electrons transporting the absorbed laser energy and in the spectrum of the reflected laser light.

  20. The frequency and damping of ion acoustic waves in collisional and collisionless two-species plasma

    Energy Technology Data Exchange (ETDEWEB)

    Berger, R L; Valeo, E J

    2004-07-15

    The dispersion properties of ion acoustic waves (IAW) are sensitive to the strength of ion-ion collisions in multi-species plasma in which the different species usually have differing charge-to-mass ratios. The modification of the frequency and damping of the fast and slow acoustic modes in a plasma composed of light (low Z) and heavy (high Z) ions is considered. In the fluid limit where the light ion scattering mean free path, {lambda}{sub th} is smaller than the acoustic wavelength, {lambda} = 2{pi}/k, the interspecies friction and heat flow carried by the light ions scattering from the heavy ions causes the damping. In the collisionless limit, k{lambda}{sub lh} >> 1, Landau damping by the light ions provides the dissipation. In the intermediate regime when k{lambda}{sub lh} {approx} 1, the damping is at least as large as the sum of the collisional and Landau damping.

  1. The Frequency and Damping of Ion Acoustic Waves in Collisional and Collisionless Two-species Plasma

    Energy Technology Data Exchange (ETDEWEB)

    R.L. Berger; E.J. Valeo

    2004-08-18

    The dispersion properties of ion acoustic waves (IAW) are sensitive to the strength of ion-ion collisions in multi-species plasma in which the different species usually have differing charge-to-mass ratios. The modification of the frequency and damping of the fast and slow acoustic modes in a plasma composed of light (low Z) and heavy (high Z) ions is considered. In the fluid limit where the light ion scattering mean free path, {lambda}{sub th} is smaller than the acoustic wavelength, {lambda} = 2{pi}/k, the interspecies friction and heat flow carried by the light ions scattering from the heavy ions causes the damping. In the collisionless limit, k{lambda}{sub th} >> 1, Landau damping by the light ions provides the dissipation. In the intermediate regime when k{lambda}{sub th} {approx} 1, the damping is at least as large as the sum of the collisional and Landau damping.

  2. First-principle description of collisional gyrokinetic turbulence in tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Dif-Pradalier, G

    2008-10-15

    This dissertation starts in chapter 1 with a comprehensive introduction to nuclear fusion, its basic physics, goals and means. It especially defines the concept of a fusion plasma and some of its essential physical properties. The following chapter 2 discusses some fundamental concepts of statistical physics. It introduces the kinetic and the fluid frameworks, compares them and highlights their respective strengths and limitations. The end of the chapter is dedicated to the fluid theory. It presents two new sets of closure relations for fluid equations which retain important pieces of physics, relevant in the weakly collisional tokamak regimes: collective resonances which lead to Landau damping and entropy production. Nonetheless, since the evolution of the turbulence is intrinsically nonlinear and deeply influenced by velocity space effects, a kinetic collisional description is most relevant. First focusing on the kinetic aspect, chapter 3 introduces the so-called gyrokinetic framework along with the numerical solver - the GYSELA code - which will be used throughout this dissertation. Very generically, code solving is an initial value problem. The impact on turbulent nonlinear evolution of out of equilibrium initial conditions is discussed while studying transient flows, self-organizing dynamics and memory effects due to initial conditions. This dissertation introduces an operational definition, now of routine use in the GYSELA code, for the initial state and concludes on the special importance of the accurate calculation of the radial electric field. The GYSELA framework is further extended in chapter 4 to describe Coulomb collisions. The implementation of a collision operator acting on the full distribution function is presented. Its successful confrontation to collisional theory (neoclassical theory) is also shown. GYSELA is now part of the few gyrokinetic codes which can self-consistently address the interplay between turbulence and collisions. While

  3. Recent progress in astrophysical plasma turbulence from solar wind observations

    CERN Document Server

    Chen, C H K

    2016-01-01

    This paper summarises some of the recent progress that has been made in understanding astrophysical plasma turbulence in the solar wind, from in situ spacecraft observations. At large scales, where the turbulence is predominantly Alfvenic, measurements of critical balance, residual energy, and 3D structure are discussed, along with comparison to recent models of strong Alfvenic turbulence. At these scales, a few percent of the energy is also in compressive fluctuations, and their nature, anisotropy, and relation to the Alfvenic component is described. In the small scale kinetic range, below the ion gyroscale, the turbulence becomes predominantly kinetic Alfven in nature, and measurements of the spectra, anisotropy, and intermittency of this turbulence are discussed with respect to recent cascade models. One of the major remaining questions is how the turbulent energy is dissipated, and some recent work on this question, in addition to future space missions which will help to answer it, are briefly discussed.

  4. Limitations of Hall MHD as a model for turbulence in weakly collisional plasmas

    Directory of Open Access Journals (Sweden)

    G. G. Howes

    2009-03-01

    Full Text Available The limitations of Hall MHD as a model for turbulence in weakly collisional plasmas are explored using quantitative comparisons to Vlasov-Maxwell kinetic theory over a wide range of parameter space. The validity of Hall MHD in the cold ion limit is shown, but spurious undamped wave modes exist in Hall MHD when the ion temperature is finite. It is argued that turbulence in the dissipation range of the solar wind must be one, or a mixture, of three electromagnetic wave modes: the parallel whistler, oblique whistler, or kinetic Alfvén waves. These modes are generally well described by Hall MHD. Determining the applicability of linear kinetic damping rates in turbulent plasmas requires a suite of fluid and kinetic nonlinear numerical simulations. Contrasting fluid and kinetic simulations will also shed light on whether the presence of spurious wave modes alters the nonlinear couplings inherent in turbulence and will illuminate the turbulent dynamics and energy transfer in the regime of the characteristic ion kinetic scales.

  5. The exact form of the Bohm criterion for a collisional plasma

    CERN Document Server

    Tsankov, Tsanko Vaskov

    2016-01-01

    A long-standing debate in the literature about the kinetic form of the Bohm criterion is resolved for plasmas with single positive ion species when transport is dominated by charge exchange collisions. The solution of the Boltzmann equation for the ions gives the exact form free of any divergence and contains an additional term that is not included in the classical result. This term includes collisional and geometric effects and leads to a noticeable correction. Further, the question is addressed whether the space charge argument at the bottom of the Bohm criterion can actually lead to a meaningful definition of the transition point between bulk and sheath. The analysis is supported by a numerical model and experiments, showing excellent agreement throughout. As a novelty in diagnostics, the theoretical results allow from the ion velocity distribution function (IVDF), measured at the wall, a reconstruction of the IVDF and the electric field at any point in the plasma. This property is used to reconstruct non-...

  6. Nonlinear wave structures in collisional plasma of auroral E-region ionosphere

    Directory of Open Access Journals (Sweden)

    A. V. Volosevich

    1997-07-01

    Full Text Available Studies of the auroral plasma with small-scale inhomogenieties producing the VHF-radar reflections (radar aurora when observed in conditions of the saturated Farley-Buneman instability within the auroral E region, show strong nonlinear interactions and density fluctuations of 5–15%. Such nonlinearity and high fluctation amplitudes are inconsistent with the limitations of the weak turbulence theory, and thus a theory for arbitrary amplitudes is needed. To this end, a nonlinear theory is described for electrostatic MHD moving plasma structures of arbitrary amplitude for conditions throughout the altitude range of the collisional auroral E region. The equations are derived, from electron and ion motion self-consistent with the electric field, for the general case of the one-dimensional problem. They take into account nonlinearity, electron and ion inertia, diffusion, deviation from quasi-neutrality, and dynamical ion viscosity. The importance of the ion viscosity for dispersion is stressed, while deviation from the quasi-neutrality can be important only at rather low plasma densities, not typical for the auroral E region. In a small amplitude limit these equations have classical nonlinear solutions of the type of "electrostatic shock wave" or of knoidal waves. In a particular case these knoidal waves degrade to a dissipative soliton. A two-dimensional case of a quasi-neutral plasma is considered in the plane perpendicular to the magnetic field by way of the Poisson brackets, but neglecting the nonlinearity and ion inertia. It is shown that in these conditions an effective saturation can be achieved at the stationary turbulence level of order of 10%.

  7. Nonlinear wave structures in collisional plasma of auroral E-region ionosphere

    Directory of Open Access Journals (Sweden)

    A. V. Volosevich

    Full Text Available Studies of the auroral plasma with small-scale inhomogenieties producing the VHF-radar reflections (radar aurora when observed in conditions of the saturated Farley-Buneman instability within the auroral E region, show strong nonlinear interactions and density fluctuations of 5–15%. Such nonlinearity and high fluctation amplitudes are inconsistent with the limitations of the weak turbulence theory, and thus a theory for arbitrary amplitudes is needed. To this end, a nonlinear theory is described for electrostatic MHD moving plasma structures of arbitrary amplitude for conditions throughout the altitude range of the collisional auroral E region. The equations are derived, from electron and ion motion self-consistent with the electric field, for the general case of the one-dimensional problem. They take into account nonlinearity, electron and ion inertia, diffusion, deviation from quasi-neutrality, and dynamical ion viscosity. The importance of the ion viscosity for dispersion is stressed, while deviation from the quasi-neutrality can be important only at rather low plasma densities, not typical for the auroral E region. In a small amplitude limit these equations have classical nonlinear solutions of the type of "electrostatic shock wave" or of knoidal waves. In a particular case these knoidal waves degrade to a dissipative soliton. A two-dimensional case of a quasi-neutral plasma is considered in the plane perpendicular to the magnetic field by way of the Poisson brackets, but neglecting the nonlinearity and ion inertia. It is shown that in these conditions an effective saturation can be achieved at the stationary turbulence level of order of 10%.

  8. Resonant scattering as a sensitive diagnostic of current collisional plasma models

    Science.gov (United States)

    Ogorzalek, Anna; Zhuravleva, Irina; Allen, Steven W.; Pinto, Ciro; Werner, Norbert; Mantz, Adam; Canning, Rebecca; Fabian, Andrew C.; Kaastra, Jelle S.; de Plaa, Jelle

    2017-08-01

    Resonant scattering is a subtle process that suppresses fluxes of some of the brightest optically thick X-ray emission lines produced by collisional plasmas in galaxy clusters and massive early-type galaxies. The amplitude of the effect depends on the turbulent structure of the hot gas, making it a sensitive velocity probe. It is therefore crucial to properly model this effect in order to correctly interpret high resolution X-ray spectra. Our measurements of resonant scattering with XMM-Newton Reflection Grating Spectrometer in giant elliptical galaxies and with Hitomi in the center of Perseus Cluster show that the potentially rich inference from this effect is limited by the uncertainties in the atomic data underlying plasma codes such as APEC and SPEX. Typically, the effect is of the order of 10-20%, while the discrepancy between the two codes is of similar order or even higher. Precise knowledge of the emissivity and oscillator strengths of lines emitted by Fe XVII and Fe XXV, as well as their respective uncertainties propagated through plasma codes are key to understanding gas dynamics and microphysics in giant galaxies and cluster ICM, respectively. This is especially crucial for massive ellipticals, where sub-eV resolution would be needed to measure line broadening precisely, making resonant scattering an important velocity diagnostic in these systems for the foreseeable future. In this poster, I will summarize current status of resonant scattering measurements and show how they depend on the assumed atomic data. I will also discuss which improvements are essential to maximize scientific inference from future high resolution X-ray spectra.

  9. Thin current sheets caused by plasma flow gradients in space and astrophysical plasma

    Directory of Open Access Journals (Sweden)

    D. H. Nickeler

    2010-08-01

    Full Text Available Strong gradients in plasma flows play a major role in space and astrophysical plasmas. A typical situation is that a static plasma equilibrium is surrounded by a plasma flow, which can lead to strong plasma flow gradients at the separatrices between field lines with different magnetic topologies, e.g., planetary magnetospheres, helmet streamers in the solar corona, or at the boundary between the heliosphere and interstellar medium. Within this work we make a first step to understand the influence of these flows towards the occurrence of current sheets in a stationary state situation. We concentrate here on incompressible plasma flows and 2-D equilibria, which allow us to find analytic solutions of the stationary magnetohydrodynamics equations (SMHD. First we solve the magnetohydrostatic (MHS equations with the help of a Grad-Shafranov equation and then we transform these static equilibria into a stationary state with plasma flow. We are in particular interested to study SMHD-equilibria with strong plasma flow gradients perpendicular to separatrices. We find that induced thin current sheets occur naturally in such situations. The strength of the induced currents depend on the Alfvén Mach number and its gradient, and on the magnetic field.

  10. An advanced time-dependent collisional-radiative model of helium plasma discharges

    Science.gov (United States)

    Claustre, J.; Boukandou-Mombo, C.; Margot, J.; Matte, J.-P.; Vidal, F.

    2017-10-01

    A new spatially averaged time-dependent collisional-radiative model for helium plasmas, coupled to the electron Boltzmann equation (EBE), has been developed. Its main novelties are: (1) full time dependence for both the multi-species kinetics and the EBE. It is shown that this is necessary to correctly simulate discharges where the parameters vary on nanoseconds-microsecond timescales. (2) All electron processes are accounted for accurately. In particular, for the various ionization and recombination processes, free electrons are added or removed at the appropriate energy, with the appropriate interpolation on the energy grid. (3) The energy dependence of the electron loss by ambipolar diffusion is taken into account approximately. (4) All of the processes which are known to be important in helium discharges for pressure P≤slant 760 Torr are included, and 42 energy levels up to n = 6, where n is the main quantum number, are taken into account. Atomic and molecular ions, as well as excimers, are also included. (5) The gas temperature is calculated self-consistently. The model is validated through comparisons with known numerical steady-state results of Santos et al (2014 J. Phys. D. 47 265201) which they compared to their experimental results, and good agreement is obtained for their measured quantities. It is then applied to post-discharge decay cases with very short power decay times. The time evolution of the population densities and reaction rates are analyzed in detail with emphasis on the observed large increase of the metastable density.

  11. An efficient, selective collisional ejection mechanism for inner-shell population inversion in laser-driven plasmas

    Energy Technology Data Exchange (ETDEWEB)

    SCHROEDER,W. ANDREAS; NELSON,THOMAS R.; BORISOV,A.B.; LONGWORTH,J.W.; BOYER,K.; RHODES,C.K.

    2000-06-07

    A theoretical analysis of laser-driven collisional ejection of inner-shell electrons is presented to explain the previously observed anomalous kilovolt L-shell x-ray emission spectra from atomic Xe cluster targets excited by intense sub-picosecond 248nrn ultraviolet radiation. For incident ponderomotively-driven electrons photoionized by strong above threshold ionization, the collisional ejection mechanism is shown to be highly l-state and significantly n-state (i.e. radially) selective for time periods shorter than the collisional dephasing time of the photoionized electronic wavefunction. The resulting preference for the collisional ejection of 2p electrons by an ionized 4p state produces the measured anomalous Xe(L) emission which contains direct evidence for (i) the generation of Xe{sup 27+}(2p{sup 5}3d{sup 10}) and Xe{sup 28+}(2p{sup 5}3d{sup 9}) ions exhibiting inner-shell population inversion and (ii) a coherent correlated electron state collision responsible for the production of double 2p vacancies. For longer time periods, the selectivity of this coherent impact ionization mechanism is rapidly reduced by the combined effects of intrinsic quantum mechanical spreading and dephasing--in agreement with the experimentally observed and extremely strong {minus}{lambda}{sup {minus}6} pump-laser wavelength dependence of the efficiency of inner-shell (2p) vacancy production in Xe clusters excited in underdense plasmas.

  12. The plasma-solid transition: some implications in astrophysics

    Directory of Open Access Journals (Sweden)

    Čelebonović Vladan A.

    2002-01-01

    Full Text Available Using a criterion proposed by Salpeter and standard solid-state physics, we have determined the Debye temperature of a solid in equilibrium with the electron gas surrounding it. The results obtained can have astrophysical applications in the determination of parameters of interstellar and interplanetary clouds.

  13. Ion acoustic wave studies near the presheath/sheath boundary in a weakly collisional argon/xenon plasma

    Science.gov (United States)

    Oksuz, Lutfi; Lee, Dongsoo; Hershkowitz, Noah

    2008-02-01

    Ion acoustic wave (IAW) phase velocities are measured near the sheath/presheath boundary in a weakly collisional argon/xenon plasma. Wave profiles versus position are measured using a boxcar averager with a gate width of 30 ns and CW excitation at 50 or 75 kHz. Variable gate delays allow measurement of details of the wave close to the boundary. It is shown that the phase velocity at the presheath/sheath boundary is approximately twice the phase velocity in the bulk plasma for both argon and argon/xenon plasmas, in agreement with a recent calculation (Lee D et al 2007 Phys. Rev. Lett. 99 155004). This result indicates each ion's drift velocity at the boundary is equal to the IAW phase velocity in the bulk plasma.

  14. Transport processes in space physics and astrophysics

    CERN Document Server

    Zank, Gary P

    2014-01-01

    Transport Processes in Space Physics and Astrophysics' is aimed at graduate level students to provide the necessary mathematical and physics background to understand the transport of gases, charged particle gases, energetic charged particles, turbulence, and radiation in an astrophysical and space physics context. Subjects emphasized in the work include collisional and collisionless processes in gases (neutral or plasma), analogous processes in turbulence fields and radiation fields, and allows for a simplified treatment of the statistical description of the system. A systematic study that addresses the common tools at a graduate level allows students to progress to a point where they can begin their research in a variety of fields within space physics and astrophysics. This book is for graduate students who expect to complete their research in an area of plasma space physics or plasma astrophysics. By providing a broad synthesis in several areas of transport theory and modeling, the work also benefits resear...

  15. Rovibrationally Resolved Time-Dependent Collisional-Radiative Model of Molecular Hydrogen and Its Application to a Fusion Detached Plasma

    Directory of Open Access Journals (Sweden)

    Keiji Sawada

    2016-12-01

    Full Text Available A novel rovibrationally resolved collisional-radiative model of molecular hydrogen that includes 4,133 rovibrational levels for electronic states whose united atom principal quantum number is below six is developed. The rovibrational X 1 Σ g + population distribution in a SlimCS fusion demo detached divertor plasma is investigated by solving the model time dependently with an initial 300 K Boltzmann distribution. The effective reaction rate coefficients of molecular assisted recombination and of other processes in which atomic hydrogen is produced are calculated using the obtained time-dependent population distribution.

  16. Plasma lasers (a strong source of coherent radiation in astrophysics)

    Science.gov (United States)

    Papadopoulos, K.

    1981-01-01

    The generation of electromagnetic radiation from the free energy available in electron streams is discussed. The fundamental principles involved in a particular class of coherent plasma radiation sources, i.e., plasma lasers, are reviewed, focusing on three wave coupling, nonlinear parametric instabilities, and negative energy waves. The simplest case of plasma lasers, that of an unmagnetized plasma containing a finite level of density fluctuations and electrons streaming with respect to the ions, is dealt with. A much more complicated application of plasma lasers to the case of auroral kilometric radiation is then examined. The concept of free electron lasers, including the role of relativistic scattering, is elucidated. Important problems involving the escape of the excited radiation from its generation region, effects due to plasma shielding and nonlinear limits, are brought out.

  17. Collisionality dependence and ion species effects on heat transport in He and H plasma, and the role of ion scale turbulence in LHD

    Science.gov (United States)

    Tanaka, K.; Nagaoka, K.; Murakami, S.; Takahashi, H.; Osakabe, M.; Yokoyama, M.; Seki, R.; Michael, C. A.; Yamaguchi, H.; Suzuki, C.; Shimizu, A.; Tokuzawa, T.; Yoshinuma, M.; Akiyama, T.; Ida, K.; Yamada, I.; Yasuhara, R.; Funaba, H.; Kobayashi, T.; Yamada, H.; Du, X. D.; Vyacheslavov, L. N.; Mikkelsen, D. R.; Yun, G. S.; the LHD Experimental Group

    2017-11-01

    Surveys of the ion and electron heat transports of neutral beam (NB) heating plasma were carried out by power balance analysis in He and H rich plasma at LHD. Collisionality was scanned by changing density and heating power. The characteristics of the transport vary depending on collisionality. In low collisionality, with low density and high heating power, an ion internal transport barrier (ITB) was formed. The ion heat conductivity (χ i) is lower than electron heat conductivity (χ e) in the core region at ρ  power, χ i is higher than χ e across the entire range of plasma. These different confinement regimes are associated with different fluctuation characteristics. In ion ITB, fluctuation has a peak at ρ  =  0.7, and in normal confinement, fluctuation has a peak at ρ  =  1.0. The two confinement modes change gradually depending on the collisionality. Scans of concentration ratio between He and H were also performed. The ion confinement improvements were investigated using gyro-Bohm normalization, taking account of the effective mass and charge. The concentration ratio affected the normalized χ i only in the edge region (ρ ~ 1.0). This indicates ion species effects vary depending on collisionality. Turbulence was modulated by the fast ion loss instability. The modulation of turbulence is higher in H rich than in He rich plasma.

  18. Nanostructured surfaces for nuclear astrophysics studies in laser-plasmas

    Science.gov (United States)

    Altana, Carmen; Amarù, Vincenzo; Castro, Giuseppe; Frassetto, Marco; Lanzalone, Gaetano; Malferrari, Luciana; Mascali, David; Muoio, Annamaria; Odorici, Fabrizio; Tudisco, Salvo

    2018-01-01

    The future availability of high-intensity laser facilities capable of delivering tens of petawatts of power (e.g. ELI-NP) into small volumes of matter at high repetition rates will give the unique opportunity to investigate nuclear reactions and fundamental interactions process under extreme plasma conditions [1]. In this context, use of targets with nanostructured surfaces is giving promising indications to reproduce plasma conditions suitable for measurements of thermonuclear reactions rates, in the domain of nanosecond laser pulses.

  19. Characteristics of symmetric and anti-symmetric Hasegawa modes of surface waves in a plasma slab including collisional electrons and flowing ions

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-12-01

    The dispersion relation for electrostatic Hasegawa surface wave propagating on the interface of a cold dusty plasma slab whose constituents are collisional electrons, collisional streaming ions and dust grains is derived. We have found that there exist high- and low-frequency branches for both symmetric and anti-symmetric modes in the plasma slab. The real frequency of the wave is found to decrease as the ion collision frequency increases for both modes. In the case of the low-frequency branch, the phase velocity of the Hasegawa surface wave in a slab is always faster (slower) than that in a semi-bounded plasma for symmetric mode (anti-symmetric mode). We also found that the Hasegawa surface waves can be damped by the collisional dissipation. However, the characteristic of damping is quite different for the two modes: the magnitude of damping rate for symmetric (anti-symmetric) mode increases (decreases) as the slab thickness decreases.

  20. Simulations of ion transport in a collisional radio-frequency plasma sheath.

    Science.gov (United States)

    Dai, Zhong-Ling; Wang, You-Nian

    2004-03-01

    A hybrid theoretical model, capable of describing the characteristics of a collisional sheath driven by a sinusoidal current source and determining the energy and angular distributions of ions incident onto the substrate, is proposed. The model consists of one-dimensional time-dependent fluid equations coupled with the Poisson equation determining spatiotemporal evolution of the sheath and the Monte Carlo simulation predicting the energy and angular distributions of ions striking the electrode, in which charge-exchange collisions between ions and neutrals are included. Additionally, an equivalent circuit model in conjunction with the fluid equations is adopted to self-consistently determine the relationship between the instantaneous potential at a rf-biased electrode and the sheath thickness. It is found that the collisional effects would influence the height of the energy peaks in the ion energy distributions and the ion angular distributions.

  1. The stability of weakly collisional plasmas with thermal and composition gradients

    DEFF Research Database (Denmark)

    Pessah, M.E.; Chakraborty, S.

    2013-01-01

    temperature and composition. This allows us to discuss for the first time the dynamics of weakly collisional environments where heat conduction, momentum transport, and ion-diffusion are anisotropic with respect to the direction of the magnetic field. We show that depending on the relative signs...... the magnetic field configurations that arise as a natural consequence of the HBI, which would be MTI stable in a homogeneous medium, could be alleviated if the mean molecular weight gradient is steep enough, i.e., (¿µ)/µ > (¿T)/T. This study constitutes a first step toward understanding the interaction between...... approximation if heavy elements are able to sediment in the inner region of the galaxy cluster. Motivated by the need to obtain a more complete picture of the dynamical properties of the ICM, we analyze the stability of a weakly collisional, magnetized plane-parallel atmosphere which is stratified in both...

  2. Self-Focusing of Elliptical Laser Beam in Collisional Plasma and Its Effect on Stimulated Brillouin Scattering Process

    Science.gov (United States)

    Singh, Arvinder; Walia, Keshav

    2012-12-01

    This paper presents an investigation of self-focusing of elliptical laser beam in a collisional plasma and its effect on stimulated Brillouin scattering (SBS) process. The non-linearity arising through non-uniform heating leads to redistribution of carriers, which modifies the background plasma density profile in a direction transverse to pump beam axis. This modification affects the incident laser beam, ion-acoustic wave and back scattered beam. Non-linear differential equations for the beam width parameters of the pump laser beam, ion-acoustic wave and back scattered beam are set up and solved numerically. It is observed from the analysis that the focusing of waves greatly enhances the SBS back-reflectivity.

  3. MHD instabilities in astrophysical plasmas: very different from MHD instabilities in tokamaks!

    Science.gov (United States)

    Goedbloed, J. P.

    2018-01-01

    The extensive studies of MHD instabilities in thermonuclear magnetic confinement experiments, in particular of the tokamak as the most promising candidate for a future energy producing machine, have led to an ‘intuitive’ description based on the energy principle that is very misleading for most astrophysical plasmas. The ‘intuitive’ picture almost directly singles out the dominant stabilizing field line bending energy of the Alfvén waves and, consequently, concentrates on expansion schemes that minimize that contribution. This happens when the wave vector {{k}}0 of the perturbations, on average, is perpendicular to the magnetic field {B}. Hence, all macroscopic instabilities of tokamaks (kinks, interchanges, ballooning modes, ELMs, neoclassical tearing modes, etc) are characterized by satisfying the condition {{k}}0 \\perp {B}, or nearly so. In contrast, some of the major macroscopic instabilities of astrophysical plasmas (the Parker instability and the magneto-rotational instability) occur when precisely the opposite condition is satisfied: {{k}}0 \\parallel {B}. How do those instabilities escape from the dominance of the stabilizing Alfvén wave? The answer to that question involves, foremost, the recognition that MHD spectral theory of waves and instabilities of laboratory plasmas could be developed to such great depth since those plasmas are assumed to be in static equilibrium. This assumption is invalid for astrophysical plasmas where rotational and gravitational accelerations produce equilibria that are at best stationary, and the associated spectral theory is widely, and incorrectly, believed to be non-self adjoint. These complications are addressed, and cured, in the theory of the Spectral Web, recently developed by the author. Using this method, an extensive survey of instabilities of astrophysical plasmas demonstrates how the Alfvén wave is pushed into insignificance under these conditions to give rise to a host of instabilities that do not

  4. A review of transport theory. [particle acceleration in astrophysical plasmas

    Science.gov (United States)

    Jones, Frank C.

    1992-01-01

    Ways in which energy change terms arise in the transport equation and how the various terms relate to the modes of energy exchange between the particles and plasma are shown. It is argued that the transport equation cannot be used to describe the initial acceleration of thermal particles by plasma shocks or relativistic shocks where the energetic particle speeds are never much greater than the flow speeds. In most other situations, it describes almost any acceleration process that can be caused by a moving plasma. It describes shock acceleration for both parallel shocks and oblique ones, and stochastic acceleration by the turbulent motion of the scatterers as well as by their motion across the magnetic field.

  5. Magnetic Reconnection, a Key Self-Organization Process in Laboratory and Astrophysical Plasmas : Recent Research Progress(Nonequilibrium Dynamics in Astrophysics and Materials Science)

    OpenAIRE

    MASAAKI, YAMADA; Center of Magnetic Self-Organization, Princeton Plasmas Physics Laboratory, Princeton University

    2012-01-01

    Magnetic reconnection is a phenomenon of nature in which magnetic field lines change their topology and convert magnetic energy to plasma particles by acceleration and heating. The process can stretch out over time or occur quite suddenly. It is one of the most fundamental processes at work in laboratory and astrophysical plasmas. Magnetic reconnection occurs everywhere: In solar flares; coronal mass ejections; the earth's magnetosphere; in the star forming galaxies; and in plasma fusion devi...

  6. Space and Astrophysical Plasmas: High energy universe–Satellite ...

    Indian Academy of Sciences (India)

    A variety of satellite missions to observe the high energy universe are currently operating and some more with more versatility and capability are on the anvil. In this paper, after giving a brief introduction to the constituents of the high energy universe and the related plasma physical problems, general as well as specific ...

  7. Evolution of intense laser pulse spot size propagating in collisional plasma embedded in magnetic field with variable direction

    Science.gov (United States)

    Malekshahi, Moslem

    2018-01-01

    In this study, propagation of an intense laser pulse through collisional, homogenous, magnetized plasma has been investigated. The plasma is embedded in an external magnetic field with the amplitude and variable direction being constant. The complex dispersion relation of the plasma medium has been obtained that predicates the Faraday rotation effect. The paraxial wave equation has been used for the study of propagation of laser pulse in plasma. The nonlinear current density vector as a source of wave equation is obtained by motion equation and continuity equation of plasma free electrons. Using the source dependent expansion method, the evolution of laser pulse spot size has been investigated. It is shown that the spot size of the laser pulse is dependent on the strength and direction of the external magnetic field significantly. The effect of collision frequency on the evolution of spot size has been studied. The space damping rate of laser pulse power along the propagation length due to collision is obtained. Results show that the increase in the external magnetic field strength increases the rate of laser energy loss.

  8. Influence of ions on relativistic double layers radiation in astrophysical plasmas

    Directory of Open Access Journals (Sweden)

    AM Ahadi

    2009-12-01

    Full Text Available As double layers (DLs are one of the most important acceleration mechanisms in space as well as in laboratory plasmas, they are studied from different points of view. In this paper, the emitted power and energy radiated from charged particles, accelerated in relativistic cosmic DLs are investigated. The effect of the presence of additional ions in a multi-species plasma, as a real example of astrophysical plasma, is also investigated. Considering the acceleration role of DLs, radiations from accelerated charged particles could be seen as a loss mechanism. These radiations are influenced directly by the additional ion species as well as their relative densities.

  9. Collisional damping of the fast magnetosonic wave in the tokamak edge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Porkolab, M.; Bonoli, P.T. [MIT Plasma Fusion Center, Cambridge, Massachusetts 02139 (United States); Chiu, S.C. [General Atomics, San Diego, California 92186 (United States)

    1996-02-01

    The collisional absorption of the fast magnetosonic wave in the tokamak edge region is re-examined. This is of concern in either fast wave current drive (FWCD) experiments with weak central absorption (i.e., DIII-D) or in high density minority heating experiments in compact, high field devices (i.e., Alcator C-Mod). Using a simple Krook-type of collision model, the present calculations indicate negligible (i.e., less than 0.1{percent}) single-pass absorption due to collisions under typical experimental conditions. {copyright} {ital 1996 American Institute of Physics.}

  10. The use of ultraviolet Thomson scattering as a versatile diagnostic for detailed measurements of a collisional laser produced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Mark David [Univ. of California, Davis, CA (United States)

    1993-01-08

    Collective Thomson scattering from ion-acoustic waves at 266nm is used to obtain spatially resolved, two-dimensional electron density, sound speed, and radial drift profiles of a collisional laser plasma. An ultraviolet diagnostic wavelength minimizes the complicating effects of inverse bremsstrahlung and refractive turning in the coronal region of interest, where the electron densities approach nc/10. Laser plasmas of this type are important because they model some of the aspects of the plasmas found in high-gain laser-fusion pellets irradiated by long pulse widths where the laser light is absorbed mostly in the corona. The experimental results and LASNEX simulations agree within a percent standard deviation of 40% for the electron density and 50% for the sound speed and radial drift velocity. Thus it is shown that the hydrodynamics equations with classical coefficients and the numerical approximations in LASNEX are valid models of laser-heated, highly collisional plasmas. The versatility of Thomson scattering is expanded upon by extending existing theory with a Fokker-Planck based model to include plasmas that are characterized by (0 ≤ kiaλii ≤ ∞) and ZTe/Ti, where kia is the ion- acoustic wave number, λii is the ion-ion mean free path, Z is the ionization state of the plasma, and Te. Ti are the electron and ion temperatures in electron volts respectively. The model is valid for plasmas in which the electrons are approximately collisionless, (kiaλei, kiaλee ≥ 1), and quasineutrality holds, (α ≥1), where α = 1/kλDE and λDe is the electron Debye length. This newly developed model predicts the lineshape of the ion-acoustic Thomson spectra and when fit to experimental data provides a direct measurement of the relative thermal flow velocity between the electrons and ions.

  11. Calibration of a miniaturized retarding field analyzer for low-temperature plasmas: geometrical transparency and collisional effects

    Energy Technology Data Exchange (ETDEWEB)

    Baloniak, Tim; Reuter, Ruediger; Floetgen, Christoph; Von Keudell, Achim [Research Group Reactive Plasmas, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

    2010-02-10

    Retarding field analyzers (RFAs) are important diagnostics to measure fluxes and energies of ions impinging onto the wall of a plasma reactor. Any quantitative use of the data requires a proper calibration, which is here performed for a miniaturized RFA. The calibration accounts for the transparencies of the RFA grids as well as for collisions inside the RFA. An analytical model is derived which covers both geometrical and collisional effects. The model is calibrated and experimentally verified using a Langmuir probe. We find that the transparency of an RFA is a random variable which depends on the individual alignment of the RFA grids. Collisions inside the RFA limit the ion current transfer through the RFA at higher pressures. A simple method is presented which allows one to remove these artefacts from the RFA data and to obtain quantitative ion velocity distributions.

  12. Magnetic turbulence in a table-top laser-plasma relevant to astrophysical scenarios

    Science.gov (United States)

    Chatterjee, Gourab; Schoeffler, Kevin M.; Kumar Singh, Prashant; Adak, Amitava; Lad, Amit D.; Sengupta, Sudip; Kaw, Predhiman; Silva, Luis O.; Das, Amita; Kumar, G. Ravindra

    2017-06-01

    Turbulent magnetic fields abound in nature, pervading astrophysical, solar, terrestrial and laboratory plasmas. Understanding the ubiquity of magnetic turbulence and its role in the universe is an outstanding scientific challenge. Here, we report on the transition of magnetic turbulence from an initially electron-driven regime to one dominated by ion-magnetization in a laboratory plasma produced by an intense, table-top laser. Our observations at the magnetized ion scale of the saturated turbulent spectrum bear a striking resemblance with spacecraft measurements of the solar wind magnetic-field spectrum, including the emergence of a spectral kink. Despite originating from diverse energy injection sources (namely, electrons in the laboratory experiment and ion free-energy sources in the solar wind), the turbulent spectra exhibit remarkable parallels. This demonstrates the independence of turbulent spectral properties from the driving source of the turbulence and highlights the potential of small-scale, table-top laboratory experiments for investigating turbulence in astrophysical environments.

  13. Astrophysics of magnetically collimated jets generated from laser-produced plasmas.

    Science.gov (United States)

    Ciardi, A; Vinci, T; Fuchs, J; Albertazzi, B; Riconda, C; Pépin, H; Portugall, O

    2013-01-11

    The generation of astrophysically relevant jets, from magnetically collimated, laser-produced plasmas, is investigated through three-dimensional, magnetohydrodynamic simulations. We show that for laser intensities I∼10(12)-10(14) W cm(-2), a magnetic field in excess of ∼0.1  MG, can collimate the plasma plume into a prolate cavity bounded by a shock envelope with a standing conical shock at its tip, which recollimates the flow into a supermagnetosonic jet beam. This mechanism is equivalent to astrophysical models of hydrodynamic inertial collimation, where an isotropic wind is focused into a jet by a confining circumstellar toruslike envelope. The results suggest an alternative mechanism for a large-scale magnetic field to produce jets from wide-angle winds.

  14. Microparticles in a collisional Rf plasma sheath under hypergravity conditions as probes for the electric field strength and the particle charge.

    Science.gov (United States)

    Beckers, J; Ockenga, T; Wolter, M; Stoffels, W W; van Dijk, J; Kersten, H; Kroesen, G M W

    2011-03-18

    We used microparticles under hypergravity conditions, induced by a centrifuge, in order to measure nonintrusively and spatially resolved the electric field strength as well as the particle charge in the collisional rf plasma sheath. The measured electric field strengths demonstrate good agreement with the literature, while the particle charge shows decreasing values towards the electrode. We demonstrate that it is indeed possible to measure these important quantities without changing or disturbing the plasma.

  15. Attenuation characteristics of electromagnetic waves in a weak collisional and fully ionized dusty plasma

    Science.gov (United States)

    Dan, Li; Guo, Li-Xin; Li, Jiang-Ting; Chen, Wei; Yan, Xu; Huang, Qing-Qing

    2017-09-01

    The expression of complex dielectric permittivity for non-magnetized fully ionized dusty plasma is obtained based on the kinetic equation in the Fokker-Planck-Landau collision model and the charging equation of the statistical theory. The influences of density, average size of dust grains, and balanced charging of the charge number of dust particles on the attenuation properties of electromagnetic waves in fully ionized dusty plasma are investigated by calculating the attenuation constant. In addition, the attenuation characteristics of weakly ionized and fully ionized dusty plasmas are compared. Results enriched the physical mechanisms of microwave attenuation for fully ionized dusty plasma and provide a theoretical basis for future studies.

  16. Global Simulations of Dynamo and Magnetorotational Instability in Madison Plasma Experiments and Astrophysical Disks

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimi, Fatima [Univ. of New Hampshire, Durham, NH (United States)

    2014-07-31

    Large-scale magnetic fields have been observed in widely different types of astrophysical objects. These magnetic fields are believed to be caused by the so-called dynamo effect. Could a large-scale magnetic field grow out of turbulence (i.e. the alpha dynamo effect)? How could the topological properties and the complexity of magnetic field as a global quantity, the so called magnetic helicity, be important in the dynamo effect? In addition to understanding the dynamo mechanism in astrophysical accretion disks, anomalous angular momentum transport has also been a longstanding problem in accretion disks and laboratory plasmas. To investigate both dynamo and momentum transport, we have performed both numerical modeling of laboratory experiments that are intended to simulate nature and modeling of configurations with direct relevance to astrophysical disks. Our simulations use fluid approximations (Magnetohydrodynamics - MHD model), where plasma is treated as a single fluid, or two fluids, in the presence of electromagnetic forces. Our major physics objective is to study the possibility of magnetic field generation (so called MRI small-scale and large-scale dynamos) and its role in Magneto-rotational Instability (MRI) saturation through nonlinear simulations in both MHD and Hall regimes.

  17. FOREWORD: The 5th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas

    Science.gov (United States)

    Tchang-Brillet, Wad Lydia; Wyart, Jean-François; Zeippen, Claude

    1996-01-01

    The 5th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas was held in Meudon, France, from August 28 to 31 1995. It was the fifth in a series started by the Atomic Spectroscopic Group at the University of Lund, Sweden, in 1983. Then followed the meetings in Toledo, USA, Amsterdam, The Nether- lands and Gaithersburg, USA, with a three year period. The original title of the series ended with "... for Astrophysics and Fusion Research" and became more general with the 4th colloquium in Gaithersburg. The purpose of the present meeting was, in line with tradition, to bring together "producers" and "users" of atomic data so as to ensure optimal coordination. Atomic physicists who study the structure of atoms and their radiative and collisional properties were invited to explain the development of their work, emphasizing the possibilities of producing precise transition wavelengths and relative line intensities. Astrophysicists and laboratory plasma physicists were invited to review their present research interests and the context in which atomic data are needed. The number of participants was about 70 for the first three meetings, then exploded to 170 at Gaithersburg. About 140 participants, coming from 13 countries, attended the colloquium in Meudon. This large gathering was partly due to a number of participants from Eastern Europe larger than in the past, and it certainly showed a steady interest for interdisciplinary exchanges between different communities of scientists. This volume includes all the invited papers given at the conference and, in the appendix, practical information on access to some databases. All invited speakers presented their talks aiming at good communication between scientists from different backgrounds. A separate bound volume containing extended abstracts of the poster papers has been published by the Publications de l'Observatoire de Paris, (Meudon 1996), under the responsibility of

  18. Generation of Electrojets in Weakly Ionized Plasmas through a Collisional Dynamo

    CERN Document Server

    Dimant, Yakov S; Fletcher, Alex C

    2016-01-01

    Intense electric currents called electrojets occur in weakly ionized magnetized plasmas. An example occurs in the Earth's ionosphere near the magnetic equator where neutral winds drive the plasma across the geomagnetic field. Similar processes take place in the Solar chromosphere and MHD generators. This letter argues that not all convective neutral flows generate electrojets and it introduces the corresponding universal criterion for electrojet formation, $\

  19. Propagation of electromagnetic waves in a weak collisional and fully ionized dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Jieshu; Yuan, Chengxun, E-mail: yuancx@hit.edu.cn; Gao, Ruilin; Wang, Ying; Zhou, Zhong-Xiang [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Liu, Sha; Yue, Feng [Shanghai Institute of Spaceflight Control Technology, Shanghai 200233 (China); Wu, Jian [China Research Institute of Radio wave Propagation, Beijing 102206 (China); Li, Hui [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); China Research Institute of Radio wave Propagation, Beijing 102206 (China)

    2016-04-15

    The propagation properties of electromagnetic (EM) waves in fully ionized dusty plasmas is the subject of this study. The dielectric relationships for EM waves propagating in a fully ionized dusty plasma was derived from the Boltzmann distribution law, taking into consideration the collision and charging effects of the dust grains. The propagation properties of the EM waves in a dusty plasma were numerically calculated and studied. The study results indicated that the dusty grains with an increased radius and charge were more likely to impede the penetration of EM waves. Dust grains with large radii and high charge cause the attenuation of the EM wave in the dusty plasma. The different density of the dust in the plasma appeared to have no obvious effect on the transmission of the EM waves. The propagation of the EM waves in a weakly ionized dusty plasma varies from that in a fully ionized dusty plasma. The results are helpful to analyze the effects of dust in dusty plasmas and also provide a theoretical basis for future studies.

  20. Collisional effect on lower hybrid waves instability in a dusty plasma ...

    African Journals Online (AJOL)

    The effect of particle collisions on lower hybrid modes in a dusty plasma is studied. The dispersion relation derived from fluid theory is numerically solved for plasma parameters relevant to determine the modification in wave propagation due to collisions. This study is relevant to the earth's lower atmosphere, in particular, the ...

  1. Comment on “Propagation of surface waves on a semi-bounded quantum magnetized collisional plasma” [Phys. Plasmas 20, 122106 (2013)

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Afshin, E-mail: a.moradi@kut.ac.ir [Department of Engineering Physics, Kermanshah University of Technology, Kermanshah (Iran, Islamic Republic of)

    2016-04-15

    In a recent article [Niknam et al., Phys. Plasmas 20, 122106 (2013)], Niknam et al. investigated the propagation of TM surface waves on a semi-bounded quantum magnetized collisional plasma in the Faraday configuration (in this case, the magnetic field is parallel to the both of the plasma surface and direction of propagation). Here, we present a fresh look at the problem and show that TM surface waves cannot propagate on surface of the present system. We find in the Faraday configuration the surface waves acquire both TM and TE components due to the cyclotron motion of electrons. Therefore, the main result of the work by Niknam et al. is incorrect.

  2. Spinning Unmagnetized Plasma for Laboratory Studies of Astrophysical Accretion Disks & Dynamos

    Science.gov (United States)

    Collins, Cami

    2015-11-01

    A technique for creating a large, fast-flowing, unmagnetized plasma has been demonstrated experimentally. This marks an important first step towards laboratory studies of phenomenon such as magnetic field generation through self-excited dynamos, or the magnetorotational instability (MRI), the mechanism of interest for its role in the efficient outward transport of angular momentum in accretion disks. In the Plasma Couette Experiment (PCX), a sufficiently hot, steady-state plasma is confined in a cylindrical, axisymmetric multicusp magnetic field, with Tetorque using toroidally localized, biased hot cathodes in the magnetized edge region. Measurements show that momentum couples viscously from the magnetized edge to the unmagnetized core, and the core rotates when collisional ion viscosity overcomes the drag due to ion-neutral collisions. Torque can be applied at the inner or outer boundaries, resulting in controlled, differential rotation. Maximum speeds are observed (He ~ 12 km/s, Ne ~ 4 km/s, Ar ~ 3.2 km/s, Xe ~ 1.4 km/s), consistent with a critical ionization velocity limit reported to occur in partially ionized plasmas. PCX has achieved magnetic Reynolds numbers of Rm ~ 65 and magnetic Prandtl numbers of Pm ~ 0.2-10, which are approaching regimes shown to excite the MRI in a global Hall-MHD stability analysis. Ion-neutral collisions effectively add a body force that undesirably changes the flow profile shape. Recent upgrades have increased the ionization fraction with an additional 6 kW of microwave heating power and stronger magnets that reduce loss area and increase plasma volume by 150%. In addition, an alternative scheme using volume-applied JxB force will maintain the shear profile and destabilize the MRI at more easily achievable plasma parameters.

  3. Spatial mode structures of electrostatic drift waves in a collisional cylindrical helicon plasma

    DEFF Research Database (Denmark)

    Schröder, C.; Grulke, O.; Klinger, T.

    2004-01-01

    In a cylindrical helicon plasma, mode structures of coherent drift waves are studied in the poloidal plane, the plane perpendicular to the ambient magnetic field. The mode structures rotate with a constant angular velocity in the direction of the electron diamagnetic drift and show significant...

  4. Parametric instabilities in shallow water magnetohydrodynamics of astrophysical plasma in external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Klimachkov, D.A., E-mail: klimachkovdmitry@gmail.com [Space Research Institute of Russian Academy of Science, 84/32, Profsoyuznaya str., Moscow, 117997 (Russian Federation); Petrosyan, A.S. [Space Research Institute of Russian Academy of Science, 84/32, Profsoyuznaya str., Moscow, 117997 (Russian Federation); Moscow Institute of Physics and Technology (State University), 9 Institutskyi per., Dolgoprudny, Moscow Region, 141700 (Russian Federation)

    2017-01-15

    This article deals with magnetohydrodynamic (MHD) flows of a thin rotating layer of astrophysical plasma in external magnetic field. We use the shallow water approximation to describe thin rotating plasma layer with a free surface in a vertical external magnetic field. The MHD shallow water equations with external vertical magnetic field are revised by supplementing them with the equations that are consequences of the magnetic field divergence-free conditions and reveal the existence of third component of the magnetic field in such approximation providing its relation with the horizontal magnetic field. It is shown that the presence of a vertical magnetic field significantly changes the dynamics of the wave processes in astrophysical plasma compared to the neutral fluid and plasma layer in a toroidal magnetic field. The equations for the nonlinear wave packets interactions are derived using the asymptotic multiscale method. The equations for three magneto-Poincare waves interactions, for three magnetostrophic waves interactions, for the interactions of two magneto-Poincare waves and for one magnetostrophic wave and two magnetostrophic wave and one magneto-Poincare wave interactions are obtained. The existence of parametric decay and parametric amplifications is predicted. We found following four types of parametric decay instabilities: magneto-Poincare wave decays into two magneto-Poincare waves, magnetostrophic wave decays into two magnetostrophic waves, magneto-Poincare wave decays into one magneto-Poincare wave and one magnetostrophic wave, magnetostrophic wave decays into one magnetostrophic wave and one magneto-Poincare wave. Following mechanisms of parametric amplifications are found: parametric amplification of magneto-Poincare waves, parametric amplification of magnetostrophic waves, magneto-Poincare wave amplification in magnetostrophic wave presence and magnetostrophic wave amplification in magneto-Poincare wave presence. The instabilities growth rates

  5. Self-focusing and defocusing of Gaussian laser beams in collisional inhomogeneous plasmas with linear density and temperature ramps

    Science.gov (United States)

    Hashemzadeh, M.

    2018-01-01

    Self-focusing and defocusing of Gaussian laser beams in collisional inhomogeneous plasmas are investigated in the presence of various laser intensities and linear density and temperature ramps. Considering the ponderomotive force and using the momentum transfer and energy equations, the nonlinear electron density is derived. Taking into account the paraxial approximation and nonlinear electron density, a nonlinear differential equation, governing the focusing and defocusing of the laser beam, is obtained. Results show that in the absence of ramps the laser beam is focused between a minimum and a maximum value of laser intensity. For a certain value of laser intensity and initial electron density, the self-focusing process occurs in a temperature range which reaches its maximum at turning point temperature. However, the laser beam is converged in a narrow range for various amounts of initial electron density. It is indicated that the σ2 parameter and its sign can affect the self-focusing process for different values of laser intensity, initial temperature, and initial density. Finally, it is found that although the electron density ramp-down diverges the laser beam, electron density ramp-up improves the self-focusing process.

  6. A Hybrid Model for Multiscale Laser Plasma Simulations with Detailed Collisional Physics

    Science.gov (United States)

    2016-11-29

    other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a ...Briefing Charts 3. DATES COVERED (From - To) 02 November 2016 – 30 November 2016 4. TITLE AND SUBTITLE A Hybrid Model for Multiscale Laser Plasma...Briefing Charts 15. SUBJECT TERMS N/ A 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE

  7. From the Telescope to the Laboratory and Back Again: The Center for Astrophysical Plasma Properties

    Science.gov (United States)

    Houston Montgomery, Michael; Winget, Don; Schaeuble, Marc; Hawkins, Keith; Wheeler, Craig

    2018-01-01

    The Center for Astrophysical Plasma Properties (CAPP) is a new center focusing on the spectroscopic properties of stars and accretion disks using “at-parameter” experiments. Currently, these experiments use the X-ray output of the Z machine at Sandia National Laboratories—the largest X-ray source in the world—to heat plasmas to the same conditions (temperature, density, and radiation environment) as those observed in astronomical objects. Current experiments include measuring (1) density-dependent opacities of iron-peak elements at solar interior conditions, (2) spectral lines of low-Z elements at white dwarf photospheric conditions, (3) atomic population kinetics of neon in a radiation-dominated environment, and (4) resonant Auger destruction (RAD) of silicon at accretion disk conditions around supermassive black holes. We will be moving to new astrophysical environments and additional experimental facilities, such as the National Ignition Facility (NIF) and the OMEGA facility at the Laboratory for Laser Energetics (LLE). We seek students and collaborators to work on these experiments as well as the calculations that complement them. CAPP has funding for 5 years and can support up to six graduate students and three post-docs.

  8. Investigation of the ionization balance of bismuth-to-tin plasmas for the extreme ultraviolet light source based on a computer-generated collisional radiative model

    Directory of Open Access Journals (Sweden)

    Akira Sasaki

    2016-10-01

    Full Text Available The ionization balance of the bismuth-to-tin plasmas is systematically investigated on the basis of a collisional radiative model, which has been generated using a computer algorithm to analyze the level structure of multiple charged ions to construct the model. The atomic energy levels and rate coefficients corresponding to the model are calculated using the HULLAC code. With this method, we investigate the plasma temperature, which is required to obtain emission in the extreme ultraviolet wavelength range from 13.5 nm to the water window.

  9. Dynamics of magnetic fields in high-energy-density plasmas for fusion and astrophysics

    Science.gov (United States)

    Gao, Lan; Ji, H.; Fox, W.; Hill, K.; Efthimion, P.; Nilson, P.; Igumenshchev, I.; Froula, D.; Betti, R.; Meyerhofer, D.; Fiksel, G.; Blackman, E.; Schneider, M.; Chen, H.; Smalyuk, V.; Li, H.; Casner, A.

    2015-11-01

    An overview of our recent experimental and theoretical work on the dynamics of magnetic fields in high-energy-density plasmas will be presented. This includes: (1) precision mapping of the self-generated magnetic fields in the coronal plasma and the Nernst effect on their evolution, (2) characterizing the strong magnetic field generated by a laser-driven capacitor-coil target using ultrafast proton radiography, and (3) creating MHD turbulence in Rayleigh-Taylor unstable plasmas. The experimental results are compared with resistive MHD simulations providing a stringent test for their predictions. Applications in relevance to ignition target designs in inertial confinement fusion, material strength studies in high-energy-density physics, and astrophysical systems such as plasma dynamos and magnetic reconnection will be discussed. Future experiments proposed on the National Ignition Facility will be described. This material is supported in part by the Department of Energy National Nuclear Security Administration under Award No. DE-NA0001944, and the National Laser Users Facility under Grant No. DE-NA0002205.

  10. Shear-induced pressure anisotropization and correlation with fluid vorticity in a low collisionality plasma

    Science.gov (United States)

    Del Sarto, Daniele; Pegoraro, Francesco

    2018-03-01

    The momentum anisotropy contained in a sheared flow may be transferred to a pressure anisotropy, both gyrotropic and non-gyrotropic, via the action of the fluid strain on the pressure tensor components. In particular, it is the traceless symmetric part of the strain tensor (i.e. the so-called shear tensor) that drives the mechanism, the fluid vorticity just inducing rotations of the pressure tensor components. This possible mechanism of anisotropy generation from an initially isotropic pressure is purely dynamical and can be described in a fluid framework where the full pressure tensor evolution is retained. Here, we interpret the correlation between vorticity and anisotropy, often observed in numerical simulations of solar wind turbulence, as due to the correlation between shear rate tensor and fluid vorticity. We then discuss some implications of this analysis for the onset of the Kelvin-Helmholtz instability in collisionless plasmas where a full pressure tensor evolution is allowed, and for the modelling of secondary reconnection in turbulence.

  11. A New Hybrid Scheme for Simulations of Highly Collisional RF-Driven Plasmas

    CERN Document Server

    Eremin, Denis; Mussenbrock, Thomas

    2015-01-01

    This work describes a new 1D hybrid approach for modeling atmospheric pressure discharges featuring complex chemistry. In this approach electrons are described fully kinetically using Particle-In-Cell/Monte-Carlo (PIC/MCC) scheme, whereas the heavy species are modeled within a fluid description. Validity of the popular drift-diffusion approximation is verified against a "full" fluid model accounting for the ion inertia and a fully kinetic PIC/MCC code for ions as well as electrons. The fluid models require knowledge of the momentum exchange frequency and dependence of the ion mobilities on the electric field when the ions are in equilibrium with the latter. To this end an auxiliary Monte-Carlo scheme is constructed. It is demonstrated that the drift-diffusion approximation can overestimate ion transport in simulations of RF-driven discharges with heavy ion species operated in the $\\gamma$ mode at the atmospheric pressure or in all discharge simulations for lower pressures. This can lead to exaggerated plasma ...

  12. First experimental measurements of the plasma potential throughout the presheath and sheath at a boundary in a weakly collisional plasma.

    Science.gov (United States)

    Oksuz, L; Hershkowitz, N

    2002-09-30

    Experimental data obtained with emissive probes and Langmuir probes show that the plasma potential profile in the presheath scales as -ephi /T(e)= sqrt[(x(0) -x)/lambda ], consistent with ion flux conservation, and that the sheath consists of a transition region and an electron-free collisionless sheath with thicknesses scaling as lambda( 1/5)lambda (4/5 )(D) and lambda(D )(ephi/ T(e))(3 /4), respectively, where lambda is the ion-neutral collision length. Results support Rieman's presheath and transitional region model [Phys. Plasmas 4, 4158 (1997)

  13. The slow collisional E×B ion drift characterized as the major instability mechanism of a poorly magnetized plasma column with an inward-directed radial electric field

    Energy Technology Data Exchange (ETDEWEB)

    Pierre, Thiéry [Centre National de la Recherche Scientifique, UMR 7345 Laboratoire PIIM, Aix*Marseille University, Marseille (France)

    2016-04-15

    The low-frequency instability of a cylindrical poorly magnetized plasma with an inward-directed radial electric field is studied changing the gas pressure and the ion cyclotron frequency. The unstable frequency always decreases when the gas pressure is increased indicating collisional effects. At a fixed pressure, the unstable frequency increases with the magnetic field when the B-field is low and decreases at larger magnetic field strength. We find that the transition between these two regimes is obtained when the ion cyclotron frequency equals the ion-neutrals collision frequency. This is in agreement with the theory of the slow-ion drift instability induced by the collisional slowing of the electric ion drift [A. Simon, Phys. Fluids 6, 382 (1963)].

  14. Experiments on Interactions of Electrons with Molecular Ions in Fusion and Astrophysical Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bannister, Mark E [ORNL; Aliabadi, Habib [ORNL; Bahati, Eric [ORNL; Fogle, Mark R. [Oak Ridge National Laboratory (ORNL); Krstic, Predrag S [ORNL; Vane, C Randy [ORNL; Ehlerding, A. [Stockholm University, Sweden; Geppert, W. [Stockholm University, Sweden; Hellberg, F. [Stockholm University, Sweden; Zhaunerchyk, Vitali [Stockholm University, Sweden; Larsson, Mats [Stockholm University, Sweden; Thomas, Richard D [ORNL

    2007-01-01

    Through beam-beam experiments at the Multicharged Ion Research Facility (MIRF) at Oak Ridge National Laboratory (ORNL) and at the CRYRING heavy ion storage ring at Stockholm University, we are seeking to formulate a more complete picture of electron-impact dissociation of molecular ions. These inelastic collisions play important roles in many low temperature plasmas such as in divertors of fusion devices and in astrophysical environments. An electron-ion crossed beams experiment at ORNL investigates the dissociative excitation and dissociative ionization of molecular ions from a few eV up to 100 eV. Measurements on dissociative recombination (DR) experiments are made at CRYRING, where chemical branching fractions and fragmentation dynamics are studied. Taking advantage of a 250-kV acceleration platform at the MIRF, a merged electron-ion beams energy loss apparatus is employed to study DR down to zero energy. Recent results on the dissociation of molecular ions of importance in fusion and astrophysics are presented.

  15. Magnetohydrodynamic waves with relativistic electrons and positrons in degenerate spin-1/2 astrophysical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Maroof, R. [Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan); Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan); National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Mushtaq, A. [Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan); National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Qamar, A. [Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan)

    2015-11-15

    Linear properties of high and low frequency waves are studied in an electron-positron-ion (e-p-i) dense plasma with spin and relativity effects. In a low frequency regime, the magnetohydrodynamic (MHD) waves, namely, the magnetoacoustic and Alfven waves are presented in a magnetized plasma, in which the inertial ions are taken as spinless and non-degenerate, whereas the electrons and positrons are treated quantum mechanically due to their smaller mass. Quantum corrections associated with the spin magnetization and density correlations for electrons and positrons are re-considered and a generalized dispersion relation for the low frequency MHD waves is derived to account for relativistic degeneracy effects. On the basis of angles of propagation, the dispersion relations of different modes are discussed analytically in a degenerate relativistic plasma. Numerical results reveal that electron and positron relativistic degeneracy effects significantly modify the dispersive properties of MHD waves. Our present analysis should be useful for understanding the collective interactions in dense astrophysical compact objects, like, the white dwarfs and in atmosphere of neutron stars.

  16. Effects of ionization and ion loss on dust ion-acoustic solitary waves in a collisional dusty plasma with suprathermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Mayout, Saliha; Gougam, Leila Ait [Faculty of Physics, Theoretical Physics Laboratory, Plasma Physics Group, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria); Tribeche, Mouloud, E-mail: mouloudtribeche@yahoo.fr, E-mail: mtribeche@usthb.dz [Faculty of Physics, Theoretical Physics Laboratory, Plasma Physics Group, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria); Algerian Academy of Sciences and Technologies, Algiers (Algeria)

    2016-03-15

    The combined effects of ionization, ion loss, and electron suprathermality on dust ion-acoustic solitary waves in a collisional dusty plasma are examined. Carrying out a small but finite amplitude analysis, a damped Korteweg-de Vries (dK–dV) equation is derived. The damping term decreases with the increase of the spectral index and saturates for Maxwellian electrons. Choosing typical plasma parameters, the analytical approximate solution of the dK-dV equation is numerically analyzed. We first neglect the ionization and ion loss effects and account only for collisions to estimate the relative importance between these damping terms which can act concurrently. Interestingly, we found that as the suprathermal character of the electrons becomes important, the strength of the collisions related dissipation becomes more important and causes the dust ion-acoustic solitary wave amplitude to decay more rapidly. Moreover, the collisional damping may largely prevail over the ionization and ion loss related damping. The latter becomes more effective as the electrons evolve far away from their thermal equilibrium. Our results complement and provide new insights into previously published work on this problem.

  17. Determination of the Electron Density and Electron Temperature in A Magnetron Discharge Plasma Using Optical Spectroscopy and the Collisional-Radiative Model of Argon

    Science.gov (United States)

    Evdokimov, K. E.; Konishchev, M. E.; Pichugin, V. F.; Pustovalova, A. A.; Ivanova, N. M.; Sun', Ch.

    2017-09-01

    A method for determining the electron temperature and electron density in a plasma is proposed that is based on minimization of the difference between the experimental relative intensities of the spectral argon (Ar) lines and those same intensities calculated with the aid of the collisional-radiative model. The model describes the kinetics of the ground state and 40 excited states of the Ar atom and takes into account the following processes: excitation and deactivation of the states of the atom by electron impact, radiative decay of the excited states, self-absorption of radiation, ionization of excited states by electron impact, and quenching of metastable states as a consequence of collisions with the chamber walls. Using the given method, we have investigated the plasma of a magnetron discharge on a laboratory setup for intermediate-frequency magnetron sputtering for a few selected operating regimes.

  18. Relativistic Shear Flow between Electron-Ion and Electron-Positron Plasmas and Astrophysical Applications

    Science.gov (United States)

    Liang, Edison; Fu, Wen; Böttcher, Markus

    2017-10-01

    We present particle-in-cell simulation results of relativistic shear boundary layers between electron-ion and electron-positron plasmas and discuss their potential applications to astrophysics. Specifically, we find that in the case of a fast electron-positron spine surrounded by a slow-moving or stationary electron-ion sheath, lepton acceleration proceeds in a highly anisotropic manner due to electromagnetic fields created at the shear interface. While the highest-energy leptons still produce a beaming pattern (as seen in the quasi-stationary frame of the sheath) of order 1/Γ, where Γ is the bulk Lorentz factor of the spine, for lower-energy particles, the beaming is much less pronounced. This is in stark contrast to the case of pure electron-ion shear layers, in which anisotropic particle acceleration leads to significantly narrower beaming patterns than 1/Γ for the highest-energy particles. In either case, shear-layer acceleration is expected to produce strongly angle-dependent lepton (hence, emanating radiation) spectra, with a significantly harder spectrum in the forward direction than viewed from larger off-axis angles, much beyond the regular Doppler boosting effect from a co-moving isotropic lepton distribution. This may solve the problem of the need for high (and apparently arbitrarily chosen) minimum Lorentz factors of radiating electrons, often plaguing current blazar and GRB jet modeling efforts.

  19. On the application of He I collisional-radiative model to the He–H{sub 2} mixture plasmas in MAP-II divertor simulator

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Y., E-mail: iida@flanker.n.t.u-tokyo.ac.jp [School of Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656 (Japan); Kado, S., E-mail: kado@iae.kyoto-u.ac.jp [School of Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656 (Japan); Tanaka, S. [School of Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656 (Japan)

    2013-07-15

    Atomic helium (He I) optical emission spectroscopy was carried out in a MAP-II divertor simulator to investigate the applicability of He I collisional-radiative (CR) model for the measurement of electron temperature (T{sub e}) and density (n{sub e}) in He–H{sub 2} mixture plasmas. The result was compared with Langmuir probe measurements. The excited population distribution of the He–H{sub 2} mixture plasma was not reproduced by the He I CR model, although it was reproduced well for pure He and He–Ar mixture plasma. Specifically, the deviation of the population ratio of singlet to triplet states became more evident as the concentration of H{sub 2} increased. This fact implies that the measurement of T{sub e} for He–H{sub 2} plasma using the He I CR model could lead to a significant error under a certain condition, such that T{sub e} < 10 eV as in the case of divertor plasmas.

  20. Study of argon ions density and electron temperature and density in magnetron plasma by optical emission spectroscopy and collisional-radiative model

    Directory of Open Access Journals (Sweden)

    Kirill E. Evdokimov

    2017-06-01

    Full Text Available Optical emission spectroscopy (OES combined with the models of plasma light emission becomes non-intrusive and versatile method of plasma parameters determination. In this paper we have studied the densities of charge carriers and electron temperature in Ar plasma of pulsed DC magnetron in different experimental conditions. Electron density and temperature were determined by fitting of relative emission line intensities calculated from collisional-radiative model (CRM to experimental ones. The model describes the kinetics of the first 40 excited states of neutral argon Ar and takes into account the following processes: electron impact excitation/deexcitation, spontaneous light emission, radiation trapping, electron impact ionization, and metastable quenching due to diffusion to walls. Then, ions density was determined from relative intensity of 488 nm Ar+ emission line and simple CRM accounting excitation from ground states of neutral Ar and ion Ar+. The values of electron and ion density agree very well. To test the stability of results, we performed Monte-Carlo calculations with random variation of experimental spectrum as well as of excitation cross-sections and estimated confidence intervals and errors for plasma parameters. Also, we validated OES study by comparison with Langmuir probe measurements. The agreement between optical and probe techniques is satisfactory.

  1. Proceedings of the eighth international colloquium on ultraviolet and x-ray spectroscopy of astrophysical and laboratory plasmas (IAU colloquium 86)

    Energy Technology Data Exchange (ETDEWEB)

    1984-01-01

    This volume represents the Proceedings of the Eighth International Colloquium on Ultraviolet and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas. The aim of this series of colloquia has been to bring together workers in the fields of astrophysical spectroscopy, laboratory spectroscopy and atomic physics in order to exchange ideas and results on problems which are common to these different disciplines. In addition to the presented papers there was a poster paper session. (WRF)

  2. Battery-powered pulsed high density inductively coupled plasma source for pre-ionization in laboratory astrophysics experiments.

    Science.gov (United States)

    Chaplin, Vernon H; Bellan, Paul M

    2015-07-01

    An electrically floating radiofrequency (RF) pre-ionization plasma source has been developed to enable neutral gas breakdown at lower pressures and to access new experimental regimes in the Caltech laboratory astrophysics experiments. The source uses a customized 13.56 MHz class D RF power amplifier that is powered by AA batteries, allowing it to safely float at 3-6 kV with the electrodes of the high voltage pulsed power experiments. The amplifier, which is capable of 3 kW output power in pulsed (<1 ms) operation, couples electrical energy to the plasma through an antenna external to the 1.1 cm radius discharge tube. By comparing the predictions of a global equilibrium discharge model with the measured scalings of plasma density with RF power input and axial magnetic field strength, we demonstrate that inductive coupling (rather than capacitive coupling or wave damping) is the dominant energy transfer mechanism. Peak ion densities exceeding 5 × 10(19) m(-3) in argon gas at 30 mTorr have been achieved with and without a background field. Installation of the pre-ionization source on a magnetohydrodynamically driven jet experiment reduced the breakdown time and jitter and allowed for the creation of hotter, faster argon plasma jets than was previously possible.

  3. Microscopic properties of xenon plasmas for density and temperature regimes of laboratory astrophysics experiments on radiative shocks.

    Science.gov (United States)

    Rodríguez, R; Espinosa, G; Gil, J M; Stehlé, C; Suzuki-Vidal, F; Rubiano, J G; Martel, P; Mínguez, E

    2015-05-01

    This work is divided into two parts. In the first one, a study of radiative properties (such as monochromatic and the Rosseland and Planck mean opacities, monochromatic emissivities, and radiative power loss) and of the average ionization and charge state distribution of xenon plasmas in a range of plasma conditions of interest in laboratory astrophysics and extreme ultraviolet lithography is performed. We have made a particular emphasis in the analysis of the validity of the assumption of local thermodynamic equilibrium and the influence of the atomic description in the calculation of the radiative properties. Using the results obtained in this study, in the second part of the work we have analyzed a radiative shock that propagated in xenon generated in an experiment carried out at the Prague Asterix Laser System. In particular, we have addressed the effect of plasma self-absorption in the radiative precursor, the influence of the radiation emitted from the shocked shell and the plasma self-emission in the radiative precursor, the cooling time in the cooling layer, and the possibility of thermal instabilities in the postshock region.

  4. Development of a hybrid gyrokinetic ion and isothermal electron fluid code and its application to turbulent heating in astrophysical plasma

    Science.gov (United States)

    Kawazura, Yohei; Barnes, Michael; Plasma theory group Team

    2017-10-01

    Understanding the ion-to-electron temperature ratio is crucial for advancing our knowledge in astrophysics. Among the possible thermalization mechanisms, we focus on the dissipation of Alfvénic turbulence. Although several theoretical studies based on linear Alfvén wave damping have estimated the dependence of heating ratio on plasma parameters, there have been no direct nonlinear simulation that has investigated the heating ratio scanning plasma parameters. Schekochihin et al. (2009) proved that the turbulent heating ratio is determined at the ion Lamor radius scale. Therefore, we do not need to resolve all the scales up to the electron dissipation scale. To investigate the ion kinetic scale effectively, we developed a new code that solves a hybrid model composed of gyrokinetic ions and an isothermal electron fluid (ITEF). The code is developed by incorporating the ITEF approximation into the gyrokinetics code type="monospace">AstroGK (Numata et al., 2010). Since electron kinetic effects are eliminated, the new hybrid code runs approximately 2√{mi /me } times faster than full gyrokinetics codes. We will present linear and nonlinear benchmark tests of the new code and our first result of the heating ratio sweeping the plasma beta and ion-to-electron temperature ratio. This work was supported by STFC Grant ST/N000919/1. The authors also acknowledge the use of ARCHER through the Plasma HEC Consortium EPSRC Grant Number EP/L000237/1 under the projects e281-gs2.

  5. Collisional Growth of Planetesimals

    Science.gov (United States)

    Schroeter, Thomas; Nyffenegger, Oliver; Benz, Willy

    2010-05-01

    orbital period but rather by the processes that contribute to the changing of the orbits. A number of processes can change these orbits. Presently, the code includes physical collisions (assumed to be perfectly sticking), gravitational encounters (e.g. relaxation), gas drag (Inaba et al. 2001), and type I migration (Fogg and Nelson 2007). In order to model the latter two effects, we assume that the planetesimals are embedded in a gaseous disk for whose time evolution and structure are computed using an alpha-disk model. We will present various tests of the approach including direct comparisons with N-Body calculations. We will also present the result of a simulation following the individual collisional evolution of several tens of millions of particles by computing for each of them the changes as a function of time in mass and orbital parameters (semi-major axis, eccentricity and inclination). References ---------- Fogg, M. J. and Nelson, R. P., Astronomy and Astrophysics, Volume 472, Issue 3, pp.1003-1015 (2007) Inaba, S. et al., Icarus, Volume 149, Issue 1, pp. 235-250 (2001)

  6. The 3D MHD code GOEMHD3 for astrophysical plasmas with large Reynolds numbers. Code description, verification, and computational performance

    Science.gov (United States)

    Skála, J.; Baruffa, F.; Büchner, J.; Rampp, M.

    2015-08-01

    Context. The numerical simulation of turbulence and flows in almost ideal astrophysical plasmas with large Reynolds numbers motivates the implementation of magnetohydrodynamical (MHD) computer codes with low resistivity. They need to be computationally efficient and scale well with large numbers of CPU cores, allow obtaining a high grid resolution over large simulation domains, and be easily and modularly extensible, for instance, to new initial and boundary conditions. Aims: Our aims are the implementation, optimization, and verification of a computationally efficient, highly scalable, and easily extensible low-dissipative MHD simulation code for the numerical investigation of the dynamics of astrophysical plasmas with large Reynolds numbers in three dimensions (3D). Methods: The new GOEMHD3 code discretizes the ideal part of the MHD equations using a fast and efficient leap-frog scheme that is second-order accurate in space and time and whose initial and boundary conditions can easily be modified. For the investigation of diffusive and dissipative processes the corresponding terms are discretized by a DuFort-Frankel scheme. To always fulfill the Courant-Friedrichs-Lewy stability criterion, the time step of the code is adapted dynamically. Numerically induced local oscillations are suppressed by explicit, externally controlled diffusion terms. Non-equidistant grids are implemented, which enhance the spatial resolution, where needed. GOEMHD3 is parallelized based on the hybrid MPI-OpenMP programing paradigm, adopting a standard two-dimensional domain-decomposition approach. Results: The ideal part of the equation solver is verified by performing numerical tests of the evolution of the well-understood Kelvin-Helmholtz instability and of Orszag-Tang vortices. The accuracy of solving the (resistive) induction equation is tested by simulating the decay of a cylindrical current column. Furthermore, we show that the computational performance of the code scales very

  7. On the Stark broadening of Cr VI spectral lines in astrophysical plasma

    Science.gov (United States)

    Dimitrijević, M. S.; Simić, Z.; Sahal-Bréchot, S.

    2017-02-01

    Stark broadening parameters for Cr VI lines have been calculated using semiclassical perturbation method for conditions of interest for stellar plasma. Here are presented, as an example of obtained results, Stark broadening parameters for electron- and proton-impact broadening for Cr VI 4s 2S-4p 2P° λ = 1430 Å and Cr VI 4p 2P°-5s 2S λ = 611.8 Å multiplets. The obtained results are used to demonstrate the importance of Stark broadening of Cr VI in DO white dwarf atmospheres. Also the obtained results will enter in STARK-B database which is included in Virtual Atomic and Molecula Data Center - VAMDC.

  8. Quantum theory of the dielectric constant of a magnetized plasma and astrophysical applications. I.

    Science.gov (United States)

    Canuto, V.; Ventura, J.

    1972-01-01

    A quantum mechanical treatment of an electron plasma in a constant and homogeneous magnetic field is considered, with the aim of (1) defining the range of validity of the magnetoionic theory (2) studying the deviations from this theory, in applications involving high densities, and intense magnetic field. While treating the magnetic field exactly, a perturbation approach in the photon field is used to derive general expressions for the dielectric tensor. Numerical estimates on the range of applicability of the magnetoionic theory are given for the case of the 'one-dimensional' electron gas, where only the lowest Landau level is occupied.

  9. Experimental plasma astrophysics using a T{sup 3} (Table-top Terawatt) laser

    Energy Technology Data Exchange (ETDEWEB)

    Tajima, T.

    1996-11-01

    Lasers that can deliver immense power of Terawatt (10{sup 12}W) and can still compactly sit on a Table-Top (T{sup 3} lasers) emerged in the 1990s. The advent of these lasers allows us to access to regimes of astronomical physical conditions that once thought impossible to realize in a terrestrial laboratory. We touch on examples that include superhigh pressure materials that may resemble the interior of giant planets and white dwarfs and of relativistic temperature plasmas that may exist in the early cosmological epoch and in the neighborhood of the blackhole event horizon.

  10. Rossby vortices, spiral structures, solitons astrophysics and plasma physics in shallow water experiments

    CERN Document Server

    Nezlin, Mikhail V

    1993-01-01

    This book can be looked upon in more ways than one. On the one hand, it describes strikingly interesting and lucid hydrodynamic experiments done in the style of the "good old days" when the physicist needed little more than a piece of string and some sealing wax. On the other hand, it demonstrates how a profound physical analogy can help to get a synoptic view on a broad range of nonlinear phenomena involving self-organization of vortical structures in planetary atmo­ spheres and oceans, in galaxies and in plasmas. In particular, this approach has elucidated the nature and the mechanism of such grand phenomena as the Great of galaxies. A number of our Red Spot vortex on Jupiter and the spiral arms predictions concerning the dynamics of spiral galaxies are now being confirmed by astronomical observations stimulated by our experiments. This book is based on the material most of which was accumulated during 1981-88 in close cooperation with our colleagues, experimenters from the Plasma Physics Department of the...

  11. FOREWORD: The 9th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas (ASOS 9)

    Science.gov (United States)

    Wahlgren, Glenn M.; Wiese, Wolfgang L.; Beiersdorfer, Peter

    2008-07-01

    For the first time since its inaugural meeting in Lund in 1983, the triennial international conference on Atomic Spectroscopy and Oscillator Strengths for Astrophysical and Laboratory Plasmas (ASOS) returned to Lund, Sweden. Lund has been a home to atomic spectroscopy since the time of Janne Rydberg, and included the pioneering work in laboratory and solar spectroscopy of Bengt Edlén, who presented the initial ASOS talk in 1983. The ninth ASOS was hosted by the Lund Observatory and the Physics Department of Lund University during from 8 to 10 August 2007 and was attended by nearly 100 registrants. An encouraging sign for the field was the number of young researchers in attendance. This volume contains the submitted contributions from the poster presentations of the conference, and represents approximately forty percent of the presented posters. A complementary volume of Physica Scripta provides the written transactions of the ASOS9 invited presentations. With these two volumes the character of ASOS9 is more fully evident, and they serve as a review of the state of atomic spectroscopy for spectrum analysis and the determination of oscillator strengths and their applications. The goal of ASOS is to be a forum for atomic spectroscopy where both the providers and users of atomic data, which includes wavelengths, energy levels, lifetimes, oscillator strengths, and line shape parameters, can meet to discuss recent advances in experimental and theoretical techniques and their application to understanding the physical processes that are responsible for producing observed spectra. The applications mainly originate from the fields of astrophysics and plasma physics, the latter including fusion energy and lighting research. As a part of ASOS9 we were honored to celebrate the retirement of Professor Sveneric Johansson. At a special session on the spectroscopy of iron, which was conducted in his honor, he presented his insights into the Fe II term system and his most recent

  12. Astrophysical Applications of Quantum Corrections to the Equation of State of a Plasma

    Science.gov (United States)

    Heckler, Andrew F.

    1994-01-01

    The quantum electrodynamic correction to the equation of state of a plasma at finite temperature is applied to the areas of solar physics and cosmology. A previously neglected, purely quantum term in the correction is found to change the equation of state in the solar core by -0.37%, which is roughly estimated to decrease the calculated high energy neutrino flux by about 2.2%. We also show that a previous calculation of the effect of this correction on big bang nucleosynthesis is incomplete, and we estimate the correction to the primordial helium abundance Y to be Delta A= 1.4 x 10(exp -4). A physical explanation for the correction is found in terms of corrections to the dispersion relation of the electron, positron, and photon.

  13. Developed turbulence and nonlinear amplification of magnetic fields in laboratory and astrophysical plasmas.

    Science.gov (United States)

    Meinecke, Jena; Tzeferacos, Petros; Bell, Anthony; Bingham, Robert; Clarke, Robert; Churazov, Eugene; Crowston, Robert; Doyle, Hugo; Drake, R Paul; Heathcote, Robert; Koenig, Michel; Kuramitsu, Yasuhiro; Kuranz, Carolyn; Lee, Dongwook; MacDonald, Michael; Murphy, Christopher; Notley, Margaret; Park, Hye-Sook; Pelka, Alexander; Ravasio, Alessandra; Reville, Brian; Sakawa, Youichi; Wan, Willow; Woolsey, Nigel; Yurchak, Roman; Miniati, Francesco; Schekochihin, Alexander; Lamb, Don; Gregori, Gianluca

    2015-07-07

    The visible matter in the universe is turbulent and magnetized. Turbulence in galaxy clusters is produced by mergers and by jets of the central galaxies and believed responsible for the amplification of magnetic fields. We report on experiments looking at the collision of two laser-produced plasma clouds, mimicking, in the laboratory, a cluster merger event. By measuring the spectrum of the density fluctuations, we infer developed, Kolmogorov-like turbulence. From spectral line broadening, we estimate a level of turbulence consistent with turbulent heating balancing radiative cooling, as it likely does in galaxy clusters. We show that the magnetic field is amplified by turbulent motions, reaching a nonlinear regime that is a precursor to turbulent dynamo. Thus, our experiment provides a promising platform for understanding the structure of turbulence and the amplification of magnetic fields in the universe.

  14. Identification of Accretion as Grain Growth Mechanism in Astrophysically Relevant Water–Ice Dusty Plasma Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Ryan S.; Chai, Kil-Byoung; Bellan, Paul M. [Applied Physics and Materials Science, Caltech, Pasadena, CA 91125 (United States)

    2017-03-01

    The grain growth process in the Caltech water–ice dusty plasma experiment has been studied using a high-speed camera and a long-distance microscope lens. It is observed that (i) the ice grain number density decreases fourfold as the average grain major axis increases from 20 to 80 μ m, (ii) the major axis length has a log-normal distribution rather than a power-law dependence, and (iii) no collisions between ice grains are apparent. The grains have a large negative charge resulting in strong mutual repulsion and this, combined with the fractal character of the ice grains, prevents them from agglomerating. In order for the grain kinetic energy to be sufficiently small to prevent collisions between ice grains, the volumetric packing factor (i.e., ratio of the actual volume to the volume of a circumscribing ellipsoid) of the ice grains must be less than ∼0.1 depending on the exact relative velocity of the grains in question. Thus, it is concluded that direct accretion of water molecules is very likely to dominate the observed ice grain growth.

  15. What does Astrophysics want to know about (Astrophysical) Reconnection?

    Science.gov (United States)

    Rosner, R.

    2005-12-01

    Magnetic reconnection is commonly invoked as a plasma energization and particle acceleration process in astrophysics, but the levels of detail regarding the underlying physics that are required are generally far demanding than what is typically encountered in laboratory or space plasma physics. Naively, one would therefore expect it to be far easier to answer questions regarding reconnection in the astrophysical context as opposed to the laboratory or space plasma physics contexts. My talk will focus on why this naive expectation is not correct, and will discuss the specifics of such astrophysics-motivated questions, as well as some possible answers.

  16. Essential astrophysics

    CERN Document Server

    Lang, Kenneth R

    2013-01-01

    Essential Astrophysics is a book to learn or teach from, as well as a fundamental reference volume for anyone interested in astronomy and astrophysics. It presents astrophysics from basic principles without requiring any previous study of astronomy or astrophysics. It serves as a comprehensive introductory text, which takes the student through the field of astrophysics in lecture-sized chapters of basic physical principles applied to the cosmos. This one-semester overview will be enjoyed by undergraduate students with an interest in the physical sciences, such as astronomy, chemistry, engineering or physics, as well as by any curious student interested in learning about our celestial science. The mathematics required for understanding the text is on the level of simple algebra, for that is all that is needed to describe the fundamental principles. The text is of sufficient breadth and depth to prepare the interested student for more advanced specialized courses in the future. Astronomical examples are provide...

  17. Experimental results of astrophysical collisionless shock experiments from NIF

    Science.gov (United States)

    Park, Hye-Sook; Higginson, D.; Huntington, C.; Pollock, B.; Remington, B.; Rinderknecht, H.; Ross, J.; Ryutov, D.; Swadling, G.; Wilks, S.; Fiuza, F.; Sakawa, Y.; Spitkovsky, A.; Petrasso, R.; Li, C.; Zylstra, A.; Lamb, D.; Tzeferacos, P.; Gregori, G.; Meinecke, J.; Manuel, M.

    2017-10-01

    We discuss our laboratory experiments using the Omega and NIF lasers to investigate the dynamics of high Mach number collisionless shock formation in two interpenetrating plasma streams. It is believed that in astrophysical environments such shocks are the sites where seed magnetic fields are generated on a cosmologically fast timescale via the Weibel instability. Particle-in-cell (PIC) numerical simulations generate magnetic fields whose magnitude and scale are consistent with this concept. We will present recent experimental results as well as simulations and theoretical interpretations of these observations. The NIF experiments were able to observe the counter-streaming flow interactions through the transition from collisional to collisionless regimes. The latest proton radiography results will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  18. Maxwell Prize Talk: Scaling Laws for the Dynamical Plasma Phenomena

    Science.gov (United States)

    Ryutov, Livermore, Ca 94550, Usa, D. D.

    2017-10-01

    The scaling and similarity technique is a powerful tool for developing and testing reduced models of complex phenomena, including plasma phenomena. The technique has been successfully used in identifying appropriate simplified models of transport in quasistationary plasmas. In this talk, the similarity and scaling arguments will be applied to highly dynamical systems, in which temporal evolution of the plasma leads to a significant change of plasma dimensions, shapes, densities, and other parameters with respect to initial state. The scaling and similarity techniques for dynamical plasma systems will be presented as a set of case studies of problems from various domains of the plasma physics, beginning with collisonless plasmas, through intermediate collisionalities, to highly collisional plasmas describable by the single-fluid MHD. Basic concepts of the similarity theory will be introduced along the way. Among the results discussed are: self-similarity of Langmuir turbulence driven by a hot electron cloud expanding into a cold background plasma; generation of particle beams in disrupting pinches; interference between collisionless and collisional phenomena in the shock physics; similarity for liner-imploded plasmas; MHD similarities with an emphasis on the effect of small-scale (turbulent) structures on global dynamics. Relations between astrophysical phenomena and scaled laboratory experiments will be discussed.

  19. Nuclear astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Haxton, W.C.

    1992-01-01

    The problem of core-collapse supernovae is used to illustrate the many connections between nuclear astrophysics and the problems nuclear physicists study in terrestrial laboratories. Efforts to better understand the collapse and mantle ejection are also motivated by a variety of interdisciplinary issues in nuclear, particle, and astrophysics, including galactic chemical evolution, neutrino masses and mixing, and stellar cooling by the emission of new particles. The current status of theory and observations is summarized.

  20. Nuclear astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Haxton, W.C.

    1992-12-31

    The problem of core-collapse supernovae is used to illustrate the many connections between nuclear astrophysics and the problems nuclear physicists study in terrestrial laboratories. Efforts to better understand the collapse and mantle ejection are also motivated by a variety of interdisciplinary issues in nuclear, particle, and astrophysics, including galactic chemical evolution, neutrino masses and mixing, and stellar cooling by the emission of new particles. The current status of theory and observations is summarized.

  1. Relativistic astrophysics

    CERN Document Server

    Demianski, Marek

    2013-01-01

    Relativistic Astrophysics brings together important astronomical discoveries and the significant achievements, as well as the difficulties in the field of relativistic astrophysics. This book is divided into 10 chapters that tackle some aspects of the field, including the gravitational field, stellar equilibrium, black holes, and cosmology. The opening chapters introduce the theories to delineate gravitational field and the elements of relativistic thermodynamics and hydrodynamics. The succeeding chapters deal with the gravitational fields in matter; stellar equilibrium and general relativity

  2. Breakdown of a space charge limited regime of a sheath in a weakly collisional plasma bounded by walls with secondary electron emission.

    Science.gov (United States)

    Sydorenko, D; Kaganovich, I; Raitses, Y; Smolyakov, A

    2009-10-02

    A new regime of plasma-wall interaction is identified in particle-in-cell simulations of a hot plasma bounded by walls with secondary electron emission. Such a plasma has a strongly non-Maxwellian electron velocity distribution function and consists of bulk plasma electrons and beams of secondary electrons. In the new regime, the plasma sheath is not in a steady space charge limited state even though the secondary electron emission produced by the plasma bulk electrons is so intense that the corresponding partial emission coefficient exceeds unity. Instead, the plasma-sheath system performs relaxation oscillations by switching quasiperiodically between the space charge limited and non-space-charge limited states.

  3. Jeans instability of inhomogeneous dusty plasma with polarization force, ionization and recombination

    Science.gov (United States)

    Jain, Shweta; Sharma, Prerana; Chhajlani, R. K.

    2017-05-01

    The self-gravitational Jeans instability has been studied in dusty plasma containing significant background of neutral pressure and recombination of ions and electrons on the dust surface. The full dynamics of charged dust grains, ions and neutral species are employed considering the electrons as Maxwellian. We have derived the general dispersion relation for collisional dusty plasma with ionization, recombination and polarization force. The general dispersion relation describes the effects of considered parameters which are solved in different dusty plasma situations. Further, the dispersion relation is solved numerically. The present work is applicable to understand the structure formation of interstellar molecular clouds in astrophysical plasma.

  4. On forms of the Coulomb approximation as a useful source of atomic data for the spectroscopy of astrophysical and fusion plasmas

    Science.gov (United States)

    Hey, J. D.

    2017-03-01

    The Coulomb approximation (CA) has long been regarded as a useful tool for rapid estimates of line strengths, absorption oscillator strengths, and spontaneous transition probabilities of the lighter multi-electron atoms and ions, in situations where large quantities of atomic data are required for the analysis of spectroscopic measurements from a variety of plasma sources, in particular interesting stellar objects (e.g. white dwarf stars) and magnetically confined fusion plasmas. This applies especially in cases where the plasma is spatially inhomogeneous, and produces several ionisation stages of the same impurity element, emitting copious radiation in bound-bound transitions from cascade processes following charge-exchange recombination. While more advanced theoretical methods are routinely used by the specialist, the CA provides a very convenient method of checking atomic data chosen by the experimentalist from extensive compilations through the internet, or by the use of machine codes provided by others. The origins, advantages and shortcomings of the method are described and discussed, as well as convenient modifications thereof, which may readily be implemented for these purposes. Particular attention is paid to the choice of electron coupling of states in which the optical electron has a large orbital angular momentum ({\\ell }≥slant 3). The text is illustrated by numerous examples of application to spectra of practical interest from astrophysical and laboratory plasmas.

  5. Astrophysical Concepts

    CERN Document Server

    Harwit, Martin

    2006-01-01

    This classic text, aimed at senior undergraduates and beginning graduate students in physics and astronomy, presents a wide range of astrophysical concepts in sufficient depth to give the reader a quantitative understanding of the subject. Emphasizing physical concepts, the book outlines cosmic events but does not portray them in detail: it provides a series of astrophysical sketches. For this fourth edition, nearly every part of the text has been reconsidered and rewritten, new sections have been added to cover recent developments, and others have been extensively revised and brought up to date. The book begins with an outline of the scope of modern astrophysics and enumerates some of the outstanding problems faced in the field today. The basic physics needed to tackle these questions are developed in the next few chapters using specific astronomical processes as examples. The second half of the book enlarges on these topics and shows how we can obtain quantitative insight into the structure and evolution of...

  6. Nuclear Astrophysics

    Science.gov (United States)

    Drago, Alessandro

    2005-04-01

    The activity of the Italian nuclear physicists community in the field of Nuclear Astrophysics is reported. The researches here described have been performed within the project "Fisica teorica del nucleo e dei sistemi a multi corpi", supported by the Ministero dell'Istruzione, dell'Università e della Ricerca.

  7. Astrophysics today

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, A.G.W.

    1984-01-01

    Examining recent history, current trends, and future possibilities, the author reports the frontiers of research on the solar system, stars, galactic physics, and cosmological physics. The book discusses the great discoveries in astronomy and astrophysics and examines the circumstances in which they occurred. It discusses the physics of white dwarfs, the inflationary universe, the extinction of dinosaurs, black hole, cosmological models, and much more.

  8. Nuclear Astrophysics

    CERN Document Server

    Langanke, K

    1999-01-01

    The manuscript reviews progress achieved in recent years in various aspects of nuclear astrophysics, including stellar nucleosynthesis, nuclear aspects of supernova collapse and explosion, neutrino-induced reactions and their possible role in the supernova mechanism and nucleosynthesis, explosive hydrogen burning in binary systems, and finally the observation of gamma-rays from supernova remnants.

  9. Relativistic astrophysics

    CERN Document Server

    Price, R H

    1993-01-01

    Work reported in the workshop on relativistic astrophysics spanned a wide varicy of topics. Two specific areas seemed of particular interest. Much attention was focussed on gravitational wave sources, especially on the waveforms they produce, and progress was reported in theoretical and observational aspects of accretion disks.

  10. Astrophysical Processes

    Indian Academy of Sciences (India)

    Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately.

  11. An introduction to astrophysical hydrodynamics

    CERN Document Server

    Shore, Steven N

    1992-01-01

    This book is an introduction to astrophysical hydrodynamics for both astronomy and physics students. It provides a comprehensive and unified view of the general problems associated with fluids in a cosmic context, with a discussion of fluid dynamics and plasma physics. It is the only book on hydrodynamics that addresses the astrophysical context. Researchers and students will find this work to be an exceptional reference. Contents include chapters on irrotational and rotational flows, turbulence, magnetohydrodynamics, and instabilities.

  12. Modeling of collisional excited x-ray lasers using short pulse laser pumping

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Akira; Moribayashi, Kengo; Utsumi, Takayuki; Tajima, Toshiki [Japan Atomic Energy Research Inst., Neyagawa, Osaka (Japan). Kansai Research Establishment

    1998-03-01

    A simple atomic kinetics model of electron collisional excited x-ray lasers has been developed. The model consists of a collisional radiative model using the average ion model (AIM) and a detailed term accounting (DTA) model of Ni-like Ta. An estimate of plasma condition to produce gain in Ni-like Ta ({lambda}=44A) is given. Use of the plasma confined in a cylinder is proposed to preform a uniform high density plasma from 1-D hydrodynamics calculations. (author)

  13. Observational astrophysics

    CERN Document Server

    Léna, Pierre; Lebrun, François; Mignard, François; Pelat, Didier

    2012-01-01

    This is the updated, widely revised, restructured and expanded third edition of Léna et al.'s successful work Observational Astrophysics. It presents a synthesis on tools and methods of observational astrophysics of the early 21st century. Written specifically for astrophysicists and graduate students, this textbook focuses on fundamental and sometimes practical limitations on the ultimate performance that an astronomical system may reach, rather than presenting particular systems in detail. In little more than a decade there has been extraordinary progress in imaging and detection technologies, in the fields of adaptive optics, optical interferometry, in the sub-millimetre waveband, observation of neutrinos, discovery of exoplanets, to name but a few examples. The work deals with ground-based and space-based astronomy and their respective fields. And it also presents the ambitious concepts behind space missions aimed for the next decades. Avoiding particulars, it covers the whole of the electromagnetic spec...

  14. astrophysical significance

    Directory of Open Access Journals (Sweden)

    Dartois E.

    2014-02-01

    Full Text Available Clathrate hydrates, ice inclusion compounds, are of major importance for the Earth’s permafrost regions and may control the stability of gases in many astrophysical bodies such as the planets, comets and possibly interstellar grains. Their physical behavior may provide a trapping mechanism to modify the absolute and relative composition of icy bodies that could be the source of late-time injection of gaseous species in planetary atmospheres or hot cores. In this study, we provide and discuss laboratory-recorded infrared signatures of clathrate hydrates in the near to mid-infrared and the implications for space-based astrophysical tele-detection in order to constrain their possible presence.

  15. Cognitive Astrophysics

    Science.gov (United States)

    Madore, Barry F.

    2012-09-01

    Cognitive Astrophysics works at the cusp between Cognitive Science and Astrophysics, drawing upon lessons learned in the Philosophy of Science, Linguistics and Artificial Intelligence. We will introduce and illustrate the concept of ``Downward Causation,'' common in philosophical discussions, but either unknown to or disdained by most physicists. A clear example operating on cosmological scales involving the origin of large-scale structure will be given. We will also make the case that on scales exceeding most laboratory experiments, self-gravitating matter can be considered to be in a ``fifth state'', characterized primarily by its negative specific heat, as first recognized by Lynden-Bell and Lynden-Bell (1977, MNRAS, 181, 405). Such systems increase their temperature as they lose energy. Numerous examples will be given and discussed.

  16. The collisional relaxation of electrons in hot flaring plasma and inferring the properties of solar flare accelerated electrons from X-ray observations

    OpenAIRE

    Jeffrey, N. L. S.; Kontar, E. P.; Emslie, A. G.; Bian, N. H.

    2015-01-01

    X-ray observations are a direct diagnostic of fast electrons produced in solar flares, energized during the energy release process and directed towards the Sun. Since the properties of accelerated electrons can be substantially changed during their transport and interaction with the background plasma, a model must ultimately be applied to X-ray observations in order to understand the mechanism responsible for their acceleration. A cold thick target model is ubiquitously used for this task, si...

  17. Evaluating a Contribution of the Knock-on Deuterons to the Neutron Yield in the Experiments with Weakly Collisional Plasma Jets (Part 1)

    Energy Technology Data Exchange (ETDEWEB)

    Ryutov, D. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-12-01

    Laser-generated interpenetrating plasma jets are widely used in the studies of collisionless interaction of counter-streaming plasmas in conjunction with possible formation of collisionless shocks. In a number of experiments of this type the plasma is formed on plastic targets made of CH or CD. The study of the DD neutron production from the interaction between two CD jets on the one hand and between a CD jet and a CH jet could serve as a qualitative indicator of the collisionless shock formation. The purpose of this memo is a discussion of the effect of collisions on the neutron generation in the interpenetrating CH and CD jets. First, the kinematics of the large-deflection collisions of the deuterons and carbon are discussed. Then the scattering angles are related with the corresponding Rutherford cross-section. After that expression for the number of the backscattered deuterons is provided, and their contribution to the neutron yield is evaluated. The results may be of some significance to the kinetic codes benchmarking and developing the neutron diagnostic.

  18. FLYCHK Collisional-Radiative Code

    Science.gov (United States)

    SRD 160 FLYCHK Collisional-Radiative Code (Web, free access)   FLYCHK provides a capability to generate atomic level populations and charge state distributions for low-Z to mid-Z elements under NLTE conditions.

  19. Using X-ray spectroscopy of relativistic laser plasma interaction to reveal parametric decay instabilities : A modeling tool for astrophysics

    OpenAIRE

    Oks, E; Dalimier, E.; Faenov, A. Ya; Angelo, P.; Pikuz, S. A.; Tubman, E.; Butler, N. M H; Dance, R. J.; Pikuz, T. A.; Skobelev, I. Yu.; Alkhimova, M. A.; Booth, N.; Green, J.; Gregory, C; Andreev, A.

    2017-01-01

    By analyzing profiles of experimental x-ray spectral lines of Si XIV and Al XIII, we found that both Langmuir and ion acoustic waves developed in plasmas produced via irradiation of thin Si foils by relativistic laser pulses (intensities ∼1021 W/cm2). We prove that these waves are due to the parametric decay instability (PDI). This is the first time that the PDI-induced ion acoustic turbulence was discovered by the x-ray spectroscopy in laser-produced plasmas. These conclusions are also suppo...

  20. Final Report for Project DE-SC0006958: "An Investigation of the Effects of magnetic Fields and Collisionality on Shock Formation in Radiatively Cooled Plasma Flows"

    Energy Technology Data Exchange (ETDEWEB)

    Bott-Suzuki, Simon

    2014-11-05

    We have developed a new experimental platform to study bow-shock formation in plasma flows generated using an inverse wire array z-pinch. We have made significant progress on the analysis of both hydrodynamic and magnetized shocks using this system. The hydrodynamic experiments show formation of a well-defined Mach cone, and highly localized shock strong associated with radiative losses and rapidly cooling over the shock. Magnetized shocks show that the balance of magnetic and ram pressures dominate the evolution of the shock region, generating a low plasma beta void around the target. Manuscripts are in preparation for publication on both these topics. We have also published the development of a novel diagnostic method which allow recovery of interferometry and self-emission data along the same line of sight. Finally, we have carried out work to integrate a kinetic routine with the 3D MHD code Gorgon, however it remains to complete this process. Both undergraduate and graduate students have been involved in both the experimental work and publications.

  1. Astrophysical cosmology

    Science.gov (United States)

    Bardeen, J. M.

    The last several years have seen a tremendous ferment of activity in astrophysical cosmology. Much of the theoretical impetus has come from particle physics theories of the early universe and candidates for dark matter, but what promise to be even more significant are improved direct observations of high z galaxies and intergalactic matter, deeper and more comprehensive redshift surveys, and the increasing power of computer simulations of the dynamical evolution of large scale structure. Upper limits on the anisotropy of the microwave background radiation are gradually getting tighter and constraining more severely theoretical scenarios for the evolution of the universe.

  2. High Energy Density Laboratory Astrophysics

    CERN Document Server

    Lebedev, Sergey V

    2007-01-01

    During the past decade, research teams around the world have developed astrophysics-relevant research utilizing high energy-density facilities such as intense lasers and z-pinches. Every two years, at the International conference on High Energy Density Laboratory Astrophysics, scientists interested in this emerging field discuss the progress in topics covering: - Stellar evolution, stellar envelopes, opacities, radiation transport - Planetary Interiors, high-pressure EOS, dense plasma atomic physics - Supernovae, gamma-ray bursts, exploding systems, strong shocks, turbulent mixing - Supernova remnants, shock processing, radiative shocks - Astrophysical jets, high-Mach-number flows, magnetized radiative jets, magnetic reconnection - Compact object accretion disks, x-ray photoionized plasmas - Ultrastrong fields, particle acceleration, collisionless shocks. These proceedings cover many of the invited and contributed papers presented at the 6th International Conference on High Energy Density Laboratory Astrophys...

  3. Calculation of collisional mixing

    Science.gov (United States)

    Koponen, I.; Hautala, M.

    1990-06-01

    Collisional mixing of markers is calculated by splitting the calculation into two parts. Relocation cross sections have been calculated using a realistic potential in a Monte Carlo simulation. The cross sections are used in the computation of marker relocation. The cumulative effect of successive relocations is assumed to be an uncorrelated transport process and it is treated as a weighted random walk. Matrix relocation was not included in the calculations. The results from this two-step simulation model are compared with analytical models. A fit to the simulated differential relocation cross sections has been found which makes the numerical integration of the Bothe formula feasible. The influence of primaries has been treated in this way. When all the recoils are included the relocation profiles are nearly Gaussian and the Pearson IV distributions yield acceptable profiles in the studied cases. The approximations and cut-off procedures which cause the major uncertainties in calculations are pointed out. The choice of the cut-off energy is shown to be the source of the largest uncertainty whereas the mathematical approximations can be used with good accuracy. The methods are used to study the broadening of a Pt marker in Si mixed by 300 keV Xe ions, broadening of a Ti marker in Al mixed by 300 keV Xe ions and broadening of a Ti marker in Hf mixed by 750 keV Kr ions. The fluence in each case is 2 × 10 16{ions}/{cm 2}. The calculated averages of half widths at half maximum vary between 11-18, 9-12 and 10-15 nm, respectively, depending on the cut-off energy and the mixing efficiencies vary between 11-29, 6-11 and 6-14 {Å5}/{eV}, respectively. The broadenings of Pt in Si and Ti in Al are about two times smaller than the measured values and the broadening of Ti in Hf is in agreement with the measured values.

  4. Astrophysical fluid dynamics

    Science.gov (United States)

    Ogilvie, Gordon I.

    2016-06-01

    > These lecture notes and example problems are based on a course given at the University of Cambridge in Part III of the Mathematical Tripos. Fluid dynamics is involved in a very wide range of astrophysical phenomena, such as the formation and internal dynamics of stars and giant planets, the workings of jets and accretion discs around stars and black holes and the dynamics of the expanding Universe. Effects that can be important in astrophysical fluids include compressibility, self-gravitation and the dynamical influence of the magnetic field that is `frozen in' to a highly conducting plasma. The basic models introduced and applied in this course are Newtonian gas dynamics and magnetohydrodynamics (MHD) for an ideal compressible fluid. The mathematical structure of the governing equations and the associated conservation laws are explored in some detail because of their importance for both analytical and numerical methods of solution, as well as for physical interpretation. Linear and nonlinear waves, including shocks and other discontinuities, are discussed. The spherical blast wave resulting from a supernova, and involving a strong shock, is a classic problem that can be solved analytically. Steady solutions with spherical or axial symmetry reveal the physics of winds and jets from stars and discs. The linearized equations determine the oscillation modes of astrophysical bodies, as well as their stability and their response to tidal forcing.

  5. Integrated mechanism that both removes accretion disk angular momentum and drives astrophysical jets

    Science.gov (United States)

    Bellan, Paul

    2016-10-01

    Using concepts from laboratory experiments, Hamiltonian mechanics, Hall MHD, and weakly ionized plasmas, I propose a mechanism that simultaneously drives astrophysical jets and removes accretion disk angular momentum. The mechanism depends on the extreme stratification of ionization between the weakly ionized accretion disk and the highly ionized exterior region. In the exterior region, axisymmetric Hamiltonian mechanics constrain charged particles to move on nested poloidal flux surfaces. In contrast, fluid elements in the weakly ionized, highly collisional accretion disk behave like collisionless meta-particles with effective q / m reduced from than that of an ion by the nominal disk 10-15 - 10-8 fractional ionization; this means that the meta-particle effective cyclotron frequency ωc can be of order of the Kepler frequency ωK =(MG /r3) 1 / 2 . Meta-particles with ωc = - 2ωK have zero canonical angular momentum, experience no centrifugal force and spiral in towards the central body. Because these inward spiraling meta-particles are positive, their accumulation near the central body produces radially and axially outward electric fields. The axial outward electric field drives an out-of-plane poloidal electric current along poloidal flux surfaces in the external region. As in lab experiments, this current and its associated toroidal magnetic field drive astrophysical jets flowing normal to and away from the disk. Supported by NSF/DOE Partnership in Plasma Physics.

  6. Rotating shallow water modeling of planetary,astrophysical and plasma vortical structures (plasma transport across a magnetic field,model of the jupiter's GRS, prediction of existence of giant vortices in spiral galaxies

    Directory of Open Access Journals (Sweden)

    M. V. Nezlin

    1999-01-01

    Full Text Available Three kinds of results have been described in this paper. Firstly, an experimental study of the Rossby vortex meridional drift on the rotating shallow water has been carried out. Owing to the stringent physical analogy between the Rossby vortices and drift vortices in the magnetized plasma, the results obtained have allowed one to make a conclusion that the transport rate of the plasma, trapped by the drift vortices, across the magnetic field is equivalent to the “gyro-Bohm” diffusion coefficient. Secondly, a model of big vortices of the type of the Great Red Spot of Jupiter, dominating in the atmospheres of the outer planets, has been produced. Thirdly, the rotating shallow water modeling has been carried out of the hydrodynamical generation mechanism of spiral structures in galaxies. Trailing spiral waves of various azimuthal modes, generated by a shear flow between fast rotating “nucleus” and slow rotating periphery, were produced. The spirals are similar to those existing in the real galaxies. The hydrodynamical concept of the spiral structure formation in galaxies has been substantiated. Strong anticyclonic vortices between the spiral arms of the structures under study have been discovered for the first time. The existence of analogous vortices in real galaxies has been predicted. (This prediction has been reliably confirmed recently in special astronomical observations, carried out on the basis of the mentioned laboratory modeling and the prediction made – see the paper by A. Fridman et al. (Astrophysics and Space Science, 1997, 252, 115.

  7. Trends in Nuclear Astrophysics

    OpenAIRE

    Schatz, Hendrik

    2016-01-01

    Nuclear Astrophysics is a vibrant field at the intersection of nuclear physics and astrophysics that encompasses research in nuclear physics, astrophysics, astronomy, and computational science. This paper is not a review. It is intended to provide an incomplete personal perspective on current trends in nuclear astrophysics and the specific role of nuclear physics in this field.

  8. Laboratory high-energy astrophysics on lasers

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, W.H.; Liedahl, D.A.; Walling, R.S.; Foord, M.E.; Osterheld, A.L.; Wilson, B.G.

    1994-12-01

    The tremendous range of temperatures and densities spanned by astrophysical plasmas has significant overlap with conditions attainable using high-power laser facilities. These facilities provide an opportunity to create, control, and characterize plasmas in the laboratory that mirror conditions in some of the most important cosmological systems. Moreover, laboratory experiments can enhance astrophysical understanding by focusing on and isolating important physical processes, without necessarily reproducing the exact conditions of the integral system. Basic study of radiative properties, transport phenomena, thermodynamic response and hydrodynamic evolution in plasmas under properly scaled conditions leads both directly and indirectly to improved models of complex astrophysical systems. In this paper, we will discuss opportunities for current and planned highpower lasers to contribute to the study of high-energy astrophysics.

  9. COLLISIONAL-RADIATIVE MODEL FOR HIGHLY STRIPPED IONS

    OpenAIRE

    E. Berthier; Delpech, J.-F.; Vuillemin, M.

    1986-01-01

    Collisional -Radiative numerical models are commonly used to design or interpret experiments in atomic physics of laser-created plasmas, including X-Ray laser studies. We describe our new code containing several options : average ion, more or less detailed configurations. It consists of an atomic data base coupled to subroutines evaluating ionic populations and emission and absorption coefficients. Numerical results are given to illustrate the capabilities of the code and to compare different...

  10. Turbulent dynamo in a collisionless plasma.

    Science.gov (United States)

    Rincon, François; Califano, Francesco; Schekochihin, Alexander A; Valentini, Francesco

    2016-04-12

    Magnetic fields pervade the entire universe and affect the formation and evolution of astrophysical systems from cosmological to planetary scales. The generation and dynamical amplification of extragalactic magnetic fields through cosmic times (up to microgauss levels reported in nearby galaxy clusters, near equipartition with kinetic energy of plasma motions, and on scales of at least tens of kiloparsecs) are major puzzles largely unconstrained by observations. A dynamo effect converting kinetic flow energy into magnetic energy is often invoked in that context; however, extragalactic plasmas are weakly collisional (as opposed to magnetohydrodynamic fluids), and whether magnetic field growth and sustainment through an efficient turbulent dynamo instability are possible in such plasmas is not established. Fully kinetic numerical simulations of the Vlasov equation in a 6D-phase space necessary to answer this question have, until recently, remained beyond computational capabilities. Here, we show by means of such simulations that magnetic field amplification by dynamo instability does occur in a stochastically driven, nonrelativistic subsonic flow of initially unmagnetized collisionless plasma. We also find that the dynamo self-accelerates and becomes entangled with kinetic instabilities as magnetization increases. The results suggest that such a plasma dynamo may be realizable in laboratory experiments, support the idea that intracluster medium turbulence may have significantly contributed to the amplification of cluster magnetic fields up to near-equipartition levels on a timescale shorter than the Hubble time, and emphasize the crucial role of multiscale kinetic physics in high-energy astrophysical plasmas.

  11. Propinquity of current and vortex structures: effects on collisionless plasma heating

    CERN Document Server

    Parashar, Tulasi N

    2016-01-01

    Intermittency of heating in weakly collisional plasma turbulence is an active subject of research, with significant potential impact on understanding of the solar wind, solar corona and astrophysical plasmas. Recent studies suggest a role of vorticity in plasma heating. In magnetohydrodynamics small scale vorticity is generated near current sheets and this effect persists in kinetic plasma, as demonstrated here with hybrid and fully kinetic Particle-In-Cell (PIC) simulations. Furthermore, vorticity enhances local kinetic effects, with a generalized resonance condition selecting sign-dependent enhancements or reductions of proton heating and thermal anisotropy. In such plasmas heating is correlated with vorticity and current density, but more strongly with vorticity. These results help explain several prior results that find kinetic effects and energization near to, but not centered on, current sheets. Evidently intermittency in kinetic plasma involves multiple physical quantities, and the associated coherent ...

  12. Collisional-radiative nonequilibrium in partially ionized atomic nitrogen

    Science.gov (United States)

    Kunc, J. A.; Soon, W. H.

    1989-01-01

    A nonlinear collisional-radiative model for determination of nonequilibrium production of electrons, excited atoms, and bound-bound, dielectronic and continuum line intensities in stationary partially ionized atomic nitrogen is presented. Populations of 14 atomic levels and line intensities are calculated in plasma with T(e) = 8000-15,000 K and N(t) = 10 to the 12th - 10 to the 18th/cu cm. Transport of radiation is included by coupling the rate equations of production of the electrons and excited atoms with the radiation escape factors, which are not constant but depend on plasma conditions.

  13. Spontaneous magnetic reconnection. Collisionless reconnection and its potential astrophysical relevance

    Science.gov (United States)

    Treumann, R. A.; Baumjohann, W.

    2015-10-01

    The present review concerns the relevance of collisionless reconnection in the astrophysical context. Emphasis is put on recent developments in theory obtained from collisionless numerical simulations in two and three dimensions. It is stressed that magnetic reconnection is a universal process of particular importance under collisionless conditions, when both collisional and anomalous dissipation are irrelevant. While collisional (resistive) reconnection is a slow, diffusive process, collisionless reconnection is spontaneous. On any astrophysical time scale, it is explosive. It sets on when electric current widths become comparable to the leptonic inertial length in the so-called lepton (electron/positron) "diffusion region", where leptons de-magnetise. Here, the magnetic field contacts its oppositely directed partner and annihilates. Spontaneous reconnection breaks the original magnetic symmetry, violently releases the stored free energy of the electric current, and causes plasma heating and particle acceleration. Ultimately, the released energy is provided by mechanical motion of either the two colliding magnetised plasmas that generate the current sheet or the internal turbulence cascading down to lepton-scale current filaments. Spontaneous reconnection in such extended current sheets that separate two colliding plasmas results in the generation of many reconnection sites (tearing modes) distributed over the current surface, each consisting of lepton exhausts and jets which are separated by plasmoids. Volume-filling factors of reconnection sites are estimated to be as large as {sheet. Lepton currents inside exhausts may be strong enough to excite Buneman and, for large thermal pressure anisotropy, also Weibel instabilities. They bifurcate and break off into many small-scale current filaments and magnetic flux ropes exhibiting turbulent magnetic power spectra of very flat power-law shape W_b∝ k^{-α } in wavenumber k with power becoming as low as α ≈ 2

  14. Astrophysical processes on the sun.

    Science.gov (United States)

    Parnell, Clare E

    2012-07-13

    Over the past two decades, there have been a series of major solar space missions, namely Yohkoh, SOHO, TRACE, and in the past 5 years, STEREO, Hinode and SDO, studying various aspects of the Sun and providing images and spectroscopic data with amazing temporal, spatial and spectral resolution. Over the same period, the type and nature of numerical models in solar physics have been completely revolutionized as a result of widespread accessibility to parallel computers. These unprecedented advances on both observational and theoretical fronts have led to significant improvements in our understanding of many aspects of the Sun's behaviour and furthered our knowledge of plasma physics processes that govern solar and other astrophysical phenomena. In this Theme Issue, the current perspectives on the main astrophysical processes that shape our Sun are reviewed. In this Introduction, they are discussed briefly to help set the scene.

  15. Astrophysical Hydrodynamics An Introduction

    CERN Document Server

    Shore, Steven N

    2007-01-01

    This latest edition of the proven and comprehensive treatment on the topic -- from the bestselling author of ""Tapestry of Modern Astrophysics"" -- has been updated and revised to reflect the newest research results. Suitable for AS0000 and AS0200 courses, as well as advanced astrophysics and astronomy lectures, this is an indispensable theoretical backup for studies on celestial body formation and astrophysics. Includes exercises with solutions.

  16. Particle Physics & Astrophysics (PPA)

    Data.gov (United States)

    Federal Laboratory Consortium — Scientists at SLAC's Particle Physics and Astrophysics develop and utilize unique instruments from underground to outer space to explore the ultimate laws of nature...

  17. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. Nagendra Kumar. Articles written in Journal of Astrophysics and Astronomy. Volume 29 Issue 1-2 March-June 2008 pp 243-248. Damping of Slow Magnetoacoustic Waves in an Inhomogeneous Coronal Plasma · Nagendra Kumar Pradeep Kumar Shiv Singh Anil ...

  18. Astronomy and astrophysics

    National Research Council Canada - National Science Library

    National Research Council Staff

    1988-01-01

    ... for the Decades 1995 to 2015 Astronomy and Astrophysics Task Group on Astronomy and Astrophysics Space Science Board Commission on Physical Sciences, Mathematics, and Resources National Research Council NATIONAL ACADEMY PRESS Washington, D.C. 1988 Copyrightoriginal retained, the be not from cannot book, paper original however, for version formatting, author...

  19. Dynamo transformation of the collisional R-T in a weakly ionized ...

    Indian Academy of Sciences (India)

    where the interstellar neutrals undergo charge exchange collisions with ions in the solar wind [1]. The presence of neutrals in plasmas can drive new instability in many ways. For ... to be based on the dynamo principle of a.c. generator. However, a pertinent question remains to be addressed: what happens to the collisional ...

  20. Hydrodynamic theory for ion structure and stopping power in quantum plasmas.

    Science.gov (United States)

    Shukla, P K; Akbari-Moghanjoughi, M

    2013-04-01

    We present a theory for the dynamical ion structure factor (DISF) and ion stopping power in an unmagnetized collisional quantum plasma with degenerate electron fluids and nondegenerate strongly correlated ion fluids. Our theory is based on the fluctuation dissipation theorem and the quantum plasma dielectric constant that is deduced from a linearized viscoelastic quantum hydrodynamical (LVQHD) model. The latter incorporates the essential physics of quantum forces, which are associated with the quantum statistical pressure, electron-exchange, and electron-correlation effects, the quantum electron recoil effect caused by the dispersion of overlapping electron wave functions that control the dynamics of degenerate electron fluids, and the viscoelastic properties of strongly correlated ion fluids. Both degenerate electrons and nondegenerate strongly correlated ions are coupled with each other via the space charge electric force. Thus, our LVQHD theory is valid for a collisional quantum plasma at atomic scales with a wide range of the ion coupling parameter, the plasma composition, and plasma number densities that are relevant for compressed plasmas in laboratories (inertial confinement fusion schemes) and in astrophysical environments (e.g., warm dense matter and the cores of white dwarf stars). It is found that quantum electron effects and viscoelastic properties of strongly correlated ions significantly affect the features of the DISF and the ion stopping power (ISP). Unlike previous theories, which have studied ion correlations in terms of the ion coupling parameter, by neglecting the essential physics of collective effects that are competing among each other, we have here developed a method to evaluate the dependence of the plasma static and dynamical features in terms of individual parameters, like the Wigner-Seitz radius, the ion atomic number, and the ion temperature. It is found that due to the complex nature of charge screening in quantum plasmas, the ion

  1. Collisional transport across the magnetic field in drift-fluid models

    DEFF Research Database (Denmark)

    Madsen, Jens; Naulin, Volker; Nielsen, Anders Henry

    2016-01-01

    altering the drift-fluid energy integral. We demonstrate that the inclusion of collisional transport in drift-fluid models gives rise to diffusion of particle density, momentum, and pressures in drift-fluid turbulence models and, thereby, obviates the customary use of artificial diffusion in turbulence......Drift ordered fluid models are widely applied in studies of low-frequency turbulence in the edge and scrape-off layer regions of magnetically confined plasmas. Here, we show how collisional transport across the magnetic field is self-consistently incorporated into drift-fluid models without...

  2. Astrophysics in a nutshell

    CERN Document Server

    Maoz, Dan

    2007-01-01

    A concise but thorough introduction to the observational data and theoretical concepts underlying modern astronomy, Astrophysics in a Nutshell is designed for advanced undergraduate science majors taking a one-semester course. This well-balanced and up-to-date textbook covers the essentials of modern astrophysics--from stars to cosmology--emphasizing the common, familiar physical principles that govern astronomical phenomena, and the interplay between theory and observation. In addition to traditional topics such as stellar remnants, galaxies, and the interstellar medium, Astrophysics in a N

  3. An invitation to astrophysics

    CERN Document Server

    Padmanabhan, Thanu

    2006-01-01

    This unique book provides a clear and lucid description of several aspects of astrophysics and cosmology in a language understandable to a physicist or beginner in astrophysics. It presents the key topics in all branches of astrophysics and cosmology in a simple and concise language. The emphasis is on currently active research areas and exciting new frontiers rather than on more pedantic topics. Many complicated results are introduced with simple, novel derivations which strengthen the conceptual understanding of the subject. The book also contains over one hundred exercises which will help s

  4. Laboratory Astrophysics on High Power Lasers and Pulsed Power Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B A

    2002-02-05

    Over the past decade a new genre of laboratory astrophysics has emerged, made possible by the new high energy density (HED) experimental facilities, such as large lasers, z-pinch generators, and high current particle accelerators. (Remington, 1999; 2000; Drake, 1998; Takabe, 2001) On these facilities, macroscopic collections of matter can be created in astrophysically relevant conditions, and its collective properties measured. Examples of processes and issues that can be experimentally addressed include compressible hydrodynamic mixing, strong shock phenomena, radiative shocks, radiation flow, high Mach-number jets, complex opacities, photoionized plasmas, equations of state of highly compressed matter, and relativistic plasmas. These processes are relevant to a wide range of astrophysical phenomena, such as supernovae and supernova remnants, astrophysical jets, radiatively driven molecular clouds, accreting black holes, planetary interiors, and gamma-ray bursts. These phenomena will be discussed in the context of laboratory astrophysics experiments possible on existing and future HED facilities.

  5. Astrophysical payloads for picosatellites

    Science.gov (United States)

    Hudec, R.

    2017-07-01

    The recent progress in cubesatellite technology allows to consider scientific applications of these minsatellites including astrophysical research. Miniature X-ray and UV-payloads may serve as an example.

  6. Astrophysics Decoding the cosmos

    CERN Document Server

    Irwin, Judith A

    2007-01-01

    Astrophysics: Decoding the Cosmos is an accessible introduction to the key principles and theories underlying astrophysics. This text takes a close look at the radiation and particles that we receive from astronomical objects, providing a thorough understanding of what this tells us, drawing the information together using examples to illustrate the process of astrophysics. Chapters dedicated to objects showing complex processes are written in an accessible manner and pull relevant background information together to put the subject firmly into context. The intention of the author is that the book will be a 'tool chest' for undergraduate astronomers wanting to know the how of astrophysics. Students will gain a thorough grasp of the key principles, ensuring that this often-difficult subject becomes more accessible.

  7. Astrophysics Program Overview; Briefing

    National Research Council Canada - National Science Library

    1998-01-01

    This is an overview briefing of the NAS Astrophysics programs. These program should lead the opening scientific frontiers and disseminate new knowledge, as the Hubble Space Telescope and Compton Gamma Ray Observatory are currently doing...

  8. Collisional Scaling of the Energy Transfer in Drift-Wave Zonal Flow Turbulence.

    Science.gov (United States)

    Schmid, B; Manz, P; Ramisch, M; Stroth, U

    2017-02-03

    The collisionality scaling of density and potential coupling together with zonal flow energy transfer and spectral power is investigated at the stellarator experiment TJ-K. With a poloidal probe array, consisting of 128 Langmuir probes, density and potential fluctuations are measured on four neighboring flux surfaces simultaneously over the complete poloidal circumference. By analyzing Reynolds stress and pseudo-Reynolds stress, it is found that, for increasing collisionality, the coupling between density and potential decreases which hinders the zonal flow drive. Also, as a consequence, the nonlinear energy transfer, as well as the zonal flow contribution to the complete turbulent spectrum, decreases the same way. This is in line with theoretical expectations and is a first experimental verification of the importance of collisionality for large-scale structure formation in magnetically confined toroidal plasmas.

  9. Theoretical physics and astrophysics

    CERN Document Server

    Ginzburg, Vitalii Lazarevich

    1979-01-01

    The aim of this book is to present, on the one hand various topics in theoretical physics in depth - especially topics related to electrodynamics - and on the other hand to show how these topics find applications in various aspects of astrophysics. The first text on theoretical physics and astrophysical applications, it covers many recent advances including those in X-ray, &ggr;-ray and radio-astronomy, with comprehensive coverage of the literature

  10. Collisional stripping of planetary crusts

    Science.gov (United States)

    Carter, Philip J.; Leinhardt, Zoë M.; Elliott, Tim; Stewart, Sarah T.; Walter, Michael J.

    2018-02-01

    Geochemical studies of planetary accretion and evolution have invoked various degrees of collisional erosion to explain differences in bulk composition between planets and chondrites. Here we undertake a full, dynamical evaluation of 'crustal stripping' during accretion and its key geochemical consequences. Crusts are expected to contain a significant fraction of planetary budgets of incompatible elements, which include the major heat producing nuclides. We present smoothed particle hydrodynamics simulations of collisions between differentiated rocky planetesimals and planetary embryos. We find that the crust is preferentially lost relative to the mantle during impacts, and we have developed a scaling law based on these simulations that approximates the mass of crust that remains in the largest remnant. Using this scaling law and a recent set of N-body simulations of terrestrial planet formation, we have estimated the maximum effect of crustal stripping on incompatible element abundances during the accretion of planetary embryos. We find that on average approximately one third of the initial crust is stripped from embryos as they accrete, which leads to a reduction of ∼20% in the budgets of the heat producing elements if the stripped crust does not reaccrete. Erosion of crusts can lead to non-chondritic ratios of incompatible elements, but the magnitude of this effect depends sensitively on the details of the crust-forming melting process on the planetesimals. The Lu/Hf system is fractionated for a wide range of crustal formation scenarios. Using eucrites (the products of planetesimal silicate melting, thought to represent the crust of Vesta) as a guide to the Lu/Hf of planetesimal crust partially lost during accretion, we predict the Earth could evolve to a superchondritic 176Hf/177Hf (3-5 parts per ten thousand) at present day. Such values are in keeping with compositional estimates of the bulk Earth. Stripping of planetary crusts during accretion can lead to

  11. Coherent collisional spin dynamics in optical lattices.

    Science.gov (United States)

    Widera, Artur; Gerbier, Fabrice; Fölling, Simon; Gericke, Tatjana; Mandel, Olaf; Bloch, Immanuel

    2005-11-04

    We report on the observation of coherent, purely collisionally driven spin dynamics of neutral atoms in an optical lattice. For high lattice depths, atom pairs confined to the same lattice site show weakly damped Rabi-type oscillations between two-particle Zeeman states of equal magnetization, induced by spin-changing collisions. Moreover, measurement of the oscillation frequency allows for precise determination of the spin-changing collisional coupling strengths, which are directly related to fundamental scattering lengths describing interatomic collisions at ultracold temperatures.

  12. Integrated accretion disk angular momentum removal and astrophysical jet acceleration mechanism

    Science.gov (United States)

    Bellan, Paul

    2015-11-01

    A model has been developed for how accretion disks discard angular momentum while powering astrophysical jets. The model depends on the extremely weak ionization of disks. This causes disk ions to be collisionally locked to adjacent disk neutrals so a clump of disk ions and neutrals has an effective cyclotron frequency αωci where α is the fractional ionization. When αωci is approximately twice the Kepler orbital frequency, conservation of canonical momentum shows that the clump spirals radially inwards producing a radially inward disk electric current as electrons cannot move radially in the disk. Upon reaching the jet radius, this current then flows axially away from the disk plane along the jet, producing a toroidal magnetic field that drives the jet. Electrons remain frozen to poloidal flux surfaces everywhere and electron motion on flux surfaces in the ideal MHD region outside the disk completes the current path. Angular momentum absorbed from accreting material in the disk by magnetic counter-torque -JrBz is transported by the electric circuit and ejected at near infinite radius in the disk plane. This is like an electric generator absorbing angular momentum and wired to a distant electric motor that emits angular momentum. Supported by USDOE/NSF Partnership in Plasma Science.

  13. Dependence of intermittent density fluctuations on collisionality in TJ-K

    Energy Technology Data Exchange (ETDEWEB)

    Reuther, Kyle; Garland, Stephen; Ramisch, Mirko [Institut fuer Grenzflaechenverfahrenstechnikund Plasmatechnologie, Universitaet Stuttgart (Germany); Manz, Peter [Physik-Department E28, Technische Universitaet Muenchen, Garching (Germany)

    2016-07-01

    Particle and heat transport losses due to edge turbulence are well known phenomena commonly seen in toroidal magnetic confinement devices. Furthermore in the scrape-off layer (SOL), turbulent density fluctuations are often observed to be intermittent and dominate particle transport to the vessel walls. In the adiabatic limit (small collisionality), of the two-field Hasegawa-Wakatani model, simulated turbulent density fluctuations are observed to couple to potential fluctuations and exhibit Gaussian behavior. However, in the hydrodynamic limit (large collisionality) the density and potential decouple. As a result, the density becomes passively advected, evolves towards the vorticity, and exhibits intermittent behavior. The relationship between collisionality and intermittency is investigated experimentally at the stellarator TJ-K. To vary the plasma collisionality, which is related to electron density and temperature, parameters such as gas type, neutral gas pressure, magnetic field, and heating power are varied. Radial profiles of plasma density, temperature, floating potential, and vorticity are recorded via a scanning 7-tip Langmuir probe array. First results are presented.

  14. Houdini for Astrophysical Visualization

    Science.gov (United States)

    Naiman, J. P.; Borkiewicz, Kalina; Christensen, A. J.

    2017-05-01

    The rapid growth in scale and complexity of both computational and observational astrophysics over the past decade necessitates efficient and intuitive methods for examining and visualizing large data sets. Here, we discuss some newly developed tools used to import and manipulate astrophysical data into the three-dimensional visual effects software, Houdini. This software is widely used by visual effects artists, but a recently implemented Python API now allows astronomers to more easily use Houdini as a visualization tool. This paper includes a description of features, workflow, and various example visualizations. The project website, www.ytini.com, is aimed at a scientific audience and contains Houdini tutorials and links to the Python script Bitbucket repository to simplify the process of importing and rendering astrophysical data.

  15. Astrophysics in a nutshell

    CERN Document Server

    Maoz, Dan

    2016-01-01

    Winner of the American Astronomical Society's Chambliss Award, Astrophysics in a Nutshell has become the text of choice in astrophysics courses for science majors at top universities in North America and beyond. In this expanded and fully updated second edition, the book gets even better, with a new chapter on extrasolar planets; a greatly expanded chapter on the interstellar medium; fully updated facts and figures on all subjects, from the observed properties of white dwarfs to the latest results from precision cosmology; and additional instructive problem sets. Throughout, the text features the same focused, concise style and emphasis on physics intuition that have made the book a favorite of students and teachers.

  16. Theoretical astrophysics an introduction

    CERN Document Server

    Bartelmann, Matthias

    2013-01-01

    A concise yet comprehensive introduction to the central theoretical concepts of modern astrophysics, presenting hydrodynamics, radiation, and stellar dynamics all in one textbook. Adopting a modular structure, the author illustrates a small number of fundamental physical methods and principles, which are sufficient to describe and understand a wide range of seemingly very diverse astrophysical phenomena and processes. For example, the formulae that define the macroscopic behavior of stellar systems are all derived in the same way from the microscopic distribution function. This function it

  17. Multiscale Modeling of Astrophysical Jets

    Directory of Open Access Journals (Sweden)

    James H. Beall

    2014-12-01

    Full Text Available We are developing the capability for a multi-scale code to model the energy deposition rate and momentum transfer rate of an astrophysical jet which generates strong plasma turbulence in its interaction with the ambient medium through which it propagates. We start with a highly parallelized version of the VH-1 Hydrodynamics Code (Coella and Wood 1984, and Saxton et al., 2005. We are also considering the PLUTO code (Mignone et al. 2007 to model the jet in the magnetohydrodynamic (MHD and relativistic, magnetohydrodynamic (RMHD regimes. Particle-in-Cell approaches are also being used to benchmark a wave-population models of the two-stream instability and associated plasma processes in order to determine energy deposition and momentum transfer rates for these modes of jet-ambient medium interactions. We show some elements of the modeling of these jets in this paper, including energy loss and heating via plasma processes, and large scale hydrodynamic and relativistic hydrodynamic simulations. A preliminary simulation of a jet from the galactic center region is used to lend credence to the jet as the source of the so-called the Fermi Bubble (see, e.g., Su, M. & Finkbeiner, D. P., 2012*It is with great sorrow that we acknowledge the loss of our colleague and friend of more than thirty years, Dr. John Ural Guillory, to his battle with cancer.

  18. Color-charged Quark Matter in Astrophysics?

    OpenAIRE

    Qiu, Congxin; Xu, Renxin

    2006-01-01

    Color confinement is only a supposition, which has not been proved in QCD yet. It is proposed here that macroscopic quark gluon plasma in astrophysics could hardly maintain colorless because of causality. The authors expected that the existence of chromatic strange quark stars as well as chromatic strangelets preserved from the QCD phase transition in the early universe could be unavoidable if their colorless correspondents do exist.

  19. Non-resonant Particle Heating due to Collisional Separatrix Crossings

    Science.gov (United States)

    Driscoll, C. Fred; Anderegg, F.; Affolter, M.; Dubin, D. H. E.

    2015-11-01

    We observe plasma heating when a pure ion column is ``sloshed'' back and forth across a trapping separatrix, with heating rate larger than expected from simple collisional viscosity. Here, an externally applied theta-symmetric ``squeeze'' potential creates a velocity separatrix between trapped and passing particles, and weak collisions at rate νc cause separatrix crossings. The trapped particles are repeatedly compressed and expanded (by δL at rate fsl) whereas the passing particles counter-stream and Debye shield the resultant potential variations. LIF diagnostics clearly show the separatrix energy Esep (r) , in close agreement with (r , z) Boltmann-Poisson equilibrium calculations. With νc Science Foundation Grant PHY-1414570, Department of Energy Grants DE-SC0002451.

  20. Experimental evidence of resonant energy collisional transfers between argon 1s and 2p states and ground state H atoms by laser collisional induced fluorescence

    Science.gov (United States)

    Carbone, Emile; van Dijk, Jan; Kroesen, Gerrit

    2015-04-01

    In this paper, laser collisional induced fluorescence (LCIF) is used to probe resonant excitation transfers in an argon/hydrogen plasma resulting from heavy particle collisions. Different radiative transitions between the 1s and 2p states (in Paschen's notation) of argon are optically pumped by a nanosecond laser pulse. The spontaneous fluorescence and collisional responses of the argon and hydrogen systems are monitored by optical emission spectroscopy. A surfatron plasma source is used to generate an argon plasma with a few per cent hydrogen addition at pressures between 0.65 and 20 mbar. The electron density is measured independently by means of Thomson scattering. The overall response of the plasma due to optical pumping of argon is briefly discussed and an overview of the known heteronuclear excitation transfers in an argon/hydrogen plasma is given. The propagation of the shortcut in the Ar(1s) to H(n = 2) excitation transfer due to the optical pumping of the Ar(1s) states is seen in the atomic hydrogen LCIF responses. For the first time, we give direct experimental evidence of the existence of an efficient excitation transfer: Additionally, measurements are performed in order to estimate the resonant energy transfer between the resonant argon 1s states and hydrogen atoms: for which no previously measured cross sections could be found in the literature. These are extra quenching channels of argon 1s and 2p states that should be included in collisional-radiative modeling of argon-hydrogen discharges. The high repetition rate of the dye laser allows us to obtain a high sensitivity in the measurements. LCIF is shown to be a powerful tool for unraveling electron and also heavy particle excitation channels in situ in the plasma phase. The technique was previously developed for measuring electron or species densities locally in the plasma, but we show that it can be advantageously used to probe collisional transfers between very short-lived species which exist

  1. The NASA Astrophysics Program

    Science.gov (United States)

    Zebulum, Ricardo S.

    2011-01-01

    NASA's scientists are enjoying unprecedented access to astronomy data from space, both from missions launched and operated only by NASA, as well as missions led by other space agencies to which NASA contributed instruments or technology. This paper describes the NASA astrophysics program for the next decade, including NASA's response to the ASTRO2010 Decadal Survey.

  2. Astrophysics: An Integrative Course

    Science.gov (United States)

    Gutsche, Graham D.

    1975-01-01

    Describes a one semester course in introductory stellar astrophysics at the advanced undergraduate level. The course aims to integrate all previously learned physics by applying it to the study of stars. After a brief introductory section on basic astronomical measurements, the main topics covered are stellar atmospheres, stellar structure, and…

  3. Dissipation of ionospheric irregularities by wave-particle and collisional interactions

    Science.gov (United States)

    Bernhardt, P. A.; Pongratz, M. B.; Gray, S. P.; Thomsen, M. F.

    1982-01-01

    The nonlinear dissipation of plasma irregularities aligned parallel to an ambient magnetic field is studied numerically using a model which employs both wave-particle and collisional diffusion. A wave-particle diffusion coefficient derived from a local theory of the universal drift instability is used. This coefficient is effective in regions of nonzero plasma gradients and produces triangular-shaped irregularities with spectra which vary as f to the -4th, where f is the spatial frequency. Collisional diffusion acts rapidly on the vertices of the irregularities to reduce their amplitude. The simultaneous action of the two dissipative processes is more efficient than collisions acting alone. In this model, wave-particle diffusion mimics the forward cascade process of wave-wave coupling.

  4. Collisional and collisionless expansion of Yukawa balls.

    Science.gov (United States)

    Piel, Alexander; Goree, John A

    2013-12-01

    The expansion of Yukawa balls is studied by means of molecular dynamics simulations of collisionless and collisional situations. High computation speed was achieved by using the parallel computing power of graphics processing units. When the radius of the Yukawa ball is large compared to the shielding length, the expansion process starts with the blow-off of the outermost layer. A rarefactive wave subsequently propagates radially inward at the speed of longitudinal phonons. This mechanism is fundamentally different from Coulomb explosions, which employ a self-similar expansion of the entire system. In the collisionless limit, the outer layers carry away most of the available energy. The simulations are compared with analytical estimates. In the collisional case, the expansion process can be described by a nonlinear diffusion equation that is a special case of the porous medium equation.

  5. On pressure balance in a low collisionality tokamak scrape-off layer

    Science.gov (United States)

    Churchill, R. M.; Chang, C. S.; Hager, R.

    2017-10-01

    Understanding the physics governing the scrape-off layer is necessary in order to reliably predict machine and operation critical quantities, such as the heat flux width at the divertor, plasma-wall interaction, material migration, effect of divertor condition on the pedestal profile, detachment of the divertor plasma, etc. Recent simulation results using the axisymmetric gyrokinetic code XGCa suggest that in a lower ion collisionality near scrape-off layer, where the plasma is highly non-Maxwellian, the fluid form of the momentum equation is not conserved between the low-field side (LFS) midplane and divertor. Taking care to include neutral friction and a Chew-Goldberger-Low (CGL) form of the pressure tensor (i.e. only the dominant diagonal terms) does not resolve the imbalance. Using the full kinetic distribution function in the XGC gyrokinetic code, we explore the effect of off-diagonal pressure tensor terms, to determine their effect in the momentum balance in the scrape-off layer. We also explore other simulations with higher ion collisionality, to begin to study the effect of ion collisionality versus proximity to the separatrix (flux surfaces closer to the separatrix can be more influenced by e.g. X-point loss).

  6. Allen's astrophysical quantities

    CERN Document Server

    2000-01-01

    This new, fourth, edition of Allen's classic Astrophysical Quantities belongs on every astronomer's bookshelf. It has been thoroughly revised and brought up to date by a team of more than ninety internationally renowned astronomers and astrophysicists. While it follows the basic format of the original, this indispensable reference has grown to more than twice the size of the earlier editions to accommodate the great strides made in astronomy and astrophysics. It includes detailed tables of the most recent data on: - General constants and units - Atoms, molecules, and spectra - Observational astronomy at all wavelengths from radio to gamma-rays, and neutrinos - Planetary astronomy: Earth, planets and satellites, and solar system small bodies - The Sun, normal stars, and stars with special characteristics - Stellar populations - Cataclysmic and symbiotic variables, supernovae - Theoretical stellar evolution - Circumstellar and interstellar material - Star clusters, galaxies, quasars, and active galactic nuclei ...

  7. High Time Resolution Astrophysics

    CERN Document Server

    Phelan, Don; Shearer, Andrew

    2008-01-01

    High Time Resolution Astrophysics (HTRA) is an important new window to the universe and a vital tool in understanding a range of phenomena from diverse objects and radiative processes. This importance is demonstrated in this volume with the description of a number of topics in astrophysics, including quantum optics, cataclysmic variables, pulsars, X-ray binaries and stellar pulsations to name a few. Underlining this science foundation, technological developments in both instrumentation and detectors are described. These instruments and detectors combined cover a wide range of timescales and can measure fluxes, spectra and polarisation. These advances make it possible for HTRA to make a big contribution to our understanding of the Universe in the next decade.

  8. Microphysics of Astrophysical Flames

    Science.gov (United States)

    Dursi, L. J.; Zingale, M.; Caceres, A.; Calder, A. C.; Timmes, F. X.; Truran, J. W.; Rosner, R.; Lamb, D. Q.; Brown, E.; Ricker, P.; Fryxell, B.; Olson, K.; Riley, K.; Siegel, A.; Vladimirova, N.

    2003-03-01

    Type Ia supernovae are thought to begin with a deflagration phase, where burning occurs as a subsonic flame which accelerates and possibly undergoes a transition to a supersonic detonation. Both the acceleration and possible transition will depend on the microphysics of astrophysical flames, and their interaction with a turbulent flow in degenerate material. Here we present recent progress in studying the interactions of astrophysical flames and curvature and strain at the FLASH center; in particular, we discuss quantitative measurements of the effects of strain on burning rate of these flames, and implications for instability growth and quenching. This work was supported by the DOE ASCI/Alliances program at the University of Chicago under grant No. B341495 and the Scientific through Advanced Computing (SciDAC) program of the DOE, grant number DE-FC02-01ER41176 to the Supernova Science Center/UCSC.

  9. Astrophysical black holes

    CERN Document Server

    Gorini, Vittorio; Moschella, Ugo; Treves, Aldo; Colpi, Monica

    2016-01-01

    Based on graduate school lectures in contemporary relativity and gravitational physics, this book gives a complete and unified picture of the present status of theoretical and observational properties of astrophysical black holes. The chapters are written by internationally recognized specialists. They cover general theoretical aspects of black hole astrophysics, the theory of accretion and ejection of gas and jets, stellar-sized black holes observed in the Milky Way, the formation and evolution of supermassive black holes in galactic centers and quasars as well as their influence on the dynamics in galactic nuclei. The final chapter addresses analytical relativity of black holes supporting theoretical understanding of the coalescence of black holes as well as being of great relevance in identifying gravitational wave signals. With its introductory chapters the book is aimed at advanced graduate and post-graduate students, but it will also be useful for specialists.

  10. Astrophysics a new approach

    CERN Document Server

    Kundt, Wolfgang

    2005-01-01

    For a quantitative understanding of the physics of the universe - from the solar system through the milky way to clusters of galaxies all the way to cosmology - these edited lecture notes are perhaps among the most concise and also among the most critical ones: Astrophysics has not yet stood the redundancy test of laboratory physics, hence should be wary of early interpretations. Special chapters are devoted to magnetic and radiation processes, supernovae, disks, black-hole candidacy, bipolar flows, cosmic rays, gamma-ray bursts, image distortions, and special sources. At the same time, planet earth is viewed as the arena for life, with plants and animals having evolved to homo sapiens during cosmic time. -- This text is unique in covering the basic qualitative and quantitative tools, formulae as well as numbers, needed for the precise interpretation of frontline phenomena in astrophysical research. The author compares mainstream interpretations with new and even controversial ones he wishes to emphasize. The...

  11. Nuclear astrophysics at DRAGON

    Energy Technology Data Exchange (ETDEWEB)

    Hager, U. [Colorado School of Mines, Golden, Colorado (United States)

    2014-05-02

    The DRAGON recoil separator is located at the ISAC facility at TRIUMF, Vancouver. It is designed to measure radiative alpha and proton capture reactions of astrophysical importance. Over the last years, the DRAGON collaboration has measured several reactions using both radioactive and high-intensity stable beams. For example, the 160(a, g) cross section was recently measured. The reaction plays a role in steady-state helium burning in massive stars, where it follows the 12C(a, g) reaction. At astrophysically relevant energies, the reaction proceeds exclusively via direct capture, resulting in a low rate. In this measurement, the unique capabilities of DRAGON enabled determination not only of the total reaction rates, but also of decay branching ratios. In addition, results from other recent measurements will be presented.

  12. Influence of collisional rate coefficients on water vapour excitation

    Science.gov (United States)

    Daniel, F.; Goicoechea, J. R.; Cernicharo, J.; Dubernet, M.-L.; Faure, A.

    2012-11-01

    Context. Water is a key molecule in many astrophysical studies that deal with star or planet forming regions, evolved stars, and galaxies. Its high dipole moment makes this molecule subthermally populated under the typical conditions of most astrophysical objects. This motivated calculation of various sets of collisional rate coefficients (CRC) for H2O (with He or H2), which are needed to model its rotational excitation and line emission. Aims: The most accurate set of CRC are the quantum rates that involve H2. However, they have been published only recently, and less accurate CRC (quantum with He or quantum classical trajectory (QCT) with H2) were used in many studies before that. This work aims to underline the impact that the new available set of CRC have on interpretations of water vapour observations. Methods: We performed accurate non-local, non-LTE radiative transfer calculations using different sets of CRC to predict the line intensities from transitions that involve the lowest energy levels of H2O (E find that the intensities based on the quantum and QCT CRC are in good agreement. However, at relatively low H2 volume density (n(H2) find differences in the predicted line intensities of up to a factor of ~3 for the bulk of the lines. Most of the recent studies interpreting early Herschel Space Observatory spectra have used the QCT CRC. Our results show that, although the global conclusions from those studies will not be drastically changed, each case has to be considered individually, since depending on the physical conditions, the use of the QCT CRC may lead to a mis-estimate of the water vapour abundance of up to a factor of ~3. Additionally, the comparison of the quantum state-to-state and thermalised CRC, including the description of the population of the H2 rotational levels, show that above TK ~ 100 K, large differences are expected from those two sets for the p-H2 symmetry. Finally, we find that at low temperature (i.e. TK < 100 K) modelled line

  13. Collisional-Radiative Model for the visible spectrum of $W^{26+}$ ions

    CERN Document Server

    Ding, Xiaobin; Koike, Fumihiro; Murakami, Izumi; Kato, Daiji; Sakaue, Hiroyuki A; Nakamura, Nobuyuki; Dong, Chenzhong

    2015-01-01

    Plasma diagnostics in magnetic confinement fusion plasmas by using visible spectrum strongly depends on the knowledge of fundamental atomic properties. A detailed collisional-radiative model of W$^{26+}$ ions has been constructed by considering radiative and electron excitation processes, in which the necessary atomic data had been calculated by relativistic configuration interaction method with the implementation of Flexible Atomic Code. The visible spectrum observed at an electron beam ion trap (EBIT) in Shanghai in the range of 332 nm to 392 nm was reproduced by present calculations. Some transition pairs of which the intensity ratio are sensitive to the electron density were selected as potential candidate of plasma diagnostics. Their electron density dependence are theoretically evaluated for the cases of EBIT plasmas and magnetic confinement fusion plasmas.

  14. Collisional-radiative model for the visible spectrum of W{sup 26+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Xiaobin, E-mail: dingxb@nwnu.edu.cn [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Liu, Jiaxin [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Koike, Fumihiro [Department of Physics, Sophia University, Tokyo, 102-8554 (Japan); Murakami, Izumi; Kato, Daiji; Sakaue, Hiroyuki A. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Nakamura, Nobuyuki [Institute for Laser Science, The University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan); Dong, Chenzhong [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2016-02-22

    Plasma diagnostics in magnetic confinement fusion plasmas by using visible spectrum strongly depends on the knowledge of fundamental atomic properties. A detailed collisional-radiative model of W{sup 26+} ions has been constructed by considering radiative and electron excitation processes, in which the necessary atomic data had been calculated by relativistic configuration interaction method with the implementation of Flexible Atomic Code. The visible spectrum observed at an electron beam ion trap (EBIT) in Shanghai in the range of 332 nm to 392 nm was reproduced by present calculations. Some transition pairs of which the intensity ratio is sensitive to the electron density were selected as potential candidates of plasma diagnostics. Their electron density dependence is theoretically evaluated for the cases of EBIT plasmas and magnetic confinement fusion plasmas.

  15. Collisional-Radiative Modeling of Tungsten at Temperatures of 1200–2400 eV

    Directory of Open Access Journals (Sweden)

    James Colgan

    2015-04-01

    Full Text Available We discuss new collisional-radiative modeling calculations of tungsten at moderate temperatures of 1200 to 2400 eV. Such plasma conditions are relevant to ongoing experimental work at ASDEX Upgrade and are expected to be relevant for ITER. Our calculations are made using the Los Alamos National Laboratory (LANL collisional-radiative modeling ATOMIC code. These calculations formed part of a submission to the recent NLTE-8 workshop that was held in November 2013. This series of workshops provides a forum for detailed comparison of plasma and spectral quantities from NLTE collisional-radiative modeling codes. We focus on the LANL ATOMIC calculations for tungsten that were submitted to the NLTE-8 workshop and discuss different models that were constructed to predict the tungsten emission. In particular, we discuss comparisons between semi-relativistic configuration-average and fully relativistic configuration-average calculations. We also present semi-relativistic calculations that include fine-structure detail, and discuss the difficult problem of ensuring completeness with respect to the number of configurations included in a CR calculation.

  16. General structure of quantum collisional models

    Science.gov (United States)

    Vacchini, Bassano

    2014-04-01

    We point to the connection between a recently introduced class of non-Markovian master equations and the general structure of quantum collisional models. The basic construction relies on three basic ingredients: a collection of time dependent completely positive maps, a completely positive trace preserving transformation and a waiting time distribution characterizing a renewal process. The relationship between this construction and a Lindblad dynamics is clarified by expressing the solution of a Lindblad master equation in terms of demixtures over different stochastic trajectories for the statistical operator weighted by suitable probabilities on the trajectory space.

  17. Plasma astrophysics: Acceleration of killer electrons

    OpenAIRE

    Horne, Richard Bertram

    2007-01-01

    Relativistic electrons in the outer Van Allen belt wreak havoc with satellites in geosynchronous orbit, but how they reach such high energies has been unclear. New data identify gyro-resonant wave-particle interactions as the culprit.

  18. Inverse Bremsstrahlung in Astrophysical Plasmas: The Absorption ...

    Indian Academy of Sciences (India)

    (λ, T ; Ne,Ni) = k q.c. i.b.. (λ, T ; Ne,Ni) · Gi.b.(λ, T ),. (2) where Gi.b.(λ, T ) is the sought Gaunt factor. The determination of such averaged. Gaunt factor as a function of λ and T was the object of investigation in majority of the previous papers devoted to the inverse Bremsstrahlung process. This is illustrated in Figure 1, where ...

  19. Transient Astrophysics Probe

    Science.gov (United States)

    Camp, Jordan

    2017-08-01

    Transient Astrophysics Probe (TAP), selected by NASA for a funded Concept Study, is a wide-field high-energy transient mission proposed for flight starting in the late 2020s. TAP’s main science goals, called out as Frontier Discovery areas in the 2010 Decadal Survey, are time-domain astrophysics and counterparts of gravitational wave (GW) detections. The mission instruments include unique imaging soft X-ray optics that allow ~500 deg2 FoV in each of four separate modules; a high sensitivity, 1 deg2 FoV soft X-ray telescope based on single crystal silicon optics; a passively cooled, 1 deg2 FoV Infrared telescope with bandpass 0.6-3 micron; and a set of ~8 small NaI gamma-ray detectors. TAP will observe many events per year of X-ray transients related to compact objects, including tidal disruptions of stars, supernova shock breakouts, neutron star bursts and superbursts, and high redshift Gamma-Ray Bursts. Perhaps most exciting is TAP’s capability to observe X-ray and IR counterparts of GWs involving stellar mass black holes detected by LIGO/Virgo, and possibly X-ray counterparts of GWs from supermassive black holes, detected by LISA and Pulsar Timing Arrays.

  20. Parallel Transport with Sheath and Collisional Effects in Global Electrostatic Turbulent Transport in FRCs

    Science.gov (United States)

    Bao, Jian; Lau, Calvin; Kuley, Animesh; Lin, Zhihong; Fulton, Daniel; Tajima, Toshiki; Tri Alpha Energy, Inc. Team

    2017-10-01

    Collisional and turbulent transport in a field reversed configuration (FRC) is studied in global particle simulation by using GTC (gyrokinetic toroidal code). The global FRC geometry is incorporated in GTC by using a field-aligned mesh in cylindrical coordinates, which enables global simulation coupling core and scrape-off layer (SOL) across the separatrix. Furthermore, fully kinetic ions are implemented in GTC to treat magnetic-null point in FRC core. Both global simulation coupling core and SOL regions and independent SOL region simulation have been carried out to study turbulence. In this work, the ``logical sheath boundary condition'' is implemented to study parallel transport in the SOL. This method helps to relax time and spatial steps without resolving electron plasma frequency and Debye length, which enables turbulent transports simulation with sheath effects. We will study collisional and turbulent SOL parallel transport with mirror geometry and sheath boundary condition in C2-W divertor.

  1. Current Perspectives in High Energy Astrophysics

    Science.gov (United States)

    Ormes, Jonathan F. (Editor)

    1996-01-01

    High energy astrophysics is a space-age discipline that has taken a quantum leap forward in the 1990s. The observables are photons and particles that are unable to penetrate the atmosphere and can only be observed from space or very high altitude balloons. The lectures presented as chapters of this book are based on the results from the Compton Gamma-Ray Observatory (CGRO) and Advanced Satellite for Cosmology and Astrophysics (ASCA) missions to which the Laboratory for High Energy Astrophysics at NASA's Goddard Space Flight Center made significant hardware contributions. These missions study emissions from very hot plasmas, nuclear processes, and high energy particle interactions in space. Results to be discussed include gamma-ray beaming from active galactic nuclei (AGN), gamma-ray emission from pulsars, radioactive elements in the interstellar medium, X-ray emission from clusters of galaxies, and the progress being made to unravel the gamma-ray burst mystery. The recently launched X-ray Timing Explorer (XTE) and prospects for upcoming Astro-E and Advanced X-ray Astronomy Satellite (AXAF) missions are also discussed.

  2. Results from colliding magnetized plasma jet experiments executed at the Trident laser facility

    Science.gov (United States)

    Manuel, M. J.-E.; Rasmus, A. M.; Kurnaz, C. C.; Klein, S. R.; Davis, J. S.; Drake, R. P.; Montgomery, D. S.; Hsu, S. C.; Adams, C. S.; Pollock, B. B.

    2015-11-01

    The interaction of high-velocity plasma flows in a background magnetic field has applications in pulsed-power and fusion schemes, as well as astrophysical environments, such as accretion systems and stellar mass ejections into the magnetosphere. Experiments recently executed at the Trident Laser Facility at the Los Alamos National Laboratory investigated the effects of an expanding aluminum plasma flow into a uniform 4.5-Tesla magnetic field created using a solenoid designed and manufactured at the University of Michigan. Opposing-target experiments demonstrate interesting collisional behavior between the two magnetized flows. Preliminary interferometry and Faraday rotation measurements will be presented and discussed. This work is funded by the U.S Department of Energy, through the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0001840. Support for this work was provided by NASA through Einstein Postdoctoral Fellowship grant number PF3-140111 awarded by the Chandra X-ray Center, which is operated by the Astrophysical Observatory for NASA under contract NAS8-03060.

  3. Diffusion and transport phenomena in a collisional magnetoplasma ...

    Indian Academy of Sciences (India)

    Abstract. Boltzmann-transport equation is analytically solved for two-component mag- netoplasma using Chapman–Enskog analysis to include collisional diffusion transport hav- ing anisotropies in both streaming velocity and temperature components. The modified collisional integrals are analytically solved with flux ...

  4. Diffusion and transport phenomena in a collisional magnetoplasma ...

    Indian Academy of Sciences (India)

    Boltzmann-transport equation is analytically solved for two-component magnetoplasma using Chapman-Enskog analysis to include collisional diffusion transport having anisotropies in both streaming velocity and temperature components. The modified collisional integrals are analytically solved with flux integrals and ...

  5. Radiation processes in astrophysics

    CERN Document Server

    Tucker, Wallace H

    1975-01-01

    The purpose of this book is twofold: to provide a brief, simple introduction to the theory of radiation and its application in astrophysics and to serve as a reference manual for researchers. The first part of the book consists of a discussion of the basic formulas and concepts that underlie the classical and quantum descriptions of radiation processes. The rest of the book is concerned with applications. The spirit of the discussion is to present simple derivations that will provide some insight into the basic physics involved and then to state the exact results in a form useful for applications. The reader is referred to the original literature and to reviews for rigorous derivations.The wide range of topics covered is illustrated by the following table of contents: Basic Formulas for Classical Radiation Processes; Basic Formulas for Quantum Radiation Processes; Cyclotron and Synchrotron Radiation; Electron Scattering; Bremsstrahlung and Collision Losses; Radiative Recombination; The Photoelectric Effect; a...

  6. Stellar Astrophysics with Arcus

    Science.gov (United States)

    Brickhouse, Nancy S.; Huenemoerder, David P.; Wolk, Scott; Schulz, Norbert; Foster, Adam; Brenneman, Laura; Poppenhaeger, Katja; Arcus Team

    2018-01-01

    The Arcus mission is now in Phase A of the NASA Medium-Class Explorer competition. We present here the Arcus science case for stellar astrophysics. With spectral resolving power of at least 2500 and effective area greater than 400 cm^2, Arcus will measure new diagnostic lines, e.g. for H- and He-like ions of oxygen and other elements. Weak dielectronic recombination lines will provide sensitive measurements of temperature to test stellar coronal heating models. Arcus will also resolve the coronal and accretion line components in young accreting stars, allowing detailed studies of accretion shocks and their post-shock behavior. Arcus can resolve line shapes and variability in hot star winds to study inhomogeneities and dynamics of wind structure. Such profiles will provide an independent measure of mass loss rates, for which theoretical and observational discrepancies can reach an order of magnitude. Arcus will also study exoplanet atmospheres through X-ray absorption, determing their extent and composition.

  7. Numerical relativity beyond astrophysics

    Science.gov (United States)

    Garfinkle, David

    2017-01-01

    Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology. (ii) investigations of critical behavior at the threshold of black hole formation in gravitational collapse. (iii) investigations inspired by string theory, in particular analogs of black holes in more than 4 spacetime dimensions and gravitational collapse in spacetimes with a negative cosmological constant.

  8. Black-hole astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Bender, P. [Univ. of Colorado, Boulder, CO (United States); Bloom, E. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Cominsky, L. [Sonoma State Univ., Rohnert Park, CA (United States). Dept. of Physics and Astronomy] [and others

    1995-07-01

    Black-hole astrophysics is not just the investigation of yet another, even if extremely remarkable type of celestial body, but a test of the correctness of the understanding of the very properties of space and time in very strong gravitational fields. Physicists` excitement at this new prospect for testing theories of fundamental processes is matched by that of astronomers at the possibility to discover and study a new and dramatically different kind of astronomical object. Here the authors review the currently known ways that black holes can be identified by their effects on their neighborhood--since, of course, the hole itself does not yield any direct evidence of its existence or information about its properties. The two most important empirical considerations are determination of masses, or lower limits thereof, of unseen companions in binary star systems, and measurement of luminosity fluctuations on very short time scales.

  9. Numerical relativity beyond astrophysics.

    Science.gov (United States)

    Garfinkle, David

    2017-01-01

    Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology. (ii) investigations of critical behavior at the threshold of black hole formation in gravitational collapse. (iii) investigations inspired by string theory, in particular analogs of black holes in more than 4 spacetime dimensions and gravitational collapse in spacetimes with a negative cosmological constant.

  10. High energy astrophysical techniques

    CERN Document Server

    Poggiani, Rosa

    2017-01-01

    This textbook presents ultraviolet and X-ray astronomy, gamma-ray astronomy, cosmic ray astronomy, neutrino astronomy, and gravitational wave astronomy as distinct research areas, focusing on the astrophysics targets and the requirements with respect to instrumentation and observation methods. The purpose of the book is to bridge the gap between the reference books and the specialized literature. For each type of astronomy, the discussion proceeds from the orders of magnitude for observable quantities. The physical principles of photon and particle detectors are then addressed, and the specific telescopes and combinations of detectors, presented. Finally the instruments and their limits are discussed with a view to assisting readers in the planning and execution of observations. Astronomical observations with high-energy photons and particles represent the newest additions to multimessenger astronomy and this book will be of value to all with an interest in the field.

  11. Exotic nuclei and astrophysics

    Directory of Open Access Journals (Sweden)

    Penionzhkevich Yu.

    2012-12-01

    Full Text Available In recent years, nuclear physics investigations of the laws of the microscopic world contributed significantly to extension of our knowledge of phenomena occurring in the macroscopic world (Universe and made a formidable contribution to the development of astrophysical and cosmological theories. First of all, this concerns the expanding universe model, the evolution of stars, and the abundances of elements, as well as the properties of various stars and cosmic objects, including “cold” and neutron stars, black holes, and pulsars. Without claiming to give a full account of all cosmological problems, we will dwell upon those of them that, in my opinion, have much in common with nuclear-matter properties manifesting themselves in nuclear interactions.

  12. Astrophysics Faces the Millennium

    Science.gov (United States)

    Trimble, Virginia

    2001-03-01

    The Medieval synthesis of Aristotelian philosophy and church doctrine, due largely to Thomas Aquinas, insisted that the universe outside the earth's atmosphere must be immutable, single-centered, fully inventoried, immaculate or perfect, including perfectly spherical, and much else that sounds strange to modern ears. The beginnings of modern astronomy can be largely described as the overthrow of these various concepts by a combination of new technologies and new ways of thinking, and many current questions in astrophysics can be directly tied to developments of those same concepts. Indeed they probably all can be, but not over time, ending with questions like: Do other stars have spots? What does it mean when quasar jets look like they are moving faster than the speed of light? Is there anything special about our star, our galaxy, our planet, or our universe? How did these all form, and what is their long-term fate?

  13. Theoretical Particle Astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Kamionkowski, Marc [Johns Hopkins Univ., Baltimore, MD (United States)

    2013-08-07

    Abstract: Theoretical Particle Astrophysics. The research carried out under this grant encompassed work on the early Universe, dark matter, and dark energy. We developed CMB probes for primordial baryon inhomogeneities, primordial non-Gaussianity, cosmic birefringence, gravitational lensing by density perturbations and gravitational waves, and departures from statistical isotropy. We studied the detectability of wiggles in the inflation potential in string-inspired inflation models. We studied novel dark-matter candidates and their phenomenology. This work helped advance the DoE's Cosmic Frontier (and also Energy and Intensity Frontiers) by finding synergies between a variety of different experimental efforts, by developing new searches, science targets, and analyses for existing/forthcoming experiments, and by generating ideas for new next-generation experiments.

  14. Magnetic field production via the Weibel instability in interpenetrating plasma flows

    Science.gov (United States)

    Huntington, C. M.; Manuel, M. J.-E.; Ross, J. S.; Wilks, S. C.; Fiuza, F.; Rinderknecht, H. G.; Park, H.-S.; Gregori, G.; Higginson, D. P.; Park, J.; Pollock, B. B.; Remington, B. A.; Ryutov, D. D.; Ruyer, C.; Sakawa, Y.; Sio, H.; Spitkovsky, A.; Swadling, G. F.; Takabe, H.; Zylstra, A. B.

    2017-04-01

    Many astrophysical systems are effectively "collisionless," that is, the mean free path for collisions between particles is much longer than the size of the system. The absence of particle collisions does not preclude shock formation, however, as shocks can be the result of plasma instabilities that generate and amplify electromagnetic fields. The magnetic fields required for shock formation may either be initially present, for example, in supernova remnants or young galaxies, or they may be self-generated in systems such as gamma-ray bursts (GRBs). In the case of GRB outflows, the Weibel instability is a candidate mechanism for the generation of sufficiently strong magnetic fields to produce shocks. In experiments on the OMEGA Laser, we have demonstrated a quasi-collisionless system that is optimized for the study of the non-linear phase of Weibel instability growth. Using a proton probe to directly image electromagnetic fields, we measure Weibel-generated magnetic fields that grow in opposing, initially unmagnetized plasma flows. The collisionality of the system is determined from coherent Thomson scattering measurements, and the data are compared to similar measurements of a fully collisionless system. The strong, persistent Weibel growth observed here serves as a diagnostic for exploring large-scale magnetic field amplification and the microphysics present in the collisional-collisionless transition.

  15. Colloidal Plasmas: Dynamo transformation of the collisional RT in a ...

    Indian Academy of Sciences (India)

    mechanical nature was first time reported by Dwivedi and Das in 1992 in the context of mesospheric modeling of observed neutral induced turbulence. Local dynamo action (due to relative neutral flow) governs the basic physical principle for linear ...

  16. Collisional Thermalization in Strongly Coupled Ultracold Neutral Plasmas

    Science.gov (United States)

    2017-01-25

    White Dwarf Stars," Keynote address at the Joint Spring 2016 Meeting of the Texas Sections of APS, AAPT, and Zone 13 of the SPS, Lamar University... White Dwarf Stars," Physics Department Colloquium, Union College, Schenectady, NY (11/16). ``Studying Collisions and Transport in Strongly

  17. Hydrodynamic Models for Multicomponent Plasmas with Collisional-Radiative Kinetics

    Science.gov (United States)

    2014-12-01

    thermal velocity xxii Zs charge number of specie s Z partition function Greek Characters σ electric conductivity βe Hall parameter ǫ0 permittivity of...al. [126], the fuel is first compressed by a low intensity laser, and then quickly ignited with a petawatt laser. The incidence of the petawatt laser...into the capsule and heat the compressed fuel . In this scenario, the electrons can be decomposed into two populations: cold and hot (superthermal

  18. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Home; Journals; Journal of Astrophysics and Astronomy; Volume 36; Issue 1. Issue front cover thumbnail. Volume 36, Issue 1. March 2015, pages a-254. Dynamical Plasma Processes in the Sun and Sun-like Stars. pp a-b. General Editorial on Publication Ethics · More Details Fulltext PDF. pp 1-3. Editorial.

  19. Collaborative Astrophysical Research in Aire

    Science.gov (United States)

    Zhou, Jianfeng

    The AIRE (Astrophysical Integrated Research Environment) consists of three main parts: a Data Archive Center (DAC) which collects and manages public astrophysical data; a web-based Data Processing Center (DPC) which enables astrophysicists to process the data in a central server at any place and anytime; and a Collaborative Astrophysical Research Project System (CARPS) with which astrophysicists in different fields can pursue a collaborative reserch efficiently. Two research examples QPO study of RXTE data and wavelet analysis of large amount of galaxies are shown here.

  20. Atoms in astrophysics

    CERN Document Server

    Eissner, W; Hummer, D; Percival, I

    1983-01-01

    It is hard to appreciate but nevertheless true that Michael John Seaton, known internationally for the enthusiasm and skill with which he pursues his research in atomic physics and astrophysics, will be sixty years old on the 16th of January 1983. To mark this occasion some of his colleagues and former students have prepared this volume. It contains articles that de­ scribe some of the topics that have attracted his attention since he first started his research work at University College London so many years ago. Seaton's association with University College London has now stretched over a period of some 37 years, first as an undergraduate student, then as a research student, and then, successively, as Assistant Lecturer, Lecturer, Reader, and Professor. Seaton arrived at University College London in 1946 to become an undergraduate in the Physics Department, having just left the Royal Air Force in which he had served as a navigator in the Pathfinder Force of Bomber Command. There are a number of stories of ho...

  1. Measurements of ion species separation in strong plasma shocks

    Science.gov (United States)

    Rinderknecht, Hans

    2017-10-01

    Shocks are important dynamic phenomena in inertial confinement fusion (ICF) and astrophysical plasmas. While the relationship between upstream and downstream plasmas far from the shock front is fully determined by conservation equations, the structure of shock fronts is determined by dynamic kinetic processes. Kinetic theory and simulations predict that the width of a strong (M >2) collisional plasma shock front is on the order of tens of ion mean-free-paths. The shock front structure plays an important role for overall dynamics when the shock front width approaches plasma scale lengths, as in the spherically converging shock in the DT-vapor in an ICF implosion. However, there has been no experimental data benchmarking shock front structure in the plasma phase. The structure of a shock front in a plasma with multiple ion species has been directly measured for the first time using a combination of Thomson scattering and proton radiography in experiments on the OMEGA laser. Thomson scattering of a 263.25 nm probe beam is used to diagnose electron density, electron and ion temperature, ion species concentration, and flow velocity in strong shocks (M 5) propagating through low-density (ρ 0.1 mg/cc) plasmas composed of H(98%) +Ne(2%). Within the shock front, velocity separation of the ion species is observed for the first time: the light species (H) accelerates to of order the shocked fluid velocity (450 microns/ns) before the heavy species (Ne) begins to move. This velocity-space separation implies that the separation of ion species occurs at the shock front, a predicted feature of shocks in multi-species plasmas but never observed experimentally until now. Comparison of experimental data with PIC, Vlasov-Fokker-Planck, and multi-component hydrodynamic simulations will be presented.

  2. An introduction to observational astrophysics

    CERN Document Server

    Gallaway, Mark

    2016-01-01

    Observational Astrophysics follows the general outline of an astrophysics undergraduate curriculum targeting practical observing information to what will be covered at the university level. This includes the basics of optics and coordinate systems to the technical details of CCD imaging, photometry, spectography and radio astronomy.  General enough to be used by students at a variety of institutions and advanced enough to be far more useful than observing guides targeted at amateurs, the author provides a comprehensive and up-to-date treatment of observational astrophysics at undergraduate level to be used with a university’s teaching telescope.  The practical approach takes the reader from basic first year techniques to those required for a final year project. Using this textbook as a resource, students can easily become conversant in the practical aspects of astrophysics in the field as opposed to the classroom.

  3. Nuclear astrophysics from direct reactions

    Energy Technology Data Exchange (ETDEWEB)

    Bertulani, C. [Department of Physics, Texas A and M University, Commerce, TX 75429 (United States)]. e-mail: carlos_bertulani@tamu-commerce.edu

    2008-12-15

    Accurate nuclear reaction rates are needed for primordial nucleosynthesis and hydrostatic burning in stars. The relevant reactions are extremely difficult to measure directly in the laboratory at the small astrophysical energies. In recent years direct reactions have been developed and applied to extract low-energy astrophysical S-factors. These methods require a combination of new experimental techniques and theoretical efforts, which are the subject of this presentation. (Author)

  4. Nuclear Data for Astrophysical Modeling

    OpenAIRE

    Pritychenko, Boris

    2016-01-01

    Nuclear physics has been playing an important role in modern astrophysics and cosmology. Since the early 1950's it has been successfully applied for the interpretation and prediction of astrophysical phenomena. Nuclear physics models helped to explain the observed elemental and isotopic abundances and star evolution and provided valuable insights on the Big Bang theory. Today, the variety of elements observed in stellar surfaces, solar system and cosmic rays, and isotope abundances are calcul...

  5. Highlights of Spanish Astrophysics VII

    Science.gov (United States)

    Guirado, J. C.; Lara, L. M.; Quilis, V.; Gorgas, J.

    2013-05-01

    "Highlights of Astronomy and Astrophysics VII" contains the Proceedings of the biannual meeting of the Spanish Astronomical Society held in Valencia from July 9 to 13, 2012. Over 300 astronomer, both national and international researchers, attended to the conference covering a wide variety of astrophysical topics: Galaxies and Cosmology, The Milky Way and Its Components, Planetary Sciences, Solar Physics, Instrumentation and Computation, and Teaching and Outreach of Astronomy.

  6. Nuclear astrophysics with radioactive beams

    CERN Document Server

    Schatz, H

    2002-01-01

    Nuclei far from stability play an important role in our understanding of astrophysical scenarios with extreme temperature and density conditions. Among these are nova explosions, accreting neutron stars, supernovae, and the site of the r-process. I will give a brief review of the important open astrophysical questions in these scenarios and discuss the radioactive beam experiments at ISOL-type and at fragmentation-type facilities that are needed to answer them.

  7. Astrophysical neutrinos and atmospheric leptons

    Directory of Open Access Journals (Sweden)

    Gaisser T.K.

    2017-01-01

    Full Text Available IceCube measurements of the neutrino flux from TeV to PeV show the signal of astrophysical neutrinos standing out at high energy well above the steeply falling foreground of atmospheric neutrinos. The astrophysical signal appears both in measurements of neutrino-induced muons and in the starting event sample, which responds preferentially to electron and tau neutrinos, but which also includes muon neutrinos. Searches for point sources of astrophysical neutrinos have, however, not yet identified a single source or class of sources for the astrophysical component. Some constraints on astrophysical sources implied by the current observations will be described in this talk. Uncertainties in the fluxes of atmospheric leptons resulting from an incomplete knowledge of the primary cosmic-ray spectrum and from a limited understanding of meson production, including charm will also be reviewed. The ultimate goal is to improve the understanding of the astrophysical spectrum in the transition to lower energy where atmospheric neutrinos dominate. The main aspects of this presentation will be included in the author's Review Talk at the end of the Symposium.

  8. Minicourses in Astrophysics, Modular Approach, Vol. I.

    Science.gov (United States)

    Illinois Univ., Chicago.

    This is the first volume of a two-volume minicourse in astrophysics. It contains chapters on the following topics: planetary atmospheres; X-ray astronomy; radio astrophysics; molecular astrophysics; and gamma-ray astrophysics. Each chapter gives much technical discussion, mathematical treatment, diagrams, and examples. References are included with…

  9. The interaction of high-power lasers with plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Eliezer, S

    2003-02-12

    This book deals with the fundamental physics of numerous plasma processes that occur during laser plasma interactions. The subject matter is related to both basic plasma physics and applied physics. The author starts with the essentials of high power lasers whose duration ranges from nanoseconds to femtoseconds, and then builds up an introduction to plasma physics by describing ionization, well known transport coefficients (electrical and thermal conductivities, diffusion, viscosity, energy transport etc), Debye length, plasma oscillations and the properties of the laser induced plasma medium. The book contains plasma dynamical equations for describing the hydrodynamic and kinetic phenomena, and treating particle dynamics by computer simulation. The ponderomotive force is discussed for small amplitude electromagnetic fields in an unmagnetized plasma. However, for intense laser beams one should obtain new expressions for the relativistic ponderomotive force, which are totally absent from this book. Furthermore, in laser plasma interactions strong magnetic fields are produced which will drastically modify the relativistic ponderomotive force expressions. The physics of collisional absorption of electromagnetic waves and their propagation in a nonuniform unmagnetized plasma has been elegantly described. The phenomena of the resonance absorption of laser light is also discussed. Simple models for the parametric processes are developed, while there are no discussions of cavitons/envelope solitons. The latter are usually regarded as possible nonlinear states of the modulational/filamentational instabilities. Rather, the author presents a description of a K-dV equation for nonlinear ion-acoustic waves without the laser field. The description of a non-envelope ion-acoustic soliton has already appeared in many plasma physics textbooks. The book contains a short chapter on the self-similar plasma expansion in vacuum, double layers, and charged particle acceleration. However

  10. Fundamental Questions in Astrophysics: Guidelines for Future UV Observatories

    CERN Document Server

    Gómez de Castro, Ana I

    2006-01-01

    Modern astrophysics is a mature science that has evolved from its early phase of discovery and classification to a physics-oriented discipline focused in finding answers to fundamental problems ranging from cosmology to the origin and diversity of life-sustainable systems in the Universe. For this very reason, progress of modern astrophysics requires the access to the electromagnetic spectrum in the broadest energy range. The Ultraviolet is a fundamental energy domain since it is one of the most powerful tool to study plasmas at temperatures in the 3,000-300,000~K range as well as electronic transitions of the most abundant molecules in the Universe. Moreover, the UV radiation field is a powerful astrochemical and photoionizing agent. This book describes the fundamental problems in modern astrophysics that cannot progress without easy and wide-spread access to modern UV instrumentation.

  11. Experimental astrophysics with high power lasers and Z pinches

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B A; Drake, R P; Ryutov, D D

    2004-12-10

    With the advent of high energy density (HED) experimental facilities, such as high-energy lasers and fast Z-pinch, pulsed-power facilities, mm-scale quantities of matter can be placed in extreme states of density, temperature, and/or velocity. This has enabled the emergence of a new class of experimental science, HED laboratory astrophysics, wherein the properties of matter and the processes that occur under extreme astrophysical conditions can be examined in the laboratory. Areas particularly suitable to this class of experimental astrophysics include the study of opacities relevant to stellar interiors; equations of state relevant to planetary interiors; strong shock driven nonlinear hydrodynamics and radiative dynamics, relevant to supernova explosions and subsequent evolution; protostellar jets and high Mach-number flows; radiatively driven molecular clouds and nonlinear photoevaporation front dynamics; and photoionized plasmas relevant to accretion disks around compact objects, such as black holes and neutron stars.

  12. The collisionality dependence of intermittency level in drift-wave turbulence in the stellarator TJ-K

    Science.gov (United States)

    Garland, S.; Reuther, K.; Ramisch, M.; Manz, P.

    2017-11-01

    The link between plasma collisionality and the intermittency of edge drift-wave turbulence is investigated experimentally in the stellarator TJ-K and compared to results obtained from slab Hasegawa-Wakatani (HW) simulations. The kurtosis of experimental time series of density and potential fluctuations was analysed at different frequency scales. Using this method on data from a range of discharges, it was found that the intermittency level increases with increasing collisionality for density fluctuations, whereas potential fluctuations are generally self-similar. In addition, a high-order structure function analysis of density time-series data also shows a trend towards higher intermittency levels as collisionality is increased. HW simulations are found to produce a qualitatively similar trend in the intermittency level compared to experimental analyses. The transition to intermittent fluctuations at higher collisionalities can be understood in the framework of the HW model as the decoupling of the density field from the self-similar potential field when moving from the adiabatic to the hydrodynamic limit, where the density behaves like a passive scalar, resulting in the intermittency levels observed in the vorticity.

  13. High energy astrophysics. An introduction

    Energy Technology Data Exchange (ETDEWEB)

    Courvoisier, Thierry J.L. [Geneva Univ., Versoix (Switzerland). ISDC, Data Centre for Astrophysics

    2013-07-01

    Based on observational examples this book reveals and explains high-energy astrophysical processes. Presents the theory of astrophysical processes in a didactic approach by deriving equations step by step. With several attractive astronomical pictures. High-energy astrophysics has unveiled a Universe very different from that only known from optical observations. It has revealed many types of objects in which typical variability timescales are as short as years, months, days, and hours (in quasars, X-ray binaries, and other objects), and even down to milli-seconds in gamma ray bursts. The sources of energy that are encountered are only very seldom nuclear fusion, and most of the time gravitation, a paradox when one thinks that gravitation is, by many orders of magnitude, the weakest of the fundamental interactions. The understanding of these objects' physical conditions and the processes revealed by high-energy astrophysics in the last decades is nowadays part of astrophysicists' culture, even of those active in other domains of astronomy. This book evolved from lectures given to master and PhD students at the University of Geneva since the early 1990s. It aims at providing astronomers and physicists intending to be active in high-energy astrophysics a broad basis on which they should be able to build the more specific knowledge they will need. While in the first part of the book the physical processes are described and derived in detail, the second part studies astrophysical objects in which high-energy astrophysics plays a crucial role. This two-pronged approach will help students recognise physical processes by their observational signatures in contexts that may differ widely from those presented here.

  14. Modification of electromagnetic fields and plasma resistance by thermal effects in helicon plasmas

    Science.gov (United States)

    Kabir, M.; Niknam, A. R.

    2017-05-01

    The effects of the thermal motion of charged particles on physical characteristics of collisional helicon plasmas are investigated. First, the dielectric permittivity tensor of a helicon plasma is obtained by considering the thermal and collisional effects in the kinetic theory. Then, the electromagnetic wave and plasma resistance equations are presented and solved in a helicon plasma source with a Nagoya type III antenna. It is shown that by increasing the temperature of plasma electrons, the effective collision frequency is increased, and consequently, the peaks of resistance profiles are lowered and broadened.

  15. A Laboratory Astrophysical Jet to Study Canonical Flux Tubes

    Energy Technology Data Exchange (ETDEWEB)

    You, Setthivoine [Univ. of Washington, Seattle, WA (United States)

    2017-12-20

    Understanding the interaction between plasma flows and magnetic fields remains a fundamental problem in plasma physics, with important applications to astrophysics, fusion energy, and advanced space propulsion. For example, flows are of primary importance in astrophysical jets even if it is not fully understood how jets become so long without becoming unstable. Theories for the origin of magnetic fields in the cosmos rely on flowing charged fluids that should generate magnetic fields, yet this remains to be demonstrated experimentally. Fusion energy reactors can be made smaller with flows that improve stability and confinement. Advanced space propulsion could be more efficient with collimated and stable plasma flows through magnetic nozzles but must eventually detach from the nozzle. In all these cases, there appears to be a spontaneous emergence of flowing and/or magnetic structures, suggesting a form of self-organization in plasmas. Beyond satisfying simple intellectual curiosity, understanding plasma self-organization could enable the development of methods to control plasma structures for fusion energy, space propulsion, and other applications. The research project has therefore built a theory and an experiment to investigate the interaction between magnetic fields and plasma flows. The theory is called canonical field theory for short, and the experiment is called Mochi after a rice cake filled with surprising, yet delicious fillings.

  16. Use of nonlocal helium microplasma for gas impurities detection by the collisional electron spectroscopy method

    Energy Technology Data Exchange (ETDEWEB)

    Kudryavtsev, Anatoly A., E-mail: akud@ak2138.spb.edu [St. Petersburg State University, 7-9 Universitetskaya nab., 199034 St. Petersburg (Russian Federation); Stefanova, Margarita S.; Pramatarov, Petko M. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria)

    2015-10-15

    The collisional electron spectroscopy (CES) method, which lays the ground for a new field for analytical detection of gas impurities at high pressures, has been verified. The CES method enables the identification of gas impurities in the collisional mode of electron movement, where the advantages of nonlocal formation of the electron energy distribution function (EEDF) are fulfilled. Important features of dc negative glow microplasma and probe method for plasma diagnostics are applied. A new microplasma gas analyzer design is proposed. Admixtures of 0.2% Ar, 0.6% Kr, 0.1% N{sub 2}, and 0.05% CO{sub 2} are used as examples of atomic and molecular impurities to prove the possibility for detecting and identifying their presence in high pressure He plasma (50–250 Torr). The identification of the particles under analysis is made from the measurements of the high energy part of the EEDF, where maxima appear, resulting from the characteristic electrons released in Penning reactions of He metastable atoms with impurity particles. Considerable progress in the development of a novel miniature gas analyzer for chemical sensing in gas phase environments has been made.

  17. Astrophysics a very short introduction

    CERN Document Server

    Binney, James

    2016-01-01

    Astrophysics is the physics of the stars, and more widely the physics of the Universe. It enables us to understand the structure and evolution of planetary systems, stars, galaxies, interstellar gas, and the cosmos as a whole. In this Very Short Introduction, the leading astrophysicist James Binney shows how the field of astrophysics has expanded rapidly in the past century, with vast quantities of data gathered by telescopes exploiting all parts of the electromagnetic spectrum, combined with the rapid advance of computing power, which has allowed increasingly effective mathematical modelling. He illustrates how the application of fundamental principles of physics - the consideration of energy and mass, and momentum - and the two pillars of relativity and quantum mechanics, has provided insights into phenomena ranging from rapidly spinning millisecond pulsars to the collision of giant spiral galaxies. This is a clear, rigorous introduction to astrophysics for those keen to cut their teeth on a conceptual trea...

  18. Hyper-Kamiokande and Astrophysics

    Science.gov (United States)

    Yano, Takatomi; Hyper-Kamiokande proto Collaboration

    2017-09-01

    Hyper-Kamiokande (Hyper-K) is a proposed next generation underground large water Cherenkov detector. Recently a new detector design of Hyper-K is presented, as the two cylindrical pure water tanks. In the new design, each detector is surrounded by 40,000 newly developed photos sensors and provids the fiducial volume of 0.187 Mt. In total, the fiducial volume will be 0.37 Mt. Hyper-K will play the important role in several sciene of the next neutrino physics frontier, even in the neutrino astrophysics. The detection with large statistics of astrophysical neutrons, i.e., solar neutrino, supernova burst neutrino and supernova relic neutrino, will be remarkable information for both of particle physics and astrophysics.

  19. Advances in astronomy and astrophysics

    CERN Document Server

    Kopal, Zdenek

    1966-01-01

    Advances in Astronomy and Astrophysics, Volume 4 brings together numerous research works on different aspects of astronomy and astrophysics. This volume is composed of five chapters, and starts with a description of objective prism and its application in space observations. The next chapter deals with the possibilities of deriving reliable models of the figure, density distribution, and gravity field of the Moon based on data obtained through Earth-bound telescopes. These topics are followed by a discussion on the ideal partially relativistic, partially degenerate gas in an exact manner. A ch

  20. Reactor neutrons in nuclear astrophysics

    Science.gov (United States)

    Reifarth, René; Glorius, Jan; Göbel, Kathrin; Heftrich, Tanja; Jentschel, Michael; Jurado, Beatriz; Käppeler, Franz; Köster, Ulli; Langer, Christoph; Litvinov, Yuri A.; Weigand, Mario

    2017-09-01

    The huge neutron fluxes offer the possibility to use research reactors to produce isotopes of interest, which can be investigated afterwards. An example is the half-lives of long-lived isotopes like 129I. A direct usage of reactor neutrons in the astrophysical energy regime is only possible, if the corresponding ions are not at rest in the laboratory frame. The combination of an ion storage ring with a reactor and a neutron guide could open the path to direct measurements of neutron-induced cross sections on short-lived radioactive isotopes in the astrophysically interesting energy regime.

  1. Advances in astronomy and astrophysics

    CERN Document Server

    Kopal, Zdenek

    1968-01-01

    Advances in Astronomy and Astrophysics, Volume 6 brings together numerous research works on different aspects of astronomy and astrophysics. This volume is composed of five chapters, and starts with the description of improved methods for analyzing and classifying families of periodic orbits in a conservative dynamical system with two degrees of freedom. The next chapter describes the variation of fractional luminosity of distorted components of close binary systems in the course of their revolution, or the accompanying changes in radial velocity. This topic is followed by discussions on vari

  2. Nuclear astrophysics lessons from INTEGRAL.

    Science.gov (United States)

    Diehl, Roland

    2013-02-01

    Measurements of high-energy photons from cosmic sources of nuclear radiation through ESA's INTEGRAL mission have advanced our knowledge: new data with high spectral resolution showed that characteristic gamma-ray lines from radioactive decays occur throughout the Galaxy in its interstellar medium. Although the number of detected sources and often the significance of the astrophysical results remain modest, conclusions derived from this unique astronomical window of radiation originating from nuclear processes are important, complementing the widely-employed atomic-line based spectroscopy. We review the results and insights obtained in the past decade from gamma-ray line measurements of cosmic sources in the context of their astrophysical questions.

  3. Advances in astronomy and astrophysics

    CERN Document Server

    Kopal, Zdenek

    1963-01-01

    Advances in Astronomy and Astrophysics, Volume 2 brings together numerous research works on different aspects of astronomy and astrophysics. This volume is composed of six chapters and begins with a summary of observational record on twilight extensions of the Venus cusps. The next chapter deals with the common and related properties of binary stars, with emphasis on the evaluation of their cataclysmic variables. Cataclysmic variables refer to an object in one of three classes: dwarf nova, nova, or supernova. These topics are followed by discussions on the eclipse phenomena and the eclipses i

  4. Advances in astronomy and astrophysics

    CERN Document Server

    Kopal, Zdenek

    1962-01-01

    Advances in Astronomy and Astrophysics, Volume 1 brings together numerous research works on different aspects of astronomy and astrophysics. This book is divided into five chapters and begins with an observational summary of the shock-wave theory of novae. The subsequent chapter provides the properties and problems of T tauri stars and related objects. These topics are followed by discussions on the structure and origin of meteorites and cosmic dust, as well as the models for evaluation of mass distribution in oblate stellar systems. The final chapter describes the methods of polarization mea

  5. Microphysics of cosmic plasmas

    CERN Document Server

    Bykov, Andrei; Cargill, Peter; Dendy, Richard; Wit, Thierry; Raymond, John

    2014-01-01

    This title presents a review of the detailed aspects of the physical processes that underlie the observed properties, structures and dynamics of cosmic plasmas. An assessment of the status of understanding of microscale processes in all astrophysical collisionless plasmas is provided. The topics discussed include  turbulence in astrophysical and solar system plasmas as a phenomenological description of their dynamic properties on all scales; observational, theoretical and modelling aspects of collisionless magnetic reconnection; the formation and dynamics of shock waves; and a review and assessment of microprocesses, such as the hierarchy of plasma instabilities, non-local and non-diffusive transport processes and ionisation and radiation processes.  In addition, some of the lessons that have been learned from the extensive existing knowledge of laboratory plasmas as applied to astrophysical problems are also covered.   This volume is aimed at graduate students and researchers active in the areas of cosmi...

  6. Background gas collisional effects on expanding fs and ns laser ablation plumes

    Science.gov (United States)

    Harilal, S. S.; Farid, N.; Freeman, J. R.; Diwakar, P. K.; LaHaye, N. L.; Hassanein, A.

    2014-10-01

    The collisional effects of a background gas on expanding ultrafast and short pulse laser ablation plumes were investigated by varying background pressure from vacuum to atmospheric pressure levels. For producing Cu ablation plumes, either 40 fs, 800 nm pulses from a Ti: Sapphire laser or 6 ns, 1,064 nm pulses from a Nd:YAG laser were used. The role of background pressure on plume hydrodynamics, spectral emission features, absolute line intensities, signal to background ratios and ablation craters was studied. Though the signal intensities were found to be maximum near to atmospheric pressure levels, the optimum signal to background ratios are observed ~20-50 Torr for both ns and fs laser ablation plumes. The differences in laser-target and laser-plasma couplings between ns and fs lasers were found to be more engraved in the crater morphologies and plasma hydrodynamic expansion features.

  7. Collisional interaction between metastable neon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Drunen, Wouter Johannes van

    2008-07-07

    In this thesis, the study of cold gases of neon atoms in different metastable states is described. It contains measurements of the collisional parameters for both the 3s[3/2]{sub 2} and the 3s'[1/2]{sub 0} metastable state and the dependence of the inelastic loss on external fields. Furthermore, the investigation of frequency dependent laser-induced collisions, and the possibility to excite photoassociation resonances is presented. For the measurements described here, neon atoms have been confined in a magnetooptical trap, in a magnetostatic trap, or in an optical dipole trap, respectively. By laser cooling inside the magnetic trap, atomic samples with more than 95 percent occupation of the magnetic substate m{sub J} = +2 could be prepared. They have a typical temperature of 0.5 mK, central densities up to 10{sup 11} cm{sup -3}, and a central phase-space density of up to 2.2.10{sup -7}. After loading the optical dipole trap from the magnetic trap, 2.5.10{sup 6} atoms with typical temperatures of 0.1 mK, and central densities up to 5.10{sup 10} cm{sup -3} were trapped. By evaporative cooling of the atoms in the magnetic trap we could increase the phase-space density by a factor of 200 to 5.10{sup -5}. Investigating the frequency dependence of laser-induced collisions did not reveal an experimental signature for the excitation of photoassociation resonances. For the {sup 3}D{sub 3} line a frequency dependence of laser enhanced Penning ionization was observed. Measurement of the two-body loss coefficient as function of the magnetic field showed a field dependence of the inelastic loss. These losses increase towards both small and large offset fields. The implementation of an optical dipole trap allowed us to trap the {sup 3}P{sub 0} metastable state. From the trap loss measurements we determined the two-body loss coefficient of the {sup 3}P{sub 0} metastable state for both bosonic isotopes {sup 20}Ne and {sup 22}Ne. For {sup 20}Ne we obtained {beta}=6{sup +5}{sub

  8. Electric Currents along Astrophysical Jets

    Directory of Open Access Journals (Sweden)

    Ioannis Contopoulos

    2017-10-01

    Full Text Available Astrophysical black holes and their surrounding accretion disks are believed to be threaded by grand design helical magnetic fields. There is strong theoretical evidence that the main driver of their winds and jets is the Lorentz force generated by these fields and their associated electric currents. Several researchers have reported direct evidence for large scale electric currents along astrophysical jets. Quite unexpectedly, their directions are not random as would have been the case if the magnetic field were generated by a magnetohydrodynamic dynamo. Instead, in all kpc-scale detections, the inferred electric currents are found to flow away from the galactic nucleus. This unexpected break of symmetry suggests that a battery mechanism is operating around the central black hole. In the present article, we summarize observational evidence for the existence of large scale electric currents and their associated grand design helical magnetic fields in kpc-scale astrophysical jets. We also present recent results of general relativistic radiation magnetohydrodynamic simulations which show the action of the Cosmic Battery in the vicinity of astrophysical black holes.

  9. Astrophysics on the Lab Bench

    Science.gov (United States)

    Hughes, Stephen W.

    2010-01-01

    In this article some basic laboratory bench experiments are described that are useful for teaching high school students some of the basic principles of stellar astrophysics. For example, in one experiment, students slam a plastic water-filled bottle down onto a bench, ejecting water towards the ceiling, illustrating the physics associated with a…

  10. Nuclear astrophysics of light nuclei

    DEFF Research Database (Denmark)

    Fynbo, Hans Otto Uldall

    2013-01-01

    A review of nuclear astrophysics of light nuclei using radioactive beams or techniques developed for radioactive beams is given. We discuss Big Bang nucleosynthesis, with special focus on the lithium problem, aspects of neutrino-physics, helium-burning and finally selected examples of studies...

  11. Electrostatic shock waves in the laboratory and astrophysics: similarities and differences

    Science.gov (United States)

    Dieckmann, M. E.; Doria, D.; Sarri, G.; Romagnani, L.; Ahmed, H.; Folini, D.; Walder, R.; Bret, A.; Borghesi, M.

    2018-01-01

    Contemporary lasers allow us to create shocks in the laboratory that propagate at a speed that matches that of energetic astrophysical shocks like those that ensheath supernova blast shells. The rapid growth time of the shocks and the spatio-temporal resolution, with which they can be sampled, allow us to identify the processes that are involved in their formation and evolution. Some laser-generated unmagnetized shocks are mediated by collective electrostatic forces and effects caused by binary collisions between particles can be neglected. Hydrodynamic models, which are valid for many large-scale astrophysical shocks, assume that collisions enforce a local thermodynamic equilibrium in the medium; laser-generated shocks are thus not always representative for astrophysical shocks. Laboratory studies of shocks can improve the understanding of their astrophysical counterparts if we can identify processes that affect electrostatic shocks and hydrodynamic shocks alike. An example is the nonlinear thin-shell instability (NTSI). We show that the NTSI destabilises collisionless and collisional shocks by the same physical mechanism.

  12. International Olympiad on Astronomy and Astrophysics

    Science.gov (United States)

    Soonthornthum, B.; Kunjaya, C.

    2011-01-01

    The International Olympiad on Astronomy and Astrophysics, an annual astronomy and astrophysics competition for high school students, is described. Examples of problems and solutions from the competition are also given. (Contains 3 figures.)

  13. A review of astrophysics experiments on intense lasers

    Science.gov (United States)

    Remington, B. A.

    1999-11-01

    Modern, high power laser facilities open new possibilities for simulating astrophysical systems in the laboratory.(S.J. Rose, Laser & Part. Beams 9, 869 (1991); B.H. Ripin et al., Laser & Part. Beams 8, 183 (1990); B.A. Remington et al., Science 284, 1488 (1999); H. Takabe et al., Plasma Phys. Contr. Fusion 41, A75 (1999); R.P. Drake, J. Geophys. Res. 104, 14505 (1999).) Scaled investigations of the hydrodynamics.(J. Kane et al., Phys. Plasmas 6, 2065 (1999); R.P. Drake et al., Ap. J. 500, L157 (1998); D. Ryutov et al., Ap. J. 518, 821 (1999).) and radiative transfer.(J. Wark et al., Phys. Plasmas 4, 2004 (1997); P.K. Patel et al., JQSRT 58, 835 (1997).) relevant to supernovae, and opacities relevant to stellar interiors.(F.J. Rogers and C.A. Iglesias, Science 263, 50 (1994); H. Merdji et al., JSQRT 58, 783 (1997).) are now possible with laser experiments. Equations of state relevant to the interiors of giant planets and brown dwarfs are also being experimentally accessed.(G.W. Collins et al., Science 281, 1178 (1998); A. Benuzzi et al., Phys. Rev. E 54, 2162 (1996).) With the construction of the NIF laser in the U.S., and the LIL and LMJ lasers in France, controlled investigations of thermonuclear burn physics will become possible in the next decade. And with existing and future ultra-high intensity short pulse lasers, investigations of relativistic astrophysical plasmas are becoming possible.(M.H. Key et al., Phys. Plasmas 5, 1966 (1998); F. Pegoraro et al., Plasma Phys. Contr. Fus. 39, B261 (1997).) A review of laboratory astrophysics experiments using intense lasers will be presented, and the potential for the future will be discussed.

  14. Nonlinear Alfvén wave dynamics in plasmas

    Science.gov (United States)

    Sarkar, Anwesa; Chakrabarti, Nikhil; Schamel, Hans

    2015-07-01

    Nonlinear Alfvén wave dynamics is presented using Lagrangian fluid approach in a compressible collisional magnetized plasma. In the framework of two fluid dynamics, finite electron inertia is shown to serve as a dispersive effect acting against the convective nonlinearity. In a moving frame, the Alfvén wave can, therefore, form an arbitrarily strong amplitude solitary wave structure due to the balance between nonlinearity and dispersion. Weak amplitude Alfvén waves are shown to be governed by a modified KdV equation, which extends for finite dissipation to a mKdV-Burgers equation. These equations have well known solutions. Next, we have analyzed the fourth order nonlinear Alfvén wave system of equations both numerically and by approximation method. The results indicate a collapse of the density and magnetic field irrespective of the presence of dispersion. The wave magnetic field, however, appears to be less singular showing collapse only when the dispersive effects are negligible. These results may contribute to our understanding of the generation of strongly localized magnetic fields (and currents) in plasmas and are expected to be of special importance in the astrophysical context of magnetic star formation.

  15. Proton collisional excitation in the lowest lying 3P terms of ions in the Be and Mg isoelectronic sequences

    Science.gov (United States)

    Landman, D. A.; Brown, T.

    1979-01-01

    Proton collisional excitation cross sections and rate constants are presented for transitions between the 3P(J) fine-structure levels of the lowest-lying sp configurations in a number of astrophysically important ions belonging to the Be and Mg isoelectronic sequences. The calculations were made by direct integration of the Schroedinger equation resulting from semiclassical Coulomb excitation theory. The cross sections and rate constants for the 3P(J) transitions in the lowest-lying P(2) configurations are expected to be similar to those for the corresponding sp configuration transitions, and this is illustrated for C III. For the high-temperature ion Ca XVII alpha particle excitation is shown to be unimportant for situations involving ordinary values of the He/H abundance ratio. A simple, but apparently accurate method for determining certain radial integrals for low-lying excited configurations is proposed.

  16. Collisional-radiative model including recombination processes for W27+ ion★

    Science.gov (United States)

    Murakami, Izumi; Sasaki, Akira; Kato, Daiji; Koike, Fumihiro

    2017-10-01

    We have constructed a collisional-radiative (CR) model for W27+ ions including 226 configurations with n ≤ 9 and ł ≤ 5 for spectroscopic diagnostics. We newly include recombination processes in the model and this is the first result of extreme ultraviolet spectrum calculated for recombining plasma component. Calculated spectra in 40-70 Å range in ionizing and recombining plasma components show similar 3 strong lines and 1 line weak in recombining plasma component at 45-50 Å and many weak lines at 50-65 Å for both components. Recombination processes do not contribute much to the spectrum at around 60 Å for W27+ ion. Dielectronic satellite lines are also minor contribution to the spectrum of recombining plasma component. Dielectronic recombination (DR) rate coefficient from W28+ to W27+ ions is also calculated with the same atomic data in the CR model. We found that larger set of energy levels including many autoionizing states gave larger DR rate coefficients but our rate agree within factor 6 with other works at electron temperature around 1 keV in which W27+ and W28+ ions are usually observed in plasmas. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, and Grzegorz Karwasz.

  17. Laser-Collisional Induced Fluorescence Measurements of a Magnetosheath in a Biasable Ring Cusp Source

    Science.gov (United States)

    Arthur, Neil; Foster, John

    2016-09-01

    This work involves exploring active control of the plasma potential and density spatial distribution in a mulitpole ion source through the active biasing of individual magnetic cusps. Cusp bias can be achieved by applying voltage to the magnetic surface generating the cusp. By controlling the current flow through the cusps, active altering of the primary electron containment length, at least at low voltages, is possible. Electrostatic probes do not work well in the presence of magnetic field and within sheaths. The Laser-Collisional Induced Fluorescence (LCIF) diagnostic is enabling in that it allows for imaging of the electron distribution in the magnetosheath. LCIF is used to quantify the response of electron density to active cusp biasing. We hope to gain insight into the physical processes occurring at the magnetic cusps and elucidate how those processes impact not only the plasma conditions in the bulk plasma, but also source efficiency and stability. The goal is to determine how bulk plasma properties change in response to modifications to current collection at the cusp magnetosheath. If the plasma properties vary with electric field in the cusp, then magnetic cusps must be considered as active rather than passive collectors.

  18. General relativistic plasma dynamics

    NARCIS (Netherlands)

    Moortgat, Joachim Benedictus

    2006-01-01

    In this thesis I discuss the importance of general relativity on plasma physics in several astrophysical and cosmological contexts. The first chapters show how gravitational waves can excite all three fundamental low frequency magnetohydrodynamic plasma modes, the Alfven, slow and fast

  19. Equilibrium and stability of tokamak plasmas and accretion disks

    NARCIS (Netherlands)

    Blokland, J.W.S.

    2007-01-01

    In both fusion research as well in astrophysics, plasmas are widely studied. These plasmas can be found in different geometric configurations, such as in a tokamak, stellarator or in astrophysical jets, accretion disks, etc. In this thesis we focus on plasmas found in tokamaks or accretion disks. In

  20. Focusing Telescopes in Nuclear Astrophysics

    CERN Document Server

    Ballmoos, Peter von

    2007-01-01

    This volume is the first of its kind on focusing gamma-ray telescopes. Forty-eight refereed papers provide a comprehensive overview of the scientific potential and technical challenges of this nascent tool for nuclear astrophysics. The book features articles dealing with pivotal technologies such as grazing incident mirrors, multilayer coatings, Laue- and Fresnel-lenses - and even an optic using the curvature of space-time. The volume also presents an overview of detectors matching the ambitious objectives of gamma ray optics, and facilities for operating such systems on the ground and in space. The extraordinary scientific potential of focusing gamma-ray telescopes for the study of the most powerful sources and the most violent events in the Universe is emphasized in a series of introductory articles. Practicing professionals, and students interested in experimental high-energy astrophysics, will find this book a useful reference

  1. Features of active-medium formation for lasers with a sectioned plasma source of metal vapor

    Energy Technology Data Exchange (ETDEWEB)

    Apollonov, V.V.; Derzhavin, S.I.; Prokhorov, A.M.; Sirotkin, A.A.

    1988-06-01

    Experimental results are presented on active-medium formation mechanisms in a laser with a sectioned plasma source of metal vapor (a SPER laser). The following processes were observed in the laser active medium: buffer-gas preionization; mixing of metal vapor and buffer gas during plasma expansion; plasma-chemical reactions in the expanding plasma; and a collisional mechanism of plasma cooling.

  2. The Fascination of Far-UV Astrophysics

    Science.gov (United States)

    Linsky, J. L.

    1998-05-01

    A one-day topical session will review the observational and theoretical status of astrophysical problems where data in the 900 to 1200 Angstroms range are essential for future advances. The session will include the study of FUV rest wavelengths at high redshifts. For example, the deuterium-to-hydrogen abundance ratio will address the Milky Way and QSO absorption line systems. The FUV spectral region is well known for its unique spectral features and important scientific problems they address. The Lyman series of atomic hydrogen provides the only means to determine the production of deuterium in the Big Bang and its subsequent processing during galactic chemical evolution. The resonance doublet of the O VI ion is the highest temperature resonance line available to study the abundance and kinematics of diffuse hot gas in the disk and halo of the Galaxy and hot gas in accretion disks. The Lyman and Werner bands, the only electronic transitions of molecular hydrogen, probe cold gas in the diffuse ISM as well as the outer regions of dense molecular clouds. Strong transitions of several ionization states of carbon, nitrogen, oxygen, neon, sulphur, and argon provide unique diagnostics for studying interstellar gas and emission plasmas. This special session focuses on recent observational material and how the data limit the range of acceptable pictures. This session will highlight key puzzles and describe anticipated progress from new instrumentation, in particular the Far Ultraviolet Spectroscopic Explorer (FUSE) mission, due to be launched in early 1999. The first talk of the session will summarize the critically important spectral diagnostics that reside in the FUV spectral region and show how they allow FUSE to address the main scientific objectives of FUV astrophysics. FUSE spectra will also enhance the value of longer wavelength spectra provided by HST and IUE, shorter wavelength spectra of EUVE and soon AXAF, lower sensitivity FUV spectra of Copernicus, and lower

  3. The Astrophysical Multipurpose Software Environment

    Science.gov (United States)

    Pelupessy, F. I.; van Elteren, A.; de Vries, N.; McMillan, S. L. W.; Drost, N.; Portegies Zwart, S. F.

    2013-09-01

    We present the open source Astrophysical Multi-purpose Software Environment (AMUSE), a component library for performing astrophysical simulations involving different physical domains and scales. It couples existing codes within a Python framework based on a communication layer using MPI. The interfaces are standardized for each domain and their implementation based on MPI guarantees that the whole framework is well-suited for distributed computation. It includes facilities for unit handling and data storage. Currently it includes codes for gravitational dynamics, stellar evolution, hydrodynamics and radiative transfer. Within each domain the interfaces to the codes are as similar as possible. We describe the design and implementation of AMUSE, as well as the main components and community codes currently supported and we discuss the code interactions facilitated by the framework. Additionally, we demonstrate how AMUSE can be used to resolve complex astrophysical problems by presenting example applications. http://www.amusecode.org The current version of the code is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/557/A84

  4. Astrophysics with Microarcsecond Accuracy Astrometry

    Science.gov (United States)

    Unwin, Stephen C.

    2008-01-01

    Space-based astrometry promises to provide a powerful new tool for astrophysics. At a precision level of a few microarcsonds, a wide range of phenomena are opened up for study. In this paper we discuss the capabilities of the SIM Lite mission, the first space-based long-baseline optical interferometer, which will deliver parallaxes to 4 microarcsec. A companion paper in this volume will cover the development and operation of this instrument. At the level that SIM Lite will reach, better than 1 microarcsec in a single measurement, planets as small as one Earth can be detected around many dozen of the nearest stars. Not only can planet masses be definitely measured, but also the full orbital parameters determined, allowing study of system stability in multiple planet systems. This capability to survey our nearby stellar neighbors for terrestrial planets will be a unique contribution to our understanding of the local universe. SIM Lite will be able to tackle a wide range of interesting problems in stellar and Galactic astrophysics. By tracing the motions of stars in dwarf spheroidal galaxies orbiting our Milky Way, SIM Lite will probe the shape of the galactic potential history of the formation of the galaxy, and the nature of dark matter. Because it is flexibly scheduled, the instrument can dwell on faint targets, maintaining its full accuracy on objects as faint as V=19. This paper is a brief survey of the diverse problems in modern astrophysics that SIM Lite will be able to address.

  5. An Efficient Statistical Method to Compute Molecular Collisional Rate Coefficients

    Science.gov (United States)

    Loreau, Jérôme; Lique, François; Faure, Alexandre

    2018-01-01

    Our knowledge about the “cold” universe often relies on molecular spectra. A general property of such spectra is that the energy level populations are rarely at local thermodynamic equilibrium. Solving the radiative transfer thus requires the availability of collisional rate coefficients with the main colliding partners over the temperature range ∼10–1000 K. These rate coefficients are notoriously difficult to measure and expensive to compute. In particular, very few reliable collisional data exist for inelastic collisions involving reactive radicals or ions. In this Letter, we explore the use of a fast quantum statistical method to determine molecular collisional excitation rate coefficients. The method is benchmarked against accurate (but costly) rigid-rotor close-coupling calculations. For collisions proceeding through the formation of a strongly bound complex, the method is found to be highly satisfactory up to room temperature. Its accuracy decreases with decreasing potential well depth and with increasing temperature, as expected. This new method opens the way to the determination of accurate inelastic collisional data involving key reactive species such as {{{H}}}3+, H2O+, and H3O+ for which exact quantum calculations are currently not feasible.

  6. Collisional Losses from a Light-Force Atom Trap

    Science.gov (United States)

    Sesko, D.; Walker, T.; Monroe, C.; Gallagher, A.; Wieman, C.

    We have studied the collisional loss rates for very cold cesium atoms held in a spontaneous-force optical trap. In contrast with previous work, we find that collisions involving excitation by the trapping light fields are the dominant loss mechanism. We also find that hyperfine-changing collisions between atoms in the ground state can be significant under some circumstances.

  7. REBOUND: Multi-purpose N-body code for collisional dynamics

    Science.gov (United States)

    Rein, Hanno; Liu, Shang-Fei

    2011-10-01

    REBOUND is a multi-purpose N-body code which is freely available under an open-source license. It was designed for collisional dynamics such as planetary rings but can also solve the classical N-body problem. It is highly modular and can be customized easily to work on a wide variety of different problems in astrophysics and beyond. REBOUND comes with three symplectic integrators: leap-frog, the symplectic epicycle integrator (SEI) and a Wisdom-Holman mapping (WH). It supports open, periodic and shearing-sheet boundary conditions. REBOUND can use a Barnes-Hut tree to calculate both self-gravity and collisions. These modules are fully parallelized with MPI as well as OpenMP. The former makes use of a static domain decomposition and a distributed essential tree. Two new collision detection modules based on a plane-sweep algorithm are also implemented. The performance of the plane-sweep algorithm is superior to a tree code for simulations in which one dimension is much longer than the other two and in simulations which are quasi-two dimensional with less than one million particles.

  8. REBOUND: an open-source multi-purpose N-body code for collisional dynamics

    Science.gov (United States)

    Rein, H.; Liu, S.-F.

    2012-01-01

    REBOUND is a new multi-purpose N-body code which is freely available under an open-source license. It was designed for collisional dynamics such as planetary rings but can also solve the classical N-body problem. It is highly modular and can be customized easily to work on a wide variety of different problems in astrophysics and beyond. REBOUND comes with three symplectic integrators: leap-frog, the symplectic epicycle integrator (SEI) and a Wisdom-Holman mapping (WH). It supports open, periodic and shearing-sheet boundary conditions. REBOUND can use a Barnes-Hut tree to calculate both self-gravity and collisions. These modules are fully parallelized with MPI as well as OpenMP. The former makes use of a static domain decomposition and a distributed essential tree. Two new collision detection modules based on a plane-sweep algorithm are also implemented. The performance of the plane-sweep algorithm is superior to a tree code for simulations in which one dimension is much longer than the other two and in simulations which are quasi-two dimensional with less than one million particles. In this work, we discuss the different algorithms implemented in REBOUND, the philosophy behind the code's structure as well as implementation specific details of the different modules. We present results of accuracy and scaling tests which show that the code can run efficiently on both desktop machines and large computing clusters.

  9. Stirring unmagnetized plasma.

    Science.gov (United States)

    Collins, C; Katz, N; Wallace, J; Jara-Almonte, J; Reese, I; Zweibel, E; Forest, C B

    2012-03-16

    A new concept for spinning unmagnetized plasma is demonstrated experimentally. Plasma is confined by an axisymmetric multicusp magnetic field and biased cathodes are used to drive currents and impart a torque in the magnetized edge. Measurements show that flow viscously couples momentum from the magnetized edge (where the plasma viscosity is small) into the unmagnetized core (where the viscosity is large) and that the core rotates as a solid body. To be effective, collisional viscosity must overcome the ion-neutral drag due to charge-exchange collisions.

  10. Development and application of a multi-fluid simulation code for modeling interpenetrating plasmas

    Science.gov (United States)

    Khodak, M.; Berger, R. L.; Chapman, T.; Hittinger, J. A. F.

    2015-11-01

    A multi-fluid model, with independent velocities for all species, is developed and implemented for the numerical simulation of the interpenetration of colliding plasmas. The Euler equations for fluid flow, coupled through electron-ion and ion-ion collisional drag terms, thermal equilibration terms, and the electric field, are solved for each ion species with the electrons treated under a quasineutrality assumption. Fourth-order spatial convergence in smooth regions is achieved using flux-conservative iterative time integration and a Weighted Essentially Non-Oscillatory (WENO) finite volume scheme employing an approximate Riemann solver. Analytic solutions of well-known shock tube tests and spectral solutions of the linearized coupled system are used to test the implementation, and the model is further numerically compared to interpenetration experiments such as those of J.S. Ross et al. [Phys. Rev. Lett. 110 145005 (2013)]. This work has applications to laser-plasma interactions, specifically to hohlraum physics, as well as to modeling laboratory experiments of collisionless shocks important in astrophysical plasmas. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 and funded by the Laboratory Research and Development Program at LLNL under project code 15-ERD-038.

  11. Comprehensive x-ray spectral code for high energy astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Liedahl, D A; Fournier, K B; Mauche, C W

    2000-08-18

    The aim of this project has been to develop a spectral analysis tool with a level of quality and completeness commensurate to that expected in data from the current generation of X-ray observatories. The code is called LXSS (Livermore X-Ray Spectral Synthesizer). X-ray-emitting astrophysical plasmas are rarely, if ever, in LTE, so they have adopted the detailed level accounting approach, in which rates for processes that populate or depopulate atomic energy levels are treated explicitly. This entails the generation of a large quantity of atomic data, most of which is calculated using ''in-house'' computer codes. Calculations are benchmarked against laboratory data, and spectral models have been used to provide first-time interpretations of astrophysical X-ray spectra. The design of a versatile graphical user interface that allows access to and manipulation of the atomic database comprises the second major part of the project.

  12. 5th International conference on High Energy Density Laboratory Astrophysics

    CERN Document Server

    Kyrala, G.A

    2005-01-01

    During the past several years, research teams around the world have developed astrophysics-relevant utilizing high energy-density facilities such as intense lasers and z-pinches. Research is underway in many areas, such as compressible hydrodynamic mixing, strong shock phenomena, radiation flow, radiative shocks and jets, complex opacities, equations o fstat, and relativistic plasmas. Beyond this current research and the papers it is producing, plans are being made for the application, to astrophysics-relevant research, of the 2 MJ National Ignition Facility (NIF) laser at Lawrence Livermore National Laboratory; the 600 kj Ligne d'Intergration Laser (LIL) and the 2 MJ Laser Megajoule (LMJ) in Bordeaux, France; petawatt-range lasers now under construction around the world; and current and future Z pinches. The goal of this conference and these proceedings is to continue focusing and attention on this emerging research area. The conference brought together different scientists interested in this emerging new fi...

  13. Special relativity in general frames from particles to astrophysics

    CERN Document Server

    Gourgoulhon, Éric

    2013-01-01

    Special relativity is the basis of many fields in modern physics: particle physics, quantum field theory, high-energy astrophysics, etc. This theory is presented here by adopting a four-dimensional point of view from the start. An outstanding feature of the book is that it doesn’t restrict itself to inertial frames but considers accelerated and rotating observers. It is thus possible to treat physical effects such as the Thomas precession or the Sagnac effect in a simple yet precise manner. In the final chapters, more advanced topics like tensorial fields in spacetime, exterior calculus and relativistic hydrodynamics are addressed. In the last, brief chapter the author gives a preview of gravity and shows where it becomes incompatible with Minkowsky spacetime. Well illustrated and enriched by many historical notes, this book also presents many applications of special relativity, ranging from particle physics (accelerators, particle collisions, quark-gluon plasma) to astrophysics (relativistic jets, active g...

  14. A simple collisional-radiative model for low-pressure argon-oxygen mixture discharges

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Ximing; Pu Yikang [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2007-09-07

    The simple collisional-radiative model is investigated in low-pressure discharges containing argon and oxygen. Using this model, one can obtain a simple relationship between the electron density and the intensity ratio of two argon emission lines without knowing electron temperature. It is found that the relationship is valid in these discharges regardless of oxygen concentration, if argon np levels with zero total angle momentum quantum numbers are selected. This is because that the kinetics of these levels is not significantly affected by the metastables under low-pressure conditions. The application and validity of this model in other kinds of low-pressure plasmas, such as discharges contain CF{sub 4}, are also discussed.

  15. Plasma transport near material boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Singer, C.E.

    1985-06-01

    The fluid theory of two-dimensional (2-d) plasma transport in axisymmetric devices is reviewed. The forces which produce flow across the magnetic field in a collisional plasma are described. These flows may lead to up-down asymmetries in the poloidal rotation and radial fluxes. Emphasis is placed on understanding the conditions under which the known 2-d plasma fluid equations provide a valid description of these processes. Attempts to extend the fluid treatment to less collisional, turbulent plasmas are discussed. A reduction to the 1-d fluid equations used in many computer simulations is possible when sources or boundary conditions provide a large enough radial scale length. The complete 1-d fluid equations are given in the text, and 2-d fluid equations are given in the Appendix.

  16. Fundamental Processes in Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Driscoll, Charles Fred [Univ. of California, San Diego, CA (United States)

    2017-11-03

    This Final Technical Report gives brief summaries of the plasma physics results developed under DOE grant DE-SC0002451; and provides reference to the published journal articles giving full scientific descriptions. General topics include 1) cyclotron modes; 2) damping and decay of Langmuir modes; 3) 2D vortex dynamics and diocotron modes; 4) separatrix-induced transport and damping; and 5) long-range collisional velocity slowing.

  17. Astrophysics of the Interstellar Medium

    CERN Document Server

    Maciel, Walter J

    2013-01-01

    The space between the stars includes a large variety of objects, where physical processes occur that are fundamental for the structure and evolution of galaxies. This book gives the reader some basic knowledge of these processes and at the same time, presents estimates of the main quantities relevant to the study of the interstellar medium. The book could be used as an introductory course on the interstellar medium  by science students or by readers interested in astrophysics with an adequate physics and mathematics background.

  18. Simulations of Astrophysical fluid instabilities

    Science.gov (United States)

    Calder, A. C.; Fryxell, B.; Rosner, R.; Dursi, L. J.; Olson, K.; Ricker, P. M.; Timmes, F. X.; Zingale, M.; MacNeice, P.; Tufo, H. M.

    2001-10-01

    We present direct numerical simulations of mixing at Rayleigh-Taylor unstable interfaces performed with the FLASH code, developed at the ASCI/Alliances Center for Astrophysical Thermonuclear Flashes at the University of Chicago. We present initial results of single-mode studies in two and three dimensions. Our results indicate that three-dimensional instabilities grow significantly faster than two-dimensional instabilities and that grid resolution can have a significant effect on instability growth rates. We also find that unphysical diffusive mixing occurs at the fluid interface, particularly in poorly resolved simulations. .

  19. High Energy Astrophysics Science Archive Research Center

    Data.gov (United States)

    National Aeronautics and Space Administration — The High Energy Astrophysics Science Archive Research Center (HEASARC) is the primary archive for NASA missions dealing with extremely energetic phenomena, from...

  20. Advances IN Explosive Nuclear Astrophysics

    Science.gov (United States)

    Lotay, Gavin

    2016-09-01

    Breathtaking results from the Planck satellite mission and Hubble space telescope have highlighted the key role modern Astronomy is playing for our understanding of Big Bang Cosmology. However, not so widely publicized is the similar wealth of observational data now available on explosive stellar phenomena, such as X-ray bursts, novae and Supernovae. These astronomical events are responsible for the synthesis of almost all the chemical elements we find on Earth and observe in our Galaxy, as well as energy generation throughout the cosmos. Regrettably, understanding the latest collection of observational data is severely hindered by the current, large uncertainties in the underlying nuclear physics processes that drive such stellar scenarios. In order to resolve this issue, it is becoming increasingly clear that there is a need to explore the unknown properties and reactions of nuclei away from the line of stability. Consequently, state-of-the-art radioactive beam facilities have become terrestrial laboratories for the reproduction of explosive astrophysical events. In this talk, both direct and indirect methods for studying key astrophysical reactions using radioactive beams will be discussed.

  1. Radiative and rovibrational collisional relaxation of sodium dimer

    Science.gov (United States)

    Bayram, Burcin; Horton, Tim; McFarland, Jacob

    2016-05-01

    Radiative and rovibrational collisional relaxation of sodium dimer of the A1Σu+ (8,30) state have been measured by direct observation of the decay fluorescence. Sodium molecular vapor is created in a heatpipe oven at 600 K and excited using a 6-ns pulsed dye laser pumped by a Nd:YAG, operating at 532 nm. The preliminary lifetime measurement was done by directly acquiring lifetime data through boxcar averager from the stored oscilloscope trace of the fluorescence. Analysis of the exponential decay of the fluorescence allows us to obtain the radiative lifetime. By introducing the argon buffer gas and varying the pressure of the heatpipe, a collisional cross section between excited sodium dimer and ground state argon atom collision can be extracted using Stern-Volmer relation.

  2. Collisional broadening of angular correlations in a multiphase transport model

    Science.gov (United States)

    Edmonds, Terrence; Li, Qingfeng; Wang, Fuqiang

    2017-10-01

    Systematic comparisons of jetlike correlation data to radiative and collisional energy loss model calculations are essential to extract transport properties of the quark-gluon medium created in relativistic heavy ion collisions. This paper presents a transport study of collisional broadening of jetlike correlations, by following parton-parton collision history in a multiphase transport (AMPT) model. The correlation shape is studied as functions of the number of parton-parton collisions suffered by a high transverse momentum probe parton (Ncoll) and the azimuth of the probe relative to the reaction plane (ϕfin.probe). Correlation is found to broaden with increasing Ncoll and ϕfin.probe from in- to out-of-plane direction. This study provides a transport model reference for future jet-medium interaction studies.

  3. Collisional Quenching of Highly-Excited H2 due to H2 Collisions

    Science.gov (United States)

    Wan, Yier; Yang, Benhui H.; Stancil, Phillip C.; Naduvalath, Balakrishnan; Forrey, Robert C.; This work was partially support by Hubble grant HST-AT-13899. We thank Kyle Walkerassistance with vrrmm.

    2017-06-01

    Collision-induced energy transfer involving H2 molecules are of significant interest, since H2 is the most abundant molecular species in the universe. Collisional de-excitation rate coefficients of the H2-H2 system are necessary to produce accurate models of astrophysical environments. However, accurate calculations of collisional energy transfer are still a challenging problem, especially for highly-excited H2 because a large number of levels must be included in the calculation.Currently, most data are limited to initial rotational levels j up to 8 or initial vibrational levels up to 3. The vast majority of these results involve some form of a reduced-dimensional approach which may be of questionable accuracy. A reliable and accurate four-dimensional PES computed by Patkowski et al. is used in this work along with two quantum scattering programs (MOLSCAT and vrrmm). Another accurate full-dimensional PES has been reported for the H2-H2 system by Hinde.Not all transitions will be explicitly calculated. A zero-energy scaling technique (ZEST) is used to estimate some intermediate transitions from calculated rate coefficients. New inelastic quenching cross section for para-H2+para-H2 collisions with initial level j= 10, 12, 14, 18, 24 are calculated. Calculations for other de-excitation transitions from higher initial levels and collisions involving other spin isomer of hydrogen, ortho-H2+para-H2, ortho-H2+ortho-H2 and para-H2+ortho-H2 are in progress. The coupled- states approximation is also applied to obtain cross sections at high energy.K. Patkowski, et al., J. Chem. Phys. 129, 094304 (2008).J. M. Hutson and S. Green, MOLSCAT Computer code, v14 (1994).K. Walker, 2013, VRRMM: Vibrational/Rotational Rich Man’s MOLSCAT v3.1.K. Walker, Song, L., Yang, B. H.,et al. 2015, ApJ, \\811,27.S. Green, J. Chem. Phys. 62, 2271 (1975).Flower, D. R., Roueff, E. 1998, J. Phys. B, 31, 2935.T. -G. Lee, N. Balakrishnan, R. C. Forrey, P. C. Stancil, G. Shaw, D. R. Schultz, and G. J

  4. Promising lines of investigations in the realms of laboratory astrophysics with the aid of powerful lasers

    Energy Technology Data Exchange (ETDEWEB)

    Belyaev, V. S., E-mail: belyaev@tsniimash.ru; Batishchev, P. A.; Bolshakov, V. V.; Elkin, K. S.; Karabadzhak, G. F.; Kovkov, D. V.; Matafonov, A. P.; Raykunov, G. G.; Yakhin, R. A. [Russian Space Agency, Central Research Institute of Machine Building (TsNIIMash) (Russian Federation); Pikuz, S. A.; Skobelev, I. Yu.; Faenov, A. Ya.; Fortov, V. E. [Russian Academy of Sciences (IVTAN), Joint Institute for High Temperatures (Russian Federation); Krainov, V. P. [Moscow Institute of Physics and Technology (State University) (Russian Federation); Rozanov, V. B. [Russian Academy of Sciences, Lebedev Institute of Physics (Russian Federation)

    2013-04-15

    The results of work on choosing and substantiating promising lines of research in the realms of laboratory astrophysics with the aid of powerful lasers are presented. These lines of research are determined by the possibility of simulating, under laboratory conditions, problematic processes of presentday astrophysics, such as (i) the generation and evolution of electromagnetic fields in cosmic space and the role of magnetic fields there at various spatial scales; (ii) the mechanisms of formation and evolution of cosmic gamma-ray bursts and relativistic jets; (iii) plasma instabilities in cosmic space and astrophysical objects, plasma jets, and shock waves; (iv) supernova explosions and mechanisms of the explosion of supernovae featuring a collapsing core; (v) nuclear processes in astrophysical objects; (vi) cosmic rays and mechanisms of their production and acceleration to high energies; and (vii) astrophysical sources of x-ray radiation. It is shown that the use of existing powerful lasers characterized by an intensity in the range of 10{sup 18}-10{sup 22} W/cm{sup 2} and a pulse duration of 0.1 to 1 ps and high-energy lasers characterized by an energy in excess of 1 kJ and a pulse duration of 1 to 10 ns makes it possible to perform investigations in laboratory astrophysics along all of the chosen promising lines. The results obtained by experimentally investigating laser plasma with the aid of the laser facility created at Central Research Institute of Machine Building (TsNIIMash) and characterized by a power level of 10 TW demonstrate the potential of such facilities for performing a number of experiments in the realms of laboratory astrophysics.

  5. Development and Application of Numerical Modules for FLASH in Palermo: Two Astrophysical Examples

    Science.gov (United States)

    Orlando, S.; Peres, G.; Reale, F.; Rosner, R.; Plewa, T.; Siegel, A.

    We collaborate with the Flash Center at the University of Chicago to help upgrading and to apply extensively the FLASH code to astrophysical problems. In particular, we have developed new modules for FLASH which extend the field of applicability of the code to some areas in astrophysics, like solar and stellar coronae, and supernova remnants. The new modules so far developed and tested describe: the non-equilibrium ionization effects of the most abundant elements in astrophysical plasmas, the thermal conduction and the viscosity according to the formulation of Spitzer (1962), and the radiative losses from an optically thin plasma according to the Raymond spectral code, and to Peres et al. (1982) for the chromosphere. We show some selected results for a coronal flare and for a supernova remnant, obtained with the version of FLASH 2.0 code including the new modules.

  6. Calculation of atomic structures and radiative properties of fusion plasmas

    Science.gov (United States)

    Jarrah, Walid; Pain, Jean-Christophe; Benredjem, Djamel

    2017-03-01

    The opacity is an important issue in the knowledge of the radiative properties of Inertial Confinement Fusion (ICF) and astrophysical plasmas. In this work we present the opacity of the mixture C+Si, composing the ablator of some ICF capsules. We have used Cowan's code to calculate the atomic structure of carbon and silicon. We also have developed a collisional-radiative model in order to obtain the opacity of the mixture. Line broadening, line shift and ionization potential depression are taken into account in the opacity profile. Comparisons to other calculations are carried out. NLTE and LTE opacity calculations show discrepancies mainly in the range 1900-2000 eV for the bound-bound contribution to the total opacity and in the range 50-350 eV for the bound-free contribution. We have also accounted for photoexcitation and photoionization processes. The corresponding rates are obtained by modeling the Hohlraum radiation by a Planckian distribution at a radiative temperature of 300 eV.

  7. Astrophysics with small satellites in Scandinavia

    DEFF Research Database (Denmark)

    Lund, Niels

    2003-01-01

    The small-satellites activities in the Scandinavian countries are briefly surveyed with emphasis on astrophysics research. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.......The small-satellites activities in the Scandinavian countries are briefly surveyed with emphasis on astrophysics research. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved....

  8. Student Research in Computational Astrophysics

    Science.gov (United States)

    Blondin, J. M.

    1999-12-01

    Computational physics can shorten the long road from freshman physics major to independent research by providing students with powerful tools to deal with the complexities of modern research problems. At North Carolina State University we have introduced dozens of students to astrophysics research using the tools of computational fluid dynamics. We have used several formats for working with students, including the traditional approach of one-on-one mentoring, a more group-oriented format in which several students work together on one or more related projects, and a novel attempt to involve an entire class in a coordinated semester research project. The advantages and disadvantages of these formats will be discussed at length, but the single most important influence has been peer support. Having students work in teams or learn the tools of research together but tackle different problems has led to more positive experiences than a lone student diving into solo research. This work is supported by an NSF CAREER Award.

  9. Astrophysically Interesting Resonances; Another Approach

    Science.gov (United States)

    Austin, Roby; Jenkins, David

    2008-10-01

    R.A.E. Austin, R. Kanungo, A. Campbell, S. Colosimo, S. Reeve Saint Mary's University; D.G. Jenkins, C.Aa.Diget, A. Robinson, University of York, UK; P.J. Woods T. Davinson University of Edinburgh; C.-Y. Wu A. Hurst J.A. Becker Lawrence Livermore National Laboratory; G.C. Ball M. Djongolov G. Hackman A.C. Morton, C. Pearson, S.J. Williams TRIUMF; A.A. Phillips, M. Schumaker, University of Guelph H.Boston, A. Grint, D. Oxley, University of Liverpool; D. Cline, A. Hayes, University of Rochester; We describe a prototype experiment to measure resonances of interest in astrophysical reactions. We use the TIGRESS to detect gamma rays in coincidence with charged particles, inelastically scattered in inverse kinematics. The particles are detected with the Bambino detector modified to a δE-E silicon telescope spanning 15-40 degrees in the lab.

  10. A Review of Astrophysical Jets

    Directory of Open Access Journals (Sweden)

    James H. Beall

    2014-12-01

    Full Text Available Astrophysical jets are ubiquitous: this simple statement has become a commonplace over the last three decades and more as a result of observing campaigns using detectors sensitive from radio to gamma-ray energies. During this epoch, theoretical models of these sources have become more complex, moving from assumptions of isotropy that made analytic calculations possible, to fully anisotropic models of emission from the jets and their interactions with the interstellar and intra-cluster medium. Such calculations are only possible because we have extensive computational resources. In addition, the degree of international cooperation required for observing campaigns of these sorts is remarkable, since the instruments include among others the Very Large Array (VLA, the Very Long Baseline Array (VLBA, and entire constellations of satellite instruments, often working in concert. In this paper, I discuss some relevant observations from these eorts and the theoretical interpretations they have occasioned.

  11. Transfer reactions in nuclear astrophysics

    Science.gov (United States)

    Bardayan, D. W.

    2016-08-01

    To a high degree many aspects of the large-scale behavior of objects in the Universe are governed by the underlying nuclear physics. In fact the shell structure of nuclear physics is directly imprinted into the chemical abundances of the elements. The tranquility of the night sky is a direct result of the relatively slow rate of nuclear reactions that control and determines a star’s fate. Understanding the nuclear structure and reaction rates between nuclei is vital to understanding our Universe. Nuclear-transfer reactions make accessible a wealth of knowledge from which we can extract much of the required nuclear physics information. A review of transfer reactions for nuclear astrophysics is presented with an emphasis on the experimental challenges and opportunities for future development.

  12. Focusing telescopes in nuclear astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Von Ballmoos, P.; Knodlseder, R.; Sazonov, S.; Griffiths, R.; Bastie, P.; Halloin, H.; Pareschi, G.; Ramsey, B.; Jensen, C.; Buis, E.J.; Ulmer, M.; Giommi, P.; Colafrancesco, S.; Comastri, A.; Barret, D.; Leising, M.; Hernanz, M.; Smith, D.; Abrosimov, N.; Smither, B.; Ubertini, P.; Olive, J.F.; Lund, N.; Pisa, A.; Courtois, P.; Roa, D.; Harrison, F.; Pareschi, G.; Frontera, F.; Von Ballmoos, P.; Barriere, N.; Rando, N.; Borde, J.; Hinglais, E.; Cledassou, R.; Duchon, P.; Sghedoni, M.; Huet, B.; Takahashi, T.; Caroli, E.; Quadrinin, L.; Buis, E.J.; Skinner, G.; Krizmanic, J.; Pareschi, G.; Loffredo, G.; Wunderer, C.; Weidenspointner, G.; Wunderer, C.; Koechlin, L.; Bignami, G.; Von Ballmoos, P.; Tueller, J.; Andritschke, T.; Laurens, A.; Evrard, J

    2005-07-01

    The objective of this workshop is to consider the next generation of instrumentation to be required within the domain of nuclear astrophysics. A small, but growing community has been pursuing various techniques for the focusing of hard X-rays and gamma-rays with the aim of achieving a factor of up to 100 improvement in sensitivity over present technologies. Balloon flight tests of both multilayer mirrors and a Laue lens have been performed and ideas abound. At present, implementation scenarios for space missions are being studied at Esa, CNES, and elsewhere. The workshop will provide a first opportunity for this new community to meet, exchange technological know-how, discuss scientific objectives and synergies, and consolidate implementation approaches within National and European Space Science programs. This document gathers the slides of all the presentations.

  13. Axions in astrophysics and cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Sikivie, P.

    1984-07-01

    Axion models often have a spontaneously broken exact discrete symmetry. In that case, they have discretely degenerate vacua and hence domain walls. The properties of the domain walls, the cosmological catastrophe they produce and the ways in which this catastrophe may be avoided are explained. Cosmology and astrophysics provide arguments that imply the axion decay constant should lie in the range 10/sup 8/ GeV less than or equal to f/sub a/ less than or equal to 10/sup 12/ GeV. Reasons are given why axions are an excellent candidate to constitute the dark matter of galactic halos. Using the coupling of the axions to the electromagnetic field, detectors are described to look for axions floating about in the halo of our galaxy and for axions emitted by the sun. (LEW)

  14. Non-Equilibrium Magnetohydrodynamic Behavior of Plasmas having Complex, Evolving Morphology

    Energy Technology Data Exchange (ETDEWEB)

    Bellan, Paul M. [Caltech

    2014-03-13

    Our main activity has been doing lab experiments where plasmas having morphology and behavior similar to solar and astrophysical plasmas are produced and studied. The solar experiment is mounted on one end of a large vacuum chamber while the astrophysical jet experiment is mounted on the other end. Diagnostics are shared between the two experiments. The solar experiment produces arched plasma loops that behave very much like solar corona loops. The astrophysical jet experiment produces plasma jets that are very much like astrophysical jets. We have also done work on plasma waves, including general wave dispersions, and specific properties of kinetic Alfven waves and of whistler waves.

  15. Particle-in-cell simulations of Magnetic Field Generation, Evolution, and Reconnection in Laser-driven Plasmas

    Science.gov (United States)

    Matteucci, Jack; Moissard, Clément; Fox, Will; Bhattacharjee, Amitava

    2016-10-01

    The advent of high-energy-density physics facilities has introduced the opportunity to experimentally investigate magnetic field dynamics relevant to both ICF and astrophysical plasmas. Recent experiments have demonstrated magnetic reconnection between colliding plasma plumes, where the reconnecting magnetic fields were self-generated in the plasma by the Biermann battery effect. In this study, we simulate these experiments from first principles using 2-D and 3-D particle-in-cell simulations. Simulations self-consistently demonstrate magnetic field generation by the Biermann battery effect, followed by advection by the Hall effect and ion flow. In 2-D simulations, we find in both the collisionless case and the semi-collisional case, defined by eVi × B >> Rei /ne (where Rei is the electron ion momentum transfer) that quantitative agreement with the generalized Ohm's law is only obtained with the inclusion of the pressure tensor. Finally, we document that significant field is destroyed at the reconnection site by the Biermann term, an inverse, `anti-Biermann' effect, which has not been considered previously in analysis of the experiment. The role of the anti-Biermann effect will be compared to standard reconnection mechanisms in 3-D reconnection simulations. This research used resources of the ORLC Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. DoE under Contract No. DE-AC05-00OR22725.

  16. Collisionless momentum transfer in space and astrophysical explosions

    Science.gov (United States)

    Bondarenko, A. S.; Schaeffer, D. B.; Everson, E. T.; Clark, S. E.; Lee, B. R.; Constantin, C. G.; Vincena, S.; van Compernolle, B.; Tripathi, S. K. P.; Winske, D.; Niemann, C.

    2017-06-01

    The AMPTE (Active Magnetospheric Particle Tracer Explorers) mission provided in situ measurements of collisionless momentum and energy exchange between an artificial, photo-ionized barium plasma cloud and the streaming, magnetized hydrogen plasma of the solar wind . One of its most significant findings was the unanticipated displacement of the barium ion `comet head’ (and an oppositely directed deflection of the streaming hydrogen ions) transverse to both the solar wind flow and the interplanetary magnetic field, defying the conventional expectation that the barium ions would simply move downwind. While subsequent theoretical and computational efforts to understand the cause of the transverse motion reached differing conclusions, several authors attributed the observations to Larmor coupling, a collisionless momentum exchange mechanism believed to occur in various astrophysical and space-plasma environments and to participate in cosmic magnetized collisionless shock formation. Here we present the detection of Larmor coupling in a reproducible laboratory experiment that combines an explosive laser-produced plasma cloud with preformed, magnetized ambient plasma in a parameter regime relevant to the AMPTE barium releases. In our experiment, time-resolved Doppler spectroscopy reveals ambient ion acceleration transverse to both the laser-produced plasma flow and the background magnetic field. Utilizing a detailed numerical simulation, we demonstrate that the ambient ion velocity distribution corresponding to the measured Doppler-shifted spectrum is qualitatively and quantitatively consistent with Larmor coupling.

  17. Theoretical and numerical study of Rayleigh-Taylor instabilities in magnetized plasmas; Etude theorique et numerique des instabilites rayleigh-taylor en plasmas magnetises

    Energy Technology Data Exchange (ETDEWEB)

    Andrei, A. Ivanov

    2001-06-15

    In this thesis we're studying both the general case of the 'classic' Rayleigh-Taylor instability (in incompressible fluids) and more specific cases of the instabilities of Rayleigh-Taylor type in magnetized plasmas, in the liners or wire array implosions etc. We have studied the influence of the Hall diffusion of magnetic field on the growth rate of the instability. We have obtained in this work a self-similar solution for the widening of the initial profile of the magnetic field and for the wave of the penetration of magnetic field. After that the subsequent evolution of the magnetic field in plasma opening switches (POS) has been examined. We have shown the possibility of the existence of a strong rarefaction wave for collisional and non-collisional cases. This wave can explain the phenomenon of the opening of POS. The effect of the suppression of Rayleigh-Taylor instability by forced oscillations of the boundary between two fluids permits us to propose some ideas for the experiments of inertial fusion. We have considered the general case of the instability, in other words - two incompressible viscous superposed fluids in a gravitational field. We have obtained an exact analytical expression for the growth rate and then we have analyzed the influence of the parameters of external 'pumping' on the instability. These results can be applied to a wide range of systems, starting from classic hydrodynamics and up to astrophysical plasmas. The scheme of wire arrays has become recently a very popular method to obtain a high power X-radiation or for a high quality implosion in Z-pinches. The experimental studies have demonstrated that the results of implosion are much better for the case of multiple thin wires situated cylindrically than in a usual liner scheme. We have examined the problem modeling the stabilization of Rayleigh-Taylor instability for a wire array system. The reason for instability suppression is the regular spatial modulation of

  18. Fine and hyperfine collisional excitation of C6H by He

    Science.gov (United States)

    Walker, Kyle M.; Lique, François; Dawes, Richard

    2018-01-01

    Hydrogenated carbon chains have been detected in interstellar and circumstellar media and accurate modelling of their abundances requires collisional excitation rate coefficients with the most abundant species. Among them, the C6H molecule is one of the most abundant towards many lines of sight. Hence, we determined fine and hyperfine-resolved rate coefficients for the excitation of C6H(X2Π) due to collisions with He. We present the first interaction potential energy surface for the C6H-He system, obtained from highly correlated ab initio calculations and characterized by a large anisotropy due to the length of the molecule. We performed dynamical calculations for transitions among the first fine structure levels (up to J = 30.5) of both spin-orbit manifolds of C6H using the close-coupling method, and rate coefficients are determined for temperatures ranging from 5 to 100 K. The largest rate coefficients for even ΔJ transitions conserve parity, while parity-breaking rate coefficients are favoured for odd ΔJ. Spin-orbit changing rate coefficients are several orders of magnitude lower than transitions within a single manifold. State-to-state hyperfine-resolved cross-sections for the first levels (up to J = 13.5) in the Ω = 3/2 spin-orbit manifold are deduced using recoupling techniques. Rate coefficients are obtained and the propensity rule ΔJ = ΔF is seen. These new data will help determine the abundance of C6H in astrophysical environments such as cold dense molecular clouds, star-forming regions and circumstellar envelopes, and will help in the interpretation of the puzzling C6H-/C6H abundance ratios deduced from observations.

  19. Experimental observation of strong coupling effects on the dispersion of dust acoustic waves in a plasma

    CERN Document Server

    Bandyopadhyay, P; Sen, A; Kaw, P K

    2016-01-01

    The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and $MnO_2$ dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of $\\partial\\omega/\\partial k < 0$ are identified as signatures of dust-dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects.

  20. Frontier Research in Astrophysics - II

    Science.gov (United States)

    2016-05-01

    The purpose of this international workshop is to bring together astrophysicists and physicists who are involved in various topics at the forefront of modern astrophysics and particle physics. The workshop will discuss the most recent experimental and theoretical results in order to advance our understanding of the physics governing our Universe. To accomplish the goals of the workshop, we believe it is necessary to use data from ground-based and space-based experiments and results from theoretical developments: work on the forefront of science which has resulted (or promises to result in) high-impact scientific papers. Hence, the main purpose of the workshop is to discuss in a unique and collaborative setting a broad range of topics in modern astrophysics, from the Big Bang to Planets and Exoplanets. We believe that this can provide a suitable framework for each participant who (while obviously not involved in all the topics discussed), will be able to acquire a general view of the main experimental and theoretical results currently obtained. Such an up-to-date view of the current research on cosmic sources can help guide future research projects by the participants, and will encourage collaborative efforts across various topical areas of research. The proceedings will be published in Proceedings of Science (PoS)- SISSA and will provide a powerful resource for all the scientific community and will be especially helpful for PhD students. The following items will be reviewed: Cosmology: Cosmic Background, Dark Matter, Dark Energy, Clusters of Galaxies. Physics of the Diffuse Cosmic Sources. Physics of Cosmic Rays. Physics of Discrete Cosmic Sources. Extragalactic Sources: Active Galaxies, Normal Galaxies, Gamma-Ray Bursts. Galactic Sources: Star Formation, Pre-Main-Sequence and Main- Sequence Stars, the Sun, Cataclysmic Variables and Novae, Supernovae and SNRs, X-Ray Binary Systems, Pulsars, Black Holes, Gamma-Ray Sources, Nucleosynthesis, Asteroseismology

  1. Studying Nuclear Astrophysics at NIF

    Energy Technology Data Exchange (ETDEWEB)

    Boyd, R; Bernstein, L; Brune, C

    2009-07-01

    The National Ignition Facility's primary goal is to generate fusion energy. But the starlike conditions that it creates will also enable NIF scientists to study astrophysically important nuclear reactions. When scientists at the stadium-sized National Ignition Facility attempt to initiate fusion next year, 192 powerful lasers will direct 1.2 MJ of light energy toward a two-mm-diameter pellet of deuterium ({sup 2}H, or D) and tritium ({sup 3}H, or T). Some of that material will be gaseous, but most will be in a frozen shell. The idea is to initiate 'inertial confinement fusion', in which the two hydrogen isotopes fuse to produce helium-4, a neutron, and 17.6 MeV of energy. The light energy will be delivered to the inside walls of a hohlraum, a heavy-metal, centimeter-sized cylinder that houses the pellet. The container's heated walls will produce x rays that impinge on the pellet and ablate its outer surface. The exiting particles push inward on the pellet and compresses the DT fuel. Ultimately a hot spot develops at the pellet's center, where fusion produces {sup 4}He nuclei that have sufficient energy to propagate outward, trigger successive reactions, and finally react the frozen shell. Ignition should last several tens of picoseconds and generate more than 10 MJ of energy and roughly 10{sup 19} neutrons. The temperature will exceed 10{sup 8} K and fuel will be compressed to a density of several hundred g/cm{sup 3}, both considerably greater than at the center of the Sun. The figure shows a cutaway view of NIF. The extreme conditions that will be produced there simulate those in nuclear weapons and inside stars. For that reason, the facility is an important part of the US stockpile stewardship program, designed to assess the nation's aging nuclear stockpile without doing nuclear tests. In this Quick Study we consider a third application of NIF - using the extraordinary conditions it will produce to perform experiments in basic

  2. Relativistic kinetic theory with applications in astrophysics and cosmology

    CERN Document Server

    Vereshchagin, Gregory V

    2017-01-01

    Relativistic kinetic theory has widespread application in astrophysics and cosmology. The interest has grown in recent years as experimentalists are now able to make reliable measurements on physical systems where relativistic effects are no longer negligible. This ambitious monograph is divided into three parts. It presents the basic ideas and concepts of this theory, equations and methods, including derivation of kinetic equations from the relativistic BBGKY hierarchy and discussion of the relation between kinetic and hydrodynamic levels of description. The second part introduces elements of computational physics with special emphasis on numerical integration of Boltzmann equations and related approaches, as well as multi-component hydrodynamics. The third part presents an overview of applications ranging from covariant theory of plasma response, thermalization of relativistic plasma, comptonization in static and moving media to kinetics of self-gravitating systems, cosmological structure formation and neut...

  3. Particle Acceleration in the Heliosphere: Implications for Astrophysics

    Science.gov (United States)

    Fisk, L. A.; Gloeckler, G.

    2012-11-01

    There has been a remarkable discovery concerning particles that are accelerated in the solar wind. At low energies, in the region where the particles are being accelerated, the spectrum of the accelerated particles is always the same: when expressed as a distribution function, the spectrum is a power law in particle speed with a spectral index of -5, and a rollover at higher particle speeds that can often be described as exponential. This common spectral shape cannot be accounted for by any conventional acceleration mechanism, such as diffusive shock acceleration or traditional stochastic acceleration. It has thus been necessary to invent a new acceleration mechanism to account for these observations, a pump mechanism in which particles are pumped up in energy through a series of adiabatic compressions and expansions. The conditions under which the pump acceleration is the dominant acceleration mechanism are quite general and are likely to occur in other astrophysical plasmas. In this paper, the most compelling observations of the -5 spectra are reviewed; the governing equation of the pump acceleration mechanism is derived in detail; the pump acceleration mechanism is applied to acceleration at shocks; and, as an illustration of the potential applicability of the pump acceleration mechanism to other astrophysical plasmas, the pump mechanism is applied to the acceleration of galactic cosmic rays in the interstellar medium.

  4. Planet signatures in collisionally active debris discs: scattered light images

    Science.gov (United States)

    Thebault, P.; Kral, Q.; Ertel, S.

    2012-11-01

    Context. Planet perturbations have been often invoked as a potential explanation for many spatial structures that have been imaged in debris discs. So far this issue has been mostly investigated with pure N-body numerical models, which neglect the crucial effect collisions within the disc can have on the disc's response to dynamical perturbations. Aims: We numerically investigate how the coupled effect of collisions and radiation pressure can affect the formation and survival of radial and azimutal structures in a disc perturbed by a planet. We consider two different set-ups: a planet embedded within an extended disc and a planet exterior to an inner debris ring. One important issue we want to address is under which conditions a planet's signature can be observable in a collisionally active disc. Methods: We use our DyCoSS code, which is designed to investigate the structure of perturbed debris discs at dynamical and collisional steady-state, and derive synthetic images of the system in scattered light. The planet's mass and orbit, as well as the disc's collisional activity (parameterized by its average vertical optical depth τ0) are explored as free parameters. Results: We find that collisions always significantly damp planet-induced spatial structures. For the case of an embedded planet, the planet's signature, mostly a density gap around its radial position, should remain detectable in head-on images if Mplanet ≥ MSaturn. If the system is seen edge-on, however, inferring the presence of the planet is much more difficult, as only weak asymmetries remain in a collisionally active disc, although some planet-induced signatures might be observable under very favourable conditions. For the case of an inner ring and an external planet, planetary perturbations cannot prevent collision-produced small fragments from populating the regions beyond the ring. The radial luminosity profile exterior to the ring is in most cases close to the one it should have in the absence

  5. Scaling Extreme Astrophysical Phenomena to the Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B A

    2007-11-01

    High-energy-density (HED) physics refers broadly to the study of macroscopic collections of matter under extreme conditions of temperature and density. The experimental facilities most widely used for these studies are high-power lasers and magnetic-pinch generators. The HED physics pursued on these facilities is still in its infancy, yet new regimes of experimental science are emerging. Examples from astrophysics include work relevant to planetary interiors, supernovae, astrophysical jets, and accreting compact objects (such as neutron stars and black holes). In this paper, we review a selection of recent results in this new field of HED laboratory astrophysics and provide a brief look ahead to the coming decade.

  6. Local models of astrophysical discs

    Science.gov (United States)

    Latter, Henrik N.; Papaloizou, John

    2017-12-01

    Local models of gaseous accretion discs have been successfully employed for decades to describe an assortment of small-scale phenomena, from instabilities and turbulence, to dust dynamics and planet formation. For the most part, they have been derived in a physically motivated but essentially ad hoc fashion, with some of the mathematical assumptions never made explicit nor checked for consistency. This approach is susceptible to error, and it is easy to derive local models that support spurious instabilities or fail to conserve key quantities. In this paper we present rigorous derivations, based on an asympototic ordering, and formulate a hierarchy of local models (incompressible, Boussinesq and compressible), making clear which is best suited for a particular flow or phenomenon, while spelling out explicitly the assumptions and approximations of each. We also discuss the merits of the anelastic approximation, emphasizing that anelastic systems struggle to conserve energy unless strong restrictions are imposed on the flow. The problems encountered by the anelastic approximation are exacerbated by the disc's differential rotation, but also attend non-rotating systems such as stellar interiors. We conclude with a defence of local models and their continued utility in astrophysical research.

  7. Colloidal Plasmas: Electrostatic sheath at the boundary of a ...

    Indian Academy of Sciences (India)

    Considering the Boltzmann response of the ions and electrons in plasma dynamics and inertial dynamics of the dust charged grains in a highly collisional dusty plasma, the nature of the electrostatic potential near a boundary is investigated. Based on the fluid approximation, the formation as well as the characteristic ...

  8. Connections between laser hydrodynamics experiments and astrophysics

    Science.gov (United States)

    Drake, R. P.; Robey, H. A.; Remington, B. A.; Ryutov, D. D.; Calder, A.; Rosner, R.; Fryxell, B.; Arnett, D.; Zhang, Y.; Glimm, J.; Knauer, J.

    2002-11-01

    Recent and ongoing experiments have studied mechanisms that affect the evolution of supernovae, supernova remnants, and related systems. These experiments are designed to be well scaled from astrophysical systems to the laboratory. The experiments and some of the astrophysical systems involve time-dependent flows with very large Reynolds number. In contrast, numerical viscosity limits computer simulations of these phenomena to a Reynolds number of order 1000. Using our own experiments and other work in fluid dynamics as a guide, we will explore the implications for astrophysical systems. The key question is whether the astrophysical systems might evolve into a turbulent state that the computer simulations cannot reproduce. The US DOE and NASA supported this work.

  9. Code Validation With Laser Astrophysics Experiments

    Science.gov (United States)

    Calder, A. C.; Fryxell, B.; Rosner, R.; Dursi, L. J.; Ricker, P. M.; Timmes, F. X.; Zingale, M.; Kane, J. O.; Remington, B. A.; Drake, R. P.; Olson, K.; MacNeice, P.; Tufo, H. M.

    2001-05-01

    An essential part of numerical modeling is validating simulation codes with laboratory experiments that capture many of the physical processes of interest. Validation is difficult in astrophysics because the problems of interest typically encompass complex physics and involve conditions that are difficult to reproduce in a terrestrial laboratory. Laboratory astrophysics with intense lasers serves as an invaluable validation tool by providing the chance to experimentally probe environments similar to those in which complex astrophysical phenomena occur. We describe the process of validating FLASH, an adaptive mesh astrophysical simulation code for compressible, reactive flows. We present the results of validation simulations, principally simulations of laser experiments involving shock propagation through multi-layer targets performed at the Omega laser facility at the University of Rochester. This work was supported by the DOE ASCI/Alliances program at the University of Chicago under grant No. B341495.

  10. Problem-based learning in astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Raine, Derek [Department of Physics and Astronomy, University of Leicester, Leicester (United Kingdom); Collett, James [Department of Physical Sciences, University of Hertfordshire, Hatfield (United Kingdom)

    2003-03-01

    Problem-based learning (PBL) can be integrated into the curriculum in many different ways. We compare three examples of PBL in undergraduate astrophysics programmes, and discuss the strengths and weaknesses of the various approaches.

  11. Underground nuclear astrophysics: why and how

    CERN Document Server

    Best, A; Fülöp, Zs; Gyürky, Gy; Laubenstein, M; Napolitani, E; Rigato, V; Roca, V; Szücs, T

    2016-01-01

    The goal of nuclear astrophysics is to measure cross sections of nuclear physics reactions of interest in astrophysics. At stars temperatures, these cross sections are very low due to the suppression of the Coulomb barrier. Cosmic ray induced background can seriously limit the determination of reaction cross sections at energies relevant to astrophysical processes and experimental setups should be arranged in order to improve the signal-to-noise ratio. Placing experiments in underground sites, however, reduces this background opening the way towards ultra low cross section determination. LUNA (Laboratory for Underground Nuclear Astrophysics) was pioneer in this sense. Two accelerators were mounted at the INFN National Laboratories of Gran Sasso (LNGS) allowing to study nuclear reactions close to stellar energies. A summary of the relevant technology used, including accelerators, target production and characterisation, and background treatment is given.

  12. Effect of collisional energy loss on particle correlations in AMPT

    Science.gov (United States)

    Wang, Fuqiang; Edmonds, Terrence; Li, Qingfeng

    2017-08-01

    Jet quenching is a powerful tool to study medium properties of relativistic heavy ion collisions via jet-medium interactions. Jet quenching studies have so far focused on high transverse momentum (pT) particle suppression. Jet shapes at low to intermediate pT, containing rich information on jet-medium interactions, have been less explored. In this talk, I will present a recent study, using a multiphase transport (AMPT) model, of effects on particle correlations from collisional energy loss of partons traversing the heavy ion medium. We follow the parton cascading history so that medium partons (associated particles) which have interacted with a high-pT probe parton (hard probe trigger particle) can be uniquely identified and hence no subtraction of combinatorial background is needed. Results on particle correlation shapes will be presented as a function of pT, the number of parton-parton collisions suffered by the probe parton, and the azimuthal angle of the probe parton relative to the reaction plane. These results reveal pathlength dependence of collisional energy loss.

  13. GAP CLEARING BY PLANETS IN A COLLISIONAL DEBRIS DISK

    Energy Technology Data Exchange (ETDEWEB)

    Nesvold, Erika R. [Department of Physics, University of Maryland Baltimore County 1000 Hilltop Circle Baltimore, MD 21250 (United States); Kuchner, Marc J., E-mail: Erika.Nesvold@umbc.edu, E-mail: Marc.Kuchner@nasa.gov [NASA Goddard Space Flight Center Exoplanets and Stellar Astrophysics Laboratory, Code 667 Greenbelt, MD 21230 (United States)

    2015-01-10

    We apply our 3D debris disk model, SMACK, to simulate a planet on a circular orbit near a ring of planetesimals that are experiencing destructive collisions. Previous simulations of a planet opening a gap in a collisionless debris disk have found that the width of the gap scales as the planet mass to the 2/7th power (α = 2/7). We find that gap sizes in a collisional disk still obey a power law scaling with planet mass, but that the index α of the power law depends on the age of the system t relative to the collisional timescale t {sub coll} of the disk by α = 0.32(t/t {sub coll}){sup –0.04}, with inferred planet masses up to five times smaller than those predicted by the classical gap law. The increased gap sizes likely stem from the interaction between collisions and the mean motion resonances near the chaotic zone. We investigate the effects of the initial eccentricity distribution of the disk particles and find a negligible effect on the gap size at Jovian planet masses, since collisions tend to erase memory of the initial particle eccentricity distributions. Finally, we find that the presence of Trojan analogs is a potentially powerful diagnostic of planets in the mass range ∼1-10 M {sub Jup}. We apply our model to place new upper limits on planets around Fomalhaut, HR 4796 A, HD 202628, HD 181327, and β Pictoris.

  14. Dynamical and collisional evolution of Kuiper belt binaries

    Science.gov (United States)

    Brunini, Adrián; Zanardi, Macarena

    2016-02-01

    We present numerical simulations of the evolution of synthetic transneptunian binaries (TNBs) under the influence of the solar perturbation, tidal friction, and collisions with the population of classical Kuiper belt objects (KBOs). We show that these effects, acting together, have strongly sculpted the primordial population of TNBs. If the population of classical KBOs have a power-law size distribution as the ones that are inferred from recent observational surveys, the fraction of surviving binaries at present would be ˜70 per cent of the primordial population. The orbits of the surviving synthetic systems match reasonably well the observed sample. The collisional process excites the mutual orbital eccentricity of the binaries, acting against the effect of tides. Therefore only ˜10 per cent of the objects reach total orbital circularization (e ≤ 10-4). In addition, our results predict that the population of contact binaries in the transneptunian region should be small. Ultrawide binaries are naturally obtained by the combined action of Kozai cycles and tidal friction and collisional evolution, being the number and orbital distribution of them very similar to the ones of the observed population.

  15. Astrophysics teaching at Assam University, Silchar

    Science.gov (United States)

    Das, Himadri Sekhar

    The Department of Physics is established in 1996 and since, then, thirteen batches of students have completed their Master’s programmes in the subject. The Department introduced in the year 2001 Astrophysics as one special paper in PG level (in the second year). The syllabus of Astrophysics is designed to include courses from observational Astronomy to Theoretical Astrophysics and Cosmology. There are two theory papers (in third and fourth semesters), one practical paper (in third semester) and one project or dissertation paper (in fourth semester), each one carries 100 marks. The major instruments available in the department for carrying out the experimental work are Meade-16 inch telescope, Celestron-8 inch inches Telescope, Meade refracting telescopes (4 inches, 2 number), SSP-5, SSP-3 photometer, Sivo Fibre-fed Spectrometer, CCD (Meade 416 XT, ST-6), Goniometer, Limb darkening apparatus etc. The practical paper includes study of the variation of sunspots; measurement of the parallax of distant objects, on moon and on planets like Jupiter and Saturn, measurement of the magnitude of different stars, study of the light scattering properties of rough surfaces, analysis of the image by image processing software (IRAF) etc. The project papers are based on research oriented topics which covers latest trends in Astrophysics including solar system studies, Interstellar medium and star formation studies and some problems in gravito-optics. There are altogether 6 scholars who have been awarded PhD and 10 are registered for PhD in Astrophysics. Besides these, 8 scholars have been awarded M. Phil. in Astrophysics. The broad research area of Astrophysics includes light scattering properties of cosmic dust, star formation, gravito optics, polarization study of comets etc. The Astrophysics group is currently doing research in different fields and have very good publications in several peer reviewed journals of international status.

  16. Cosmological and astrophysical neutrino mass measurements

    DEFF Research Database (Denmark)

    Abazajian, K.N.; Calabrese, E.; Cooray, A.

    2011-01-01

    Cosmological and astrophysical measurements provide powerful constraints on neutrino masses complementary to those from accelerators and reactors. Here we provide a guide to these different probes, for each explaining its physical basis, underlying assumptions, current and future reach.......Cosmological and astrophysical measurements provide powerful constraints on neutrino masses complementary to those from accelerators and reactors. Here we provide a guide to these different probes, for each explaining its physical basis, underlying assumptions, current and future reach....

  17. EMPIRE: A code for nuclear astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Palumbo, A. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2013-12-11

    The nuclear reaction code EMPIRE is presented as a useful tool for nuclear astrophysics. EMPIRE combines a variety of the reaction models with a comprehensive library of input parameters providing a diversity of options for the user. With exclusion of the directsemidirect capture all reaction mechanisms relevant to the nuclear astrophysics energy range of interest are implemented in the code. Comparison to experimental data show consistent agreement for all relevant channels.

  18. Dictionary of geophysics, astrophysics, and astronomy

    CERN Document Server

    Matzner, Richard A

    2001-01-01

    The Dictionary of Geophysics, Astrophysics, and Astronomy provides a lexicon of terminology covering fields such as astronomy, astrophysics, cosmology, relativity, geophysics, meteorology, Newtonian physics, and oceanography. Authors and editors often assume - incorrectly - that readers are familiar with all the terms in professional literature. With over 4,000 definitions and 50 contributing authors, this unique comprehensive dictionary helps scientists to use terminology correctly and to understand papers, articles, and books in which physics-related terms appear.

  19. Nonlinear evolution of longitudinal plasma waves

    Science.gov (United States)

    Pao, Young-Ping

    1988-01-01

    Long-time nonlinear behavior of single-mode longitudinal plasma waves is studied on the basis of the Vlasov equation with Fokker-Planck collision terms. The resonant layer, trapped island, collisional sublayers, and X-point neighborhoods are analyzed. A nonlinear evolution equation is obtained and the wave-generated current is also evaluated.

  20. Nuclear astrophysics: a new era

    Energy Technology Data Exchange (ETDEWEB)

    Wiescher, Michael; Aprahamian, Ani [Department of Physics, University of Notre Dame (United States); Regan, Paddy [Department of Physics, University of Surrey (United Kingdom)

    2002-02-01

    The latest generation of radioactive-ion-beam facilities promises to shed light on the complex nuclear processes that control the evolution of stars and stellar explosions. The most fundamental question in nature is where do we come from, or, put another way, what are we made of? The late Carl Sagan poetically said that we are all made of stardust, but the origin of the elements has fascinated scientists for thousands of years. Many of the greatest medieval and renaissance scientists dabbled in alchemy, trying to create the elements that make up the cosmos, but we had to wait until the early 20th century to recognize that elements are really defined by the number of protons in the nucleus. According to our current understanding, after the big bang most of the normal or baryonic material in the universe consisted of the lightest two elements, hydrogen and helium, with only trace amounts of lithium and beryllium. All the heavier elements that occur naturally on Earth were created from this original material via a series of nuclear reactions in the cores of stars or in stellar explosions. Over the last decade, ground-based telescopes and satellite-based Observatories have opened new windows on the stars across the electromagnetic spectrum, from infrared to gamma radiation. New technology now makes it possible to observe and analyse short-lived stellar explosions. Indeed, the distribution of elements in 'planetary nebula' and in the ejecta of supernovae and novae give a direct glimpse of individual nucleosynthesis processes. In the February issue of Physics World, Michael Wiescher, Paddy Regan and Ani Aprahamian describe how sate-of-the-art facilities are set to plug many of the gaps in our understanding of nuclear astrophysics. (U.K.)

  1. Astrophysical applications of gravitational microlensing

    Science.gov (United States)

    Mao, Shude

    2012-08-01

    Since the first discovery of microlensing events nearly two decades ago, gravitational microlensing has accumulated tens of TBytes of data and developed into a powerful astrophysical technique with diverse applications. The review starts with a theoretical overview of the field and then proceeds to discuss the scientific highlights. (1) Microlensing observations toward the Magellanic Clouds rule out the Milky Way halo being dominated by MAssive Compact Halo Objects (MACHOs). This confirms most dark matter is non-baryonic, consistent with other observations. (2) Microlensing has discovered about 20 extrasolar planets (16 published), including the first two Jupiter-Saturn like systems and the only five “cold Neptunes" yet detected. They probe a different part of the parameter space and will likely provide the most stringent test of core accretion theory of planet formation. (3) Microlensing provides a unique way to measure the mass of isolated stars, including brown dwarfs and normal stars. Half a dozen or so stellar mass black hole candidates have also been proposed. (4) High-resolution, target-of-opportunity spectra of highly-magnified dwarf stars provide intriguing “age" determinations which may either hint at enhanced helium enrichment or unusual bulge formation theories. (5) Microlensing also measured limb-darkening profiles for close to ten giant stars, which challenges stellar atmosphere models. (6) Data from surveys also provide strong constraints on the geometry and kinematics of the Milky Way bar (through proper motions); the latter indicates predictions from current models appear to be too anisotropic compared with observations. The future of microlensing is bright given the new capabilities of current surveys and forthcoming new telescope networks from the ground and from space. Some open issues in the field are identified and briefly discussed.

  2. Distance Measurement Solves Astrophysical Mysteries

    Science.gov (United States)

    2003-08-01

    Location, location, and location. The old real-estate adage about what's really important proved applicable to astrophysics as astronomers used the sharp radio "vision" of the National Science Foundation's Very Long Baseline Array (VLBA) to pinpoint the distance to a pulsar. Their accurate distance measurement then resolved a dispute over the pulsar's birthplace, allowed the astronomers to determine the size of its neutron star and possibly solve a mystery about cosmic rays. "Getting an accurate distance to this pulsar gave us a real bonanza," said Walter Brisken, of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. Monogem Ring The Monogem Ring, in X-Ray Image by ROSAT satellite CREDIT: Max-Planck Institute, American Astronomical Society (Click on Image for Larger Version) The pulsar, called PSR B0656+14, is in the constellation Gemini, and appears to be near the center of a circular supernova remnant that straddles Gemini and its neighboring constellation, Monoceros, and is thus called the Monogem Ring. Since pulsars are superdense, spinning neutron stars left over when a massive star explodes as a supernova, it was logical to assume that the Monogem Ring, the shell of debris from a supernova explosion, was the remnant of the blast that created the pulsar. However, astronomers using indirect methods of determining the distance to the pulsar had concluded that it was nearly 2500 light-years from Earth. On the other hand, the supernova remnant was determined to be only about 1000 light-years from Earth. It seemed unlikely that the two were related, but instead appeared nearby in the sky purely by a chance juxtaposition. Brisken and his colleagues used the VLBA to make precise measurements of the sky position of PSR B0656+14 from 2000 to 2002. They were able to detect the slight offset in the object's apparent position when viewed from opposite sides of Earth's orbit around the Sun. This effect, called parallax, provides a direct measurement of

  3. The kinematic behaviour of optical recombination lines and collisionally excited lines in Galactic planetary nebulae*†

    Science.gov (United States)

    Peña, Miriam; Ruiz-Escobedo, Francisco; Rechy-García, Jackeline S.; García-Rojas, Jorge

    2017-11-01

    The kinematics of the plasma in 14 planetary nebulae (PNe) is analysed by measuring the expansion velocities (Vexp) of different ions as derived from their collisionally excited lines (CELs) and optical recombination lines (ORLs). Vexp is analysed as a function of the ionization potential of ions, which at a first approximation represents the distance of the ion from the central star. In most cases, the kinematics of ORLs is incompatible with the kinematics of CELs at the same ionization potential, especially if CELs and ORLs are considered for the same ion. In general, Vexp from ORLs is lower than Vexp from CELs, indicating that, if the gas is in ionization equilibrium, ORLs are emitted by a gas located closer to the central star. The velocity field derived from CELs shows a gradient accelerating outwards as predicted from hydrodynamic modelling of PNe ionization structures. The velocity field derived from ORLs is different. In many cases, the velocity gradient is flatter or non-existent and highly and lowly ionized species present nearly the same Vexp. In addition, the full width at half-maximum (FWHM) for ORLs is usually smaller than FWHM(CEL). Our interpretation is that ORLs are mainly emitted by a plasma that coexists with the plasma emitting CELs, but does not fit the ionization structures predicted by models. Such a plasma should have been ejected in a different event from the plasma emitting CELs.

  4. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Editorial Board. Journal of Astrophysics and Astronomy. Chief Editor. Ram Sagar, Indian Institute of Astrophysics, Bengaluru. Associate Editor. Annapurni Subramaniam, Indian Institute of Astrophysics, Bengaluru T.P. Prabhu, Indian Institute of Astrophysics, Bengaluru. Editorial Board. P. Ajith, International Center for ...

  5. Scattering from isotropic plasma coated nihility sphere

    Science.gov (United States)

    Hussan, M. M.; Ghaffar, A.; Alkanhal, Majeed A. S.; Naz, M. Y.; Ur Rehman, Sajjad; Khan, Y.

    2017-06-01

    In this study, it is observed that when an isotropic collisional plasma coating layer is produced on a nihility sphere, its back scattering efficiency becomes non-zero. Field equations, at each interface, are expanded in terms of spherical wave vector functions (SWVFs) by enforcing the extended classical wave scattering theory. Electromagnetic boundary conditions are applied at both interfaces, i.e., free space-plasma and plasma layer-nihility sphere core to obtain the scattering coefficients. The obtained scattering coefficients are used to calculate the forward scattering, back scattering, and extinction efficiencies. The obtained computational results show that an increase in collisional frequency causes a decrease in both forward and backscattered efficiencies and an increase in extinction efficiency. Furthermore, the numerical results indicate that an increase in plasma density causes an increase in both forward and backscattered efficiencies and a decrease in extinction efficiency.

  6. Analysis of microscopic magnitudes of radiative blast waves launched in xenon clusters with collisional-radiative steady-state simulations

    Science.gov (United States)

    Rodriguez, R.; Espinosa, G.; Gil, J. M.; Florido, R.; Rubiano, J. G.; Mendoza, M. A.; Martel, P.; Minguez, E.; Symes, D. R.; Hohenberger, M.; Smith, R. A.

    2013-08-01

    Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shocks such as radiative blast waves propagate. In this work, by means of collisional-radiative steady-state calculations, a characterization and an analysis of microscopic magnitudes of laboratory blast waves launched in xenon clusters are made. Thus, for example, the average ionization, the charge state distribution, the cooling time or photon mean free paths are studied. Furthermore, for a particular experiment, the effects of the self-absorption and self-emission in the specific intensity emitted by the shock front and that is going through the radiative precursor are investigated. Finally, for that experiment, since the electron temperature is not measured experimentally, an estimation of this magnitude is made both for the shock shell and the radiative precursor.

  7. Upper bounds on collisional Penrose processes near rotating black-hole horizons

    Energy Technology Data Exchange (ETDEWEB)

    Piran, T.; Shaham, J.

    1977-09-15

    In this paper, we develop a general formalism for calculating energies of particles which escape to infinity after a collision in black-hole ergospheres. A few examples, in particular the Compton scattering, are discussed. For the latter, some model numerical calculations are presented which demonstrate the conversion of infalling low-energy photons into soft ..gamma.. rays by equatorial plasma rings in black-hole ergospheres. The main conclusion to be drawn from this paper is that Compton-Penrose processes in black-hole ergospheres could produce characteristic soft ..gamma.. rays, whose spectrum is strongly governed by the electron mass, and rather weakly controlled by other parameters. Such Penrose processes seem to be quite unique to black holes, and further thought might be given to their possible realizations in astrophysics. The processes are only effective in rapidly rotating black holes.

  8. The violent collisional history of asteroid 4 Vesta.

    Science.gov (United States)

    Marchi, S; McSween, H Y; O'Brien, D P; Schenk, P; De Sanctis, M C; Gaskell, R; Jaumann, R; Mottola, S; Preusker, F; Raymond, C A; Roatsch, T; Russell, C T

    2012-05-11

    Vesta is a large differentiated rocky body in the main asteroid belt that accreted within the first few million years after the formation of the earliest solar system solids. The Dawn spacecraft extensively imaged Vesta's surface, revealing a collision-dominated history. Results show that Vesta's cratering record has a strong north-south dichotomy. Vesta's northern heavily cratered terrains retain much of their earliest history. The southern hemisphere was reset, however, by two major collisions in more recent times. We estimate that the youngest of these impact structures, about 500 kilometers across, formed about 1 billion years ago, in agreement with estimates of Vesta asteroid family age based on dynamical and collisional constraints, supporting the notion that the Vesta asteroid family was formed during this event.

  9. Space and Astrophysical Plasmas: Dromion solutions for an electron ...

    Indian Academy of Sciences (India)

    –Stewartson I equation which admits so called dromion solutions. The importance of these two dimensional localized solutions for recent satellite observations of wave structures in the day side polar cap regions is discussed and the parameter ...

  10. The solar corona - A testing ground for plasma astrophysics

    Science.gov (United States)

    Rosner, R.

    1982-01-01

    The extension of solar surface activity models to the domain of stellar activity, and the possibility of testing such extensions, are discussed. The extrapolation of three canonical solar activity indicators, sunspots, Ca II emission, and solar flares, to other stars is considered. The use of satellites to study stellar activity at wavelengths at which surface activity is most prominent is briefly reviewed. The correlation of stellar activity with intrinsic stellar parameters, especially those relating to rotation, is briefly considered, and the use of phenomenological models of stellar coronal X-ray emission to deduce the magnetic flux production rate for observed stars as a function of rotation rate is discussed.

  11. Space and Astrophysical Plasmas: Sun–Earth connection: Boundary ...

    Indian Academy of Sciences (India)

    Author Affiliations. G S Lakhina1 B T Tsurutani2 J K Arballo2 C Galvan2. Indian Institute of Geomagnetism, Colaba, Mumbai 400 005, India; Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA ...

  12. Complexity methods applied to turbulence in plasma astrophysics

    Science.gov (United States)

    Vlahos, L.; Isliker, H.

    2016-09-01

    In this review many of the well known tools for the analysis of Complex systems are used in order to study the global coupling of the turbulent convection zone with the solar atmosphere where the magnetic energy is dissipated explosively. Several well documented observations are not easy to interpret with the use of Magnetohydrodynamic (MHD) and/or Kinetic numerical codes. Such observations are: (1) The size distribution of the Active Regions (AR) on the solar surface, (2) The fractal and multi fractal characteristics of the observed magnetograms, (3) The Self-Organised characteristics of the explosive magnetic energy release and (4) the very efficient acceleration of particles during the flaring periods in the solar corona. We review briefly the work published the last twenty five years on the above issues and propose solutions by using methods borrowed from the analysis of complex systems. The scenario which emerged is as follows: (a) The fully developed turbulence in the convection zone generates and transports magnetic flux tubes to the solar surface. Using probabilistic percolation models we were able to reproduce the size distribution and the fractal properties of the emerged and randomly moving magnetic flux tubes. (b) Using a Non Linear Force Free (NLFF) magnetic extrapolation numerical code we can explore how the emerged magnetic flux tubes interact nonlinearly and form thin and Unstable Current Sheets (UCS) inside the coronal part of the AR. (c) The fragmentation of the UCS and the redistribution of the magnetic field locally, when the local current exceeds a Critical threshold, is a key process which drives avalanches and forms coherent structures. This local reorganization of the magnetic field enhances the energy dissipation and influences the global evolution of the complex magnetic topology. Using a Cellular Automaton and following the simple rules of Self Organized Criticality (SOC), we were able to reproduce the statistical characteristics of the observed time series of the explosive events, (d) finally, when the AR reaches the turbulently reconnecting state (in the language of the SOC theory this is called SOC state) it is densely populated by UCS which can act as local scatterers (replacing the magnetic clouds in the Fermi scenario) and enhance dramatically the heating and acceleration of charged particles.

  13. Astrophysical disks Collective and Stochastic Phenomena

    CERN Document Server

    Fridman, Alexei M; Kovalenko, Ilya G

    2006-01-01

    The book deals with collective and stochastic processes in astrophysical discs involving theory, observations, and the results of modelling. Among others, it examines the spiral-vortex structure in galactic and accretion disks , stochastic and ordered structures in the developed turbulence. It also describes sources of turbulence in the accretion disks, internal structure of disk in the vicinity of a black hole, numerical modelling of Be envelopes in binaries, gaseous disks in spiral galaxies with shock waves formation, observation of accretion disks in a binary system and mass distribution of luminous matter in disk galaxies. The editors adaptly brought together collective and stochastic phenomena in the modern field of astrophysical discs, their formation, structure, and evolution involving the methodology to deal with, the results of observation and modelling, thereby advancing the study in this important branch of astrophysics and benefiting Professional Researchers, Lecturers, and Graduate Students.

  14. The Astrophysics Science Division Annual Report 2008

    Science.gov (United States)

    Oegerle, William; Reddy, Francis; Tyler, Pat

    2009-01-01

    The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radio wavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. This report includes the Division's activities during 2008.

  15. Review of Astrophysics Experiments on Intense Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B A; Drake, R P; Takabe, H; Arnett, D

    2000-01-19

    Astrophysics has traditionally been pursued at astronomical observatories and on theorists' computers. Observations record images from space, and theoretical models are developed to explain the observations. A component often missing has been the ability to test theories and models in an experimental setting where the initial and final states are well characterized. Intense lasers are now being used to recreate aspects of astrophysical phenomena in the laboratory, allowing the creation of experimental testbeds where theory and modeling can be quantitatively tested against data. We describe here several areas of astrophysics--supernovae, supernova remnants, gamma-ray bursts, and giant planets--where laser experiments are under development to test our understanding of these phenomena.

  16. Relevance of collisionality in the transport model assumptions for divertor detachment multi-fluid modelling on JET

    DEFF Research Database (Denmark)

    Wiesen, S.; Fundamenski, W.; Wischmeier, M.

    2011-01-01

    A revised formulation of the perpendicular diffusive transport model in 2D multi-fluid edge codes is proposed. Based on theoretical predictions and experimental observations a dependence on collisionality is introduced into the transport model of EDGE2D–EIRENE. The impact on time-dependent JET gas...... fuelled ramp-up scenario modelling of the full transient from attached divertor into the high-recycling regime, following a target flux roll over into divertor detachment, ultimately ending in a density limit is presented. A strong dependence on divertor geometry is observed which can mask features...... of the new transport model: a smoothly decaying target recycling flux roll over, an asymmetric drop of temperature and pressure along the field lines as well as macroscopic power dependent plasma oscillations near the density limit which had been previously observed also experimentally. The latter effect...

  17. Laboratory Astrophysics Division of the AAS (LAD)

    Science.gov (United States)

    Salama, Farid; Drake, R. P.; Federman, S. R.; Haxton, W. C.; Savin, D. W.

    2012-01-01

    The purpose of the Laboratory Astrophysics Division (LAD) is to advance our understanding of the Universe through the promotion of fundamental theoretical and experimental research into the underlying processes that drive the Cosmos. LAD represents all areas of astrophysics and planetary sciences. The first new AAS Division in more than 30 years, the LAD traces its history back to the recommendation from the scientific community via the White Paper from the 2006 NASA-sponsored Laboratory Astrophysics Workshop. This recommendation was endorsed by the Astronomy and Astrophysics Advisory Committee (AAAC), which advises the National Science Foundation (NSF), the National Aeronautics and Space Administration (NASA), and the U.S. Department of Energy (DOE) on selected issues within the fields of astronomy and astrophysics that are of mutual interest and concern to the agencies. In January 2007, at the 209th AAS meeting, the AAS Council set up a Steering Committee to formulate Bylaws for a Working Group on Laboratory Astrophysics (WGLA). The AAS Council formally established the WGLA with a five-year mandate in May 2007, at the 210th AAS meeting. From 2008 through 2012, the WGLA annually sponsored Meetings in-a-Meeting at the AAS Summer Meetings. In May 2011, at the 218th AAS meeting, the AAS Council voted to convert the WGLA, at the end of its mandate, into a Division of the AAS and requested draft Bylaws from the Steering Committee. In January 2012, at the 219th AAS Meeting, the AAS Council formally approved the Bylaws and the creation of the LAD. The inaugural gathering and the first business meeting of the LAD were held at the 220th AAS meeting in Anchorage in June 2012. You can learn more about LAD by visiting its website at http://lad.aas.org/ and by subscribing to its mailing list.

  18. ENZO: AN ADAPTIVE MESH REFINEMENT CODE FOR ASTROPHYSICS

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, Greg L.; Turk, Matthew J. [Columbia University, Department of Astronomy, New York, NY 10025 (United States); Norman, Michael L.; Bordner, James; Xu, Hao; Kritsuk, Alexei G. [CASS, University of California, San Diego, 9500 Gilman Drive La Jolla, CA 92093-0424 (United States); O' Shea, Brian W.; Smith, Britton [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Abel, Tom; Wang, Peng; Skillman, Samuel W. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Menlo Park, CA 94025 (United States); Wise, John H. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA (United States); Reynolds, Daniel R. [Department of Mathematics, Southern Methodist University, Box 750156, Dallas, TX 75205-0156 (United States); Collins, David C. [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Harkness, Robert P. [NICS, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831 (United States); Kim, Ji-hoon [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Kuhlen, Michael [Theoretical Astrophysics Center, University of California Berkeley, Hearst Field Annex, Berkeley, CA 94720 (United States); Goldbaum, Nathan [Institute for Astronomy, University of Edinburgh, Edinburgh EH9 3HJ (United Kingdom); Hummels, Cameron [Department of Astronomy/Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Tasker, Elizabeth [Physics Department, Faculty of Science, Hokkaido University, Kita-10 Nishi 8, Kita-ku, Sapporo 060-0810 (Japan); Collaboration: Enzo Collaboration; and others

    2014-04-01

    This paper describes the open-source code Enzo, which uses block-structured adaptive mesh refinement to provide high spatial and temporal resolution for modeling astrophysical fluid flows. The code is Cartesian, can be run in one, two, and three dimensions, and supports a wide variety of physics including hydrodynamics, ideal and non-ideal magnetohydrodynamics, N-body dynamics (and, more broadly, self-gravity of fluids and particles), primordial gas chemistry, optically thin radiative cooling of primordial and metal-enriched plasmas (as well as some optically-thick cooling models), radiation transport, cosmological expansion, and models for star formation and feedback in a cosmological context. In addition to explaining the algorithms implemented, we present solutions for a wide range of test problems, demonstrate the code's parallel performance, and discuss the Enzo collaboration's code development methodology.

  19. Applications of electrodynamics in theoretical physics and astrophysics.

    Science.gov (United States)

    Ginzburg, V. L.

    This book, revised from the third Russian edition of "Teoreticheskaya fizika i astrofizika", is translated by Oleg Glebov. The problems dealt with are associated with microscopic and macroscopic electrodynamics and material concerning the theory of transition radiation and transition scattering. Contents: 1. The Hamiltonian approach to electrodynamics. 2. Radiation reaction. 3. Uniformly accelerated charges. 4. Radiation emitted by relativistic and non-relativistic moving particles. 5. Synchrotron radiation. 6. Electrodynamics of a continuous medium. 7. The Čerenkov and Doppler effects. 8. Transition radiation and transition scattering. 9. Superluminal sources of radiation. 10. Reabsorption and transfer of radiation. 11. Electrodynamics of media with spatial dispersion. 12. Permittivity and wave propagation in plasmas. 13. The energy-momentum tensor and forces in macroscopic electrodynamics. Energy and heat liberated in a dispersive absorbing medium. 14. Fluctuations and van der Waals forces. 15. Wave scattering in a medium. 16. Astrophysics of cosmic rays. 17. X-ray astronomy. 18. Gamma-ray astronomy.

  20. The Astrophysics of Emission-Line Stars

    CERN Document Server

    Kogure, Tomokazu

    2007-01-01

    Many types of stars show conspicuous emission lines in their optical spectra. These stars are broadly referred to as emission line stars. Emission line stars are attractive to many people because of their spectacular phenomena and their variability. The Astrophysics of Emission Line Stars offers general information on emission line stars, starting from a brief introduction to stellar astrophysics, and then moving toward a broad overview of emission line stars including early and late type stars as well as pre-main sequence stars. Detailed references have been prepared along with an index for further reading.

  1. Byurakan Astrophysical Observatory as Cultural Centre

    Science.gov (United States)

    Mickaelian, A. M.; Farmanyan, S. V.

    2017-07-01

    NAS RA V. Ambartsumian Byurakan Astrophysical Observatory is presented as a cultural centre for Armenia and the Armenian nation in general. Besides being scientific and educational centre, the Observatory is famous for its unique architectural ensemble, rich botanical garden and world of birds, as well as it is one of the most frequently visited sightseeing of Armenia. In recent years, the Observatory has also taken the initiative of the coordination of the Cultural Astronomy in Armenia and in this field, unites the astronomers, historians, archaeologists, ethnographers, culturologists, literary critics, linguists, art historians and other experts. Keywords: Byurakan Astrophysical Observatory, architecture, botanic garden, tourism, Cultural Astronomy.

  2. On the saturation of astrophysical dynamos

    DEFF Research Database (Denmark)

    Dorch, Bertil; Archontis, Vasilis

    2004-01-01

    In the context of astrophysical dynamos we illustrate that the no-cosines flow, with zero mean helicity, can drive fast dynamo action and we study the dynamo's mode of operation during both the linear and non-linear saturation regimes. It turns out that in addition to a high growth rate in the li......In the context of astrophysical dynamos we illustrate that the no-cosines flow, with zero mean helicity, can drive fast dynamo action and we study the dynamo's mode of operation during both the linear and non-linear saturation regimes. It turns out that in addition to a high growth rate...

  3. Advances in astronomy and astrophysics 9

    CERN Document Server

    Kopal, Zdenek

    1972-01-01

    Advances in Astronomy and Astrophysics, Volume 9 covers reviews on the advances in astronomy and astrophysics. The book presents reviews on the Roche model and its applications to close binary systems. The text then describes the part played by lunar eclipses in the evolution of astronomy; the classical theory of lunar eclipses; deviations from geometrical theory; and the methods of photometric observations of eclipses. The problems of other phenomena related in one way or another to lunar eclipses are also considered. The book further tackles the infrared observation on the eclipsed moon, as

  4. Advances in astronomy and astrophysics 7

    CERN Document Server

    Kopal, Zdenek

    2013-01-01

    Advances in Astronomy and Astrophysics, Volume 7 covers reviews about the advances in astronomy and astrophysics. The book presents reviews on the scattering of electrons by diatomic molecules and on Babcock's theory of the 22-year solar cycle and the latitude drift of the sunspot zone. The text then describes reviews on the structures of the terrestrial planets (Earth, Venus, Mars, Mercury) and on type III solar radio bursts. The compact and dispersed cosmic matter is also considered with regard to the search for new cosmic objects and phenomena and on the nature of the ref shift from compact

  5. Magnetic processes in astrophysics theory, simulations, experiments

    CERN Document Server

    Rüdiger, Günther; Hollerbach, Rainer

    2013-01-01

    In this work the authors draw upon their expertise in geophysical and astrophysical MHD to explore the motion of electrically conducting fluids, the so-called dynamo effect, and describe the similarities and differences between different magnetized objects. They also explain why magnetic fields are crucial to the formation of the stars, and discuss promising experiments currently being designed to investigate some of the relevant physics in the laboratory. This interdisciplinary approach will appeal to a wide audience in physics, astrophysics and geophysics. This second edition covers such add

  6. White Paper on Nuclear Astrophysics and Low Energy Nuclear Physics - Part 1. Nuclear Astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Arcones, Almudena [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Escher, Jutta E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Others, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-04-04

    This white paper informs the nuclear astrophysics community and funding agencies about the scientific directions and priorities of the field and provides input from this community for the 2015 Nuclear Science Long Range Plan. It summarizes the outcome of the nuclear astrophysics town meeting that was held on August 21 - 23, 2014 in College Station at the campus of Texas A&M University in preparation of the NSAC Nuclear Science Long Range Plan. It also reflects the outcome of an earlier town meeting of the nuclear astrophysics community organized by the Joint Institute for Nuclear Astrophysics (JINA) on October 9 - 10, 2012 Detroit, Michigan, with the purpose of developing a vision for nuclear astrophysics in light of the recent NRC decadal surveys in nuclear physics (NP2010) and astronomy (ASTRO2010). The white paper is furthermore informed by the town meeting of the Association of Research at University Nuclear Accelerators (ARUNA) that took place at the University of Notre Dame on June 12 - 13, 2014. In summary we find that nuclear astrophysics is a modern and vibrant field addressing fundamental science questions at the intersection of nuclear physics and astrophysics. These questions relate to the origin of the elements, the nuclear engines that drive life and death of stars, and the properties of dense matter. A broad range of nuclear accelerator facilities, astronomical observatories, theory efforts, and computational capabilities are needed. With the developments outlined in this white paper, answers to long-standing key questions are well within reach in the coming decade.

  7. What is a plasma?

    Energy Technology Data Exchange (ETDEWEB)

    Intrator, Thomas P. [Los Alamos National Laboratory

    2012-08-30

    This introduction will define the plasma fourth state of matter, where we find plasmas on earth and beyond, and why they are useful. There are applications to many consumer items, fusion energy, scientific devices, satellite communications, semiconductor processing, spacecraft propulsion, and more. Since 99% of our observable universe is ionized gas, plasma physics determines many important features of astrophysics, space physics, and magnetosphere physics in our solar system. We describe some plasma characteristics, examples in nature, some useful applications, how to create plasmas. A brief introduction to the theoretical framework includes the connection between kinetic and fluid descriptions, quasi neutrality, Debye shielding, ambipolar electric fields, some plasma waves. Hands-on demonstrations follow. More complete explanations will follow next week.

  8. Dust production by collisional grinding during Planetesimal-Driven Migration

    Science.gov (United States)

    Salmon, Julien; Walsh, Kevin J.; Levison, Harold F.

    2017-10-01

    Many main-sequence stars are surrounded by optically thin disks of dust in the absence of any detectable gas (e.g. Su et al. 2006, Meyer et al. 2008). IR and sub-millimeter observations suggest that most of the observed emission comes from grains with sizes between 1-100 microns. Since radiation forces are expected to remove these grains on timescales much shorter than the age of the parent stars (Backman & Parsce 1993, Wyatt 2008), it implies that some process is replenishing the dust, such as collisional grinding. The latter requires large impact velocities between planetesimals, which can be achieved if large objects are dynamically exciting a disk of 1-10km planetesimals. Such debris disks could be hosting ongoing planet formation, and present a powerful tool to test planet formation theories.If a planet is embedded in a gas-free planetesimal disk, the mutual gravitational interactions will force the planet to migrate (e.g. Fernandez & Ip 1984). Planetesimals situated along the direction of migration can be trapped in mean motion resonances (MMRs) with the planet (Malhotra 1993, 1995, Hahn & Malholtra 1999). Planetesimals trapped in such resonances will have their eccentricities pumped to large values as the planet continues to migrate, thereby leading to energetic collisions and dust production (Wyatt 2003, Reche et al. 2008, Mustill & Wyatt 2011).We have performed an extensive suite of simulations in which we explore the likelihood that a given set of disk parameters (mass, surface density slope, number of planetesimals) can sustain planetesimal-driven migration (PDM). We confirm the strong dependence on resolution found in previous works (e.g. Kirsch et al 2009), and find that an embryo to planetesimal mass ratio of 400 is necessary to mitigate the effects of stochasticity, which may cause migration to stall and/or reverse. After having identified disks suitable for sustained PDM, we model their evolution using LIPAD (Levison et al. 2012) taking into account

  9. Collisional transfer of population and orientation in NaK.

    Science.gov (United States)

    Wolfe, C M; Ashman, S; Bai, J; Beser, B; Ahmed, E H; Lyyra, A M; Huennekens, J

    2011-05-07

    Collisional satellite lines with |ΔJ| ≤ 58 have been identified in recent polarization spectroscopy V-type optical-optical double resonance (OODR) excitation spectra of the Rb(2) molecule [H. Salami et al., Phys. Rev. A 80, 022515 (2009)]. Observation of these satellite lines clearly requires a transfer of population from the rotational level directly excited by the pump laser to a neighboring level in a collision of the molecule with an atomic perturber. However to be observed in polarization spectroscopy, the collision must also partially preserve the angular momentum orientation, which is at least somewhat surprising given the extremely large values of ΔJ that were observed. In the present work, we used the two-step OODR fluorescence and polarization spectroscopy techniques to obtain quantitative information on the transfer of population and orientation in rotationally inelastic collisions of the NaK molecules prepared in the 2(A)(1)Σ(+)(v' = 16, J' = 30) rovibrational level with argon and potassium perturbers. A rate equation model was used to study the intensities of these satellite lines as a function of argon pressure and heat pipe oven temperature, in order to separate the collisional effects of argon and potassium atoms. Using a fit of this rate equation model to the data, we found that collisions of NaK molecules with potassium atoms are more likely to transfer population and destroy orientation than collisions with argon atoms. Collisions with argon atoms show a strong propensity for population transfer with ΔJ = even. Conversely, collisions with potassium atoms do not show this ΔJ = even propensity, but do show a propensity for ΔJ = positive compared to ΔJ = negative, for this particular initial state. The density matrix equations of motion have also been solved numerically in order to test the approximations used in the rate equation model and to calculate fluorescence and polarization spectroscopy line shapes. In addition, we have measured

  10. Workshop on gravitational waves and relativistic astrophysics

    Indian Academy of Sciences (India)

    Discussions related to gravitational wave experiments viz. LIGO and LISA as well as to observations of supermassive black holes dominated the workshop sessions on gravitational waves and relativistic astrophysics in the ICGC-2004. A summary of seven papers that were presented in these workshop sessions has been ...

  11. Nuclear astrophysics and the Trojan Horse Method

    Energy Technology Data Exchange (ETDEWEB)

    Spitaleri, C. [University of Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); Laboratori Nazionali del Sud - INFN, Catania (Italy); La Cognata, M.; Pizzone, R.G. [Laboratori Nazionali del Sud - INFN, Catania (Italy); Lamia, L. [University of Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); Mukhamedzhanov, A.M. [Texas A and M University, Cyclotron Institute, College Station, TX (United States)

    2016-04-15

    In this review, we discuss the new recent results of the Trojan Horse Method that is used to determine reaction rates for nuclear processes in several astrophysical scenarios. The theory behind this technique is shortly presented. This is followed by an overview of some new experiments that have been carried out using this indirect approach. (orig.)

  12. Minicourses in Astrophysics, Modular Approach, Vol. II.

    Science.gov (United States)

    Illinois Univ., Chicago.

    This is the second of a two-volume minicourse in astrophysics. It contains chapters on the following topics: stellar nuclear energy sources and nucleosynthesis; stellar evolution; stellar structure and its determination; and pulsars. Each chapter gives much technical discussion, mathematical treatment, diagrams, and examples. References are…

  13. Astronomical optical interferometry, II: Astrophysical results

    Directory of Open Access Journals (Sweden)

    Jankov S.

    2011-01-01

    Full Text Available Optical interferometry is entering a new age with several ground- based long-baseline observatories now making observations of unprecedented spatial resolution. Based on a great leap forward in the quality and quantity of interferometric data, the astrophysical applications are not limited anymore to classical subjects, such as determination of fundamental properties of stars; namely, their effective temperatures, radii, luminosities and masses, but the present rapid development in this field allowed to move to a situation where optical interferometry is a general tool in studies of many astrophysical phenomena. Particularly, the advent of long-baseline interferometers making use of very large pupils has opened the way to faint objects science and first results on extragalactic objects have made it a reality. The first decade of XXI century is also remarkable for aperture synthesis in the visual and near-infrared wavelength regimes, which provided image reconstructions from stellar surfaces to Active Galactic Nuclei. Here I review the numerous astrophysical results obtained up to date, except for binary and multiple stars milliarcsecond astrometry, which should be a subject of an independent detailed review, taking into account its importance and expected results at microarcsecond precision level. To the results obtained with currently available interferometers, I associate the adopted instrumental settings in order to provide a guide for potential users concerning the appropriate instruments which can be used to obtain the desired astrophysical information.

  14. Astronomical Optical Interferometry. II. Astrophysical Results

    Science.gov (United States)

    Jankov, S.

    2011-12-01

    Optical interferometry is entering a new age with several ground-based long-baseline observatories now making observations of unprecedented spatial resolution. Based on a great leap forward in the quality and quantity of interferometric data, the astrophysical applications are not limited anymore to classical subjects, such as determination of fundamental properties of stars; namely, their effective temperatures, radii, luminosities and masses, but the present rapid development in this field allowed to move to a situation where optical interferometry is a general tool in studies of many astrophysical phenomena. Particularly, the advent of long-baseline interferometers making use of very large pupils has opened the way to faint objects science and first results on extragalactic objects have made it a reality. The first decade of XXI century is also remarkable for aperture synthesis in the visual and near-infrared wavelength regimes, which provided image reconstructions from stellar surfaces to Active Galactic Nuclei. Here I review the numerous astrophysical results obtained up to date, except for binary and multiple stars milli-arcsecond astrometry, which should be a subject of an independent detailed review, taking into account its importance and expected results at micro-arcsecond precision level. To the results obtained with currently available interferometers, I associate the adopted instrumental settings in order to provide a guide for potential users concerning the appropriate instruments which can be used to obtain the desired astrophysical information.

  15. Virtually Lossless Compression of Astrophysical Images

    Directory of Open Access Journals (Sweden)

    Stefano Baronti

    2005-09-01

    Full Text Available We describe an image compression strategy potentially capable of preserving the scientific quality of astrophysical data, simultaneously allowing a consistent bandwidth reduction to be achieved. Unlike strictly lossless techniques, by which moderate compression ratios are attainable, and conventional lossy techniques, in which the mean square error of the decoded data is globally controlled by users, near-lossless methods are capable of locally constraining the maximum absolute error, based on user's requirements. An advanced lossless/near-lossless differential pulse code modulation (DPCM scheme, recently introduced by the authors and relying on a causal spatial prediction, is adjusted to the specific characteristics of astrophysical image data (high radiometric resolution, generally low noise, etc.. The background noise is preliminarily estimated to drive the quantization stage for high quality, which is the primary concern in most of astrophysical applications. Extensive experimental results of lossless, near-lossless, and lossy compression of astrophysical images acquired by the Hubble space telescope show the advantages of the proposed method compared to standard techniques like JPEG-LS and JPEG2000. Eventually, the rationale of virtually lossless compression, that is, a noise-adjusted lossles/near-lossless compression, is highlighted and found to be in accordance with concepts well established for the astronomers' community.

  16. Evolution and seismic tools for stellar astrophysics

    CERN Document Server

    Monteiro, Mario JPFG

    2008-01-01

    A collection of articles published by the journal "Astrophysics and Space Science, Volume 316, Number 1-4", August 2008. This work covers 10 evolution codes and 9 oscillation codes. It is suitable for researchers and research students working on the modeling of stars and on the implementation of seismic test of stellar models.

  17. Experimental Measurement of Self-Diffusion in a Strongly Coupled Plasma

    Science.gov (United States)

    2016-08-04

    collisional relaxation of ion velocities in a strongly coupled, ultracold neutral plasma on short time scales compared to the inverse collision rate. The... collisional correlations at the microscopic level [15,19,47,48]. It can be derived from a generalized Langevin equation describing the motion of a single...test particle experiencing memory effects and fluctuating forces , which is familiar from treatments of Brownian motion [19,47]. The evolution of the

  18. High-Energy-Density, Laboratory-Astrophysics Studies of Jets and Bow Shocks

    Energy Technology Data Exchange (ETDEWEB)

    Foster, J M; Wilde, B H; Rosen, P A; Perry, T S; Khokhlov, A M; Coker, R F; Frank, A; Keiter, P A; Blue, B E; Drake, R P; Knauer, J P; Williams, R R

    2005-01-24

    Large-scale directional outflows of supersonic plasma, also known as ''jets'', are ubiquitous phenomena in astrophysics [1]. The interaction of such jets with surrounding matter often results in spectacular bow shocks, and intense radiation from radio to gamma-ray wavelengths. The traditional approach to understanding such phenomena is through theoretical analysis and numerical simulations. However, such numerical simulations have limited resolution, often assume axial symmetry, do not include all relevant physical processes, and fail to scale correctly in Reynolds number and perhaps other key dimensionless parameters. Additionally, they are frequently not tested by comparison with laboratory experiments. Recent advances in high-energy-density physics using large inertial-confinement-fusion devices now allow controlled laboratory experiments on macroscopic volumes of plasma of direct relevance relevant to astrophysics [2]. In this Letter we report the first results of experiments designed to study the evolution of supersonic plasma jets and the bow shocks they drive into a surrounding medium. Our experiments reveal both regular and highly complex flow patterns in the bow shock, thus opening a new window--complementary to computer simulations--into understanding the nature of three-dimensional astrophysical jets.

  19. The Astrophysics Simulation Collaboratory portal: A framework foreffective distributed research

    Energy Technology Data Exchange (ETDEWEB)

    Bondarescu, Ruxandra; Allen, Gabrielle; Daues, Gregory; Kelly,Ian; Russell, Michael; Seidel, Edward; Shalf, John; Tobias, Malcolm

    2003-03-03

    We describe the motivation, architecture, and implementation of the Astrophysics Simulation Collaboratory (ASC) portal. The ASC project provides a web-based problem solving framework for the astrophysics community that harnesses the capabilities of emerging computational grids.

  20. Current-Driven Filament Instabilities in Relativistic Plasmas. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Chuang

    2013-02-13

    This grant has supported a study of some fundamental problems in current- and flow-driven instabilities in plasmas and their applications in inertial confinement fusion (ICF) and astrophysics. It addressed current-driven instabilities and their roles in fast ignition, and flow-driven instabilities and their applications in astrophysics.

  1. HIDING IN THE SHADOWS. II. COLLISIONAL DUST AS EXOPLANET MARKERS

    Energy Technology Data Exchange (ETDEWEB)

    Dobinson, Jack; Leinhardt, Zoë M.; Lines, Stefan; Carter, Philip J. [University of Bristol, School of Physics, H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Dodson-Robinson, Sarah E. [University of Delaware, Department of Physics and Astronomy, 217 Sharp Lab, Newark, DE 19716 (United States); Teanby, Nick A. [University of Bristol, School of Earth Sciences, H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)

    2016-03-20

    Observations of the youngest planets (∼1–10 Myr for a transitional disk) will increase the accuracy of our planet formation models. Unfortunately, observations of such planets are challenging and time-consuming to undertake, even in ideal circumstances. Therefore, we propose the determination of a set of markers that can preselect promising exoplanet-hosting candidate disks. To this end, N-body simulations were conducted to investigate the effect of an embedded Jupiter-mass planet on the dynamics of the surrounding planetesimal disk and the resulting creation of second-generation collisional dust. We use a new collision model that allows fragmentation and erosion of planetesimals, and dust-sized fragments are simulated in a post-process step including non-gravitational forces due to stellar radiation and a gaseous protoplanetary disk. Synthetic images from our numerical simulations show a bright double ring at 850 μm for a low-eccentricity planet, whereas a high-eccentricity planet would produce a characteristic inner ring with asymmetries in the disk. In the presence of first-generation primordial dust these markers would be difficult to detect far from the orbit of the embedded planet, but would be detectable inside a gap of planetary origin in a transitional disk.

  2. Collisional disruption of gravitational aggregates in the tidal environment

    Energy Technology Data Exchange (ETDEWEB)

    Hyodo, Ryuki; Ohtsuki, Keiji [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan)

    2014-05-20

    The degree of disruption in collisions in free space is determined by specific impact energy, and the mass fraction of the largest remnant is a monotonically decreasing function of impact energy. However, it has not been shown whether such a relationship is applicable to collisions under the influence of a planet's tidal force, which is important in ring dynamics and satellite accretion. Here we examine the collisional disruption of gravitational aggregates in the tidal environment by using local N-body simulations. We find that outcomes of such a collision largely depend on the impact velocity, the direction of impact, and the radial distance from the planet. In the case of a strong tidal field corresponding to Saturn's F ring, collisions in the azimuthal direction are much more destructive than those in the radial direction. Numerical results of collisions sensitively depend on the impact velocity, and a complete disruption of aggregates can occur even in impacts with velocity much lower than their escape velocity. In such low-velocity collisions, the deformation of colliding aggregates plays an essential role in determining collision outcomes, because the physical size of the aggregate is comparable to its Hill radius. On the other hand, the dependence of collision outcomes on impact velocity becomes similar to the case in free space when the distance from the planet is sufficiently large. Our results are consistent with Cassini observations of the F ring, which suggest ongoing creation and disruption of aggregates within the ring.

  3. Cancellation of Collisional Frequency Shifts in Optical Lattice Clocks with Rabi Spectroscopy

    OpenAIRE

    Lee, Sangkyung; Park, Chang Yong; Lee, Won-Kyu; Yu, Dai-Hyuk

    2015-01-01

    We analyze both the s- and p-wave collision induced frequency shifts and propose a over-$\\pi$ pulse scheme to cancel the shifts in optical lattice clocks interrogated by a Rabi pulse. The collisional frequency shifts are analytically solved as a function of the pulse area and the inhomogeneity of the Rabi frequencies. Experimentally measured collisional frequency shifts in an Yb optical lattice clock are in good agreement with the analytical calculations. Based on our analysis, the over-$\\pi$...

  4. 3rd Session of the Sant Cugat Forum on Astrophysics

    CERN Document Server

    Gravitational wave astrophysics

    2015-01-01

    This book offers review chapters written by invited speakers of the 3rd Session of the Sant Cugat Forum on Astrophysics — Gravitational Waves Astrophysics. All chapters have been peer reviewed. The book goes beyond normal conference proceedings in that it provides a wide panorama of the astrophysics of gravitational waves and serves as a reference work for researchers in the field.

  5. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. Anjan A. Sen. Articles written in Journal of Astrophysics and Astronomy. Volume 37 Issue 4 December 2016 pp 33 Review. Cosmology and Astrophysics using the Post-Reionization HI · Tapomoy Guha Sarkar Anjan A. Sen · More Details Abstract Fulltext PDF.

  6. On the Quasicollisionality of Plasmas with Small-Scale Electric Turbulence

    CERN Document Server

    Keenan, Brett D

    2016-01-01

    Chaotic electromagnetic fields are common in many relativistic plasma environments, where they can be excited by instabilities on kinetic spatial scales. When strong electric fluctuations exist on sub-electron scales, they may lead to small-angle, stochastic deflections of the electrons' pitch-angles. Under certain conditions, this closely resembles the effect of Coulomb collisions in collisional plasmas. The electric pitch-angle diffusion coefficient acts as an effective collision -- or "quasi-collision" -- frequency. We show that quasi-collisions may radically alter the expected radiative transport properties of candidate plasmas. In particular, we consider the quasi-collisional generalization of the classical Faraday effect.

  7. 78 FR 20356 - NASA Advisory Council; Science Committee; Astrophysics Subcommittee; Meeting

    Science.gov (United States)

    2013-04-04

    ... SPACE ADMINISTRATION NASA Advisory Council; Science Committee; Astrophysics Subcommittee; Meeting AGENCY... Administration (NASA) announces a meeting of the Astrophysics Subcommittee of the NASA Advisory Council (NAC... following topics: --Astrophysics Division Update --Report from Astrophysics Roadmap Team --James Webb Space...

  8. 76 FR 66998 - NASA Advisory Council; Science Committee; Astrophysics Subcommittee; Meeting.

    Science.gov (United States)

    2011-10-28

    ... SPACE ADMINISTRATION NASA Advisory Council; Science Committee; Astrophysics Subcommittee; Meeting... Space Administration (NASA) announces a meeting of the Astrophysics Subcommittee of the NASA Advisory... following topic: --Astrophysics Division Update --Results from Acting Astrophysics Division Director...

  9. Stark broadening data for stellar plasma research.

    Science.gov (United States)

    Dimitrijević, M. S.

    Results of an effort to provide to astrophysicists and physicists an as much as possible complete set of Stark broadening parameters needed for stellar opacity calculations, stellar atmosphere modelling, abundance determinations and diagnostics of different plasmas in astrophysics, physics and plasma technology, are presented. Stark broadening has been considered within the semiclassical perturbation, and the modified semiempirical approaches.

  10. Plasma physics

    CERN Document Server

    Cairns, R A

    1985-01-01

    This book is intended as an introduction to plasma physics at a level suitable for advanced undergraduates or beginning postgraduate students in physics, applied mathematics or astrophysics. The main prerequisite is a knowledge of electromagnetism and of the associated mathematics of vector calculus. SI units are used throughout. There is still a tendency amongst some plasma physics researchers to· cling to C.g.S. units, but it is the author's view that universal adoption of SI units, which have been the internationally agreed standard since 1960, is to be encouraged. After a short introductory chapter, the basic properties of a plasma con­ cerning particle orbits, fluid theory, Coulomb collisions and waves are set out in Chapters 2-5, with illustrations drawn from problems in nuclear fusion research and space physics. The emphasis is on the essential physics involved and (he theoretical and mathematical approach has been kept as simple and intuitive as possible. An attempt has been made to draw attention t...

  11. NASA Astrophysics Funds Strategic Technology Development

    Science.gov (United States)

    Seery, Bernard D.; Ganel, Opher; Pham, Bruce

    2016-01-01

    The COR and PCOS Program Offices (POs) reside at the NASA Goddard Space Flight Center (GSFC), serving as the NASA Astrophysics Division's implementation arm for matters relating to the two programs. One aspect of the PO's activities is managing the COR and PCOS Strategic Astrophysics Technology (SAT) program, helping mature technologies to enable and enhance future astrophysics missions. For example, the SAT program is expected to fund key technology developments needed to close gaps identified by Science and Technology Definition Teams (STDTs) planned to study several large mission concept studies in preparation for the 2020 Decadal Survey.The POs are guided by the National Research Council's "New Worlds, New Horizons in Astronomy and Astrophysics" Decadal Survey report, NASA's Astrophysics Implementation Plan, and the visionary Astrophysics Roadmap, "Enduring Quests, Daring Visions." Strategic goals include dark energy, gravitational waves, and X-ray observatories. Future missions pursuing these goals include, e.g., US participation in ESA's Euclid, Athena, and L3 missions; Inflation probe; and a large UV/Optical/IR (LUVOIR) telescope.To date, 65 COR and 71 PCOS SAT proposals have been received, of which 15 COR and 22 PCOS projects were funded. Notable successes include maturation of a new far-IR detector, later adopted by the SOFIA HAWC instrument; maturation of the H4RG near-IR detector, adopted by WFIRST; development of an antenna-coupled transition-edge superconducting bolometer, a technology deployed by BICEP2/BICEP3/Keck to measure polarization in the CMB signal; advanced UV reflective coatings implemented on the optics of GOLD and ICON, two heliophysics Explorers; and finally, the REXIS instrument on OSIRIS-REx is incorporating CCDs with directly deposited optical blocking filters developed by another SAT-funded project.We discuss our technology development process, with community input and strategic prioritization informing calls for SAT proposals and

  12. Ultracold neutral plasmas

    Science.gov (United States)

    Lyon, M.; Rolston, S. L.

    2017-01-01

    By photoionizing samples of laser-cooled atoms with laser light tuned just above the ionization limit, plasmas can be created with electron and ion temperatures below 10 K. These ultracold neutral plasmas have extended the temperature bounds of plasma physics by two orders of magnitude. Table-top experiments, using many of the tools from atomic physics, allow for the study of plasma phenomena in this new regime with independent control over the density and temperature of the plasma through the excitation process. Characteristic of these systems is an inhomogeneous density profile, inherited from the density distribution of the laser-cooled neutral atom sample. Most work has dealt with unconfined plasmas in vacuum, which expand outward at velocities of order 100 m/s, governed by electron pressure, and with lifetimes of order 100 μs, limited by stray electric fields. Using detection of charged particles and optical detection techniques, a wide variety of properties and phenomena have been observed, including expansion dynamics, collective excitations in both the electrons and ions, and collisional properties. Through three-body recombination collisions, the plasmas rapidly form Rydberg atoms, and clouds of cold Rydberg atoms have been observed to spontaneously avalanche ionize to form plasmas. Of particular interest is the possibility of the formation of strongly coupled plasmas, where Coulomb forces dominate thermal motion and correlations become important. The strongest impediment to strong coupling is disorder-induced heating, a process in which Coulomb energy from an initially disordered sample is converted into thermal energy. This restricts electrons to a weakly coupled regime and leaves the ions barely within the strongly coupled regime. This review will give an overview of the field of ultracold neutral plasmas, from its inception in 1999 to current work, including efforts to increase strong coupling and effects on plasma properties due to strong coupling.

  13. Ultracold neutral plasmas.

    Science.gov (United States)

    Lyon, M; Rolston, S L

    2017-01-01

    By photoionizing samples of laser-cooled atoms with laser light tuned just above the ionization limit, plasmas can be created with electron and ion temperatures below 10 K. These ultracold neutral plasmas have extended the temperature bounds of plasma physics by two orders of magnitude. Table-top experiments, using many of the tools from atomic physics, allow for the study of plasma phenomena in this new regime with independent control over the density and temperature of the plasma through the excitation process. Characteristic of these systems is an inhomogeneous density profile, inherited from the density distribution of the laser-cooled neutral atom sample. Most work has dealt with unconfined plasmas in vacuum, which expand outward at velocities of order 100 m/s, governed by electron pressure, and with lifetimes of order 100 μs, limited by stray electric fields. Using detection of charged particles and optical detection techniques, a wide variety of properties and phenomena have been observed, including expansion dynamics, collective excitations in both the electrons and ions, and collisional properties. Through three-body recombination collisions, the plasmas rapidly form Rydberg atoms, and clouds of cold Rydberg atoms have been observed to spontaneously avalanche ionize to form plasmas. Of particular interest is the possibility of the formation of strongly coupled plasmas, where Coulomb forces dominate thermal motion and correlations become important. The strongest impediment to strong coupling is disorder-induced heating, a process in which Coulomb energy from an initially disordered sample is converted into thermal energy. This restricts electrons to a weakly coupled regime and leaves the ions barely within the strongly coupled regime. This review will give an overview of the field of ultracold neutral plasmas, from its inception in 1999 to current work, including efforts to increase strong coupling and effects on plasma properties due to strong coupling.

  14. Theoretical and numerical studies of Rayleigh-Taylor instabilities in magnetized plasmas; Etude theorique et numerique des instabilites Rayleigh-Taylor en plasmas magnetises

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, A.A

    2001-06-01

    The instabilities of Rayleigh-Taylor type are considered in the thesis. The topic of the thesis was inspired by recent advances in the physics of plasma compression, especially with the aid of systems like Z-pinch. Rayleigh-Taylor instability (RTI) plays an important role in the evolution of magnetized plasmas in these experiments, as well as in stellar plasmas and classic fluids. For the phenomena concerning the nuclear fusion the RTI is very often the factor limiting the possibility of compression. In the current work we try to examine in detail the characteristic features of the instabilities of this type in order to eliminate their detrimental influence. In this thesis we are studying both the general case of the 'classic' Rayleigh-Taylor instability (in incompressible fluids) and more specific cases of the instabilities of Rayleigh-Taylor type in magnetized plasmas, in the liners or wire array implosions etc. We have studied the influence of the Hall diffusion of magnetic field on the growth rate of the instability. We have obtained in this work a self-similar solution for the widening of the initial profile of the magnetic field and for the wave of the penetration of magnetic field. After that the subsequent evolution of the magnetic field in plasma opening switches (POS) has been examined. We have shown the possibility of the existence of a strong rarefaction wave for collisional and non-collisional cases. This wave can explain the phenomenon of the opening of POS. The effect of the suppression of Rayleigh-Taylor instability by forced oscillations of the boundary between two fluids permits us to propose some ideas for the experiments of inertial fusion. We have considered the general case of the instability, in other words, two incompressible viscous superposed fluids in a gravitational field. We have obtained an exact analytical expression for the growth rate and then we have analyzed the influence of the parameters of external &apos

  15. Modeling Transport of Relativistic Electrons through Warm-Dense Matter Using Collisional PIC

    Science.gov (United States)

    May, J.; McGuffey, C.; Yabuuchi, T.; Wei, Ms; Beg, F.; Mori, Wb

    2017-10-01

    In electron transport experiments performed on the OMEGA EP laser system, a relativistic electron beam was created by focusing a high intensity (eA /me c > 1) laser onto a gold (Au) foil. Behind the Au foil was a layer of plastic (CH) foam, with an initial density of 200mg /cm3 . Before the high intensity laser was switched on, this foam was either left unperturbed; or it was shocked using a lower intensity laser (eA /me c 10-4) with beam path perpendicular to the high intensity laser, which left the CH layer in a warm dense matter (WDM) state with temperature of 40 eV and density of 30mg /cm3 . The electron beam was imaged by observing the k- α signal from a copper foil on the far side from the Au. The result was that transport was decreased by an order of magnitude in the WDM compared to the cold foam. We have modeled this experiment using the PIC code OSIRIS, with also a Monte Carlo Coulomb collision package. Our simulations indicate that the main cause of the differences in transport is a collimating magnetic field in the higher density, cold foam, created by collisional resistivity. The plasma density of the Au layer, difficult to model fully in PIC, appears to effect the heat capacity and therefore temperature and resistivity of the target. The authors acknowledge the support of the Department of Energy under contract DE-NA 0001833 and the National Science Foundation under contract ACI 1339893.

  16. White paper on nuclear astrophysics and low energy nuclear physics Part 1: Nuclear astrophysics

    Science.gov (United States)

    Arcones, Almudena; Bardayan, Dan W.; Beers, Timothy C.; Bernstein, Lee A.; Blackmon, Jeffrey C.; Messer, Bronson; Brown, B. Alex; Brown, Edward F.; Brune, Carl R.; Champagne, Art E.; Chieffi, Alessandro; Couture, Aaron J.; Danielewicz, Pawel; Diehl, Roland; El-Eid, Mounib; Escher, Jutta E.; Fields, Brian D.; Fröhlich, Carla; Herwig, Falk; Hix, William Raphael; Iliadis, Christian; Lynch, William G.; McLaughlin, Gail C.; Meyer, Bradley S.; Mezzacappa, Anthony; Nunes, Filomena; O'Shea, Brian W.; Prakash, Madappa; Pritychenko, Boris; Reddy, Sanjay; Rehm, Ernst; Rogachev, Grigory; Rutledge, Robert E.; Schatz, Hendrik; Smith, Michael S.; Stairs, Ingrid H.; Steiner, Andrew W.; Strohmayer, Tod E.; Timmes, F. X.; Townsley, Dean M.; Wiescher, Michael; Zegers, Remco G. T.; Zingale, Michael

    2017-05-01

    This white paper informs the nuclear astrophysics community and funding agencies about the scientific directions and priorities of the field and provides input from this community for the 2015 Nuclear Science Long Range Plan. It summarizes the outcome of the nuclear astrophysics town meeting that was held on August 21-23, 2014 in College Station at the campus of Texas A&M University in preparation of the NSAC Nuclear Science Long Range Plan. It also reflects the outcome of an earlier town meeting of the nuclear astrophysics community organized by the Joint Institute for Nuclear Astrophysics (JINA) on October 9-10, 2012 Detroit, Michigan, with the purpose of developing a vision for nuclear astrophysics in light of the recent NRC decadal surveys in nuclear physics (NP2010) and astronomy (ASTRO2010). The white paper is furthermore informed by the town meeting of the Association of Research at University Nuclear Accelerators (ARUNA) that took place at the University of Notre Dame on June 12-13, 2014. In summary we find that nuclear astrophysics is a modern and vibrant field addressing fundamental science questions at the intersection of nuclear physics and astrophysics. These questions relate to the origin of the elements, the nuclear engines that drive life and death of stars, and the properties of dense matter. A broad range of nuclear accelerator facilities, astronomical observatories, theory efforts, and computational capabilities are needed. With the developments outlined in this white paper, answers to long standing key questions are well within reach in the coming decade.

  17. The Future of Gamma Ray Astrophysics

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Over the past decade, gamma ray astrophysics has entered the astrophysical mainstream. Extremely successful space-borne (GeV) and ground-based (TeV) detectors, combined with a multitude of partner telescopes, have revealed a fascinating “astroscape" of active galactic nuclei, pulsars, gamma ray bursts, supernova remnants, binary stars, star-forming galaxies, novae much more, exhibiting major pathways along which large energy releases can flow. From  a basic physics perspective, exquisitely sensitive measurements have constrained the nature of dark matter, the cosmological origin of magnetic field and the properties of black holes. These advances have motivated the development of new facilities, including HAWC, DAMPE, CTA and SVOM, which will further our understanding of the high energy universe. Topics that will receive special attention include merging neutron star binaries, clusters of galaxies, galactic cosmic rays and putative, TeV dark matter.

  18. Modern fluid dynamics for physics and astrophysics

    CERN Document Server

    Regev, Oded; Yecko, Philip A

    2016-01-01

    This book grew out of the need to provide students with a solid introduction to modern fluid dynamics. It offers a broad grounding in the underlying principles and techniques used, with some emphasis on applications in astrophysics and planetary science. The book comprehensively covers recent developments, methods and techniques, including, for example, new ideas on transitions to turbulence (via transiently growing stable linear modes), new approaches to turbulence (which remains the enigma of fluid dynamics), and the use of asymptotic approximation methods, which can give analytical or semi-analytical results and complement fully numerical treatments. The authors also briefly discuss some important considerations to be taken into account when developing a numerical code for computer simulation of fluid flows. Although the text is populated throughout with examples and problems from the field of astrophysics and planetary science, the text is eminently suitable as a general introduction to fluid dynamics. It...

  19. Neutrino particle astrophysics: status and outlook

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    The discovery of astrophysical neutrinos at high energy by IceCube raises a host of questions: What are the sources? Is there a Galactic as well as an extragalactic component? How does the astrophysical spectrum continue to lower energy where the dominant signal is from atmospheric neutrinos? Is there a measureable flux of cosmogenic neutrinos at higher energy? What is the connection to cosmic rays? At what level and in what energy region should we expect to see evidence of the π0 decay photons that must accompany the neutrinos at production? Such questions are stimulating much theoretical activity and many multi-wavelength follow-up observations as well as driving plans for new detectors. My goal in this presentation will be to connect the neutrino data and their possible interpretations to ongoing multi-messenger observations and to the design of future detectors.

  20. Numerical Methods for Radiation Magnetohydrodynamics in Astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Klein, R I; Stone, J M

    2007-11-20

    We describe numerical methods for solving the equations of radiation magnetohydrodynamics (MHD) for astrophysical fluid flow. Such methods are essential for the investigation of the time-dependent and multidimensional dynamics of a variety of astrophysical systems, although our particular interest is motivated by problems in star formation. Over the past few years, the authors have been members of two parallel code development efforts, and this review reflects that organization. In particular, we discuss numerical methods for MHD as implemented in the Athena code, and numerical methods for radiation hydrodynamics as implemented in the Orion code. We discuss the challenges introduced by the use of adaptive mesh refinement in both codes, as well as the most promising directions for future developments.

  1. International Conference on Particle Physics and Astrophysics

    CERN Document Server

    2015-01-01

    The International Conference on Particle Physics and Astrophysics (ICPPA-2015) will be held in Moscow, Russia, from October 5 to 10, 2015. The conference is organized by Center of Basic Research and Particle Physics of National Research Nuclear University “MEPhI”. The aim of the Conference is to promote contacts between scientists and development of new ideas in fundamental research. Therefore we will bring together experts and young scientists working on experimental and theoretical aspects of nuclear, particle, astroparticle physics and cosmology. ICPPA-2015, aims to present the most recent results in astrophysics and collider physics and reports from the main experiments currently taking data. The working languages of the conference are English and Russian.

  2. Electrodynamics and spacetime geometry: Astrophysical applications

    CERN Document Server

    Cabral, Francisco

    2016-01-01

    After a brief review of the foundations of (pre-metric) electromagnetism in differential forms, we proceed with the tensor formulation and explore physical consequences of Maxwell's equations in curved spacetime. The generalized Gauss and Maxwell-Amp\\`ere laws, as well as the wave equations, reveal potentially interesting astrophysical applications. The physical implications of these equations are explored and some solutions are obtained. In all cases new electromagnetic couplings and related phenomena are induced by the spacetime curvature. The applications of astrophysical interest considered here correspond essentially to the following geometries: the Schwarzschild spacetime and the spacetime around a rotating spherical mass in the weak field and slow rotation regime. In the latter, we use the Parameterised Post-Newtonian (PPN) formalism. In general, new electromagnetic effects induced by spacetime curvature include the following: Gravitational contributions for the decay of electric and magnetic fields in...

  3. A pair spectrometer for nuclear astrophysics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Guerro, L.; Saltarelli, A.; Tabassam, U. [University of Camerino, Division of Physics, School of Science and Technology, Camerino (Italy); INFN, Sezione di Perugia, Perugia (Italy); Di Leva, A. [INFN, Napoli (Italy); University of Naples ' ' Federico II' ' , Physics Department, Naples (Italy); Gialanella, L.; De Cesare, N.; D' Onofrio, A.; Terrasi, F. [Second University of Naples, Department of Mathematics and Physics, Caserta (Italy); INFN, Napoli (Italy); Schuermann, D.; Romoli, M. [INFN, Napoli (Italy); Busso, M. [INFN, Sezione di Perugia, Perugia (Italy); University of Perugia, Department of Physics, Perugia (Italy)

    2014-11-15

    Non-radiative transitions in nuclear capture reactions between light nuclei play a relevant role in stellar nuclear astrophysics, where nuclear processes occur at typical energies from tens to hundreds of keV. At higher energies, instead, the E0 contributions may be shadowed by more intense transitions. The experimental study of E0 transitions requires a specific detection setup, able to uniquely identify events where an electron-positron pair is produced. A compact ΔE-E charged-particle spectrometer based on two silicon detectors has been designed to be installed in the jet gas target chamber of the recoil mass separator ERNA (European Recoil separator for Nuclear Astrophysics) at the CIRCE laboratory of Caserta, Italy. The detector design, its performances and the first foreseen applications are described. (orig.)

  4. Clocking femtosecond collisional dynamics via resonant X-ray spectroscopy

    Czech Academy of Sciences Publication Activity Database

    van den Berg, Q.Y.; Fernandez-Tello, E.V.; Burian, Tomáš; Chalupský, Jaromír; Chung, H.-K.; Ciricosta, O.; Dakovski, G.L.; Hájková, Věra; Hollebon, P.; Juha, Libor; Krzywinski, J.; Lee, R. W.; Minitti, M.P.; Preston, T.R.; de la Varga, A.G.; Vozda, Vojtěch; Zastrau, U.; Wark, J. S.; Velarde, P.; Vinko, S.M.

    2018-01-01

    Roč. 120, č. 5 (2018), s. 1-6, č. článku 055002. ISSN 0031-9007 R&D Projects: GA ČR(CZ) GA17-05167s; GA MŠk LG15013 Institutional support: RVO:68378271 Keywords : hot dense matter * highly-charged ions * electron-impact-ionization * laser * plasmas Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 8.462, year: 2016

  5. Spin states of asteroids in the Eos collisional family

    Science.gov (United States)

    Hanuš, J.; Delbo', M.; Alí-Lagoa, V.; Bolin, B.; Jedicke, R.; Ďurech, J.; Cibulková, H.; Pravec, P.; Kušnirák, P.; Behrend, R.; Marchis, F.; Antonini, P.; Arnold, L.; Audejean, M.; Bachschmidt, M.; Bernasconi, L.; Brunetto, L.; Casulli, S.; Dymock, R.; Esseiva, N.; Esteban, M.; Gerteis, O.; de Groot, H.; Gully, H.; Hamanowa, Hiroko; Hamanowa, Hiromi; Krafft, P.; Lehký, M.; Manzini, F.; Michelet, J.; Morelle, E.; Oey, J.; Pilcher, F.; Reignier, F.; Roy, R.; Salom, P. A.; Warner, B. D.

    2018-01-01

    Eos family was created during a catastrophic impact about 1.3 Gyr ago. Rotation states of individual family members contain information about the history of the whole population. We aim to increase the number of asteroid shape models and rotation states within the Eos collision family, as well as to revise previously published shape models from the literature. Such results can be used to constrain theoretical collisional and evolution models of the family, or to estimate other physical parameters by a thermophysical modeling of the thermal infrared data. We use all available disk-integrated optical data (i.e., classical dense-in-time photometry obtained from public databases and through a large collaboration network as well as sparse-in-time individual measurements from a few sky surveys) as input for the convex inversion method, and derive 3D shape models of asteroids together with their rotation periods and orientations of rotation axes. We present updated shape models for 15 asteroids and new shape model determinations for 16 asteroids. Together with the already published models from the publicly available DAMIT database, we compiled a sample of 56 Eos family members with known shape models that we used in our analysis of physical properties within the family. Rotation states of asteroids smaller than ∼ 20 km are heavily influenced by the YORP effect, whilst the large objects more or less retained their rotation state properties since the family creation. Moreover, we also present a shape model and bulk density of asteroid (423) Diotima, an interloper in the Eos family, based on the disk-resolved data obtained by the Near InfraRed Camera (Nirc2) mounted on the W.M. Keck II telescope.

  6. Coulomb dissociation studies for astrophysical thermonuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Motobayashi, T. [Dept. of Physics, Rikkyo Univ., Toshima, Tokyo (Japan)

    1998-06-01

    The Coulomb dissociation method was applied to several radiative capture processes of astrophysical interest. The method has an advantage of high experimental efficiency, which allow measurements with radioactive nuclear beams. The reactions {sup 13}N(p,{gamma}){sup 14}O and {sup 7}Be(p,{gamma}){sup 8}B are mainly discussed. They are the key reaction in the hot CNO cycle in massive stars and the one closely related to the solar neutrino problem, respectively. (orig.)

  7. Neutrino masses in astrophysics and cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Raffelt, G.G. [Max-Planck-Institut fuer Physik, Muenchen (Germany)

    1996-11-01

    Astrophysical and cosmological arguments and observations give us the most restrictive constraints on neutrino masses, electromagnetic couplings, and other properties. Conversely, massive neutrinos would contribute to the cosmic dark-matter density and would play an important role for the formation of structure in the universe. Neutrino oscillations may well solve the solar neutrino problem, and can have a significant impact on supernova physics. (author) 14 figs., tabs., 33 refs.

  8. Cosmology and Particle Astrophysics at Kavli Ipmu

    Science.gov (United States)

    Aihara, Hiroaki

    2013-12-01

    Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) currently undertakes two large-scale projects in cosmology and particle astrophysics. One is Subaru Measurement of Images and Redshifts, the Sumire project. It observes images and redshifts of the galaxies using Subaru telescope to study cosmology and astronomy. The other is XMASS experiment aiming to detect the cold dark matter using liquid Xenon. We provide a brief introductory description of these projects.

  9. A self-consistent kinetic modeling of a 1-D, bounded, plasma in ...

    Indian Academy of Sciences (India)

    non-Maxwellian features near the last mfp, and strong modifications of the sheath criterion. Keywords. Plasma kinetic equation; ion-neutral collision; presheath. PACS Nos 52.65; 52.40H; 72.30; 52.50D; 52.20. 1. Introduction. The nature of the collisional presheath of a plasma has been an elusive matter for investiga- tion.

  10. Emission of strong Terahertz pulses from laser wakefields in weakly coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Divya, E-mail: dsingh@rajdhani.du.ac.in [PWAPA Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India); Department of Physics & Electronics, Rajdhani College, University of Delhi, Raja Garden, Ring Road, New Delhi 110015 (India); Malik, Hitendra K. [PWAPA Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India)

    2016-09-01

    The present paper discusses the laser plasma interaction for the wakefield excitation and the role of external magnetic field for the emission of Terahertz radiation in a collisional plasma. Flat top lasers are shown to be more appropriate than the conventional Gaussian lasers for the effective excitation of wakefields and hence, the generation of strong Terahertz radiation through the transverse component of wakefield.

  11. Hybrid plasma modeling.

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, Matthew Morgan; DeChant, Lawrence Justin.; Piekos, Edward Stanley; Pointon, Timothy David

    2009-02-01

    This report summarizes the work completed during FY2007 and FY2008 for the LDRD project ''Hybrid Plasma Modeling''. The goal of this project was to develop hybrid methods to model plasmas across the non-continuum-to-continuum collisionality spectrum. The primary methodology to span these regimes was to couple a kinetic method (e.g., Particle-In-Cell) in the non-continuum regions to a continuum PDE-based method (e.g., finite differences) in continuum regions. The interface between the two would be adjusted dynamically ased on statistical sampling of the kinetic results. Although originally a three-year project, it became clear during the second year (FY2008) that there were not sufficient resources to complete the project and it was terminated mid-year.

  12. On Validating an Astrophysical Simulation Code

    Science.gov (United States)

    Calder, A. C.; Fryxell, B.; Plewa, T.; Rosner, R.; Dursi, L. J.; Weirs, V. G.; Dupont, T.; Robey, H. F.; Kane, J. O.; Remington, B. A.; Drake, R. P.; Dimonte, G.; Zingale, M.; Timmes, F. X.; Olson, K.; Ricker, P.; MacNeice, P.; Tufo, H. M.

    2002-11-01

    We present a case study of validating an astrophysical simulation code. Our study focuses on validating FLASH, a parallel, adaptive-mesh hydrodynamics code for studying the compressible, reactive flows found in many astrophysical environments. We describe the astrophysics problems of interest and the challenges associated with simulating these problems. We describe methodology and discuss solutions to difficulties encountered in verification and validation. We describe verification tests regularly administered to the code, present the results of new verification tests, and outline a method for testing general equations of state. We present the results of two validation tests in which we compared simulations to experimental data. The first is of a laser-driven shock propagating through a multilayer target, a configuration subject to both Rayleigh-Taylor and Richtmyer-Meshkov instabilities. The second test is a classic Rayleigh-Taylor instability, where a heavy fluid is supported against the force of gravity by a light fluid. Our simulations of the multilayer target experiments showed good agreement with the experimental results, but our simulations of the Rayleigh-Taylor instability did not agree well with the experimental results. We discuss our findings and present results of additional simulations undertaken to further investigate the Rayleigh-Taylor instability.

  13. Astrophysically Relevant Instabilities at a Decelerating Interface.

    Science.gov (United States)

    Calder, A. C.; Fryxell, B.; Rosner, R.; Kane, J.; Remington, B. A.; Robey, H.; Keiter, P.; Drake, R. P.; Knauer, J.; Dursi, L. J.; Olson, K.; Ricker, P. M.; Timmes, F. X.; Zingale, M.; Tufo, H.; MacNeice, P.

    2000-10-01

    Hydrodynamic instabilities play an important role in many astrophysical phenomena, and modern intense lasers offer the chance to experimentally investigate these instabilities in similar environments in a laboratory. In this poster, we report on experimental and theoretical progress in ongoing research in laser astrophysics. We presents results of simulations of experiments performed using the University of Rochester's Omega laser facility. These experiments involve shock propagation through multi-layer targets, and are designed to replicate the complex hydrodynamic instabilities thought to arise during supernovae explosions. The simulations were performed with the FLASH code, developed by the ASCI/ASAP Center for Astrophysical Thermonuclear Flashes at the University of Chicago, and we are planning on a study making use of a realistic equation of state. We present results of an experimental study of 2-D vs. 3-D perturbation growth rates also performed at the Omega laser facility. Data from experiments with nominally identical two-layer targets, but 2-D or 3-D perturbations, show clear differences between the evolution of 2-D vs. 3-D perturbations. We also present simulations showing qualitatively similar features for comparison. This work is supported by the US Department of Energy.

  14. Goddard's Astrophysics Science Division Annual Report 2013

    Science.gov (United States)

    Weaver, Kimberly A. (Editor); Reddy, Francis J. (Editor); Tyler, Patricia A. (Editor)

    2014-01-01

    The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radio wavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for two orbiting astrophysics missions Fermi Gamma-ray Space Telescope and Swift as well as the Science Support Center for Fermi. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contrast imaging techniques to search for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and support the astronomical community, and enable future missions by conceiving new concepts and inventing new technologies.

  15. Goddard's Astrophysics Science Division Annual Report 2011

    Science.gov (United States)

    Centrella, Joan; Reddy, Francis; Tyler, Pat

    2012-01-01

    The Astrophysics Science Division(ASD) at Goddard Space Flight Center(GSFC)is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radiowavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contract imaging techniques to serch for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, and provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and suppport the astronomical community, and enable future missions by conceiving new conepts and inventing new technologies.

  16. Traversable braneworld wormholes supported by astrophysical observations

    Science.gov (United States)

    Wang, Deng; Meng, Xin-He

    2018-02-01

    In this study, we investigate the characteristics and properties of a traversable wormhole constrained by the current astrophysical observations in the framework of modified theories of gravity (MOG). As a concrete case, we study traversable wormhole space-time configurations in the Dvali-Gabadadze-Porrati (DGP) braneworld scenario, which are supported by the effects of the gravity leakage of extra dimensions. We find that the wormhole space-time structure will open in terms of the 2 σ confidence level when we utilize the joint constraints supernovae (SNe) Ia + observational Hubble parameter data (OHD) + Planck + gravitational wave (GW) and z wormholes can be divided into four classes during the evolutionary processes of the universe based on various energy conditions; (ii) we can offer a strict restriction to the local wormhole space-time structure by using the current astrophysical observations; and (iii) we can clearly identify a physical gravitational resource for the wormholes supported by astrophysical observations, namely the dark energy components of the universe or equivalent space-time curvature effects from MOG. Moreover, we find that the strong energy condition is always violated at low redshifts.

  17. The Astrophysics Science Division Annual Report 2009

    Science.gov (United States)

    Oegerle, William (Editor); Reddy, Francis (Editor); Tyler, Pat (Editor)

    2010-01-01

    The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum - from gamma rays to radio wavelengths - as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions - WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contrast imaging techniques to search for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and support the astronomical community, and enable future missions by conceiving new concepts and inventing new technologies.

  18. Goddard's Astrophysics Science Divsion Annual Report 2014

    Science.gov (United States)

    Weaver, Kimberly (Editor); Reddy, Francis (Editor); Tyler, Pat (Editor)

    2015-01-01

    The Astrophysics Science Division (ASD, Code 660) is one of the world's largest and most diverse astronomical organizations. Space flight missions are conceived, built and launched to observe the entire range of the electromagnetic spectrum, from gamma rays to centimeter waves. In addition, experiments are flown to gather data on high-energy cosmic rays, and plans are being made to detect gravitational radiation from space-borne missions. To enable these missions, we have vigorous programs of instrument and detector development. Division scientists also carry out preparatory theoretical work and subsequent data analysis and modeling. In addition to space flight missions, we have a vibrant suborbital program with numerous sounding rocket and balloon payloads in development or operation. The ASD is organized into five labs: the Astroparticle Physics Lab, the X-ray Astrophysics Lab, the Gravitational Astrophysics Lab, the Observational Cosmology Lab, and the Exoplanets and Stellar Astrophysics Lab. The High Energy Astrophysics Science Archive Research Center (HEASARC) is an Office at the Division level. Approximately 400 scientists and engineers work in ASD. Of these, 80 are civil servant scientists, while the rest are resident university-based scientists, contractors, postdoctoral fellows, graduate students, and administrative staff. We currently operate the Swift Explorer mission and the Fermi Gamma-ray Space Telescope. In addition, we provide data archiving and operational support for the XMM mission (jointly with ESA) and the Suzaku mission (with JAXA). We are also a partner with Caltech on the NuSTAR mission. The Hubble Space Telescope Project is headquartered at Goddard, and ASD provides Project Scientists to oversee operations at the Space Telescope Science Institute. Projects in development include the Neutron Interior Composition Explorer (NICER) mission, an X-ray timing experiment for the International Space Station; the Transiting Exoplanet Sky Survey (TESS

  19. NIF Laboratory Astrophysics Experiments Investigating The Effects Of A Radiative Shock On Hydrodynamic Instabilities

    Science.gov (United States)

    Kuranz, Carolyn C.; Drake, R. P.; Huntington, C. M.; Klein, S. R.; Trantham, M. R.; Park, H. S.; Remington, B. A.; Miles, A. R.; Raman, K.; Kline, J. L.; Plewa, T.

    2012-05-01

    This paper will describe ongoing laboratory astrophysics experiments at the National Ignition Facility (NIF) relevant to the complex radiation hydrodynamics that occurs in red supergiant, and core-collapse supernovae. Experiments on NIF can deliver 300 eV radiative heating that can be utilized uniquely access the regime in which radiation affects the development of hydrodynamic instabilities within an evolving object. This is relevant to the dynamics that occur during the core-collapse explosions of red supergiant stars. These stars have dense circumstellar plasma, producing a strongly radiative shock whose radiation interacts with the hydrodynamic structures produced by instabilities during the explosion. While published astrophysical simulations have not included complex, multidimensional radiation hydrodynamics, such effects are very physical and expected to affect the evolution of early stages of astrophysical objects described above. This presentation will include a summary of the two test shots that we have performed on NIF, including a 0.7 scale, gas-filled hohlraum test shot, and a description of the integrated physics shots scheduled at the facility. This work is funded by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas under grant number DE-FG52-09NA29548 , the Lawrence Livermore National Security, LLC, under Contract No. DE-AC52-07NA27344 and Predictive Sciences Academic Alliances Program in NNSA-ASC via grant DEFC52- 08NA28616.

  20. The Plasma Archipelago: Plasma Physics in the 1960s

    Science.gov (United States)

    Weisel, Gary J.

    2017-09-01

    With the foundation of the Division of Plasma Physics of the American Physical Society in April 1959, plasma physics was presented as the general study of ionized gases. This paper investigates the degree to which plasma physics, during its first decade, established a community of interrelated specialties, one that brought together work in gaseous electronics, astrophysics, controlled thermonuclear fusion, space science, and aerospace engineering. It finds that, in some regards, the plasma community was indeed greater than the sum of its parts and that its larger identity was sometimes glimpsed in inter-specialty work and studies of fundamental plasma behaviors. Nevertheless, the plasma specialties usually worked separately for two inter-related reasons: prejudices about what constituted "basic physics," both in the general physics community and within the plasma community itself; and a compartmentalized funding structure, in which each funding agency served different missions.

  1. Physical Mechanism of the Lower-Hybrid-Drift Instability in a Collisional Plasma.

    Science.gov (United States)

    1981-01-30

    SERVICES DIVISION 01CY ATTN DOST U.S. ARMY COMMUNICATIONS M lD 03CY ATTN R.AE PENTAGON RN 15269 WASHINGTON, D.C. 20310 CommADER OlCY ATTN C-E-SERVICES...S’REE 6565 ARE~ ~ OFLVER FHALS CHURl VRP AO TOY 22346 NEEZMAM MAl 02134 ,15(N.ONY 555 TECNOLOGY QUAREODCY A,’’N NEASAL ROSSCN’-O Y 01Cr A’-N D..N SP

  2. Collisional-Radiative Modeling of Free-Burning Arc Plasma in Argon

    Science.gov (United States)

    2013-06-01

    shall be briefly presented in the following. A tungsten inert gas ( TIG ) arc at normal pressure is burning between a tungsten cathode with a...temperature Te (Te≠T). Melting effects and metal vapor from the weld pool are not included. In the hydrodynamic model, the Navier-Stokes equations provide

  3. Optimum point of acceleration of an electron inside the collisional plasma-filled elliptical waveguide

    Science.gov (United States)

    Hadad, M.; Torkiha-Esfhani, M.

    2015-04-01

    In this paper, the effect of the electron collision frequency with background ions on TMmr mode field components, the trajectory and the electron energy gain is studied. The field components of the TMmr mode in the elliptical waveguides are calculated. The ohmic heating for three different value of collision frequency calculated and the power losses is obtained. The deflection angle and acceleration gradient of an electron in the fields associated with a transverse magnetic (TM) wave propagating inside a elliptical waveguide for TMmr mode is studied. The relativistic momentum and energy equations for an electron are solved, which was injected initially along the propagation direction of the microwave. The results for TMmr mode are graphically represented. Finally, the optimum point of acceleration for the even mode TM 11 is obtained and it is shown that in a cross section of elliptical waveguide optimum point is center of ellipse.

  4. Collision effects on propagation characteristics of electromagnetic waves in a sub-wavelength plasma slab of partially ionized dense plasmas

    Science.gov (United States)

    Bowen, LI; Zhibin, WANG; Qiuyue, NIE; Xiaogang, WANG; Fanrong, KONG; Zhenyu, WANG

    2018-01-01

    Intensive collisions between electrons and neutral particles in partially ionized plasmas generated in atmospheric/sub-atmospheric pressure environments can sufficiently affect the propagation characteristics of electromagnetic waves, particularly in the sub-wavelength regime. To investigate the collisional effect in such plasmas, we introduce a simplified plasma slab model with a thickness on the order of the wavelength of the incident electromagnetic wave. The scattering matrix method (SMM) is applied to solve the wave equation in the plasma slab with significant nonuniformity. Results show that the collisions between the electrons and the neutral particles, as well as the incident angle and the plasma thickness, can disturb the transmission and reduce reflection significantly.

  5. The role of collisional compaction in primitive asteroids and comets

    Science.gov (United States)

    Trigo-Rodríguez, J. M.; Blum, J.

    2008-09-01

    During the early stages of solar system formation the consolidation of asteroids and comets took place. We have just learnt from recent space missions that some of these minor bodies have been preserved in a pristine way in several regions of our Solar System. From our experience on primitive meteorites we know that these bodies should contain valuable clues on the origin of the Solar System. Studies of the physical, chemical, and isotopic properties of the components of these minor bodies will provide important clues on their origin. We expect very different collisional histories undergone by these bodies depending on their particular formation, migration, and storage regions [1]. In Fig. 1 appears a schematic representation of the protoplanetary disk in the region of consolidation of the terrestrial planets about 4565 million years ago. Bodies located in the outer part of the main belt would have incorporated significant amounts of ice in their volume, but their migration to and residence times in other regions would have defined their physico-chemical properties. Recent laboratory studies and observational data compiled from comets, meteorites and meteoroids [2] suggest that the porosity of these bodies should have decreased with time depending on the degree of collisions, aqueous alteration and heating. For typical stony targets, the tensile strength and gravity are the main properties that are defining the formation of impact craters and subsequently the degree of impact metamorphism and mineralogy of the shocked materials. However, little is known about the influence of porosity on the impact process although the crushing of pore space is an efficient mechanism for absorbing shock waves, also increasing the postshock temperatures [2]. In this context, a Near-Earth Object (NEO) sample return mission called Marco Polo is being studied within the Cosmic Vision programme. Such kind of mission would be returning to the Earth unaltered material from a NEO, just

  6. Exploring the collisional evolution of the asteroid belt

    Science.gov (United States)

    Bottke, W.; Broz, M.; O'Brien, D.; Campo Bagatin, A.; Morbidelli, A.

    2014-07-01

    The asteroid belt is a remnant of planet-formation processes. By modeling its collisional and dynamical history, and linking the results to constraints, we can probe how the planets and small bodies formed and evolved. Some key model constraints are: (i) The wavy shape of the main-belt size distribution (SFD), with inflection points near 100-km, 10--20-km, 1 to a few km, and ˜0.1-km diameter; (ii) The number of asteroid families created by the catastrophic breakup of large asteroid bodies over the last ˜ 4 Gy, with the number of disrupted D > 100 km bodies as small as ˜20 or as large as 60; (iii) the flux of small asteroids derived from the main belt that have struck the Moon over the last 3.5 Ga --- crater SFDs on lunar terrains with known ages suggest the D value may seem strange, considering the solar system is only 4.56 Gy old. One way to interpret it is that the main belt once had more mass that was eliminated by early dynamical processes between 4--4.56 Ga. This would allow for more early grinding, and it would suggest the main belt's wavy-shaped SFD is a ''fossil'' from a more violent early epoch. Simulations suggest that most D > 100 km bodies have been significantly battered, but only a fraction have been catastrophically disrupted. Conversely, most small asteroids today are byproducts of fragmentation events. These results are consistent with growing evidence that most of the prominent meteorite classes were produced by young asteroid families. The big question is how to use what we know to determine the main belt's original size and state. This work is ongoing, but dynamical models hint at many possibilities, including both the late arrival and late removal of material from the main belt. In addition, no model has yet properly accounted for the bombardment of the primordial main belt by leftover planetesimals in the terrestrial planet region. It is also possible to use additional constraints, such as the apparent paucity of Vesta-like or V

  7. Benchmarking Atomic Data for Astrophysics: Be-like Ions between B II and Ne VII

    Science.gov (United States)

    Wang, Kai; Chen, Zhan Bin; Zhang, Chun Yu; Si, Ran; Jönsson, Per; Hartman, Henrik; Gu, Ming Feng; Chen, Chong Yang; Yan, Jun

    2018-02-01

    Large-scale self-consistent multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction calculations are reported for the n≤slant 6 levels in Be-like ions from B II to Ne VII. Effects from electron correlation are taken into account by means of large expansions in terms of a basis of configuration state functions, and a complete and accurate data set of excitation energies; lifetimes; wavelengths; electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole line strengths; transition rates; and oscillator strengths for these levels is provided for each ion. Comparisons are made with available experimental and theoretical results. The uncertainty of excitation energies is assessed to be 0.01% on average, which makes it possible to find and rule out misidentifications and aid new line identifications involving high-lying levels in astrophysical spectra. The complete data set is also useful for modeling and diagnosing astrophysical plasmas.

  8. High-energy-density physics foundation of inertial fusion and experimental astrophysics

    CERN Document Server

    Drake, R Paul

    2018-01-01

    The raw numbers of high-energy-density physics are amazing: shock waves at hundreds of km/s (approaching a million km per hour), temperatures of millions of degrees, and pressures that exceed 100 million atmospheres. This title surveys the production of high-energy-density conditions, the fundamental plasma and hydrodynamic models that can describe them and the problem of scaling from the laboratory to the cosmos. Connections to astrophysics are discussed throughout. The book is intended to support coursework in high-energy-density physics, to meet the needs of new researchers in this field, and also to serve as a useful reference on the fundamentals. Specifically the book has been designed to enable academics in physics, astrophysics, applied physics and engineering departments to provide in a single-course, an introduction to fluid mechanics and radiative transfer, with dramatic applications in the field of high-energy-density systems. This second edition includes pedagogic improvements to the presentation ...

  9. FOREWORD: Nuclear Physics in Astrophysics V

    Science.gov (United States)

    Auerbach, Naftali; Hass, Michael; Paul, Michael

    2012-02-01

    The fifth edition of the bi-annual 'Nuclear Physics in Astrophysics (NPA)' conference series was held in Eilat, Israel on April 3-8, 2011. This Conference is also designated as the 24th Nuclear Physics Divisional Conference of the EPS. The main purpose of this conference, as that of the four previous ones in this series, is to deal with those aspects of nuclear physics that are directly related to astrophysics. The concept of such a meeting was conceived by the Nuclear Physics Board of the European Physical Society in 1998. At that time, the idea of such a conference was quite new and it was decided that this meeting would be sponsored by the EPS. The first meeting, in January 2001, was planned and organized in Eilat, Israel. Due to international circumstances the conference was moved to Debrecen, Hungary. Subsequent conferences were held in Debrecen again, in Dresden, Germany, and in Frascati, Italy (moved from Gran Sasso due to the tragic earthquake that hit the L'Aquila region). After 10 years the conference finally returned to Eilat, the originally envisioned site. Eilat is a resort town located on the shore of the Gulf of Eilat, which connects Israel to the Red Sea and further south to the Indian Ocean. It commands spectacular views of the desert and mountains, offering unique touristic attractions. The local scientific backdrop of the conference is the fact that the Israeli scientific scene exhibits a wide variety of research activities in many areas of nuclear physics and astrophysics. A new accelerator, SARAF at Soreq Nuclear Research Center is presently undergoing final acceptance tests. SARAF will serve as a platform for production of radioactive ion beams and nuclear-astrophysics research in Israel. The meeting in Eilat was organized by four Israeli scientific institutions, Hebrew University, Soreq Nuclear Research Center, Tel Aviv University and the Weizmann Institute of Science. The welcome reception and lectures were held at the King Solomon hotel and

  10. Quasi-linear landau kinetic equations for magnetized plasmas: compact propagator formalism, rotation matrices and interaction

    Energy Technology Data Exchange (ETDEWEB)

    Misguich, J.H

    2004-04-01

    As a first step toward a nonlinear renormalized description of turbulence phenomena in magnetized plasmas, the lowest order quasi-linear description is presented here from a unified point of view for collisionless as well as for collisional plasmas in a constant magnetic field. The quasi-linear approximation is applied to a general kinetic equation obtained previously from the Klimontovich exact equation, by means of a generalised Dupree-Weinstock method. The so-obtained quasi-linear description of electromagnetic turbulence in a magnetoplasma is applied to three separate physical cases: -) weak electrostatic turbulence, -) purely magnetic field fluctuations (the classical quasi-linear results are obtained for cosmic ray diffusion in the 'slab model' of magnetostatic turbulence in the solar wind), and -) collisional kinetic equations of magnetized plasmas. This mathematical technique has allowed us to derive basic kinetic equations for turbulent plasmas and collisional plasmas, respectively in the quasi-linear and Landau approximation. In presence of a magnetic field we have shown that the systematic use of rotation matrices describing the helical particle motion allows for a much more compact derivation than usually performed. Moreover, from the formal analogy between turbulent and collisional plasmas, the results derived here in detail for the turbulent plasmas, can be immediately translated to obtain explicit results for the Landau kinetic equation.

  11. A Coupled Plasma-Sheath Model for High Density Sources

    Science.gov (United States)

    Bose, Deepak; Govindan, T. R.; Meyyappan, M.

    2000-01-01

    High density, low pressure plasmas are used for etching and deposition in microelectronics fabrication processes. The process characteristics are strongly determined by the ion energy distribution (IED) and the ion flux arriving at the substrate that are responsible for desorption of etch products and neutral dissociation at the surface. The ion flux and energy are determined by a self- consistent modeling of the bulk plasma, where the ions and the neutral radicals are produced, and the sheath, where the ions are accelerated. Due to their widely different time scales, it is a formidable task to self-consistently resolve non-collisional sheath in a high density bulk plasma model. In this work, we first describe a coupled plasma-sheath model that attempts to resolve the non-collisional sheath in a reactor scale model. Second, we propose a semianalytical radio frequency (RF) sheath model to improve ion dynamics.

  12. Electron density and plasma dynamics of a colliding plasma experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wiechula, J., E-mail: wiechula@physik.uni-frankfurt.de; Schönlein, A.; Iberler, M.; Hock, C.; Manegold, T.; Bohlender, B.; Jacoby, J. [Plasma Physics Group, Institute of Applied Physics, Goethe University, 60438 Frankfurt am Main (Germany)

    2016-07-15

    We present experimental results of two head-on colliding plasma sheaths accelerated by pulsed-power-driven coaxial plasma accelerators. The measurements have been performed in a small vacuum chamber with a neutral-gas prefill of ArH{sub 2} at gas pressures between 17 Pa and 400 Pa and load voltages between 4 kV and 9 kV. As the plasma sheaths collide, the electron density is significantly increased. The electron density reaches maximum values of ≈8 ⋅ 10{sup 15} cm{sup −3} for a single accelerated plasma and a maximum value of ≈2.6 ⋅ 10{sup 16} cm{sup −3} for the plasma collision. Overall a raise of the plasma density by a factor of 1.3 to 3.8 has been achieved. A scaling behavior has been derived from the values of the electron density which shows a disproportionately high increase of the electron density of the collisional case for higher applied voltages in comparison to a single accelerated plasma. Sequences of the plasma collision have been taken, using a fast framing camera to study the plasma dynamics. These sequences indicate a maximum collision velocity of 34 km/s.

  13. Modules for Experiments in Stellar Astrophysics (MESA)

    Science.gov (United States)

    Paxton, Bill; Bildsten, Lars; Dotter, Aaron; Herwig, Falk; Lesaffre, Pierre; Timmes, Frank

    2011-01-01

    Stellar physics and evolution calculations enable a broad range of research in astrophysics. Modules for Experiments in Stellar Astrophysics (MESA) is a suite of open source, robust, efficient, thread-safe libraries for a wide range of applications in computational stellar astrophysics. A one-dimensional stellar evolution module, MESAstar, combines many of the numerical and physics modules for simulations of a wide range of stellar evolution scenarios ranging from very low mass to massive stars, including advanced evolutionary phases. MESAstar solves the fully coupled structure and composition equations simultaneously. It uses adaptive mesh refinement and sophisticated timestep controls, and supports shared memory parallelism based on OpenMP. State-of-the-art modules provide equation of state, opacity, nuclear reaction rates, element diffusion data, and atmosphere boundary conditions. Each module is constructed as a separate Fortran 95 library with its own explicitly defined public interface to facilitate independent development. Several detailed examples indicate the extensive verification and testing that is continuously performed and demonstrate the wide range of capabilities that MESA possesses. These examples include evolutionary tracks of very low mass stars, brown dwarfs, and gas giant planets to very old ages; the complete evolutionary track of a 1 M sun star from the pre-main sequence (PMS) to a cooling white dwarf; the solar sound speed profile; the evolution of intermediate-mass stars through the He-core burning phase and thermal pulses on the He-shell burning asymptotic giant branch phase; the interior structure of slowly pulsating B Stars and Beta Cepheids; the complete evolutionary tracks of massive stars from the PMS to the onset of core collapse; mass transfer from stars undergoing Roche lobe overflow; and the evolution of helium accretion onto a neutron star. MESA can be downloaded from the project Web site (http://mesa.sourceforge.net/).

  14. Cancellation of Collisional Frequency Shifts in Optical Lattice Clocks with Rabi Spectroscopy

    CERN Document Server

    Lee, Sangkyung; Lee, Won-Kyu; Yu, Dai-Hyuk

    2015-01-01

    We analyze both the s- and p-wave collision induced frequency shifts and propose a over-$\\pi$ pulse scheme to cancel the shifts in optical lattice clocks interrogated by a Rabi pulse. The collisional frequency shifts are analytically solved as a function of the pulse area and the inhomogeneity of the Rabi frequencies. Experimentally measured collisional frequency shifts in an Yb optical lattice clock are in good agreement with the analytical calculations. Based on our analysis, the over-$\\pi$ pulse combined with a small inhomogeneity below 0.1 allows a fractional uncertainty on a level of $10^{-18}$ in both Sr and Yb optical lattice clocks by canceling the collisional frequency shift. \\end{abstract}

  15. Cancellation of collisional frequency shifts in optical lattice clocks with Rabi spectroscopy

    Science.gov (United States)

    Lee, Sangkyung; Park, Chang Yong; Lee, Won-Kyu; Yu, Dai-Hyuk

    2016-03-01

    We analyze both the s- and p-wave collision induced frequency shifts and propose an over-π pulse scheme to cancel the shifts in optical lattice clocks interrogated by a Rabi pulse. The collisional frequency shifts are analytically solved as a function of the pulse area and the inhomogeneity of the Rabi frequencies. Experimentally measured collisional frequency shifts in an Yb optical lattice clock are in good agreement with the analytical calculations. Based on our analysis, the over-π pulse combined with a small inhomogeneity below 0.1 allows a fractional uncertainty on a level of 10-18 in both Sr and Yb optical lattice clocks by canceling the collisional frequency shift.

  16. Bibliometric indicators of young authors in astrophysics

    DEFF Research Database (Denmark)

    Havemann, Frank; Larsen, Birger

    2015-01-01

    their first landmark paper with the distributions of these indicators over a random control group of young authors in astronomy and astrophysics. We find that field and citation-window normalisation substantially improves the predicting power of citation indicators. The sum of citation numbers normalised...... with expected citation numbers is the only indicator which shows differences between later stars and random authors significant on a 1 % level. Indicators of paper output are not very useful to predict later stars. The famous h-index makes no difference at all between later stars and the random control group....

  17. 3D Immersive Visualization with Astrophysical Data

    Science.gov (United States)

    Kent, Brian R.

    2017-01-01

    We present the refinement of a new 3D immersion technique for astrophysical data visualization.Methodology to create 360 degree spherical panoramas is reviewed. The 3D software package Blender coupled with Python and the Google Spatial Media module are used together to create the final data products. Data can be viewed interactively with a mobile phone or tablet or in a web browser. The technique can apply to different kinds of astronomical data including 3D stellar and galaxy catalogs, images, and planetary maps.

  18. Dimensional analysis and group theory in astrophysics

    CERN Document Server

    Kurth, Rudolf

    2013-01-01

    Dimensional Analysis and Group Theory in Astrophysics describes how dimensional analysis, refined by mathematical regularity hypotheses, can be applied to purely qualitative physical assumptions. The book focuses on the continuous spectral of the stars and the mass-luminosity relationship. The text discusses the technique of dimensional analysis, covering both relativistic phenomena and the stellar systems. The book also explains the fundamental conclusion of dimensional analysis, wherein the unknown functions shall be given certain specified forms. The Wien and Stefan-Boltzmann Laws can be si

  19. Physics, Astrophysics and Cosmology with Gravitational Waves.

    Science.gov (United States)

    Sathyaprakash, B S; Schutz, Bernard F

    2009-01-01

    Gravitational wave detectors are already operating at interesting sensitivity levels, and they have an upgrade path that should result in secure detections by 2014. We review the physics of gravitational waves, how they interact with detectors (bars and interferometers), and how these detectors operate. We study the most likely sources of gravitational waves and review the data analysis methods that are used to extract their signals from detector noise. Then we consider the consequences of gravitational wave detections and observations for physics, astrophysics, and cosmology.

  20. ASTROPHYSICS: Neutron Stars Imply Relativity's a Drag.

    Science.gov (United States)

    Schilling, G

    2000-09-01

    A new finding, based on x-rays from distant neutron stars, could be the first clear evidence of a weird relativistic effect called frame dragging, in which a heavy chunk of spinning matter wrenches the space-time around it like an eggbeater. Using data from NASA's Rossi X-ray Timing Explorer, three astronomers in Amsterdam found circumstantial evidence for frame dragging in the flickering of three neutron stars in binary systems. They announced their results in the 1 September issue of The Astrophysical Journal.

  1. Light dark matter versus astrophysical constraints

    OpenAIRE

    Cline, James M.; Frey, Andrew R.

    2011-01-01

    Hints of direct dark matter detection coming from the DAMA, CoGeNT experiments point toward light dark matter with isospin-violating and possibly inelastic couplings. However an array of astrophysical constraints are rapidly closing the window on light dark matter. We point out that if the relic density is determined by annihilation into invisible states, these constraints can be evaded. As an example we present a model of quasi-Dirac dark matter, interacting via two U(1) gauge bosons, one of...

  2. Showing Complex Astrophysical Settings Through Virtual Reality

    Science.gov (United States)

    Green, Joel; Smith, Denise; Smith, Louis Chad; Lawton, Brandon; Lockwood, Alexandra; Jirdeh, Hussein

    2018-01-01

    The James Webb Space Telescope (JWST), NASA’s next great observatory launching in spring 2019, will routinely showcase astrophysical concepts that will challenge the public's understanding. Emerging technologies such as virtual reality bring the viewer into the data and the concept in previously unimaginable immersive detail. For example, we imagine a spacefarer inside a protoplanetary disk, seeing the accretion process directly. STScI is pioneering some tools related to JWST for showcasing at AAS, and in local events, which I highlight here. If we develop materials properly tailored to this medium, we can reach more diverse audiences than ever before.

  3. Alpha resonant scattering for astrophysical reaction studies

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, H.; Kahl, D.; Nakao, T. [Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Wakabayashi, Y.; Kubano, S. [The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Hashimoto, T. [Research Center for Nuclear Physics (RCNP), Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Hayakawa, S. [Istituto Nazionale Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), Via S. Sofia 62, 95125 Catania (Italy); Kawabata, T. [Department of Physics, Kyoto University, Kita-Shirakawa, Kyoto 606-8502 (Japan); Iwasa, N. [Department of Physics, Tohoku University, Aoba, Sendai, Miyagi 980-8578 (Japan); Teranishi, T. [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Kwon, Y. K. [Institute for Basic Science, 70, Yuseong-daero 1689-gil, Yuseong-gu, Daejeon 305-811 (Korea, Republic of); Binh, D. N. [30 MeV Cyclotron Center, Tran Hung Dao Hospital, Hoan Kiem District, Hanoi (Viet Nam); Khiem, L. H.; Duy, N. G. [Institute of Physics, Vietnam Academy of Science and Technology, 18 Hong Quoc Viet, Nghia do, Hanoi (Viet Nam)

    2014-05-02

    Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the α resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of {sup 7}Be+α resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the {sup 7}Be(α,γ) reaction, and proposed a new cluster band in {sup 11}C.

  4. High energy particles and quanta in astrophysics

    Science.gov (United States)

    Mcdonald, F. B. (Editor); Fichtel, C. E.

    1974-01-01

    The various subdisciplines of high-energy astrophysics are surveyed in a series of articles which attempt to give an overall view of the subject as a whole by emphasizing the basic physics common to all fields in which high-energy particles and quanta play a role. Successive chapters cover cosmic ray experimental observations, the abundances of nuclei in the cosmic radiation, cosmic electrons, solar modulation, solar particles (observation, relationship to the sun acceleration, interplanetary medium), radio astronomy, galactic X-ray sources, the cosmic X-ray background, and gamma ray astronomy. Individual items are announced in this issue.

  5. Reaction Studies for Explosive Nuclear Astrophysics

    Science.gov (United States)

    Woods, Philip J.

    The paper describes experimental approaches to measuring key nuclear astrophysical reactions involving radioactive isotopes. Specifically the paper considers the utilisation of (d, n) and (d, p) transfer reactions to probe the strengths of key resonances in the hydrogen burning/proton capture reactions 30P(p, γ) and 26Al(p, γ). The use of a radioactive target and silicon strip detector set-ups to study the key 26Al(n, p) and (n, α) destruction reactions relevant to explosive burning conditions in core collapse supernovae is also reported.

  6. Physics, Astrophysics and Cosmology with Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Sathyaprakash B. S.

    2009-03-01

    Full Text Available Gravitational wave detectors are already operating at interesting sensitivity levels, and they have an upgrade path that should result in secure detections by 2014. We review the physics of gravitational waves, how they interact with detectors (bars and interferometers, and how these detectors operate. We study the most likely sources of gravitational waves and review the data analysis methods that are used to extract their signals from detector noise. Then we consider the consequences of gravitational wave detections and observations for physics, astrophysics, and cosmology.

  7. Determination of collisional quenching rate coefficients of metastable nitrogen molecules by air pollutants

    Science.gov (United States)

    Suzuki, Susumu; Itoh, Haruo

    2009-10-01

    It has already been investigated on the determination of the collisional quenching rate coefficients of the metastable nitrogen molecules N2(A^3σu^+ ) by some air pollutants [1] in our laboratory. In this report, we present the result on the collisional quenching rate coefficient of N2(A^3σu^+ ) by formaldehyde (CH2O) using a theoretical procedure that takes into account the reflection of metastables at the boundary. As far as we know, this report is the first result of the collisional quenching rate coefficients of N2(A^3σu^+ ) by CH2O. Formaldehyde is a colorless gas with the foul odor, and elements of the adhesive, paints, and preservative, etc. It is widely used for construction materials such as houses, because it is low cost. It is released from paint of construction materials in air, and, in that case, it is known as one of the causative agents of so-called ``Sick building syndrome'' to influence the human body harmfully even if it is a low concentration. The obtained collisional quenching rate coefficient of N2(A^3σu^+ ) by CH2O is (4.7±0.4) x 10-12 cm^3/s. Because the collisional quenching rate coefficient by CH2O is large, it is understood that CH2O receives energy easily from N2(A^3σu^+ ). In addition, we reports on the obtained collisional quenching rate coefficient of N2(A^3σu^+ ) by some air pollutants. [1] S. Suzuki, T.Suzuki and H.Itoh: Proc. of XXVIII ICPIG (Prague, Czech Republic), (2007) 1P01-40.

  8. Exponentially long Equilibration times in a 1-D Collisional Model of a classical gas

    DEFF Research Database (Denmark)

    Hjorth, Poul; Benettin, G.

    1999-01-01

    separation between the time scale for the vibration and the time scale associated with a typical binary collision in the gas. We consider here a simple 1-D model, and show how, when these time scales are well separated, the collisional dynamics is constrained by a many-particle adiabatic invariant....... The effect is that the collisional energy exchanges between the translational and the vibrational degrees of freedom are slowed down by an exponential factor (as Jeans conjectured). A metastable situation thus occurs, in which the fast vibrational degrees of freedom effectivly do not contribute...... the time scale for the evolution to statistical equilibrium. The theoretical analysis is supported by numerical examples....

  9. The finite-amplitude behavior of the Joule mode under astrophysical conditions

    Science.gov (United States)

    Bodo, G.; Massaglia, S.; Rosner, R.; Ferrari, A.

    1991-01-01

    Magnetized astrophysical plasmas reveal a great deal of structure when spatially resolved. One possible explanation for this structuring is based on the existence of filamenting instabilities driven by radiation. In this paper, previous linear calculations are extended by considering the weakly nonlinear (finite-amplitude) development of such filamenting instabilities in magnetized unstratified plasmas. It is shown that under most conditions these instabilities (in particular, the Jouse model) are unstable at finite amplitude; in particular, in the temperature and plasma-beta domains characteristic of, for example, much of the solar transition region, these modes - which can be linearly stable under these conditions - become unstable to finite-amplitude perturbations. The relevance of this to the problem of heating the solar low transition region by current dissipation is discussed.

  10. Predicting the statistics of high-energy astrophysical backgrounds

    NARCIS (Netherlands)

    Feyereisen, M.R.

    2017-01-01

    This thesis presents improvements to a methodology for predicting the probability distribution of diffuse isotropic astrophysical backgrounds, applied to high-energy extragalactic gamma rays and neutrinos.

  11. Solar, Stellar and Galactic Connections between Particle Physics and Astrophysics

    CERN Document Server

    Carraminana, Alberto

    2007-01-01

    This book collects extended and specialized reviews on topics linking astrophysics and particle physics at a level intermediate between a graduate student and a young researcher. The book includes also three reviews on observational techniques used in forefront astrophysics and short articles on research performed in Latin America. The reviews, updated and written by specialized researchers, describe the state of the art in the related research topics. This book is a valuable complement not only for research but also for lecturers in specialized course of high energy astrophysics, cosmic ray astrophysics and particle physics.

  12. Spin light of neutrino in astrophysical environments

    Science.gov (United States)

    Grigoriev, Alexander; Lokhov, Alexey; Studenikin, Alexander; Ternov, Alexei

    2017-11-01

    The spin light of neutrino (SLν) is a new possible mechanism of electromagnetic radiation by a massive neutrino (with a nonzero magnetic moment) moving in media. Since the prediction of this mechanism, the question has been debated in a number of publications as whether the effect can be of any significance for realistic astrophysical conditions. Although this effect is strongly suppressed due to smallness of neutrino magnetic moment, for ultra-high energy neutrinos (PeV neutrinos recently observed by the IceCube collaboration, for instance) the SLν might be of interest in the case of neutrinos propagating in dense matter. An advanced view on the SLν in matter is given, and several astrophysical settings (a neutron star, supernova, Gamma-Ray Burst (GRB), and relic neutrino background) for which the effect can be realized are considered. Taking into account the threshold condition and also several competing processes, we determine conditions for which the SLν mechanism is possible. We conclude that the most favorable case of the effect manifestation is provided by ultra dense matter of neutron stars and ultrahigh energy of the radiating neutrino, and note that these conditions can be met within galaxy clusters. It is also shown that due to the SLν specific polarization properties this electromagnetic mechanism is of interest in the connection with the observed polarization of GRB emission.

  13. Electrodynamics and spacetime geometry: Astrophysical applications

    Science.gov (United States)

    Cabral, Francisco; Lobo, Francisco S. N.

    2017-07-01

    After a brief review of the foundations of (pre-metric) electromagnetism, we explore some physical consequences of electrodynamics in curved spacetime. In general, new electromagnetic couplings and related phenomena are induced by the spacetime curvature. The applications of astrophysical interest considered here correspond essentially to the following geometries: the Schwarzschild spacetime and the spacetime around a rotating spherical mass in the weak field and slow rotation regime. In the latter, we use the Parameterised Post-Newtonian (PPN) formalism. We also explore the hypothesis that the electric and magnetic properties of vacuum reflect the spacetime isometries. Therefore, the permittivity and permeability tensors should not be considered homogeneous and isotropic a priori. For spherical geometries we consider the effect of relaxing the homogeneity assumption in the constitutive relations between the fields and excitations. This affects the generalized Gauss and Maxwell-Ampère laws, where the electric permittivity and magnetic permeability in vacuum depend on the radial coordinate in accordance with the local isometries of space. For the axially symmetric geometries we relax both the assumptions of homogeneity and isotropy. We explore simple solutions and discuss the physical implications related to different phenomena, such as the decay of electromagnetic fields in the presence of gravity, magnetic terms in Gauss law due to the gravitomagnetism of the spacetime around rotating objects, a frame-dragging effect on electric fields and the possibility of a spatial (radial) variability of the velocity of light in vacuum around spherical astrophysical objects for strong gravitational fields.

  14. Highlights of the NASA particle astrophysics program

    Energy Technology Data Exchange (ETDEWEB)

    Jones, William Vernon, E-mail: w.vernon.jones@nasa.gov [Astrophysics Division DH000, Science Mission Directorate, NASA Headquarters, Washington DC (United States)

    2014-07-01

    The NASA Particle Astrophysics Program covers Origin of the Elements, Nearest Sources of Cosmic Rays, How Cosmic Particle Accelerators Work, The Nature of Dark Matter, and Neutrino Astrophysics. Progress in each of these topics has come from sophisticated instrumentation flown on long duration balloon (LDB) flights around Antarctica over the past two decades. New opportunities including Super Pressure Balloons (SPB) and International Space Station (ISS) platforms are emerging for the next major step. Stable altitudes and long durations enabled by SPB flights ensure ultra-long duration balloon (ULDB) missions that can open doors to new science opportunities. The Alpha Magnetic Spectrometer (AMS) has been operating on the ISS since May 2011. The CALorimetric Electron Telescope (CALET) and Cosmic Ray Energetics And Mass (CREAM) experiments are being developed for launch to the Japanese Experiment Module Exposed Facility (JEM-EF) in 2015. And, the Extreme Universe Space Observatory (EUSO) is planned for launch to the ISS JEM-EF after 2017. Collectively, these four complementary ISS missions covering a large portion of the cosmic ray energy spectrum serve as a cosmic ray observatory. (author)

  15. Astrophysical Model Selection in Gravitational Wave Astronomy

    Science.gov (United States)

    Adams, Matthew R.; Cornish, Neil J.; Littenberg, Tyson B.

    2012-01-01

    Theoretical studies in gravitational wave astronomy have mostly focused on the information that can be extracted from individual detections, such as the mass of a binary system and its location in space. Here we consider how the information from multiple detections can be used to constrain astrophysical population models. This seemingly simple problem is made challenging by the high dimensionality and high degree of correlation in the parameter spaces that describe the signals, and by the complexity of the astrophysical models, which can also depend on a large number of parameters, some of which might not be directly constrained by the observations. We present a method for constraining population models using a hierarchical Bayesian modeling approach which simultaneously infers the source parameters and population model and provides the joint probability distributions for both. We illustrate this approach by considering the constraints that can be placed on population models for galactic white dwarf binaries using a future space-based gravitational wave detector. We find that a mission that is able to resolve approximately 5000 of the shortest period binaries will be able to constrain the population model parameters, including the chirp mass distribution and a characteristic galaxy disk radius to within a few percent. This compares favorably to existing bounds, where electromagnetic observations of stars in the galaxy constrain disk radii to within 20%.

  16. $\\alpha$-cluster ANCs for nuclear astrophysics

    CERN Document Server

    Avila, M L; Koshchiy, E; Baby, L T; Belarge, J; Kemper, K W; Kuchera, A N; Santiago-Gonzalez, D

    2014-01-01

    Background. Many important $\\alpha$-particle induced reactions for nuclear astrophysics may only be measured using indirect techniques due to small cross sections at the energy of interest. One of such indirect technique, is to determine the Asymptotic Normalization Coefficients (ANC) for near threshold resonances extracted from sub-Coulomb $\\alpha$-transfer reactions. This approach provides a very valuable tool for studies of astrophysically important reaction rates since the results are practically model independent. However, the validity of the method has not been directly verified. Purpose. The aim of this letter is to verify the technique using the $^{16}$O($^6$Li,$d$)$^{20}$Ne reaction as a benchmark. The $^{20}$Ne nucleus has a well known $1^-$ state at excitation energy of 5.79 MeV with a width of 28 eV. Reproducing the known value with this technique is an ideal opportunity to verify the method. Method. The 1$^-$ state at 5.79 MeV is studied using the $\\alpha$-transfer reaction $^{16}$O($^6$Li,$d$)$^...

  17. Nuclear and High-Energy Astrophysics

    Science.gov (United States)

    Weber, Fridolin

    2003-10-01

    There has never been a more exciting time in the overlapping areas of nuclear physics, particle physics and relativistic astrophysics than today. Orbiting observatories such as the Hubble Space Telescope, Rossi X-ray Timing Explorer (RXTE), Chandra X-ray satellite, and the X-ray Multi Mirror Mission (XMM) have extended our vision tremendously, allowing us to see vistas with an unprecedented clarity and angular resolution that previously were only imagined, enabling astrophysicists for the first time ever to perform detailed studies of large samples of galactic and extragalactic objects. On the Earth, radio telescopes (e.g., Arecibo, Green Bank, Parkes, VLA) and instruments using adaptive optics and other revolutionary techniques have exceeded previous expectations of what can be accomplished from the ground. The gravitational wave detectors LIGO, LISA VIRGO, and Geo-600 are opening up a window for the detection of gravitational waves emitted from compact stellar objects such as neutron stars and black holes. Together with new experimental forefront facilities like ISAC, ORLAND and RIA, these detectors provide direct, quantitative physical insight into nucleosynthesis, supernova dynamics, accreting compact objects, cosmic-ray acceleration, and pairproduction in high energy sources which reinforce the urgent need for a strong and continuous feedback from nuclear and particle theory and theoretical astrophysics. In my lectures, I shall concentrate on three selected topics, which range from the behavior of superdense stellar matter, to general relativistic stellar models, to strange quark stars and possible signals of quark matter in neutron stars.

  18. Advancing Astrophysics with the Square Kilometre Array

    CERN Document Server

    Fender, Rob; Govoni, Federica; Green, Jimi; Hoare, Melvin; Jarvis, Matt; Johnston-Hollitt, Melanie; Keane, Evan; Koopmans, Leon; Kramer, Michael; Maartens, Roy; Macquart, Jean-Pierre; Mellema, Garrelt; Oosterloo, Tom; Prandoni, Isabella; Pritchard, Jonathan; Santos, Mario; Seymour, Nick; Stappers, Ben; Staveley-Smith, Lister; Tian, Wen Wu; Umana, Grazia; Wagg, Jeff; Bourke, Tyler L; AASKA14

    2015-01-01

    In 2014 it was 10 years since the publication of the comprehensive ‘Science with the Square Kilometre Array’ book and 15 years since the first such volume appeared in 1999. In that time numerous and unexpected advances have been made in the fields of astronomy and physics relevant to the capabilities of the Square Kilometre Array (SKA). The SKA itself progressed from an idea to a developing reality with a baselined Phase 1 design (SKA1) and construction planned from 2017. To facilitate the publication of a new, updated science book, which will be relevant to the current astrophysical context, the meeting "Advancing Astrophysics with the Square Kilometre Array" was held in Giardina Naxos, Sicily. Articles were solicited from the community for that meeting to document the scientific advances enabled by the first phase of the SKA and those pertaining to future SKA deployments, with expected gains of 5 times the Phase 1 sensitivity below 350 MHz, about 10 times the Phase 1 sensitivity above 350 MHz and with f...

  19. The CATS Service: An Astrophysical Research Tool

    Directory of Open Access Journals (Sweden)

    O V Verkhodanov

    2009-03-01

    Full Text Available We describe the current status of CATS (astrophysical CATalogs Support system, a publicly accessible tool maintained at Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS (http://cats.sao.ru allowing one to search hundreds of catalogs of astronomical objects discovered all along the electromagnetic spectrum. Our emphasis is mainly on catalogs of radio continuum sources observed from 10 MHz to 245 GHz, and secondly on catalogs of objects such as radio and active stars, X-ray binaries, planetary nebulae, HII regions, supernova remnants, pulsars, nearby and radio galaxies, AGN and quasars. CATS also includes the catalogs from the largest extragalactic surveys with non-radio waves. In 2008 CATS comprised a total of about 109 records from over 400 catalogs in the radio, IR, optical and X-ray windows, including most source catalogs deriving from observations with the Russian radio telescope RATAN-600. CATS offers several search tools through different ways of access, e.g. via Web-interface and e-mail. Since its creation in 1997 CATS has managed about 105requests. Currently CATS is used by external users about 1500 times per day and since its opening to the public in 1997 has received about 4000 requests for its selection and matching tasks.

  20. Black Hole Astrophysics The Engine Paradigm

    CERN Document Server

    Meier, David L

    2012-01-01

    As a result of significant research over the past 20 years, black holes are now linked to some of the most spectacular and exciting phenomena in the Universe, ranging in size from those that have the same mass as stars to the super-massive objects that lie at the heart of most galaxies, including our own Milky Way. This book first introduces the properties of simple isolated holes, then adds in complications like rotation, accretion, radiation, and magnetic fields, finally arriving at a basic understanding of how these immense engines work. Black Hole Astrophysics • reviews our current knowledge of cosmic black holes and how they generate the most powerful observed pheonomena in the Universe; • highlights the latest, most up-to-date theories and discoveries in this very active area of astrophysical research; • demonstrates why we believe that black holes are responsible for important phenomena such as quasars, microquasars and gammaray bursts; • explains to the reader the nature of the violent and spe...

  1. Time-symmetric integration in astrophysics

    Science.gov (United States)

    Hernandez, David M.; Bertschinger, Edmund

    2018-01-01

    Calculating the long term solution of ordinary differential equations, such as those of the N-body problem, is central to understanding a wide range of dynamics in astrophysics, from galaxy formation to planetary chaos. Because generally no analytic solution exists to these equations, researchers rely on numerical methods which are prone to various errors. In an effort to mitigate these errors, powerful symplectic integrators have been employed. But symplectic integrators can be severely limited because they are not compatible with adaptive stepping and thus they have difficulty accommodating changing time and length scales. A promising alternative is time-reversible integration, which can handle adaptive time stepping, but the errors due to time-reversible integration in astrophysics are less understood. The goal of this work is to study analytically and numerically the errors caused by time-reversible integration, with and without adaptive stepping. We derive the modified differential equations of these integrators to perform the error analysis. As an example, we consider the trapezoidal rule, a reversible non-symplectic integrator, and show it gives secular energy error increase for a pendulum problem and for a Hénon-Heiles orbit. We conclude that using reversible integration does not guarantee good energy conservation and that, when possible, use of symplectic integrators is favored. We also show that time-symmetry and time-reversibility are properties that are distinct for an integrator.

  2. Art as a Vehicle for Nuclear Astrophysics

    Science.gov (United States)

    Kilburn, Micha

    2013-04-01

    One aim of the The Joint Institute for Nuclear Astrophysics (JINA) is to teach K-12 students concepts and ideas related to nuclear astrophysics. For students who have not yet seen the periodic table, this can be daunting, and we often begin with astronomy concepts. The field of astronomy naturally lends itself to an art connection through its beautiful images. Our Art 2 Science programming adopts a hands-on approach by teaching astronomy through student created art projects. This approach engages the students, through tactile means, visually and spatially. For younger students, we also include physics based craft projects that facilitate the assimilation of problem solving skills. The arts can be useful for aural and kinetic learners as well. Our program also includes singing and dancing to songs with lyrics that teach physics and astronomy concepts. The Art 2 Science programming has been successfully used in after-school programs at schools, community centers, and art studios. We have even expanded the program into a popular week long summer camp. I will discuss our methods, projects, specific goals, and survey results for JINA's Art 2 Science programs.

  3. Consequences of entropy bifurcation in non-Maxwellian astrophysical environments

    Science.gov (United States)

    Leubner, M. P.

    2008-07-01

    Non-extensive systems, accounting for long-range interactions and correlations, are fundamentally related to non-Maxwellian distributions where a duality of equilibria appears in two families, the non-extensive thermodynamic equilibria and the kinetic equilibria. Both states emerge out of particular entropy generalization leading to a class of probability distributions, where bifurcation into two stationary states is naturally introduced by finite positive or negative values of the involved entropic index kappa. The limiting Boltzmann-Gibbs-Shannon state (BGS), neglecting any kind of interactions within the system, is subject to infinite entropic index and thus characterized by self-duality. Fundamental consequences of non-extensive entropy bifurcation, manifest in different astrophysical environments, as particular core-halo patterns of solar wind velocity distributions, the probability distributions of the differences of the fluctuations in plasma turbulence as well as the structure of density distributions in stellar gravitational equilibrium are discussed. In all cases a lower entropy core is accompanied by a higher entropy halo state as compared to the standard BGS solution. Data analysis and comparison with high resolution observations significantly support the theoretical requirement of non-extensive entropy generalization when dealing with systems subject to long-range interactions and correlations.

  4. Plasma ionization frequency, edge-to-axis density ratio, and density on axis of a cylindrical gas discharge

    Energy Technology Data Exchange (ETDEWEB)

    Palacio Mizrahi, J. H. [Physics Department, Technion, Haifa 32000 (Israel)

    2014-06-15

    A rigorous derivation of expressions, starting from the governing equations, for the ionization frequency, edge-to-axis ratio of plasma density, plasma density at the axis, and radially averaged plasma density in a cylindrical gas discharge has been obtained. The derived expressions are simple and involve the relevant parameters of the discharge: Cylinder radius, axial current, and neutral gas pressure. The found expressions account for ion inertia, ion temperature, and changes in plasma ion collisionality.

  5. Collisional-Radiative Nonequilibrium and Precursor Effects in a Nitrogen Shock Wave

    Science.gov (United States)

    Cambier, Jean-Luc; Edwards, Thomas A. (Technical Monitor)

    1994-01-01

    Improvements to a plasma code with a Collisional-Radiative (CR) non-equilibrium model are made, allowing for a more accurate description of the physical processes. The code allows for non-Boltzmann distributions of the electronic excited states by convecting separately each excited state, as a pseudo-specie. Each molecular state has also its own vibrational temperature, while a global rotational temperature is assumed. The free electron temperature is different from those of the excited states, and the electron heat conduction is also included. The CR model also uses a unique coupling between chemistry and vibrational energy (C-V coupling), which is fully coherent, and has the property of establishing thermal equilibrium as well as chemical equilibrium, on its own. We have also included a coupling between electronic excitations and vibrational energy (X-V coupling), which can have a strong influence on the vibrational temperature of some states. The recent improvements include the multi- temperature dependence of the chemical rates for associative ionization, as well as the estimation of the internal energies transferred during this process. Additionally, the distribution of energy into different translational modes (electron and heavy particles) is now correctly modeled. This provides a very rapid heating mechanism for the free electrons, since it is found that the electrons are generated with an average thermal energy of the same order as the heavy particle translational energy. This effect was observed by Gorelov et al in a recent paper, and lead to pronounced peaks in electron temperature immediately behind the shock. We will attempt ro reproduce this phenomenon. The last modification concerns the inclusion of the radiative terms into the calculations, thus enabling us to observe the effect of radiative losses and radiation transport. Preliminary tests have shown that the radiative losses are not negligible, i.e. the shock velocity drops when the radiative

  6. Suppression of phase mixing in drift-kinetic plasma turbulence

    CERN Document Server

    Parker, J T; Schekochihin, A A; Dellar, P J

    2016-01-01

    Transfer of free energy from large to small velocity-space scales by phase mixing leads to Landau damping in a linear plasma. In a turbulent drift-kinetic plasma, this transfer is statistically nearly canceled by an inverse transfer from small to large velocity-space scales due to "anti-phase-mixing" modes excited by a stochastic form of plasma echo. Fluid moments (density, velocity, temperature) are thus approximately energetically isolated from the higher moments of the distribution function, so phase mixing is ineffective as a dissipation mechanism when the plasma collisionality is small.

  7. Experimental verification of the Bohm criterion for two species plasmas

    Science.gov (United States)

    Hershkowitz, Noah; Oksuz, Lutfi; Lee, Dongsoo

    2007-11-01

    Ion acoustic wave (IAW) phase velocities are measured near the sheath/presheath boundary in weakly collisional argon/xenon plasmas. Wave profiles vs. position are measured using a boxcar averager with a gate of 30 nsec and CW excitation. Variable gate delays allow measurement of details of the wave close to the boundary. It is shown that the phase velocity at the presheath/sheath boundary is approximately twice the phase velocity in the bulk plasma for mixture and single species plasmas. This indicates each ion species drift velocity at the boundary is equal to the IAW phase velocity in the bulk plasma. This result is independent of relative ion concentration.

  8. Electron beam injection during active experiments. II - Collisional effects

    Science.gov (United States)

    Winglee, R. M.

    1990-01-01

    During active beam experiments, the presence of high neutral densities at low altitudes and/or during thruster firings has been observed to modify the spacecraft charging and the properties of the beam. Two-dimensional (three-velocity) electromagnetic particle simulations with ionizing collisions incorporated are used to investigate the modification of the beam-plasma interaction as the neutral density is increased. It is shown that when the spacecraft is uniformly immersed in a neutral cloud, most of the ionization is produced by direct ionization by the beam and its secondaries, rather than via vehicle-induced or wave-induced ionization for the neutral densities considered.

  9. Poloidal potential in the low-collisionality regime in a nonaxisymmetric torus

    Energy Technology Data Exchange (ETDEWEB)

    Hastings, D.E.; Tolliver, J.S.

    1986-01-01

    The poloidal potential is calculated numerically in the low-collisionality regime for nonaxisymmetric tori such as stellarators and bumpy tori. It is found that even fairly deep into the superbanana regime, the poloidal potential retains the simple azimuthal dependence of the plateau regime. 12 refs., 8 figs.

  10. Comparison of continuous and discontinuous collisional bumpers: Dimensionally scaled impact experiments into single wire meshes

    Science.gov (United States)

    Hoerz, Friedrich; Cintala, Mark; See, Thomas; Bernhard, Ronald; Cardenas, Frank; Davidson, William; Haynes, Jerry

    1992-01-01

    An experimental inquiry into the utility of discontinuous bumpers was conducted to investigate the collisional outcomes of impacts into single grid-like targets and to compare the results with more traditional bumper designs that employ continuous sheet stock. We performed some 35 experiments using 6.3 and 3.2 mm diameter spherical soda-lime glass projectiles at low velocities (less than 2.5 km/s) and 13 at velocities between 5 and 6 km/s, using 3.2 mm spheres only. The thrust of the experiments related to the characterization of collisional fragments as a function of target thickness or areal shield mass of both bumper designs. The primary product of these experiments was witness plates that record the resulting population of collisional fragments. Substantial interpretive and predictive insights into bumper performance were obtained. All qualitative observations (on the witness plates) and detailed measurements of displaced masses seem simply and consistently related only to bumper mass available for interaction with the impactor. This renders the grid bumper into the superior shield design. These findings present evidence that discontinuous bumpers are a viable concept for collisional shields, possibly superior to continuous geometries.

  11. Occultations of Astrophysical Radio Sources as Probes of (Exo)Planetary Environments

    Science.gov (United States)

    Dalba, Paul A.; Withers, Paul; Vogt, Marissa F.

    2017-05-01

    The passage of a radio signal through a planetary atmosphere, ionosphere, or magnetosphere affects the polarization, frequency, and power of the radio signal. Radio occultations are a common experiment used to measure planetary atmospheres, but they traditionally rely on radio transmissions from a spacecraft near the planet. We explore whether similar measurements of planetary and exoplanetary environments can be made using distant astrophysical radio sources such as pulsars, active galactic nuclei, and masers. We find that occultations by solar system planets, such as Jupiter, can be used to measure planetary magnetic field strength, plasma density, and neutral density. Based on the number of known distant astrophysical radio sources, occultations by solar system planets are likely to occur often. Occultations are most likely when the solar system planets are near the intersection of the ecliptic and galactic planes. For even the closest exoplanetary systems, the low probability of alignment of the Earth, an exoplanet, and a suitable distant astrophysical radio source presents a considerable challenge. The concentration of both exoplanets and galactic radio sources in the galactic plane may alleviate this challenge somewhat, but it still appears formidable. An alternative type of occultation may be more promising for exoplanets: high-resolution radio imaging of an exoplanet as it transits in front of its parent star.

  12. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. P. Venkatakrishnan. Articles written in Journal of Astrophysics and Astronomy. Volume 21 Issue 3-4 September-December 2000 pp 171-172 Session III – Sunspots & Solar Cycle. Is a Sunspot in Static or Dynamic Equilibrium? P. Venkatakrishnan · More Details ...

  13. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Home; Journals; Journal of Astrophysics and Astronomy. Shibu K. Mathew. Articles written in Journal of Astrophysics and Astronomy. Volume 21 Issue 3-4 September-December 2000 pp 233-236 Session V – Vector Magnetic Fields, Prominences, CMEs & Flares. A Rapidly Evolving Active Region NOAA ...

  14. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. Samir Dhurde. Articles written in Journal of Astrophysics and Astronomy. Volume 28 Issue 1 March 2007 pp 29-40. Kinematical Diagrams for Conical Relativistic Jets · Gopal-Krishna Pronoy Sircar Samir Dhurde · More Details Abstract Fulltext PDF. We present ...

  15. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. K. Duorah. Articles written in Journal of Astrophysics and Astronomy. Volume 36 Issue 3 September 2015 pp 375-383. A Comparative Study on SN II Progenitors for the Synthesis of Li and B with the help of Neutrinos · N. Lahkar S. Kalita H. L. Duorah K. Duorah.

  16. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. Visweshwar Ram Marthi. Articles written in Journal of Astrophysics and Astronomy. Volume 38 Issue 1 March 2017 pp 12 Review Article. Prowess – A Software Model for the Ooty Wide Field Array · Visweshwar Ram Marthi · More Details Abstract Fulltext PDF.

  17. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. Liu Zhong-bao. Articles written in Journal of Astrophysics and Astronomy. Volume 37 Issue 2 June 2016 pp 12. Stellar Spectral Classification with Locality Preserving Projections and Support Vector Machine · Liu Zhong-bao · More Details Abstract Fulltext PDF.

  18. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. F. Reale. Articles written in Journal of Astrophysics and Astronomy. Volume 29 Issue 1-2 March-June 2008 pp 339-343. SphinX: A Fast Solar Photometer in X-rays · J. Sylwester S. Kuzin Yu. D. Kotov F. Farnik F. Reale · More Details Abstract Fulltext PDF. The scientific ...

  19. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. B. B. Nath. Articles written in Journal of Astrophysics and Astronomy. Volume 37 Issue 4 December 2016 pp 34 Review. From Nearby Low Luminosity AGN to High Redshift Radio Galaxies: Science Interests with Square Kilometre Array · P. Kharb D. V. Lal V. Singh J.

  20. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. C. Mito. Articles written in Journal of Astrophysics and Astronomy. Volume 38 Issue 4 December 2017 pp 71 Research Article. Relativistic Dynamics in a Matter-Dominated Friedmann Universe · M. Langa D. S. Wamalwa C. Mito · More Details Abstract Fulltext PDF.