Liu, Chang
2015-01-01
The nonlinear frequency shift is derived in a transparent asymptotic form for intense Langmuir waves in general collisionless plasma. The formula describes both fluid and kinetic effects simultaneously. The fluid nonlinearity is expressed, for the ?first time, through the plasma dielectric function, and the kinetic nonlinearity accounts for both smooth distributions and trapped-particle beams. Various known limiting scalings are reproduced as special cases. The calculation avoids differential equations and can be extended straightforwardly to other nonlinear plasma waves.
Feng, Q S; Wang, Q; Zheng, C Y; Liu, Z J; Cao, L H; He, X T
2016-01-01
The properties of the nonlinear frequency shift (NFS) especially the fluid NFS from the harmonic generation of the ion-acoustic wave (IAW) in multi-ion species plasmas have been researched by Vlasov simulation. The pictures of the nonlinear frequency shift from harmonic generation and particles trapping are shown to explain the mechanism of NFS qualitatively. The theoretical model of the fluid NFS from harmonic generation in multi-ion species plasmas is given and the results of Vlasov simulation are consistent to the theoretical result of multi-ion species plasmas. When the wave number $k\\lambda_{De}$ is small, such as $k\\lambda_{De}=0.1$, the fluid NFS dominates in the total NFS and will reach as large as nearly $15\\%$ when the wave amplitude $|e\\phi/T_e|\\sim0.1$, which indicates that in the condition of small $k\\lambda_{De}$, the fluid NFS dominates in the saturation of stimulated Brillouin scattering especially when the nonlinear IAW amplitude is large.
Energy Technology Data Exchange (ETDEWEB)
Morrison, P.J., E-mail: morrison@physics.utexas.edu [Department of Physics and Institute for Fusion Studies, University of Texas, Austin (United States); Vanneste, J. [School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh (United Kingdom)
2016-05-15
A method, called beatification, is presented for rapidly extracting weakly nonlinear Hamiltonian systems that describe the dynamics near equilibria of systems possessing Hamiltonian form in terms of noncanonical Poisson brackets. The procedure applies to systems like fluids and plasmas in terms of Eulerian variables that have such noncanonical Poisson brackets, i.e., brackets with nonstandard and possibly degenerate form. A collection of examples of both finite and infinite dimensions is presented.
A General Nonlinear Fluid Model for Reacting Plasma-Neutral Mixtures
Energy Technology Data Exchange (ETDEWEB)
Meier, E T; Shumlak, U
2012-04-06
A generalized, computationally tractable fluid model for capturing the effects of neutral particles in plasmas is derived. The model derivation begins with Boltzmann equations for singly charged ions, electrons, and a single neutral species. Electron-impact ionization, radiative recombination, and resonant charge exchange reactions are included. Moments of the reaction collision terms are detailed. Moments of the Boltzmann equations for electron, ion, and neutral species are combined to yield a two-component plasma-neutral fluid model. Separate density, momentum, and energy equations, each including reaction transfer terms, are produced for the plasma and neutral equations. The required closures for the plasma-neutral model are discussed.
Nonlinear plasma wave in magnetized plasmas
Energy Technology Data Exchange (ETDEWEB)
Bulanov, Sergei V. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Prokhorov Institute of General Physics, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 (Russian Federation); Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Hosokai, Tomonao; Zhidkov, Alexei G. [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Science and Technology Agency, CREST, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Kodama, Ryosuke [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)
2013-08-15
Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic “Four-Ray Star” pattern.
Kono, Mitsuo
2010-01-01
A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.
Nonlinear Plasma Wave in Magnetized Plasmas
Bulanov, Sergei V; Kando, Masaki; Koga, James K; Hosokai, Tomonao; Zhidkov, Alexei G; Kodama, Ryosuke
2013-01-01
Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic "Four-Ray Star" pattern which has been observed in the image of the electron bunch in experiments [T. Hosokai, et al., Phys. Rev. Lett. 97, 075004 (2006)].
Nonlinear Electrostatic Wave Equations for Magnetized Plasmas
DEFF Research Database (Denmark)
Dysthe, K.B.; Mjølhus, E.; Pécseli, Hans
1984-01-01
The lowest order kinetic effects are included in the equations for nonlinear electrostatic electron waves in a magnetized plasma. The modifications of the authors' previous analysis based on a fluid model are discussed.......The lowest order kinetic effects are included in the equations for nonlinear electrostatic electron waves in a magnetized plasma. The modifications of the authors' previous analysis based on a fluid model are discussed....
Nonlinear waves in strongly interacting relativistic fluids
Fogaça, D A; Filho, L G Ferreira
2013-01-01
During the past decades the study of strongly interacting fluids experienced a tremendous progress. In the relativistic heavy ion accelerators, specially the RHIC and LHC colliders, it became possible to study not only fluids made of hadronic matter but also fluids of quarks and gluons. Part of the physics program of these machines is the observation of waves in this strongly interacting medium. From the theoretical point of view, these waves are often treated with li-nearized hydrodynamics. In this text we review the attempts to go beyond linearization. We show how to use the Reductive Perturbation Method to expand the equations of (ideal and viscous) relativistic hydrodynamics to obtain nonlinear wave equations. These nonlinear wave equations govern the evolution of energy density perturbations (in hot quark gluon plasma) or baryon density perturbations (in cold quark gluon plasma and nuclear matter). Different nonlinear wave equations, such as the breaking wave, Korteweg-de Vries and Burgers equations, are...
Ema, S. A.; Hossen, M. R.; Mamun, A. A.
2016-04-01
The nonlinear propagation of ion-acoustic (IA) waves in a strongly coupled plasma system containing Maxwellian electrons and nonthermal ions has been theoretically and numerically investigated. The well-known reductive perturbation technique is used to derive both the Burgers and Korteweg-de Vries (KdV) equations. Their shock and solitary wave solutions have also been numerically analyzed in understanding localized electrostatic disturbances. It has been observed that the basic features (viz. polarity, amplitude, width, etc.) of IA waves are significantly modified by the effect of polarization force and other plasma parameters (e.g., the electron-to-ion number density ratio and ion-to-electron temperature ratio). This is a unique finding among all theoretical investigations made before, whose probable implications are discussed in this investigation. The implications of the results obtained from this investigation may be useful in understanding the wave propagation in both space and laboratory plasmas.
Parallel plasma fluid turbulence calculations
Energy Technology Data Exchange (ETDEWEB)
Leboeuf, J.N.; Carreras, B.A.; Charlton, L.A.; Drake, J.B.; Lynch, V.E.; Newman, D.E.; Sidikman, K.L.; Spong, D.A.
1994-12-31
The study of plasma turbulence and transport is a complex problem of critical importance for fusion-relevant plasmas. To this day, the fluid treatment of plasma dynamics is the best approach to realistic physics at the high resolution required for certain experimentally relevant calculations. Core and edge turbulence in a magnetic fusion device have been modeled using state-of-the-art, nonlinear, three-dimensional, initial-value fluid and gyrofluid codes. Parallel implementation of these models on diverse platforms--vector parallel (National Energy Research Supercomputer Center`s CRAY Y-MP C90), massively parallel (Intel Paragon XP/S 35), and serial parallel (clusters of high-performance workstations using the Parallel Virtual Machine protocol)--offers a variety of paths to high resolution and significant improvements in real-time efficiency, each with its own advantages. The largest and most efficient calculations have been performed at the 200 Mword memory limit on the C90 in dedicated mode, where an overlap of 12 to 13 out of a maximum of 16 processors has been achieved with a gyrofluid model of core fluctuations. The richness of the physics captured by these calculations is commensurate with the increased resolution and efficiency and is limited only by the ingenuity brought to the analysis of the massive amounts of data generated.
Directory of Open Access Journals (Sweden)
S. A. El-Wakil
2012-01-01
Full Text Available The reductive perturbation method has been employed to derive the Korteweg-de Vries (KdV equation for small- but finite-amplitude electrostatic ion-acoustic waves in weakly relativistic plasma consisting of warm ions and isothermal electrons. An algebraic method with computerized symbolic computation is applied in obtaining a series of exact solutions of the KdV equation. Numerical studies have been made using plasma parameters which reveal different solutions, that is, bell-shaped solitary pulses, rational pulses, and solutions with singularity at finite points, which called “blowup” solutions in addition to the propagation of an explosive pulses. The weakly relativistic effect is found to significantly change the basic properties (namely, the amplitude and the width of the ion-acoustic waves. The result of the present investigation may be applicable to some plasma environments, such as ionosphere region.
Nonlinear PIC Simulations for Nonneutral Plasmas
Lapenta, Giovanni; Luca Delzanno, Gian; Finn, John M.
2002-11-01
We present nonlinear simulations of the low frequency dynamics of electrons in a Malmberg-Penning trap, including compressional and thermal effects [1,2]. First, we consider a 2D model where we assume the effective plasma length constant in time. In this framework, we further neglect the thermal effect on the velocity field, and show with the PIC code KANDINSKY that Penning traps could be used to perform geophysical fluid dynamics experiments [3]. We also observe that, due to the presence of the nonlinear m=1 instability, the initially hollow density profile becomes peaked, as in the experiments. Then, we show 2D results including thermal effects. In this case, the development of the m=1 instability is slowed since the equilibrium plasma length profile is closer to the integrable profile, namely the length profile for which there are no discrete unstable modes [4]. Finally, we present simulations of the 3D fluiddynamics model of Ref. [2]. In particular, we investigate the evolution of a m=1 perturbation for different electron temperatures, when compressional and thermal effects are included. [1] J.M. Finn, D. del-Castillo-Negrete, D.C. Barnes,Phys. Plasmas, 6, 3744, 1999. [2] G.G.M. Coppa, A. D'Angola, G.L. Delzanno, G. Lapenta, Phys. Plasmas, 8, 1133, 2001. [3] G.L. Delzanno, J.M. Finn, G. Lapenta, "Nonlinear Phase of the Compressional m=1 Diocotron Instability: Saturation and Analogy with Geophysical Fluid Dynamics", submitted to Phys. Plasmas. [4] G.L. Delzanno, V.I. Pariev, J.M. Finn, G. Lapenta, "Stability Analysis of Hollow Electron Columns Including Compression and Thermal Effects: Integrability Condition and Numerical Simulations", submitted to Phys. Plasmas.
Fluid transport due to nonlinear fluid-structure interaction
Energy Technology Data Exchange (ETDEWEB)
Soendergaard Jensen, J.
1996-08-01
This work considers nonlinear fluid-structure interaction for a vibrating pipe containing fluid. Transverse pipe vibrations will force the fluid to move relative to the pipe creating uni-directional fluid flow towards the pipe end. The fluid flow induced affects the damping and the stiffness of the pipe. The behavior of the system in response to lateral resonant base excitation is analyzed numerically mode of vibration seems to be most effective for high mean fluid speed, whereas higher modes of vibration can be used to transport fluid with the same fluid speed but with smaller magnitude of pipe vibrations. The effect of the nonlinear geometrical terms is analyzed and these terms are shown to affect the response for higher modes of vibration. Experimental investigations show good agreement with theoretical predictions. (au) 16 refs.
Fluid transport due to nonlinear fluid-structure interaction
DEFF Research Database (Denmark)
Jensen, Jakob Søndergaard
1997-01-01
This work considers nonlinear fluid-structure interaction for a vibrating pipe containing fluid. Transverse pipe vibrations will force the fluid to move relative to the pipe creating unidirectional fluid flow towards the pipe end. The fluid flow induced affects the damping and the stiffness...... of the pipe. The behavior of the system in response to lateral resonant base excitation is analysed numerically and by the use of a perturbation method (multiple scales). Exciting the pipe in the fundamental mode of vibration seems to be most effective for transferring energy from the shaker to the fluid......, whereas higher modes of vibration can be used to transport fluid with pipe vibrations of smaller amplitude. The effect of the nonlinear geometrical terms is analysed and these terms are shown to affect the response for higher modes of vibration. Experimental investigations show good agreement...
Fluid moments of the nonlinear Landau collision operator
Hirvijoki, E.; Lingam, M.; Pfefferlé, D.; Comisso, L.; Candy, J.; Bhattacharjee, A.
2016-08-01
An important problem in plasma physics is the lack of an accurate and complete description of Coulomb collisions in associated fluid models. To shed light on the problem, this Letter introduces an integral identity involving the multivariate Hermite tensor polynomials and presents a method for computing exact expressions for the fluid moments of the nonlinear Landau collision operator. The proposed methodology provides a systematic and rigorous means of extending the validity of fluid models that have an underlying inverse-square force particle dynamics to arbitrary collisionality and flow.
The Nonlinear Rheology of Electrorheological Fluids
Martin, James E.
1998-03-01
When a colloidal suspension is exposed to a uniaxial electric field the polarized particles chain along field lines causing a macroscopic "solidification" of the fluid, the basis of the so-called electrorheological (ER) effect. Likewise, in a rotating electric field particles form sheets in the plane of the field, which we call the rotary ER effect. Both of these fluids exhibit a nonlinear, shear thinning rheology, due to shear-induced structural relaxations. Because the fluid stress can be controlled by the applied field, a number of applications are possible, including electromechanical actuators, clutches, and active vibration dampers. To design these devices, and to develop effective control loop algorithms, it is necessary to understand the strongly nonlinear rheology of these fluids. We have used time-resolved, two-dimensional light scattering on a concentrated colloidal silica fluid in steady and oscillatory shear to demonstrate that the fragmentation and aggregation of chain-like particle microstructures is the cause of flow nonlinearities. We show that the light scattering is an indirect measure of the fluid stress. These observations form the basis of a kinetic chain model we developed to describe the nonlinear dynamics of the microstructures in ER fluids in nonstationary shear flows. Understanding the microstructural dynamics then leads us to a theory of the macroscopic rheology of these fluids in nonstationary, low Reynolds number flows. Finally, we have conducted extensive large-scale (1000-10000 particles) simulations of these fluids in steady and oscillatory shear, and will compare these results to theory and experiment.
Nonlinear spacial instability of a fluid sheet
Rangel, R. H.; Hess, C. F.
1990-01-01
The mechanism of nonlinear distortion of a fluid sheet leading to atomization is investigated numerically with the use of vortex dynamics and experimentally by means of holography. The configuration investigated consists of a planar fluid sheet emerging from a rectangular slit with and without coflowing air. The numerical model is two-dimensional, inviscid, and includes surface tension effects. The experimental results indicate the existence of well-defined three-dimensional structures. These are formed mainly by the nonlinear interaction of transverse and streamwise disturbances. The transverse disturbances are associated with the Kelvin-Helmholtz instability while the streamwise disturbances appear related to streamwise vortices possibly originating inside the nozzle.
3D electron fluid turbulence at nanoscales in dense plasmas
Energy Technology Data Exchange (ETDEWEB)
Shaikh, Dastgeer [Center for Space Plasma and Aeronomy Research, The University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Shukla, P K [Institut fuer Theoretische Physik IV, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)], E-mail: dastgeer@cspar.uah.edu, E-mail: ps@tp4.rub.de
2008-08-15
We have performed three-dimensional (3D) nonlinear fluid simulations of electron fluid turbulence at nanoscales in an unmagnetized warm dense plasma in which mode coupling between wave function and electrostatic (ES) potential associated with underlying electron plasma oscillations (EPOs) lead to nonlinear cascades in inertial range. While the wave function cascades towards smaller length scales, ES potential follows an inverse cascade. We find from our simulations that the quantum diffraction effect associated with a Bohm potential plays a critical role in determining the inertial range turbulent spectrum and the subsequent transport level exhibited by the 3D EPOs.
3D Electron Fluid Turbulence at Nanoscales in Dense Plasmas
Shaikh, Dastgeer
2008-01-01
We have performed three dimensional nonlinear fluid simulations of electron fluid turbulence at nanoscales in an unmagnetized warm dense plasma in which mode coupling between wave function and electrostatic potential associated with underlying electron plasma oscillations (EPOs) lead to nonlinear cascades in inertial range. While the wave function cascades towards smaller length scales, electrostatic potential follows an inverse cascade. We find from our simulations that quantum diffraction effect associated with a Bohm potential plays a critical role in determining the inertial range turbulent spectrum and the subsequent transport level exhibited by the 3D EPOs.
Fluid transport due to nonlinear fluid-structure interaction
DEFF Research Database (Denmark)
Jensen, Jakob Søndergaard
1997-01-01
of the pipe. The behavior of the system in response to lateral resonant base excitation is analysed numerically and by the use of a perturbation method (multiple scales). Exciting the pipe in the fundamental mode of vibration seems to be most effective for transferring energy from the shaker to the fluid......, whereas higher modes of vibration can be used to transport fluid with pipe vibrations of smaller amplitude. The effect of the nonlinear geometrical terms is analysed and these terms are shown to affect the response for higher modes of vibration. Experimental investigations show good agreement...
Nonlinear Electron Waves in Strongly Magnetized Plasmas
DEFF Research Database (Denmark)
Pécseli, Hans; Juul Rasmussen, Jens
1980-01-01
dynamics in the analysis is also demonstrated. As a particular case the authors investigate nonlinear waves in a strongly magnetized plasma filled wave-guide, where the effects of finite geometry are important. The relevance of this problem to laboratory experiments is discussed.......Weakly nonlinear dispersive electron waves in strongly magnetized plasma are considered. A modified nonlinear Schrodinger equation is derived taking into account the effect of particles resonating with the group velocity of the waves (nonlinear Landau damping). The possibility of including the ion...
Fluid moments of the nonlinear Landau collision operator
Hirvijoki, Eero; Lingam, Manasvi; Pfefferlé, David; Comisso, Luca; Candy, Jeff; Bhattacharjee, Amitava
2016-10-01
One important problem in plasma physics is the lack of an accurate and complete description of Coulomb collisions in associated fluid models. To shed light on the problem, this work introduces an integral identity involving the multivariate Hermite tensor polynomials and presents a method for computing exact expressions for the fluid moments of the nonlinear Landau collision operator. The proposed methodology provides a systematic and rigorous means of extending the validity of fluid models that have an underlying inverse-square force particle dynamics to arbitrary collisionality and flow. (For details, see arXiv:1605.07589) This research is supported by the Department of Energy Contract No. DE-AC02-09CH11466 and the National Science Foundation Grant Nos. AGS-1338944 and AGS-1552142.
Algorithm Development for the Multi-Fluid Plasma Model
2011-05-30
ities of a Hall-MHD wave increase without bound with wave number. The large wave speeds increases the stiffness of the equation system making accu- rate...illustrates the dispersive nature of the waves which makes capturing the effect difficult in MHD algorithms. The electromagnetic plasma shock serves to...Nonlinear full two-fluid study of m = 0 sausage instabilities in an axisymmetric Z pinch. Physics of Plasmas, 13(8):082310, 2006. [5] A. Hakim and U. Shumlak
The pseudoforce approach to fully nonlinear plasma excitations
Akbari-Moghanjoughi, M.
2017-08-01
In this paper, we develop a technique to study the dynamic structure of oscillations in plasmas. We consider the hydrodynamic model and reduce the system of closed equations to the system of differential equations with integrable Hamiltonian. Then, using the analogy of pseudoparticle oscillation in the pseudoforce field, we generalize the Hamiltonian to include the dissipation and external driving force effects. The developed method is used to study various features of electron-ion plasmas with different equations of state for ions. It is shown that this method can be used in the analysis of superposed fully nonlinear oscillations and even the sheath structure of plasmas. The generalized pseudoforce equation is then used to study the dynamics of damped periodically forced nonlinear ion acoustic oscillations in plasmas with adiabatic and isothermal ion fluids. We found striking differences in dynamics of oscillations in these plasmas. The fundamental difference in the dynamic character of oscillations between adiabatic and isothermal ion fluids is described based on the fast ion fluid response to external perturbations in the case of adiabatic ion fluid compression. The current approach may be easily extended to more complex situations with different species and in the presence of electromagnetic interactions.
Plasma metamaterials as cloaking and nonlinear media
Sakai, O.; Yamaguchi, S.; Bambina, A.; Iwai, A.; Nakamura, Y.; Tamayama, Y.; Miyagi, S.
2017-01-01
Plasma metamaterials, composites of low-temperature plasmas and periodic functional microstructures, work as cloaking and nonlinear media. Due to functions of the microstructures like negative permeability, electromagnetic waves in and around plasma metamaterials propagate in a quite different manner from the case with the conventional space in which relative permeability is positive and unity. Using plasmas and plasma metamaterials, we achieve various controls of microwave propagating paths such as unidirectionality and cloaking in the two- or 3D spaces. For instance, a concentric plasma layer makes wave propagation unidirectional, and waves propagate in different routes when they start inside or outside the concentric layer. Furthermore, due to spatial permittivity gradient and anisotropic refractive index, electromagnetic waves detour in plasma metamaterial layers. Another significant point that plasma metamaterials can realize is nonlinearity. When we study high-power electromagnetic waves propagating in them, we observe several properties describable in terms of nonlinear dynamics and nonlinear photonics. Microwaves beyond threshold energy trigger bifurcations in plasma permittivity, and the second harmonic wave detected simultaneously is generated with strong emission levels. Such electromagnetic wave propagation is achieved with advantages over other materials, since plasmas and metallic microstructures work in harmony and in synergy.
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...
Solitons and Weakly Nonlinear Waves in Plasmas
DEFF Research Database (Denmark)
Pécseli, Hans
1985-01-01
Theoretical descriptions of solitons and weakly nonlinear waves propagating in plasma media are reviewed, with particular attention to the Korteweg-de Vries (KDV) equation and the Nonlinear Schrödinger equation (NLS). The modifications of these basic equations due to the effects of resonant...
Colloquium: Nonlinear Collective Interactions in Dense Plasmas
Shukla, P K
2010-01-01
The current understanding of some important collective processes in dense quantum plasmas is presented. After reviewing the basic properties of dense quantum plasmas with degenerate electrons, we present model equations (e.g. the quantum hydrodynamic and effective nonlinear Schr\\"odinger-Poisson equations) that describe collective nonlinear phenomena at nanoscales. The effects of the electron degeneracy arise due to Heisenberg's uncertainty principle and Pauli's exclusion principle for overlapping electron wave functions that result in a nonlinear quantum electron pressure and tunneling/diffusion of electrons through a nonlinear quantum Bohm potential. Since degenerate electrons have $1/2-$spin due to their Fermionic nature, there also appear a spin electron current and a spin force acting on the electrons due to the Bohr magnetization. The present nonlinear equations do not include strong electron correlations and electron-exchange interactions. The quantum effects caused by the electron degeneracy produce n...
Nonlinear lower hybrid modeling in tokamak plasmas
Energy Technology Data Exchange (ETDEWEB)
Napoli, F.; Schettini, G. [Università Roma Tre, Dipartimento di Ingegneria, Roma (Italy); Castaldo, C.; Cesario, R. [Associazione EURATOM/ENEA sulla Fusione, Centro Ricerche Frascati (Italy)
2014-02-12
We present here new results concerning the nonlinear mechanism underlying the observed spectral broadening produced by parametric instabilities occurring at the edge of tokamak plasmas in present day LHCD (lower hybrid current drive) experiments. Low frequency (LF) ion-sound evanescent modes (quasi-modes) are the main parametric decay channel which drives a nonlinear mode coupling of lower hybrid (LH) waves. The spectrum of the LF fluctuations is calculated here considering the beating of the launched LH wave at the radiofrequency (RF) operating line frequency (pump wave) with the noisy background of the RF power generator. This spectrum is calculated in the frame of the kinetic theory, following a perturbative approach. Numerical solutions of the nonlinear LH wave equation show the evolution of the nonlinear mode coupling in condition of a finite depletion of the pump power. The role of the presence of heavy ions in a Deuterium plasma in mitigating the nonlinear effects is analyzed.
Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves.
Schroeder, C B; Esarey, E
2010-05-01
A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a nonrelativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for Langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three-velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for nonrelativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances.
Exact collisional moments for plasma fluid theories
Pfefferlé, D.; Hirvijoki, E.; Lingam, M.
2017-04-01
The velocity-space moments of the often troublesome nonlinear Landau collision operator are expressed exactly in terms of multi-index Hermite-polynomial moments of distribution functions. The collisional moments are shown to be generated by derivatives of two well-known functions, namely, the Rosenbluth-MacDonald-Judd-Trubnikov potentials for a Gaussian distribution. The resulting formula has a nonlinear dependency on the relative mean flow of the colliding species normalised to the root-mean-square of the corresponding thermal velocities and a bilinear dependency on densities and higher-order velocity moments of the distribution functions, with no restriction on temperature, flow, or mass ratio of the species. The result can be applied to both the classic transport theory of plasmas that relies on the Chapman-Enskog method, as well as to derive collisional fluid equations that follow Grad's moment approach. As an illustrative example, we provide the collisional ten-moment equations with exact conservation laws for momentum- and energy-transfer rates.
Dissipative nonlinear structures in tokamak plasmas
Directory of Open Access Journals (Sweden)
K. A. Razumova
2001-01-01
Full Text Available A lot of different kinds of instabilities may be developed in high temperature plasma located in a strong toroidal magnetic field (tokamak plasma. Nonlinear effects in the instability development result in plasma self-organization. Such plasma has a geometrically complicated configuration, consisting of the magnetic surfaces imbedded into each other and split into islands with various characteristic numbers of helical twisting. The self-consistency of the processes means that the transport coefficients in plasma do not depend just on the local parameters, being a function of the whole plasma configuration and of the forces affecting it. By disrupting the bonds between separate magnetic surfaces filled with islands, one can produce zones of reduced transport in the plasma, i.e. “internal thermal barriers”, allowing one essentially to increase the plasma temperature and density.
Nonlinear magnetic field transport in opening switch plasmas
Mason, R. J.; Auer, P. L.; Sudan, R. N.; Oliver, B. V.; Seyler, C. E.; Greenly, J. B.
1993-04-01
The nonlinear transport of magnetic field in collisionless plasmas, as present in the plasma opening switch (POS), using the implicit multifluid simulation code anthem [J. Comput. Phys. 71, 429 (1987)] is studied. The focus is on early time behavior in the electron-magnetohydrodynamic (EMHD) limit, with the ions fixed, and the electrons streaming as a fluid under the influence of ve×B Hall forces. Through simulation, magnetic penetration and magnetic exclusion waves are characterized, due to the Hall effect in the presence of transverse density gradients, and the interaction of these Hall waves with nonlinear diffusive disturbances from electron velocity advection, (veṡ∇)ve, is studied. It is shown how these mechanisms give rise to the anode magnetic insulation layer, central diffusion, and cathode potential hill structures seen in earlier opening switch plasmas studies.
Evolution Of Nonlinear Waves in Compressing Plasma
Energy Technology Data Exchange (ETDEWEB)
P.F. Schmit, I.Y. Dodin, and N.J. Fisch
2011-05-27
Through particle-in-cell simulations, the evolution of nonlinear plasma waves is examined in one-dimensional collisionless plasma undergoing mechanical compression. Unlike linear waves, whose wavelength decreases proportionally to the system length L(t), nonlinear waves, such as solitary electron holes, conserve their characteristic size {Delta} during slow compression. This leads to a substantially stronger adiabatic amplification as well as rapid collisionless damping when L approaches {Delta}. On the other hand, cessation of compression halts the wave evolution, yielding a stable mode.
Nonextensivity, Complexity and Nonlinearity in Space Plasmas
Pavlos, G. P.
2017-01-01
Experimental time series, extracted from many and different space plasma systems corresponding to, solar wind, magnetospheric and other space plasma systems reveal common dynamical, geometrical, or statistical characteristics. Such characteristics are the low dimensionality, the typical intermittent turbulence multifractality, the temporal or spatial multiscale correlations and power laws scale invariance, non Gaoussianity and others. This universal aspect of experimental time series profiles was understood in the past as the chaos or SOC universality. However, after two or three decades of theoretical development in understanding of the nonlinearity and complexity, we can give a more compact theoretical description of the underline universal physical processes that produce the experimental time series complexity. Finally, in this study, we present and explain the modern complex set of theoretical concepts from the point of view of physics as the unification theory of nonlinear theory of non-equilibrium plasma systems as well as the presupposed theoretical framework of time series analysis of space plasma charachteristics.
The Nonlinear Langmuir Waves in a Multi-ion-Component Plasma
Institute of Scientific and Technical Information of China (English)
CHEN Yin-Hua; LU Wei; WANG Wen-Hao
2001-01-01
We investigated the nonlinear Langmuir waves in a multi-ion-component low-temperature plasma. Beginning with the fluid theory of plasma, and taking fully nonlinear response of the low-frequency ion motion into account, we derived a set of equations governing the nonlinear coupling of the amplitude of the Langmuir wave and the Iow-frequency perturbation density. Using the Sagdeev potential method, we analyzed the characteristics of solitary wave. In the limit of small amplitude, the envelope soliton was found. Our investigation demonstrates that the properties of soliton in a multi-ion-component plasma are different from those of soliton in an electron-ion plasma.
Nonlinear processes in the strong wave-plasma interaction
Pegoraro, Francesco; Califano, Francesco; Attico, Nicola; Bulanov, Sergei
2000-10-01
Nonlinear interactions in hot laboratory and/or astrophysical plasmas are a very efficient mechanism able to transfer the energy from the large to the small spatial scales of the system. As a result, kinetic processes are excited and play a key role in the plasma dynamics since the typical fluid dissipative length scales (where the nonlinear cascade is stopped) are (much) smaller then the kinetic length scales. Then, the key point is the role of the kinetic effects in the global plasma dynamics, i.e. whether the kinetic effects remains confined to the small scales of the system or whether there is a significant feedback on the large scales. Here we will address this problem by discussing the nonlinear kinetic evolution of the electromagnetic beam plasma instability where phase space vortices, as well as large scale vortex like magnetic structures in the physical space, are generated by wave - particle interactions. The role and influence of kinetic effects on the large scale plasma dynamics will be also discussed by addressing the problem of collisionless magnetic reconection.
Nonlinear Alfvén wave dynamics in plasmas
Energy Technology Data Exchange (ETDEWEB)
Sarkar, Anwesa; Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Schamel, Hans [Theoretical Physics, University of Bayreuth, D-95440 Bayreuth (Germany)
2015-07-15
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.
Nonlinear Alfvén wave dynamics in plasmas
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.
Collapse of nonlinear electron plasma waves in a plasma layer
Grimalsky, V.; Koshevaya, S.; Rapoport, Yu; Kotsarenko, A.
2016-10-01
The excitation of nonlinear electron plasma waves in the plasma layer is investigated theoretically. This excitation is realized by means of initial oscillatory perturbations of the volume electron concentration or by initial oscillatory distributions of the longitudinal electron velocity. The amplitudes of the initial perturbations are small and the manifestation of the volume nonlinearity is absent. When the amplitudes of the initial perturbations exceed some thresholds, the values of the electron concentration near the plasma boundary increase catastrophically. The maxima of the electron concentration reach extremely high magnitudes, and sharp peaks in the electron concentration occur, which are localized both in the longitudinal and transverse directions. This effect is interpreted as wave collapse near the plasma boundary.
Nonlinear ultrasound wave propagation in thermoviscous fluids
DEFF Research Database (Denmark)
Sørensen, Mads Peter
coupled nonlinear partial differential equations, which resembles those of optical chi-2 materials. We think this result makes a remarkable link between nonlinear acoustics and nonlinear optics. Finally our analysis reveal an exact kink solution to the nonlinear acoustic problem. This kink solution...
Charged relativistic fluids and non-linear electrodynamics
Dereli, T.; Tucker, R. W.
2010-01-01
The electromagnetic fields in Maxwell's theory satisfy linear equations in the classical vacuum. This is modified in classical non-linear electrodynamic theories. To date there has been little experimental evidence that any of these modified theories are tenable. However with the advent of high-intensity lasers and powerful laboratory magnetic fields this situation may be changing. We argue that an approach involving the self-consistent relativistic motion of a smooth fluid-like distribution of matter (composed of a large number of charged or neutral particles) in an electromagnetic field offers a viable theoretical framework in which to explore the experimental consequences of non-linear electrodynamics. We construct such a model based on the theory of Born and Infeld and suggest that a simple laboratory experiment involving the propagation of light in a static magnetic field could be used to place bounds on the fundamental coupling in that theory. Such a framework has many applications including a new description of the motion of particles in modern accelerators and plasmas as well as phenomena in astrophysical contexts such as in the environment of magnetars, quasars and gamma-ray bursts.
Shocks, singularities and oscillations in nonlinear optics and fluid mechanics
Santo, Daniele; Lannes, David
2017-01-01
The book collects the most relevant results from the INdAM Workshop "Shocks, Singularities and Oscillations in Nonlinear Optics and Fluid Mechanics" held in Rome, September 14-18, 2015. The contributions discuss recent major advances in the study of nonlinear hyperbolic systems, addressing general theoretical issues such as symmetrizability, singularities, low regularity or dispersive perturbations. It also investigates several physical phenomena where such systems are relevant, such as nonlinear optics, shock theory (stability, relaxation) and fluid mechanics (boundary layers, water waves, Euler equations, geophysical flows, etc.). It is a valuable resource for researchers in these fields. .
Chaotic saddles in nonlinear modulational interactions in a plasma
Energy Technology Data Exchange (ETDEWEB)
Miranda, Rodrigo A. [Institute of Aeronautical Technology (ITA) and World Institute for Space Environment Research (WISER), Sao Jose dos Campos, SP 12228-900 (Brazil); National Institute for Space Research (INPE) and World Institute for Space Environment Research (WISER), P.O. Box 515, Sao Jose dos Campos, SP 12227-010 (Brazil); University of Brasilia (UnB), Gama Campus, and Plasma Physics Laboratory, Institute of Physics, Brasilia, DF 70910-900 (Brazil); Rempel, Erico L. [Institute of Aeronautical Technology (ITA) and World Institute for Space Environment Research (WISER), Sao Jose dos Campos, SP 12228-900 (Brazil); National Institute for Space Research (INPE) and World Institute for Space Environment Research (WISER), P.O. Box 515, Sao Jose dos Campos, SP 12227-010 (Brazil); Chian, Abraham C.-L. [Institute of Aeronautical Technology (ITA) and World Institute for Space Environment Research (WISER), Sao Jose dos Campos, SP 12228-900 (Brazil); National Institute for Space Research (INPE) and World Institute for Space Environment Research (WISER), P.O. Box 515, Sao Jose dos Campos, SP 12227-010 (Brazil); Observatoire de Paris, LESIA, CNRS, 92195 Meudon (France)
2012-11-15
A nonlinear model of modulational processes in the subsonic regime involving a linearly unstable wave and two linearly damped waves with different damping rates in a plasma is studied numerically. We compute the maximum Lyapunov exponent as a function of the damping rates in a two-parameter space, and identify shrimp-shaped self-similar structures in the parameter space. By varying the damping rate of the low-frequency wave, we construct bifurcation diagrams and focus on a saddle-node bifurcation and an interior crisis associated with a periodic window. We detect chaotic saddles and their stable and unstable manifolds, and demonstrate how the connection between two chaotic saddles via coupling unstable periodic orbits can result in a crisis-induced intermittency. The relevance of this work for the understanding of modulational processes observed in plasmas and fluids is discussed.
Chaotic saddles in nonlinear modulational interactions in a plasma
Miranda, Rodrigo A; Chian, Abraham C -L
2012-01-01
A nonlinear model of modulational processes in the subsonic regime involving a linearly unstable wave and two linearly damped waves with different damping rates in a plasma is studied numerically. We compute the maximum Lyapunov exponent as a function of the damping rates in a two-parameter space, and identify shrimp-shaped self-similar structures in the parameter space. By varying the damping rate of the low-frequency wave, we construct bifurcation diagrams and focus on a saddle-node bifurcation and an interior crisis associated with a periodic window. We detect chaotic saddles and their stable and unstable manifolds, and demonstrate how the connection between two chaotic saddles via coupling unstable periodic orbits can result in a crisis-induced intermittency. The relevance of this work for the understanding of modulational processes observed in plasmas and fluids is discussed.
Vortex dynamics in plasmas and fluids
DEFF Research Database (Denmark)
Juul Rasmussen, J.; Lynov, Jens-Peter; Hesthaven, J.S.;
1994-01-01
The existence and dynamics of vortical structures in both homogeneous and inhomogeneous systems will be discussed. In particular the dynamics of monopolar and dipolar vortices in a plasma with nonuniform density and in a rotating fluid with varying Coriolis force is described. The role of vortical...
Swimming speeds of filaments in nonlinearly viscoelastic fluids
Fu, Henry C; Powers, Thomas R; 10.1063/1.3086320
2010-01-01
Many microorganisms swim through gels and non-Newtonian fluids in their natural environments. In this paper, we focus on microorganisms which use flagella for propulsion. We address how swimming velocities are affected in nonlinearly viscoelastic fluids by examining the problem of an infinitely long cylinder with arbitrary beating motion in the Oldroyd-B fluid. We solve for the swimming velocity in the limit in which deflections of the cylinder from its straight configuration are small relative to the radius of the cylinder and the wavelength of the deflections; furthermore, the radius of the cylinder is small compared to the wavelength of deflections. We find that swimming velocities are diminished by nonlinear viscoelastic effects. We apply these results to examine what types of swimming motions can produce net translation in a nonlinear fluid, comparing to the Newtonian case, for which Purcell's "scallop" theorem describes how time-reversibility constrains which swimming motions are effective. We find that...
Nonlinear behavior of electron acoustic waves in an un-magnetized plasma
Energy Technology Data Exchange (ETDEWEB)
Dutta, Manjistha; Khan, Manoranjan [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Roychoudhury, Rajkumar [Indian Statistical Institute, Kolkata 700 108 (India)
2011-10-15
The nonlinear electron acoustic wave, which is found in the earth's magnetosphere by satellite observations, is studied analytically by Lagrangian fluid description. The basic linear mode is observed in a two temperature electron species plasma where ions form stationary charge neutral background. We have obtained nonlinear description of this mode, which depends on both time and space. A possible solution shows a soliton like structure, which is localized in space, and the amplitude increases with time in the absence of dispersion. Small dispersive correction, however, shows spread of the solution in space. This method can be generalized to study the nonlinear behavior of a general class of multispecies plasma.
Compressible hydromagnetic nonlinearities in the predecoupling plasma
Giovannini, Massimo
2012-01-01
The adiabatic inhomogeneities of the scalar curvature lead to a compressible flow affecting the dynamics of the hydromagnetic nonlinearities. The influence of the plasma on the evolution of a putative magnetic field is explored with the aim of obtaining an effective description valid for sufficiently large scales. The bulk velocity of the plasma, computed in the framework of the LambdaCDM scenario, feeds back into the evolution of the magnetic power spectra leading to a (nonlocal) master equation valid in Fourier space and similar to the ones discussed in the context of wave turbulence. Conversely, in physical space, the magnetic power spectra obey a Schroedinger-like equation whose effective potential depends on the large-scale curvature perturbations. Explicit solutions are presented both in physical space and in Fourier space. It is argued that curvature inhomogeneities, compatible with the WMAP 7yr data, shift to lower wavenumbers the magnetic diffusivity scale.
Moderately nonlinear ultrasound propagation in blood-mimicking fluid.
Kharin, Nikolay A; Vince, D Geoffrey
2004-04-01
In medical diagnostic ultrasound (US), higher than-in-water nonlinearity of body fluids and tissue usually does not produce strong nonlinearly distorted waves because of the high absorption. The relative influence of absorption and nonlinearity can be characterized by the Gol'dberg number Gamma. There are two limiting cases in nonlinear acoustics: weak waves (Gamma 1). However, at diagnostic frequencies in tissue and body fluids, the nonlinear effects and effects of absorption more likely are comparable (Gol'dberg number Gamma approximately 1). The aim of this work was to study the nonlinear propagation of a moderately nonlinear US second harmonic signal in a blood-mimicking fluid. Quasilinear solutions to the KZK equation are presented, assuming radiation from a flat and geometrically focused circular Gaussian source. The solutions are expressed in a new simplified closed form and are in very good agreement with those of previous studies measuring and modeling Gaussian beams. The solutions also show good agreement with the measurements of the beams produced by commercially available transducers, even without special Gaussian shading.
Hermes: Global plasma edge fluid turbulence simulations
Dudson, Ben
2016-01-01
The transport of heat and particles in the relatively collisional edge regions of magnetically confined plasmas is a scientifically challenging and technologically important problem. Understanding and predicting this transport requires the self-consistent evolution of plasma fluctuations, global profiles and flows, but the numerical tools capable of doing this in realistic (diverted) geometry are only now being developed. Here a 5-field reduced 2-fluid plasma model for the study of instabilities and turbulence in magnetised plasmas is presented, built on the BOUT++ framework. This cold ion model allows the evolution of global profiles, electric fields and flows on transport timescales, with flux-driven cross-field transport determined self-consistently by electromagnetic turbulence. Developments in the model formulation and numerical implementation are described, and simulations are performed in poloidally limited and diverted tokamak configurations.
Global existence and uniqueness of nonlinear evolutionary fluid equations
Qin, Yuming; Wang, Taige
2015-01-01
This book presents recent results on nonlinear evolutionary fluid equations such as the compressible (radiative) magnetohydrodynamics (MHD) equations, compressible viscous micropolar fluid equations, the full non-Newtonian fluid equations and non-autonomous compressible Navier-Stokes equations. These types of partial differential equations arise in many fields of mathematics, but also in other branches of science such as physics and fluid dynamics. This book will be a valuable resource for graduate students and researchers interested in partial differential equations, and will also benefit practitioners in physics and engineering.
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.
Nonlinear ship waves and computational fluid dynamics
National Research Council Canada - National Science Library
MIYATA, Hideaki; ORIHARA, Hideo; SATO, Yohei
2014-01-01
.... Finding of the occurrence of nonlinear waves (named Free-Surface Shock Waves) in the vicinity of a ship advancing at constant speed provided the start-line for the progress of innovative technologies in the ship hull-form design...
Using Space as a Nonlinear Plasma Laboratory
Papadopoulos, Konstantinos
2008-11-01
Ionospheric heaters have been an important tool of plasma physics investigations. The extent that non-linear plasma phenomena can be triggered and observed depends critically on the heater power, its Effective Radiative Power (ERP) and its scanning capability. Increasing these parameters allows us to reach thresholds associated with effects that were not previously observed. The latest entry to ionospheric heating, the HF transmitter associated with the High Frequency Active Ionospheric Research Program (HAARP) was completed in June 2007. The transmitter consists of 180 antenna elements spanning 30.6 acres and can radiate 3.6 MW of HF power (a factor of almost 4 higher than any previous heater) in the 2.8-10.0 MHz range. With increasing frequency the beam-width varies from 15-5 degrees, corresponding to 20-30 dB gain and resulting in ERP between 1-5 GW. The antenna can point to any direction in a cone 30 degrees from the vertical, with reposition time of 15 microseconds resulting in superluminal scanning speeds. The transmitter can synthesize essentially any waveform and transmit any polarization. These capabilities far exceed those of any previous heater and allow for new frontier research in non-linear plasma physics. The presentation will focus first on the relationship of the new capabilities of the facility with thresholds of physical processes that had not been achieved previously. It will then present new spectacular results that have been achieved during the last year. They include whistler injection and amplification, injection of shear and magnetosonic waves in the magnetosphere, Langmuir turbulence, upper hybrid waves and thermal instabilities, electron acceleration, optical emissions and formation of artificial ducts for whistler propagation. The presentation will also discuss future experiments made possible for the first time by the new transmitter capabilities, large bandwidth and high ERP.
Fluid echoes in a pure electron plasma.
Yu, J H; O'Neil, T M; Driscoll, C F
2005-01-21
Experimental observations of diocotron wave echoes on a magnetized electron column are reported, representing Kelvin wave echoes on a rotating near-ideal fluid. The echoes occur by reversal of an inviscid wave damping process, and the phase-space mixing and unmixing are directly imaged. The basic echo characteristics agree with a simple nonlinear ballistic theory. At late times, the echo is degraded, and the maximal observed echo times agree with a theory of electron-electron collisions acting on separately evolving velocity classes.
NONLINEAR RESPONSES OF A FLUID-CONVEYING PIPE EMBEDDED IN NONLINEAR ELASTIC FOUNDATIONS
Institute of Scientific and Technical Information of China (English)
Qin Qian; Lin Wang; Qiao Ni
2008-01-01
The nonlinear responses of planar motions of a fluid-conveying pipe embedded in nonlinear elastic foundations are investigated via the differential quadrature method diseretization (DQMD) of the governing partial differential equation. For the analytical model, the effect of the nonlinear elastic foundation is modeled by a nonlinear restraining force. By using an iterative algorithm, a set of ordinary differential dynamical equations derived from the equation of motion of the system are solved numerically and then the bifurcations are analyzed. The numerical results, in which the existence of chaos is demonstrated, are presented in the form of phase portraits of the oscillations. The intermittency transition to chaos has been found to arise.
Nonlinear Landau damping in quark-gluon plasma
Xiaofei, Zhang; Jiarong, Li
1995-08-01
The semiclassical kinetic equations for the quark-gluon plasma (QGP) are discussed by the multiple time-scale method. The mechanism of nonlinear Landau damping owing to non-Abelian and nonlinear wave-particle interactions in QGP is investigated, and the nonlinear Landau damping rate for the longitudinal color eigenwaves in the long-wavelength limit is calculated.
Study of nonlinear waves in astrophysical quantum plasmas
Energy Technology Data Exchange (ETDEWEB)
Hossen, M.R.; Mamun, A.A., E-mail: rasel.plasma@gmail.com [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh)
2015-10-01
The nonlinear propagation of the electron acoustic solitary waves (EASWs) in an unmagnetized, collisionless degenerate quantum plasma system has been investigated theoretically. Our considered model consisting of two distinct groups of electrons (one of inertial non-relativistic cold electrons and other of inertialess ultrarelativistic hot electrons) and positively charged static ions. The Korteweg-de Vries (K-dV) equation has been derived by employing the reductive perturbation method and numerically examined to identify the basic features (speed, amplitude, width, etc.) of EASWs. It is shown that only rarefactive solitary waves can propagate in such a quantum plasma system. It is found that the effect of degenerate pressure and number density of hot and cold electron fluids, and positively charged static ions, significantly modify the basic features of EASWs. It is also noted that the inertial cold electron fluid is the source of dispersion for EA waves and is responsible for the formation of solitary structures. The applications of this investigation in astrophysical compact objects (viz. non-rotating white dwarfs, neutron stars, etc.) are briefly discussed. (author)
APS presents prizes in fluid dynamics and plasma physics
Energy Technology Data Exchange (ETDEWEB)
1992-12-01
This article reviews the presentation of the American Physical Society awards in fluid dynamics and plasma physics. The recipient of the plasma physics James Clerk Maxwell Prize was John M. Green for contributions to the theory of magnetohydrodynamics equilibria and ideal and resistive instabilities, for discovering the inverse scattering transform leading to soliton solutions of many nonlinear partial differential equations and for inventing the residue method of determining the transition to global chaos. The excellence in Plasma Physics Research Award was presented to Nathaniel A. Fisch for theoretical investigations of noninductive current generation in toroidally confined plasma. Wim Pieter Leemans received the Simon Ramo Award for experimental and simulational contributions to laser-plasma physics. William R. Sears was given the 1992 Fuid Dynamics Prize for contributions to the study of steady and unsteady aerodynamics, aeroacoustics, magnetoaerodynamics,and wind tunnel design. William C. Reynolds received the Otto Laporte Award for experimental, theoretical, and computational work in turbulence modeling and control and leadership in direct numerical simulation and large eddy simulation.
Nonlinear electromagnetic waves in a degenerate electron-positron plasma
Energy Technology Data Exchange (ETDEWEB)
El-Labany, S.K., E-mail: skellabany@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta (Egypt); El-Taibany, W.F., E-mail: eltaibany@hotmail.com [Department of Physics, College of Science for Girls in Abha, King Khalid University, Abha (Saudi Arabia); El-Samahy, A.E.; Hafez, A.M.; Atteya, A., E-mail: ahmedsamahy@yahoo.com, E-mail: am.hafez@sci.alex.edu.eg, E-mail: ahmed_ateya2002@yahoo.com [Department of Physics, Faculty of Science, Alexandria University, Alexandria (Egypt)
2015-08-15
Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed. (author)
Nonlinear Electromagnetic Waves in a Degenerate Electron-Positron Plasma
El-Labany, S. K.; El-Taibany, W. F.; El-Samahy, A. E.; Hafez, A. M.; Atteya, A.
2015-08-01
Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed.
Entropy Stable Numerical Schemes for Two-Fluid Plasma Equations
Kumar, Harish
2011-01-01
Two-fluid ideal plasma equations are a generalized form of the ideal MHD equations in which electrons and ions are considered as separate species. The design of efficient numerical schemes for the these equations is complicated on account of their non-linear nature and the presence of stiff source terms, especially for high charge to mass ratios and for low Larmor radii. In this article, we design entropy stable finite difference schemes for the two-fluid equations by combining entropy conservative fluxes and suitable numerical diffusion operators. Furthermore, to overcome the time step restrictions imposed by the stiff source terms, we devise time-stepping routines based on implicit-explicit (IMEX)-Runge Kutta (RK) schemes. The special structure of the two-fluid plasma equations is exploited by us to design IMEX schemes in which only local (in each cell) linear equations need to be solved at each time step. Benchmark numerical experiments are presented to illustrate the robustness and accuracy of these schem...
Infinitely-many conservation laws for two (2+1)-dimensional nonlinear evolution equations in fluids
Indian Academy of Sciences (India)
Yan Jiang; Bo Tian; Pan Wang; Kun Su
2014-07-01
In this paper, a method that can be used to construct the infinitely-many conservation laws with the Lax pair is generalized from the (1+1)-dimensional nonlinear evolution equations (NLEEs) to the (2+1)-dimensional ones. Besides, we apply that method to the Kadomtsev– Petviashvili (KP) and Davey–Stewartson equations in fluids, and respectively obtain their infinitelymany conservation laws with symbolic computation. Based on that method, we can also construct the infinitely-many conservation laws for other multidimensional NLEEs possessing the Lax pairs, including the cylindrical KP, modified KP and (2+1)-dimensional Gardner equations, in fluids, plasmas, optical fibres and Bose–Einstein condensates.
Turbulence theories and modelling of fluids and plasmas
Energy Technology Data Exchange (ETDEWEB)
Yoshizawa, Akira; Yokoi, Nobumitsu [Institute of Industrial Science, Univ. of Tokyo, Tokyo (Japan); Itoh, Sanae-I. [Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, Fukuoka (Japan); Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan)
2001-04-01
Theoretical and heuristic modelling methods are reviewed for studying turbulence phenomena of fluids and plasmas. Emphasis is put on understanding of effects on turbulent characteristics due to inhomogeneities of field and plasma parameters. The similarity and dissimilarity between the methods for fluids and plasmas are sought in order to shed light on the properties that are shared or not by fluid and plasma turbulence. (author)
Turbulence theories and modelling of fluids and plasmas
Energy Technology Data Exchange (ETDEWEB)
Yoshizawa, Akira; Yokio, Nobumitsu [Institute of Industrial Science, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Itoh, Sanae-I [Research Institute for Applied Mechanics, Kyushu University, 87, Kasuga 816-8580 (Japan); Itoh, Kimitaka [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)
2001-03-01
Theoretical and heuristic modelling methods are reviewed for studying turbulence phenomena of fluids and plasmas. Emphasis is placed on understanding of effects on turbulence characteristics due to inhomogeneities of field and plasma parameters. The similarity and dissimilarity between the methods for fluids and plasmas are sought in order to shed light on the properties that are shared or not by fluid and plasma turbulence. (author)
Doxepin concentrations in plasma and cerebrospinal fluid.
Schomburg, Robert; Remane, Daniela; Fassbender, Klaus; Maurer, Hans H; Spiegel, Jörg
2011-04-01
Doxepin--like other antidepressant drugs (ADs)--shows a variable antidepressant effect in clinical practice. The cause for this variability is as yet unclear; however, pharmacokinetic factors such as the variable permeability of doxepin into the cerebrospinal fluid (CSF), may contribute to the difference in therapeutic efficacy. We measured and correlated the concentration of doxepin and its active metabolite nordoxepin in both the plasma and CSF. Plasma and CSF samples were taken simultaneously from 21 patients who were treated with doxepin due to different clinical indications. The plasma concentration of both doxepin and nordoxepin correlated significantly with the oral dosage of doxepin (doxepin: r = +0.66, p < 0.001; nordoxepin: r = +0.78, p < 0.0001; Spearman's correlation). Furthermore, we found significant correlations between the plasma and CSF concentrations of both doxepin (r = +0.71; p < 0.001; Pearson's correlation) and nordoxepin (r = +0.74; p < 0.001). These highly significant correlations between the plasma and CSF concentrations indicate a constant CSF permeability of doxepin and its active metabolite nordoxepin.
Cosmic neutrinos: A dispersive and nonlinear fluid
Inman, Derek; Pen, Ue-Li
2017-03-01
We present a description of cosmic neutrinos as a dispersive fluid. In this approach, the neutrino phase space is reduced to density and velocity fields alongside a scale-dependent sound speed. This sound speed depends on redshift, the initial neutrino phase space density and the cold dark matter gravitational potential. The latter is a new coupling between neutrinos and large scale structure not described by previous fluid approaches. We compute the sound speed in linear theory and find that it asymptotes to constants at small and large scales regardless of the gravitational potential. By comparing with neutrino N-body simulations, we measure the small scale sound speed and find it to be lower than linear theory predictions. This allows for an explanation of the discrepancy between N-body and linear response predictions for the neutrino power spectrum: neutrinos are still driven predominantly by the cold dark matter, but the sound speed on small scales is not stable to perturbations and decreases. Finally, we present a calibrated model for the neutrino power spectrum that requires no additional integrations outside of standard Boltzmann codes.
Energy Technology Data Exchange (ETDEWEB)
Kakad, Amar [Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011 (Japan); Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410-218 (India); Omura, Yoshiharu [Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011 (Japan); Kakad, Bharati [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410-218 (India)
2013-06-15
We perform one-dimensional fluid simulation of ion acoustic (IA) solitons propagating parallel to the magnetic field in electron-ion plasmas by assuming a large system length. To model the initial density perturbations (IDP), we employ a KdV soliton type solution. Our simulation demonstrates that the generation mechanism of IA solitons depends on the wavelength of the IDP. The short wavelength IDP evolve into two oppositely propagating identical IA solitons, whereas the long wavelength IDP develop into two indistinguishable chains of multiple IA solitons through a wave breaking process. The wave breaking occurs close to the time when electrostatic energy exceeds half of the kinetic energy of the electron fluid. The wave breaking amplitude and time of its initiation are found to be dependent on characteristics of the IDP. The strength of the IDP controls the number of IA solitons in the solitary chains. The speed, width, and amplitude of IA solitons estimated during their stable propagation in the simulation are in good agreement with the nonlinear fluid theory. This fluid simulation is the first to confirm the validity of the general nonlinear fluid theory, which is widely used in the study of solitary waves in laboratory and space plasmas.
Nonlinear Waves in an Inhomogeneous Fluid Filled Elastic Tube
Institute of Scientific and Technical Information of China (English)
DUAN Wen-Shan
2004-01-01
In a thin-walled, homogeneous, straight, long, circular, and incompressible fluid filled elastic tube, small but finite long wavelength nonlinear waves can be describe by a KdV (Korteweg de Vries) equation, while the carrier wave modulations are described by a nonlinear Schrodinger equation (NLSE). However if the elastic tube is slowly inhomogeneous, then it is found, in this paper, that the carrier wave modulations are described by an NLSE-like equation. There are soliton-like solutions for them, but the stability and instability regions for this soliton-like waves will change,depending on what kind of inhomogeneity the tube has.
Nonlocal and nonlinear electrostatics of a dipolar Coulomb fluid.
Sahin, Buyukdagli; Ralf, Blossey
2014-07-16
We study a model Coulomb fluid consisting of dipolar solvent molecules of finite extent which generalizes the point-like dipolar Poisson-Boltzmann model (DPB) previously introduced by Coalson and Duncan (1996 J. Phys. Chem. 100 2612) and Abrashkin et al (2007 Phys. Rev. Lett. 99 077801). We formulate a nonlocal Poisson-Boltzmann equation (NLPB) and study both linear and nonlinear dielectric response in this model for the case of a single plane geometry. Our results shed light on the relevance of nonlocal versus nonlinear effects in continuum models of material electrostatics.
Nonlinear electromagnetic fields in 0.5 MHz inductively coupled plasmas
DEFF Research Database (Denmark)
Ostrikov, K.N.; Tsakadze, E.L.; Xu, S.
2003-01-01
Radial profiles of magnetic fields in the electrostatic (E) and electromagnetic (H) modes of low-frequency (similar to500 kHz) inductively coupled plasmas have been measured using miniature magnetic probes. In the low-power (similar to170 W) E-mode, the magnetic field pattern is purely linear......, with the fundamental frequency harmonics only. After transition to higher-power (similar to1130 W) H-mode, the second-harmonic nonlinear azimuthal magnetic field B-phi(2omega) that is in 4-6 times larger than the fundamental frequency component B-phi(omega), has been observed. A simplified plasma fluid model...... explaining the generation of the second harmonics of the azimuthal magnetic field in the plasma source is proposed. The nonlinear second harmonic poloidal (r-z) rf current generating the azimuthal magnetic field B-phi(2omega) is attributed to nonlinear interactions between the fundamental frequency radial...
Physics through the 1990s: Plasmas and fluids
1986-01-01
The volume contains recommendations for programs in, and government support of, plasma and fluid physics. Four broad areas are covered: the physics of fluids, general plasma physics, fusion, and space and astrophysical plasmas. In the first section, the accomplishments of fluid physics and a detailed review of its sub-fields, such as combustion, non-Newtonian fluids, turbulence, aerodynamics, and geophysical fluid dynamics, are described. The general plasma physics section deals with the wide scope of the theoretical concepts involved in plasma research, and with the machines; intense beam systems, collective and laser-driven accelerators, and the associated diagnostics. The section on the fusion plasma research program examines confinement and heating systems, such as Tokamaks, magnetic mirrors, and inertial-confinement systems, and several others. Finally, theory and experiment in space and astrophysical plasma research is detailed, ranging from the laboratory to the solar system and beyond. A glossary is included.
Emergent geometries and nonlinear-wave dynamics in photon fluids.
Marino, F; Maitland, C; Vocke, D; Ortolan, A; Faccio, D
2016-03-22
Nonlinear waves in defocusing media are investigated in the framework of the hydrodynamic description of light as a photon fluid. The observations are interpreted in terms of an emergent curved spacetime generated by the waves themselves, which fully determines their dynamics. The spacetime geometry emerges naturally as a result of the nonlinear interaction between the waves and the self-induced background flow. In particular, as observed in real fluids, different points of the wave profile propagate at different velocities leading to the self-steepening of the wave front and to the formation of a shock. This phenomenon can be associated to a curvature singularity of the emergent metric. Our analysis offers an alternative insight into the problem of shock formation and provides a demonstration of an analogue gravity model that goes beyond the kinematic level.
Nonlinear interaction of electromagnetic field with quantum plasma
Latyshev, A V
2014-01-01
The analysis of nonlinear interaction of transversal electromagnetic field with quantum collisionless plasma is carried out. Formulas for calculation electric current in quantum collisionless plasma at any temperature are deduced. It has appeared, that the nonlinearity account leads to occurrence of the longitudinal electric current directed along a wave vector. This second current is orthogonal to the known transversal classical current, received at the classical linear analysis. The case of degenerate electronic plasma is considered. It is shown, that for degenerate plasmas the electric current is calculated under the formula, not containing quadratures.
Linear and Nonlinear MHD Wave Processes in Plasmas. Final Report
Energy Technology Data Exchange (ETDEWEB)
Tataronis, J. A.
2004-06-01
This program treats theoretically low frequency linear and nonlinear wave processes in magnetized plasmas. A primary objective has been to evaluate the effectiveness of MHD waves to heat plasma and drive current in toroidal configurations. The research covers the following topics: (1) the existence and properties of the MHD continua in plasma equilibria without spatial symmetry; (2) low frequency nonresonant current drive and nonlinear Alfven wave effects; and (3) nonlinear electron acceleration by rf and random plasma waves. Results have contributed to the fundamental knowledge base of MHD activity in symmetric and asymmetric toroidal plasmas. Among the accomplishments of this research effort, the following are highlighted: Identification of the MHD continuum mode singularities in toroidal geometry. Derivation of a third order ordinary differential equation that governs nonlinear current drive in the singular layers of the Alfvkn continuum modes in axisymmetric toroidal geometry. Bounded solutions of this ODE implies a net average current parallel to the toroidal equilibrium magnetic field. Discovery of a new unstable continuum of the linearized MHD equation in axially periodic circular plasma cylinders with shear and incompressibility. This continuum, which we named “accumulation continuum” and which is related to ballooning modes, arises as discrete unstable eigenfrequency accumulate on the imaginary frequency axis in the limit of large mode numbers. Development of techniques to control nonlinear electron acceleration through the action of multiple coherent and random plasmas waves. Two important elements of this program aye student participation and student training in plasma theory.
Non-Linear Langmuir Wave Modulation in Collisionless Plasmas
DEFF Research Database (Denmark)
Dysthe, K. B.; Pécseli, Hans
1977-01-01
A non-linear Schrodinger equation for Langmuir waves is presented. The equation is derived by using a fluid model for the electrons, while both a fluid and a Vlasov formulation are considered for the ion dynamics. The two formulations lead to significant differences in the final results, especially...
Nonlinear waves in a fluid-filled thin viscoelastic tube
Zhang, Shan-Yuan; Zhang, Tao
2010-11-01
In the present paper the propagation property of nonlinear waves in a thin viscoelastic tube filled with incompressible inviscid fluid is studied. The tube is considered to be made of an incompressible isotropic viscoelastic material described by Kelvin—Voigt model. Using the mass conservation and the momentum theorem of the fluid and radial dynamic equilibrium of an element of the tube wall, a set of nonlinear partial differential equations governing the propagation of nonlinear pressure wave in the solid—liquid coupled system is obtained. In the long-wave approximation the nonlinear far-field equations can be derived employing the reductive perturbation technique (RPT). Selecting the exponent α of the perturbation parameter in Gardner—Morikawa transformation according to the order of viscous coefficient η, three kinds of evolution equations with soliton solution, i.e. Korteweg—de Vries (KdV)—Burgers, KdV and Burgers equations are deduced. By means of the method of traveling-wave solution and numerical calculation, the propagation properties of solitary waves corresponding with these evolution equations are analysed in detail. Finally, as a example of practical application, the propagation of pressure pulses in large blood vessels is discussed.
Nonlinear waves in a fluid-filled thin viscoelastic tube
Institute of Scientific and Technical Information of China (English)
Zhang Shan-Yuan; Zhang Tao
2010-01-01
In the present paper the propagation property of nonlinear waves in a thin viscoelastic tube filled with incom-pressible inviscid fluid is studied. The tube is considered to be made of an incompressible isotropic viscoelastic material described by Kelvin-Voigt model. Using the mass conservation and the momentum theorem of the fluid and radial dynamic equilibrium of an element of the tube wall, a set of nonlinear partial differential equations governing the prop-agation of nonlinear pressure wave in the solid-liquid coupled system is obtained. In the long-wave approximation the nonlinear far-field equations can be derived employing the reductive perturbation technique (RPT). Selecting the expo-η, three kinds of evolution equations with soliton solution, i.e. Korteweg-de Vries (KdV)-Burgers, KdV and Burgers equations are deduced. By means of the method of traveling-wave solution and numerical calculation, the propagation properties of solitary waves corresponding with these evolution equations are analysed in detail. Finally, as a example of practical application, the propagation of pressure pulses in large blood vessels is discussed.
Coherent vortex structures in fluids and plasmas
Tur, Anatoli
2017-01-01
This monograph introduces readers to the hydrodynamics of vortex formation, and reviews the last decade of active research in the field, offering a unique focus on research topics at the crossroads of traditional fluids and plasmas. Vortices are responsible for the process of macroscopic transport of momentum, energy and mass, and are formed as the result of spontaneous self-organization. Playing an important role in nature and technology, localized, coherent vortices are regularly observed in shear flows, submerged jets, afterbody flows and in atmospheric boundary layers, sometimes taking on the form of vortex streets. In addition, the book addresses a number of open issues, including but not limited to: which singularities are permitted in a 2D Euler equation besides point vortices? Which other, even more complex, localized vortices could be contained in the Euler equation? How do point vortices interact with potential waves?
Delzanno, G. L.; Finn, J. M.; Lapenta, G.
2002-12-01
The nonlinear dynamics of a Penning trap plasma, including the effect of the finite length and end curvature of the plasma column, is studied. A new cylindrical particle-in-cell code, called KANDINSKY, has been implemented by using a new interpolation scheme. The principal idea is to calculate the volume of each cell from a particle volume, in the same manner as is done for the cell charge. With this new method, the density is conserved along streamlines and artificial sources of compressibility are avoided. The code has been validated with a number of tests. The code is then used to compare the dynamics of three different models: the standard Euler or drift-Poisson model, the modified drift-Poisson model [J. Finn et al. Phys. Plasmas 6, 3744 (1999); Phys. Rev. Lett. 84, 2401 (2000)] with compressional effects, and the quasigeostrophic model of geophysical fluid dynamics in the limit of the γ-plane approximation. The results of this investigation show that Penning traps can be used to simulate geophysical fluids. Moreover, the results for the m=1 diocotron instability reproduce qualitatively the experiments [C. F. Driscoll, Phy. Rev. Lett. 64, 645 (1990); C. F. Driscoll et al. Phys. Fluids B 2, 1359 (1990)]: The instability turns the plasma "inside-out" resulting at the end in a stable, monotonic profile.
Quantifying terpenes in rumen fluid, serum, and plasma from sheep
Determining the fate of terpenes consumed by browsing ruminants require methods to quantify their presence in blood and rumen fluid. Our objective was to modify an existing procedure for plasma terpenes to quantify 25 structurally diverse mono- and sesquiterpenes in serum, plasma, and rumen fluid fr...
Viscous Fluid Conduits as a Prototypical Nonlinear Dispersive Wave Platform
Lowman, Nicholas K.
This thesis is devoted to the comprehensive characterization of slowly modulated, nonlinear waves in dispersive media for physically-relevant systems using a threefold approach: analytical, long-time asymptotics, careful numerical simulations, and quantitative laboratory experiments. In particular, we use this interdisciplinary approach to establish a two-fluid, interfacial fluid flow setting known as viscous fluid conduits as an ideal platform for the experimental study of truly one dimensional, unidirectional solitary waves and dispersively regularized shock waves (DSWs). Starting from the full set of fluid equations for mass and linear momentum conservation, we use a multiple-scales, perturbation approach to derive a scalar, nonlinear, dispersive wave equation for the leading order interfacial dynamics of the system. Using a generalized form of the approximate model equation, we use numerical simulations and an analytical, nonlinear wave averaging technique, Whitham-El modulation theory, to derive the key physical features of interacting large amplitude solitary waves and DSWs. We then present the results of quantitative, experimental investigations into large amplitude solitary wave interactions and DSWs. Overtaking interactions of large amplitude solitary waves are shown to exhibit nearly elastic collisions and universal interaction geometries according to the Lax categories for KdV solitons, and to be in excellent agreement with the dynamics described by the approximate asymptotic model. The dispersive shock wave experiments presented here represent the most extensive comparison to date between theory and data of the key wavetrain parameters predicted by modulation theory. We observe strong agreement. Based on the work in this thesis, viscous fluid conduits provide a well-understood, controlled, table-top environment in which to study universal properties of dispersive hydrodynamics. Motivated by the study of wave propagation in the conduit system, we
Nonlinear structures for extended Korteweg–de Vries equation in multicomponent plasma
Indian Academy of Sciences (India)
Abdelsalam U M; Allehiany F M; Moslem W M; El-Labany S K
2016-03-01
Using the fluid hydrodynamic equations of positive and negative ions, as well as$q$-nonextensive electron density distribution, an extended Korteweg–de Vries (EKdV) equation describing a small but finite amplitude dust ion-acoustic waves (DIAWs) is derived. Extended homogeneous balance method is used to obtain a new class of solutions of the EKdV equation. The effects of different physical parameters on the propagating nonlinear structures and their relevanceto particle acceleration in space plasma are reported.
Fluid flow of incompressible viscous fluid through a non-linear elastic tube
Energy Technology Data Exchange (ETDEWEB)
Lazopoulos, A.; Tsangaris, S. [National Technical University of Athens, Fluids Section, School of Mechanical Engineering, Zografou, Athens (Greece)
2008-11-15
The study of viscous flow in tubes with deformable walls is of specific interest in industry and biomedical technology and in understanding various phenomena in medicine and biology (atherosclerosis, artery replacement by a graft, etc) as well. The present work describes numerically the behavior of a viscous incompressible fluid through a tube with a non-linear elastic membrane insertion. The membrane insertion in the solid tube is composed by non-linear elastic material, following Fung's (Biomechanics: mechanical properties of living tissue, 2nd edn. Springer, New York, 1993) type strain-energy density function. The fluid is described through a Navier-Stokes code coupled with a system of non linear equations, governing the interaction with the membrane deformation. The objective of this work is the study of the deformation of a non-linear elastic membrane insertion interacting with the fluid flow. The case of the linear elastic material of the membrane is also considered. These two cases are compared and the results are evaluated. The advantages of considering membrane nonlinear elastic material are well established. Finally, the case of an axisymmetric elastic tube with variable stiffness along the tube and membrane sections is studied, trying to substitute the solid tube with a membrane of high stiffness, exhibiting more realistic response. (orig.)
Axisymmetric Nonlinear Waves And Structures in Hall Plasmas
Islam, Tanim
2011-01-01
A Hall plasma consists of a plasma with not all species frozen into the magnetic field. In this paper, a general equation for the evolution of an axisymmetric magnetic field in a Hall plasma is derived, with an integral similar to the Grad-Shafranov equation. Special solutions arising from curvature -- whistler drift modes that propagate along the electron drift as a Burger's shock, and nonlinear periodic and soliton-like solutions to the generalized Grad-Shafranov integral -- are analyzed. We derive analytical and numerical solutions in an electron-ion Hall plasma, in which electrons and ions are the only species in the plasmas. Results may then be applied to electron-ion-gas Hall plasmas, in which the ions are coupled to the motion of gases in low ionized plasmas (lower ionosphere and protostellar disks), and to dusty Hall plasmas (such as molecular clouds), in which the much heavier charged dust may be collisionally coupled to the gas.
Two-dimensional simulations of nonlinear beam-plasma interaction in isotropic and magnetized plasmas
Timofeev, I V
2012-01-01
Nonlinear interaction of a low density electron beam with a uniform plasma is studied using two-dimensional particle-in-cell (PIC) simulations. We focus on formation of coherent phase space structures in the case, when a wide two-dimensional wave spectrum is driven unstable, and we also study how nonlinear evolution of these structures is affected by the external magnetic field. In the case of isotropic plasma, nonlinear buildup of filamentation modes due to the combined effects of two-stream and oblique instabilities is found to exist and growth mechanisms of secondary instabilities destroying the BGK--type nonlinear wave are identified. In the weak magnetic field, the energy of beam-excited plasma waves at the nonlinear stage of beam-plasma interaction goes predominantly to the short-wavelength upper-hybrid waves propagating parallel to the magnetic field, whereas in the strong magnetic field the spectral energy is transferred to the electrostatic whistlers with oblique propagation.
Laser Plasma Physics - Forces and Nonlinear Principle
Hora, Heinrich
2014-01-01
This work is an electronic pre-publication of a book manuscript being under consideration in order to provide information to interested researchers about a review of mechanical forces in plasmas by electro-dynamic fields. Beginning with Kelvin's ponderomotive force of 1845 in electrostatics, the hydrodynamic force in a plasma is linked with quadratic force quantities of electric and magnetic fields. Hydrodynamics is interlinked with single particle motion of plasma particles electric field generation and double layers and sheaths due to properties of inhomogeneous plasmas. Consequences relate to laser driven particle acceleration and fusion energy. Beyond the very broad research field of fusion using nanosecond laser pulses based on thermodynamics, the new picosecond pulses of ultrahigh power opened a categorically different non-thermal interaction finally permitting proton-boron fusion with eliminating problems of nuclear radiation.
Nonlinear dynamics of electromagnetic pulses in cold relativistic plasmas
Energy Technology Data Exchange (ETDEWEB)
Bonatto, A.; Pakter, R.; Rizzato, F.B. [Universidade Federal do Rio Grande do Sul, Instituto de Fisica, Rio Grande do Sul (Brazil)
2004-07-01
The propagation of intense electromagnetic pulses in plasmas is a subject of current interest particularly for particle acceleration and laser fusion.In the present analysis we study the self consistent propagation of nonlinear electromagnetic pulses in a one dimensional relativistic electron-ion plasma, from the perspective of nonlinear dynamics. We show how a series of Hamiltonian bifurcations give rise to the electric fields which are of relevance in the subject of particle acceleration. Connections between these bifurcated solutions and results of earlier analysis are made. (authors)
Nonlinear magnetoplasmons in strongly coupled Yukawa plasmas
Bonitz, M; Ott, T; Kaehlert, H; Hartmann, P
2010-01-01
The existence of plasma oscillations at multiples of the magnetoplasmon frequency in a strongly coupled two-dimensional magnetized Yukawa plasma is reported, based on extensive molecular dynamics simulations. These modes are the analogues of Bernstein modes which are renormalized by strong interparticle correlations. Their properties are theoretically explained by a dielectric function incorporating the combined effect of a magnetic field, strong correlations and finite temperature.
Three-dimensional global fluid simulations of cylindrical magnetized plasmas
DEFF Research Database (Denmark)
Naulin, Volker; Windisch, T.; Grulke, O.
2008-01-01
. Thus, it is possible to assess the reproductive and predictive capabilities of plasma simulations in unprecedented detail. Here, three-dimensional global fluid simulations of a cylindrical magnetized plasma are presented. This plasma is characterized by the existence of spatially localized sources...... and sinks. The traditional scale separation paradigm is not applied in the simulation model to account for the important evolution of the background profiles due to the dynamics of turbulent fluctuations. Furthermore, the fluid modeling of sheath boundary conditions, which determine the plasma conditions...
Energy Technology Data Exchange (ETDEWEB)
Hussain, S.; Mahmood, S.; Rehman, Aman-ur- [Theoretical Physics Division (TPD), PINSTECH, P.O. Nilore, Islamabad 44000, Pakistan and Pakistan Institute of Engineering and Applied Sciences (PIEAS), P.O. Nilore, Islamabad 44000 (Pakistan)
2014-11-15
Linear and nonlinear propagation of magnetosonic waves in the perpendicular direction to the ambient magnetic field is studied in dense plasmas for non-relativistic and ultra-relativistic degenerate electrons pressure. The sources of nonlinearities are the divergence of the ions and electrons fluxes, Lorentz forces on ions and electrons fluids and the plasma current density in the system. The Korteweg-de Vries equation for magnetosonic waves propagating in the perpendicular direction of the magnetic field is derived by employing reductive perturbation method for non-relativistic as well as ultra-relativistic degenerate electrons pressure cases in dense plasmas. The plots of the magnetosonic wave solitons are also shown using numerical values of the plasma parameters such a plasma density and magnetic field intensity of the white dwarfs from literature. The dependence of plasma density and magnetic field intensity on the magnetosonic wave propagation is also pointed out in dense plasmas for both non-relativistic and ultra-relativistic degenerate electrons pressure cases.
Linear and nonlinear heavy ion-acoustic waves in a strongly coupled plasma
Energy Technology Data Exchange (ETDEWEB)
Ema, S. A., E-mail: ema.plasma@gmail.com; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka-1342 (Bangladesh); Hossen, M. R. [Deparment of Natural Sciences, Daffodil International University, Sukrabad, Dhaka-1207 (Bangladesh)
2015-09-15
A theoretical study on the propagation of linear and nonlinear heavy ion-acoustic (HIA) waves in an unmagnetized, collisionless, strongly coupled plasma system has been carried out. The plasma system is assumed to contain adiabatic positively charged inertial heavy ion fluids, nonextensive distributed electrons, and Maxwellian light ions. The normal mode analysis is used to study the linear behaviour. On the other hand, the well-known reductive perturbation technique is used to derive the nonlinear dynamical equations, namely, Burgers equation and Korteweg-de Vries (K-dV) equation. They are also numerically analyzed in order to investigate the basic features of shock and solitary waves. The adiabatic effects on the HIA shock and solitary waves propagating in such a strongly coupled plasma are taken into account. It has been observed that the roles of the adiabatic positively charged heavy ions, nonextensivity of electrons, and other plasma parameters arised in this investigation have significantly modified the basic features (viz., polarity, amplitude, width, etc.) of the HIA solitary/shock waves. The findings of our results obtained from this theoretical investigation may be useful in understanding the linear as well as nonlinear phenomena associated with the HIA waves both in space and laboratory plasmas.
Fractal structures in nonlinear plasma physics.
Viana, R L; da Silva, E C; Kroetz, T; Caldas, I L; Roberto, M; Sanjuán, M A F
2011-01-28
Fractal structures appear in many situations related to the dynamics of conservative as well as dissipative dynamical systems, being a manifestation of chaotic behaviour. In open area-preserving discrete dynamical systems we can find fractal structures in the form of fractal boundaries, associated to escape basins, and even possessing the more general property of Wada. Such systems appear in certain applications in plasma physics, like the magnetic field line behaviour in tokamaks with ergodic limiters. The main purpose of this paper is to show how such fractal structures have observable consequences in terms of the transport properties in the plasma edge of tokamaks, some of which have been experimentally verified. We emphasize the role of the fractal structures in the understanding of mesoscale phenomena in plasmas, such as electromagnetic turbulence.
Nonlinear ion-acoustic solitary waves with warm ions and non-Maxwellian electrons in space plasmas
Hussain Shah, Khalid; Qureshi, Nouman
2017-04-01
Electrons velocity distributions are often observed with non-Maxwellian features such flat tops at low energies and/or superthermal tails at high energies from different regions of near Earth plasmas such as Earth's bow shock, auroral zone and magnetosphere by numerous satellites. Such non-Maxwellian distributions are well modelled by generalized (r,q) distribution or Cairns distribution. Solitons are nonlinear solitary structures and are integral part of space plasmas. In this paper, we present a fluid model containing Cairns (r,q) distributed non-Maxwellian electrons and derive the Sagdeev potential for fully nonlinear fluid equations. We found that compressive solitons can be developed in such a plasma. The results from our model can be used to interpret solitary structures in space plasmas when electrons are obeying the non-Maxwellian flat tops along with the high energy tails.
Crystal growth in fluid flow: Nonlinear response effects
Peng, H. L.; Herlach, D. M.; Voigtmann, Th.
2017-08-01
We investigate crystal-growth kinetics in the presence of strong shear flow in the liquid, using molecular-dynamics simulations of a binary-alloy model. Close to the equilibrium melting point, shear flow always suppresses the growth of the crystal-liquid interface. For lower temperatures, we find that the growth velocity of the crystal depends nonmonotonically on the shear rate. Slow enough flow enhances the crystal growth, due to an increased particle mobility in the liquid. Stronger flow causes a growth regime that is nearly temperature-independent, in striking contrast to what one expects from the thermodynamic and equilibrium kinetic properties of the system, which both depend strongly on temperature. We rationalize these effects of flow on crystal growth as resulting from the nonlinear response of the fluid to strong shearing forces.
Coherent effects in the stochastic electrodynamics of two-fluid plasma
Auluck, S K H
2012-01-01
Random electromagnetic fields are ubiquitous in plasmas, the most common example being electromagnetic radiation of thermal origin. They should exert a random force on electrons and ions in a plasma, adding a random component to their motion. Products of randomly fluctuating quantities, such as velocity and magnetic field, which are correlated through the dynamical equations of the two-fluid model of plasma, should then exhibit non-zero average values. Investigation of such effects requires spatial-spectral representation of the non-linear equations of the two-fluid model. Chandrasekhar-Kendall (CK) functions, their generating function and its gradient defined over an infinite domain are shown to simultaneously provide orthogonal basis for solenoidal, scalar and irrotational fields respectively, facilitating transformation from coordinate space to mode number space and back. This paper constructs a theoretical framework for studying coherent effects of random forces due to random electromagnetic fields in a t...
Two-dimensional convection and interchange motions in fluids and magnetized plasmas
DEFF Research Database (Denmark)
Garcia, O.E.; Bian, N.H.; Naulin, V.
2006-01-01
In this contribution some recent investigations of two- dimensional thermal convection relevant to ordinary fluids as well as magnetized plasmas are reviewed. An introductory discussion is given of the physical mechanism for baroclinic vorticity generation and convective motions in stratified...... fluids, emphasizing its relation to interchange motions of non- uniformly magnetized plasmas. This is followed by a review of the theories for the onset of convection and quasi-linear saturation in driven-dissipative systems. Non-linear numerical simulations which result in stationary convective states....... The global bursting is interpreted in terms of a predator-prey regulation from the point of view of energetics. Finally, a discussion is given of the relevance of these phenomena to a variety of magnetized plasma experiments....
Axisymmetric nonlinear waves and structures in Hall plasmas
Energy Technology Data Exchange (ETDEWEB)
Islam, Tanim [Lawrence Livermore National Laboratory, P. O. Box 808, Livermore, California 94551-0808 (United States)
2012-06-15
In this paper, a general equation for the evolution of an axisymmetric magnetic field in a Hall plasma is derived, with an integral similar to the Grad-Shafranov equation. Special solutions arising from curvature-whistler drift modes that propagate along the electron drift as a Burger's shock and nonlinear periodic and soliton-like solutions to the generalized Grad-Shafranov integral-are analyzed. We derive analytical and numerical solutions in a classical electron-ion Hall plasma, in which electrons and ions are the only species in the plasmas. Results may then be applied to the following low-ionized astrophysical plasmas: in protostellar disks, in which the ions may be coupled to the motion of gases; and in molecular clouds and protostellar jets, in which the much heavier charged dust in a dusty Hall plasma may be collisionally coupled to the gas.
Nonlinear Mirror Modes in Space Plasmas
Sulem, P -L
2011-01-01
Since the first observations by Kaufmann et al.\\ (1970), special attention has been paid to static pressure-balanced structures in the form of magnetic holes or humps observed in regions of the solar wind and of planetary magnetosheaths where the $\\beta$ parameter is relatively large and the ion perpendicular temperature exceeds the parallel one. Although alternative interpretations have been proposed, these structures are usually viewed as associated with the mirror instability discovered in 1957 by Vedenov and Sagdeev. After reviewing observational results provided by satellite missions, high-resolution numerical simulations of the Vlasov--Maxwell equations together with asymptotic and phenomenological models of the nonlinear dynamics near the instability threshold are discussed. The constraining effect of the mirror instability on the temperature anisotropy associated with a dominant perpendicular ion heating observed in the solar wind is reported, and recent simulations of this phenomenon based on an elab...
Schamel, Hans; Mandal, Debraj; Sharma, Devendra
2017-03-01
An outstanding notion for collisionless plasmas is the essential nonlinear character of their coherent structures, which in the stationary, weak amplitude limit are described by a continuum of cnoidal electron and ion hole modes governed by a multiparametric nonlinear dispersion relation. The well-known discrete structure of undamped linear plasma modes is seamlessly embedded in this nonlinear continuum as the microscopic texture of plasma begins to reveal itself in the high temperature collisionless plasma limit. This transforms the linear-threshold-based operating mechanism of plasma turbulence into a fundamental nonlinear, multifaceted one. Based on a comprehensive three-level description of increasing profundity, a proof of this novel dictum is presented, which makes use of the joint properties of such structures, their coherency and stationarity, and uses in succession a fluid, linear Vlasov and a full Vlasov description. It unifies discrete and continuum limits by resolving the inevitable resonant region and shows that coherent electrostatic equilibria are generally controlled by kinetic particle trapping and are hence fundamentally nonlinear. By forging a link between damped and growing wave solutions, these modes render plasma stability complex and difficult to evaluate due to the entangled pattern of the stability boundary in function and parameter space, respectively. A direct consequence is the existence of negative energy modes of arbitrarily small amplitudes in the subcritical region of the two-stream instability as well as the failure of linear Landau (Vlasov, van Kampen) theory, whenever resonant particles are involved, in addressing the onset of instability in a current-carrying plasma. Responsible for this subtle phase space behavior is hence the thresholdless omnipresence of the trapping nonlinearity originating from coherency. A high resolution, exact-mass-ratio, multispecies, and collisionless plasma simulation is employed to illustrate
Shukla, P K; Eliasson, B
2007-08-31
We consider nonlinear interactions between intense circularly polarized electromagnetic (CPEM) waves and electron plasma oscillations (EPOs) in a dense quantum plasma, taking into account the electron density response in the presence of the relativistic ponderomotive force and mass increase in the CPEM wave fields. The dynamics of the CPEM waves and EPOs is governed by the two coupled nonlinear Schrödinger equations and Poisson's equation. The nonlinear equations admit the modulational instability of an intense CPEM pump wave against EPOs, leading to the formation and trapping of localized CPEM wave pipes in the electron density hole that is associated with a positive potential distribution in our dense plasma. The relevance of our investigation to the next generation intense laser-solid density plasma interaction experiments is discussed.
A NUMERICAL METHOD FOR SIMULATING NONLINEAR FLUID-RIGID STRUCTURE INTERACTION PROBLEMS
Institute of Scientific and Technical Information of China (English)
XingJ.T; PriceW.G; ChenY.G
2005-01-01
A numerical method for simulating nonlinear fluid-rigid structure interaction problems is developed. The structure is assumed to undergo large rigid body motions and the fluid flow is governed by nonlinear, viscous or non-viscous, field equations with nonlinear boundary conditions applied to the free surface and fluid-solid interaction interfaces. An Arbitrary-Lagrangian-Eulerian (ALE) mesh system is used to construct the numerical model. A multi-block numerical scheme of study is adopted allowing for the relative motion between moving overset grids, which are independent of one another. This provides a convenient method to overcome the difficulties in matching fluid meshes with large solid motions. Nonlinear numerical equations describing nonlinear fluid-solid interaction dynamics are derived through a numerical discretization scheme of study. A coupling iteration process is used to solve these numerical equations. Numerical examples are presented to demonstrate applications of the model developed.
Characterization of a plasma photonic crystal using the multi-fluid plasma model
Thomas, Whitney; Shumlak, Uri; Miller, Sean
2016-10-01
Plasma photonic crystals have great potential to expand the capabilities of current microwave filtering and switching technologies by providing high speed control of energy band-gap/pass characteristics. While there has been considerable research into dielectric, semiconductor, metallic, and even liquid crystal based radiation manipulation, using plasmas is a relatively new field. Concurrently, processing power has reached levels where realistic, computationally expensive, multi-fluid plasma simulations are now possible. Unlike single-fluid magnetohydrodynamic (MHD) models, multi-fluid plasma models capture the electron fluid response to electromagnetic waves, a key process responsible for reflecting radiation. In this study, a 5-moment multi-fluid plasma model is implemented in University of Washington's WARPXM computational plasma physics code to examine the energy band-gap characteristics of an array of plasma-filled rods. This configuration permits the thorough analysis of the effect that plasma temperature, density, and array configuration have on energy transmission, absorption, and reflection. Furthermore, high-resolution simulations of the plasma columns gives a detailed window into plasma-radiation interactions. This work is supported by a Grant from the United States Air Force Office of Scientific Research.
Multi-CPU plasma fluid turbulence calculations on a CRAY Y-MP C90
Energy Technology Data Exchange (ETDEWEB)
Lynch, V.E.; Carreras, B.A.; Leboeuf, J.N. [Oak Ridge National Lab., TN (United States); Curtis, B.C.; Troutman, R.L. [National Energy Research Supercomputer Center, Livermore, CA (United States)
1993-06-01
Significant improvements in real-time efficiency have been obtained for plasma fluid turbulence calculations by microtasking the nonlinear fluid code KITE in which they are implemented on the CRAY Y-MP C90 at the National Energy Research Supercomputer Center (NERSC). The number of processors accessed concurrently scales linearly with problem size. Close to six concurrent processors have so far been obtained with a three-dimensional nonlinear production calculation at the currently allowed memory size of 80 Mword. With a calculation size corresponding to the maximum allowed memory of 200 Mword in the next system configuration, we expect to be able to access close to nine processors of the C90 concurrently with a commensurate improvement in real-time efficiency. These improvements in performance are comparable to those expected from a massively parallel implementation of the same calculations on the Intel Paragon.
Indian Academy of Sciences (India)
ALY R SEADAWY
2017-09-01
Nonlinear two-dimensional Kadomtsev–Petviashvili (KP) equation governs the behaviour of nonlinear waves in dusty plasmas with variable dust charge and two temperature ions. By using the reductive perturbation method, the two-dimensional dust-acoustic solitary waves (DASWs) in unmagnetized cold plasma consisting of dust fluid, ions and electrons lead to a KP equation. We derived the solitary travelling wave solutions of the twodimensional nonlinear KP equation by implementing sech–tanh, sinh–cosh, extended direct algebraic and fraction direct algebraicmethods. We found the electrostatic field potential and electric field in the form travellingwave solutions for two-dimensional nonlinear KP equation. The solutions for the KP equation obtained by using these methods can be demonstrated precisely and efficiency. As an illustration, we used the readymade package of $\\it{Mathematica}$ program 10.1 to solve the original problem. These solutions are in good agreement with the analytical one.
ALFVEN WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA
Energy Technology Data Exchange (ETDEWEB)
Soler, R.; Ballester, J. L.; Terradas, J. [Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Carbonell, M., E-mail: roberto.soler@uib.es, E-mail: joseluis.ballester@uib.es, E-mail: jaume.terradas@uib.es, E-mail: marc.carbonell@uib.es [Departament de Matematiques i Informatica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)
2013-04-20
Alfven waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfven waves is affected by the interaction between ionized and neutral species. Here we study Alfven waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible, we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cutoff values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mode approach and solve the initial-value problem in order to study the time-dependent evolution of the wave perturbations in the two fluids. An application to Alfven waves in the low solar atmospheric plasma is performed and the implication of partial ionization for the energy flux is discussed.
Optical Multi-hysteresises and "Rogue Waves" in Nonlinear Plasma
Kaplan, A E
2010-01-01
An overdense plasma layer irradiated by an intense light can exhibit dramatic nonlinear-optical effects due to a relativistic mass-effect of free electrons: highly-multiple hysteresises of reflection and transition, and emergence of gigantic "rogue waves". Those are trapped quasi-soliton field spikes inside the layer, sustained by an incident radiation with a tiny fraction of their peak intensity once they have been excited by orders of magnitude larger pumping. The phenomenon persists even in the layers with "soft" boundaries, as well as in a semi-infinite plasma with low absorption.
Nonlinear electrostatic wave equations for magnetized plasmas - II
DEFF Research Database (Denmark)
Dysthe, K. B.; Mjølhus, E.; Pécseli, H. L.
1985-01-01
For pt.I see ibid., vol.26, p.443-7 (1984). The problem of extending the high frequency part of the Zakharov equations for nonlinear electrostatic waves to magnetized plasmas, is considered. Weak electromagnetic and thermal effects are retained on an equal footing. Direction dependent (electrosta......For pt.I see ibid., vol.26, p.443-7 (1984). The problem of extending the high frequency part of the Zakharov equations for nonlinear electrostatic waves to magnetized plasmas, is considered. Weak electromagnetic and thermal effects are retained on an equal footing. Direction dependent...... (electrostatic) cut-off implies that various cases must be considered separately, leading to equations with rather different properties. Various equations encountered previously in the literature are recovered as limiting cases....
Sanbonmatsu, K. Y.; Goldman, M. V.; Newman, D. L.
A hybrid kinetic-fluid model is developed which is relevant to lower hybrid spikelets observed in the topside auroral ionosphere [Vago et al., 1992; Eriksson et al., 1994]. In contrast to previous fluid models [Shapiro et al., 1995; Tam and Chang, 1995; Seyler, 1994; Shapiro et al., 1993] our linear low frequency plasma response is magnetized and kinetic. Fluid theory is used to incorporate the nonlinear wave coupling. Performing a linear stability analysis, we calculate the growth rate for the modulational instability, driven by a lower hybrid wave pump. We find that both the magnetic and kinetic effects inhibit the modulational instability.
Some Nonlinear Phenomena in a Preformed Underdense Plasma
Institute of Scientific and Technical Information of China (English)
曹莉华; 刘智勇; 常文蔚; 岳宗五
2001-01-01
The propagation of a laser pulse with a peak intensity 1019 W/cm2 through the preformed underdense plasmawith the density 0.014nc are studied by using two-dimensional particle-in-cell simulations. The longitudinal electron heating is identified and verified, and its major property agrees with the theoretical prediction. The electron distributions in phase space, patterns of the electric fields, profiles of the ion or electron density and other plasma nonlinear phenomena are presented and discussed.
Institute of Scientific and Technical Information of China (English)
WangLin; NiQiao; HuangYuying
2003-01-01
This paper proposes a new method for investigating the Hopf bifurcation of a curved pipe conveying fluid with nonlinear spring support. The nonlinear equation of motion is derived by forces equilibrium on microelement of the system under consideration. The spatial coordinate of the system is discretized by the differential quadrature method and then the dynamic equation is solved by the Newton-Raphson method. The numerical solutions show that the inner fluid velocity of the Hopf bifurcation point of the curved pipe varies with different values of the parameter,nonlinear spring stiffness. Based on this, the cycle and divergent motions are both found to exist at specific fluid flow velocities with a given value of the nonlinear spring stiffness. The results are useful for further study of the nonlinear dynamic mechanism of the curved fluid conveying pipe.
Iizuka, S.
1998-02-01
The Table of Contents for the book is as follows: * PREFACE * INTERNATIONAL SCIENTIFIC COMMITTEE * LOCAL ORGANIZING COMMITTEE AT TOHOKU UNIVERSITY * CHAPTER 1: DOUBLE LAYERS, SHEATHS, AND POTENTIAL STRUCTURES * 1.1 Double Layers * On Fluid Models of Stationary, Acoustic Double Layers (Invited) * Particle Simulation of Double Layer (Invited) * Space-Time Dependence of Non-Steady Double Layers * The Role of Low Energy Electrons for the Generation of Anode Double Layers in Glow Discharges * Arbitrary Amplitude Ion-Acoustic Double Layers in a Dusty Plasma * 1.2 Sheaths * Bounded Plasma Edge Physics as Observed from Simulations in 1D and 2D (Invited) * Control of RF Sheath Structure in RF Diode Discharge * Observation of Density Gradients with Fine Structures and Low Frequency Wave Excitation at the Plasma-Sheath Boundary * Double Sheath Associated with an Electron Emission to a Plasma Containing Negative Ions * Sheath Edge and Floating Potential for Multi-Species Plasmas Including Dust Particles * 1.3 Potential Structures and Oscillations * Potential Structure Formed at a Constriction of a DC He Positive Column and its Coupling with Ionization Wave * Potential Structure in a New RF Magnetron Device with a Hollow Electrode * Potential Disruption in a RF Afterglow Electronegative Plasma * Potential Oscillation in a Strongly Asymmetry RF Discharge Containing Negative Ions * Effects of External Potential Control on Coulomb Dust Behavior * Potential Structure of Carbon Arc Discharge for High-Yield Fullerenes Formation * Control of Axial and Radial Potential Profiles in Tandem Mirrors (Invited) * CHAPTER 2: FIELD-ALIGNED ELECTRIC FIELDS AND RELATED PARTICLE ACCELERATIONS * 2.1 Field-Aligned Potential Formation * Formation of Large Potential Difference in a Plasma Flow along Converging Magnetic Field Lines (Invited) * Presheath Formation in front of an Oblique End-Plate in a Magnetized Sheet Plasma * Plasma Potential Formation Due to ECRH in a Magnetic Well * Electrostatic
Versatile and Robust Software for Multi-Fluid Plasma Modeling
2013-01-21
models , MHD , Hall MHD , two...described by two-‐fluid or Hall MHD initially evolves to something where only kinetic model is strictly...AFRL-OSR-VA-TR-2013-0153 "Versatile and Robust Software forMulti‐Fluid Plasma Modeling ” John Loverich and Uri Shumlak
Nonlinear laser-plasma interaction in magnetized liner inertial fusion
Geissel, Matthias; Awe, T. J.; Bliss, D. E.; Campbell, M. E.; Gomez, M. R.; Harding, E.; Harvey-Thompson, A. J.; Hansen, S. B.; Jennings, C.; Kimmel, M. W.; Knapp, P.; Lewis, S. M.; McBride, R. D.; Peterson, K.; Schollmeier, M.; Scoglietti, D. J.; Sefkow, A. B.; Shores, J. E.; Sinars, D. B.; Slutz, S. A.; Smith, I. C.; Speas, C. S.; Vesey, R. A.; Porter, J. L.
2016-03-01
Sandia National Laboratories is pursuing a variation of Magneto-Inertial Fusion called Magnetized Liner Inertial Fusion, or MagLIF. The MagLIF approach requires magnetization of the deuterium fuel, which is accomplished by an initial external B-Field and laser-driven pre-heat. While magnetization is crucial to the concept, it is challenging to couple sufficient energy to the fuel, since laser-plasma instabilities exist, and a compromise between laser spot size, laser entrance window thickness, and fuel density must be found. Nonlinear processes in laser plasma interaction, or laser-plasma instabilities (LPI), complicate the deposition of laser energy by enhanced absorption, backscatter, filamentation and beam-spray. Key LPI processes are determined, and mitigation methods are discussed. Results with and without improvement measures are presented.
Fluid and gyrokinetic modelling of particle transport in plasmas with hollow density profiles
Tegnered, D.; Oberparleiter, M.; Nordman, H.; Strand, P.
2016-11-01
Hollow density profiles occur in connection with pellet fuelling and L to H transitions. A positive density gradient could potentially stabilize the turbulence or change the relation between convective and diffusive fluxes, thereby reducing the turbulent transport of particles towards the center, making the fuelling scheme inefficient. In the present work, the particle transport driven by ITG/TE mode turbulence in regions of hollow density profiles is studied by fluid as well as gyrokinetic simulations. The fluid model used, an extended version of the Weiland transport model, Extended Drift Wave Model (EDWM), incorporates an arbitrary number of ion species in a multi-fluid description, and an extended wavelength spectrum. The fluid model, which is fast and hence suitable for use in predictive simulations, is compared to gyrokinetic simulations using the code GENE. Typical tokamak parameters are used based on the Cyclone Base Case. Parameter scans in key plasma parameters like plasma β, R/LT , and magnetic shear are investigated. It is found that β in particular has a stabilizing effect in the negative R/Ln region, both nonlinear GENE and EDWM show a decrease in inward flux for negative R/Ln and a change of direction from inward to outward for positive R/Ln . This might have serious consequences for pellet fuelling of high β plasmas.
A Warm Fluid Model of Intense Laser-Plasma Interactions
Tarkenton, G. M.; Shadwick, B. A.; Esarey, E. H.; Leemans, W. P.
2001-10-01
Following up on our previous work on modeling intense laser-plasma interactions with cold fluids,(B.A.Shadwick, G. M. Tarkenton, E.H. Esarey, and W.P. Leemans, ``Fluid Modeling of Intense Laser-Plasma Interactions'', in Advanced Accelerator Concepts), P. Colestock and S. Kelley editors, AIP Conf. Proc. 569 (AIP, NY 2001), pg. 154. we are exploring warm fluid models. These models represent the next level in a hierarchy of complexity beyond the cold fluid approximation. With only a modest increase in computation effort, warm fluids incorporate effects that are relevant to a variety of technologically interesting cases. We present a derivation of the warm fluid from a kinetic (i.e. Vlasov) perspective and make a connection with the usual relativistic thermodynamic approach.(S. R. de Groot, W. A. van Leeuwen and Ch. G. van Weert, Relativistic Kinetic Theory: Principles and Applications), North-Holland (1980). We will provide examples where the warm fluids yield physics results not contained in the cold model and discuss experimental parameters where these effects are believed to be important.
Smolyakov, A. I.; Chapurin, O.; Frias, W.; Koshkarov, O.; Romadanov, I.; Tang, T.; Umansky, M.; Raitses, Y.; Kaganovich, I. D.; Lakhin, V. P.
2017-01-01
Partially-magnetized plasmas with magnetized electrons and non-magnetized ions are common in Hall thrusters for electric propulsion and magnetron material processing devices. These plasmas are usually in strongly non-equilibrium state due to presence of crossed electric and magnetic fields, inhomogeneities of plasma density, temperature, magnetic field and beams of accelerated ions. Free energy from these sources make such plasmas prone to various instabilities resulting in turbulence, anomalous transport, and appearance of coherent structures as found in experiments. This paper provides an overview of instabilities that exist in such plasmas. A nonlinear fluid model has been developed for description of the Simon-Hoh, lower-hybrid and ion-sound instabilities. The model also incorporates electron gyroviscosity describing the effects of finite electron temperature. The nonlinear fluid model has been implemented in the BOUT++ framework. The results of nonlinear simulations are presented demonstrating turbulence, anomalous current and tendency toward the formation of coherent structures.
Boundary layer flow and heat transfer to Carreau fluid over a nonlinear stretching sheet
Masood Khan; Hashim
2015-01-01
This article studies the Carreau viscosity model (which is a generalized Newtonian model) and then use it to obtain a formulation for the boundary layer equations of the Carreau fluid. The boundary layer flow and heat transfer to a Carreau model over a nonlinear stretching surface is discussed. The Carreau model, adequate for many non-Newtonian fluids, is used to characterize the behavior of the fluids having shear thinning properties and fluids with shear thickening properties for numerical ...
Verification strategies for fluid-based plasma simulation models
Mahadevan, Shankar
2012-10-01
Verification is an essential aspect of computational code development for models based on partial differential equations. However, verification of plasma models is often conducted internally by authors of these programs and not openly discussed. Several professional research bodies including the IEEE, AIAA, ASME and others have formulated standards for verification and validation (V&V) of computational software. This work focuses on verification, defined succinctly as determining whether the mathematical model is solved correctly. As plasma fluid models share several aspects with the Navier-Stokes equations used in Computational Fluid Dynamics (CFD), the CFD verification process is used as a guide. Steps in the verification process: consistency checks, examination of iterative, spatial and temporal convergence, and comparison with exact solutions, are described with examples from plasma modeling. The Method of Manufactured Solutions (MMS), which has been used to verify complex systems of PDEs in solid and fluid mechanics, is introduced. An example of the application of MMS to a self-consistent plasma fluid model using the local mean energy approximation is presented. The strengths and weaknesses of the techniques presented in this work are discussed.
Relabeling symmetry in relativistic fluids and plasmas
Kawazura, Yohei; Fukumoto, Yasuhide
2014-01-01
The conservation of the recently formulated relativistic canonical helicity [Yoshida Z, Kawazura Y, and Yokoyama T 2014 J. Math. Phys. 55 043101] is derived from Noether's theorem by constructing an action principle on the relativistic Lagrangian coordinates (we obtain general cross helicities that include the helicity of the canonical vorticity). The conservation law is, then, explained by the relabeling symmetry pertinent to the Lagrangian label of fluid elements. Upon Eulerianizing the Noether current, the purely spatial volume integral on the Lagrangian coordinates is mapped to a space-time mixed three-dimensional integral on the four-dimensional Eulerian coordinates. The relativistic conservation law in the Eulerian coordinates is no longer represented by any divergence-free current; hence, it is not adequate to regard the relativistic helicity (represented by the Eulerian variables) as a Noether charge, and this stands the reason why the "conventional helicity" is no longer a constant of motion. We have...
Magnetoacoustic waves in a partially ionized two-fluid plasma
Soler, Roberto; Ballester, Jose Luis
2013-01-01
Compressible disturbances propagate in a plasma in the form of magnetoacoustic waves driven by both gas pressure and magnetic forces. In partially ionized plasmas the dynamics of ionized and neutral species are coupled due to ion-neutral collisions. As a consequence, magnetoacoustic waves propagating through a partially ionized medium are affected by the ion-neutral coupling. The degree to which the behavior of the classic waves is modified depends on the physical properties of the various species and on the relative value of the wave frequency compared to the ion-neutral collision frequency. Here, we perform a comprehensive theoretical investigation of magnetoacoustic wave propagation in a partially ionized plasma using the two-fluid formalism. We consider an extensive range of values for the collision frequency, ionization ratio, and plasma $\\beta$, so that the results are applicable to a wide variety of astrophysical plasmas. We determine the modification of the wave frequencies and study the frictional da...
Existence of solutions of a nonlinear system modelling fluid flow in porous media
Directory of Open Access Journals (Sweden)
dam Besenyei
2006-12-01
Full Text Available We investigate the existence of weak solutions for nonlinear differential equations that describe fluid flow through a porous medium. Existence is proved using the theory of monotone operators, and some examples are given.
Nonlinear Optical Parameters of Magnetoactive Semiconductor-Plasmas
Singh, M.; Joseph, D.; Duhan, S.
The nonlinear optical parameters (absorption coefficient and refractive index) of semiconductor-plasmas subjected to a transverse magnetic field have been investigated analytically. By employing the coupled-mode scheme, an expression of third-order optical susceptibility and resultant nonlinear absorption and refractive index of the medium are obtained. The analysis has been applied to both cases, viz., centrosymmetric (β = 0) and noncentrosymmetric (β ≠ 0) in the presence of magnetic field. The numerical estimates are made for InSb crystal at liquid nitrogen temperature duly irradiated by a 10-nanosecond pulsed 10.6 μm CO2 laser. The influence of doping concentration and magnetic field on both the nonlinear absorption and refractive index has been explored, and the results are found to be well in agreement with theory and experiment. Analysis further establishes that absorption coefficient and refractive index can be controlled with precision in semiconductors by the proper selection of doping concentration and an external magnetic field, and hence these media may be used for fabrication of fast cubic nonlinear optical devices under off-resonant transition regime.
Nonlinear tearing mode in inhomogeneous plasma: I. Unmagnetized islands
Energy Technology Data Exchange (ETDEWEB)
Waelbroeck, F L [Institute for Fusion Studies, University of Texas, Austin, TX 78712-0262 (United States)
2007-06-15
A theory of the nonlinear growth and propagation of magnetic islands in the semi-collisional regime is presented. The theory includes the effects of finite electron temperature gradients and uses a fluid model with cold ions in slab geometry to describe islands that are unmagnetized in the sense that their width is less than {rho}{sub s}, the ion Larmor radius calculated with the electron temperature. The polarization integral and the natural phase velocity are both calculated. It is found that increasing the electron temperature gradient reduces the natural phase velocity below the electron diamagnetic frequency and thus causes the polarization current to become stabilizing.
Alfven waves in a partially ionized two-fluid plasma
Soler, R; Ballester, J L; Terradas, J
2013-01-01
Alfv\\'en waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfv\\'en waves is affected by the interaction between ionized and neutral species. Here we study Alfv\\'en waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cut-off values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mo...
Non-linear Plasma Wake Growth of Electron Holes
Hutchinson, I H; Zhou, C
2015-01-01
An object's wake in a plasma with small Debye length that drifts \\emph{across} the magnetic field is subject to electrostatic electron instabilities. Such situations include, for example, the moon in the solar wind wake and probes in magnetized laboratory plasmas. The instability drive mechanism can equivalently be considered drift down the potential-energy gradient or drift up the density-gradient. The gradients arise because the plasma wake has a region of depressed density and electrostatic potential into which ions are attracted along the field. The non-linear consequences of the instability are analysed in this paper. At physical ratios of electron to ion mass, neither linear nor quasilinear treatment can explain the observation of large-amplitude perturbations that disrupt the ion streams well before they become ion-ion unstable. We show here, however, that electron holes, once formed, continue to grow, driven by the drift mechanism, and if they remain in the wake may reach a maximum non-linearly stable...
Non-linear plasma wake growth of electron holes
Hutchinson, I. H.; Haakonsen, C. B.; Zhou, C.
2015-03-01
An object's wake in a plasma with small Debye length that drifts across the magnetic field is subject to electrostatic electron instabilities. Such situations include, for example, the moon in the solar wind and probes in magnetized laboratory plasmas. The instability drive mechanism can equivalently be considered drift down the potential-energy gradient or drift up the density-gradient. The gradients arise because the plasma wake has a region of depressed density and electrostatic potential into which ions are attracted along the field. The non-linear consequences of the instability are analysed in this paper. At physical ratios of electron to ion mass, neither linear nor quasilinear treatment can explain the observation of large-amplitude perturbations that disrupt the ion streams well before they become ion-ion unstable. We show here, however, that electron holes, once formed, continue to grow, driven by the drift mechanism, and if they remain in the wake may reach a maximum non-linearly stable size, beyond which their uncontrolled growth disrupts the ions. The hole growth calculations provide a quantitative prediction of hole profile and size evolution. Hole growth appears to explain the observations of recent particle-in-cell simulations.
Fluid Modes of a Spherically Confined Yukawa Plasma
Kaehlert, Hanno; Bonitz, Michael
2010-11-01
The normal modes of a three-dimensional Yukawa plasma in an isotropic, harmonic confinement are investigated by solving the linearized cold fluid equations. The eigenmodes are found analytically in terms of hypergeometric functions. The mode frequencies solely depend on the dimensionless plasma parameter ξ=κR, where R is the plasma radius and κ the inverse screening length. The eigenfrequencies increase monotonically with ξ and saturate in the limit ξ->∞. Compared with the results in the Coulomb limit [D. H. E. Dubin, Phys. Rev. Lett. 66, 2076 (1991)], we find a new class of modes characterized by the number n which determines the number of radial nodes in the perturbed potential. We compare the fluid modes with molecular dynamics simulations and find good agreement for low order modes and weak to moderate screening.
Towards a collisionless fluid closure in plasma turbulence
Energy Technology Data Exchange (ETDEWEB)
Dif Pradalier, G
2005-07-01
In this work 2 generic possible descriptions of a plasma have been compared namely the kinetic and the fluid approaches. The latter focuses on the successive moments (n, u, p, q,...) of the distribution function, whereas the former describes the time-evolution in phase space of this distribution function, both being based on the Vlasov equation. The fluid description is attractive for the Vlasov equation is tractable with great difficulties. Nevertheless it rests on a major difficulty: as the set of fluid equations constitute an infinite hierarchy, a closure equation must be chosen. The first chapter details physical characteristics of a fundamental kinetic interaction mechanism between waves and particles. In chapter 2 we propose a fluid closure that allows analytic comparison with a linear fully kinetic result, near an homogeneous, electrostatic, Maxwellian equilibrium. This approach consists in adjusting chosen parameters in order to minimize the discrepancies between fluid and kinetic linear response functions. In chapter 3 we present a general frame for a fluid closure in a magnetized plasma. This is attempted in a linear, simplified model with low dimensionality.
Nonlinear Debye screening in strongly-coupled plasmas
Sarmah, D; Tessarotto, M
2006-01-01
An ubiquitous property of plasmas is the so-called Debye shielding of the electrostatic potential. Important aspects of Debye screening concern, in particular, the investigation of non-linear charge screening effects taking place in strongly-coupled plasmas, that imply a reduction of the effective charge characterizing the Debye-H\\"{u}ckel potential. These effects are particularly relevant in dusty plasmas which are characterized by high-Z particles. The investigation of the effective interactions of these particles has attracted interest in recent years especially for numerical simulations. In this work we intend to analyze the consistency of the traditional mathematical model for the Debye screening. In particular, we intend to prove that the 3D Poisson equation involved in the DH model does not admit strong solutions. For this purpose a modified model is proposed which takes into account the effect of local plasma sheath (i.e., the local domain near test particles where the plasma must be considered discre...
Nonlinear instability in simulations of Large Plasma Device turbulence
Friedman, B; Umansky, M V; Schaffner, D; Joseph, I
2013-01-01
Several simulations of turbulence in the Large Plasma Device (LAPD) [W. Gekelman et al., Rev. Sci. Inst. 62, 2875 (1991)] are energetically analyzed and compared with each other and with the experiment. The simulations use the same model, but different axial boundary conditions. They employ either periodic, zero-value, zero-derivative, or sheath axial boundaries. The linear stability physics is different between the scenarios because the various boundary conditions allow the drift wave instability to access different axial structures, and the sheath boundary simulation contains a conducting wall mode instability which is just as unstable as the drift waves. Nevertheless, the turbulence in all the simulations is relatively similar because it is primarily driven by a robust nonlinear instability that is the same for all cases. The nonlinear instability preferentially drives $k_\\parallel = 0$ potential energy fluctuations, which then three-wave couple to $k_\\parallel \
Phase mixing versus nonlinear advection in drift-kinetic plasma turbulence
Schekochihin, A. A.; Parker, J. T.; Highcock, E. G.; Dellar, P. J.; Dorland, W.; Hammett, G. W.
2016-04-01
> A scaling theory of long-wavelength electrostatic turbulence in a magnetised, weakly collisional plasma (e.g. drift-wave turbulence driven by ion temperature gradients) is proposed, with account taken both of the nonlinear advection of the perturbed particle distribution by fluctuating flows and of its phase mixing, which is caused by the streaming of the particles along the mean magnetic field and, in a linear problem, would lead to Landau damping. It is found that it is possible to construct a consistent theory in which very little free energy leaks into high velocity moments of the distribution function, rendering the turbulent cascade in the energetically relevant part of the wavenumber space essentially fluid-like. The velocity-space spectra of free energy expressed in terms of Hermite-moment orders are steep power laws and so the free-energy content of the phase space does not diverge at infinitesimal collisionality (while it does for a linear problem); collisional heating due to long-wavelength perturbations vanishes in this limit (also in contrast with the linear problem, in which it occurs at the finite rate equal to the Landau damping rate). The ability of the free energy to stay in the low velocity moments of the distribution function is facilitated by the `anti-phase-mixing' effect, whose presence in the nonlinear system is due to the stochastic version of the plasma echo (the advecting velocity couples the phase-mixing and anti-phase-mixing perturbations). The partitioning of the wavenumber space between the (energetically dominant) region where this is the case and the region where linear phase mixing wins its competition with nonlinear advection is governed by the `critical balance' between linear and nonlinear time scales (which for high Hermite moments splits into two thresholds, one demarcating the wavenumber region where phase mixing predominates, the other where plasma echo does).
Nonlinear free vibration of single walled Carbone NanoTubes conveying fluid
Directory of Open Access Journals (Sweden)
Azrar A.
2014-04-01
Full Text Available Nonlinear free vibration of single-walled carbon nanotubes (CNTs conveying fluid are modeled and numerically simulated based on von Kármán geometric nonlinearity and Eringen’s nonlocal elasticity theory. The CNTs are modelled as nanobeams where the effects of transverse shear deformation and rotary inertia are considered within the framework of Timoshenko beam theory. The governing equations and boundary conditions are derived using the Hamilton’s principle and the nonlinear equation of motion is solved by the Galerkin’s method. The small scale parameter and the fluid-tube interaction effects on the dynamic behaviours of the CNT-fluid system as well as the instabilities induced by the fluid-velocity can be investigated. The critical fluid-velocity and frequency-amplitude relationships as well as the flutter and divergence instability types and the associated time responses are obtained based on the presented methodological approach.
Application of nonlinear dynamic techniques to high pressure plasma jets
Ghorui, S.; Das, A. K.
2010-02-01
Arcs and arc plasmas have been known and used for welding, cutting, chemical synthesis and multitude of other industrial applications for more than hundred years. Though a copious source of heat, light and active species, plasma arc is inherently unstable, turbulent and difficult to control. During recent years, primarily driven by the need of new and energy efficient materials processing, various research groups around the world have been studying new and innovative ways of looking at the issues related to arc dynamics, arc stabilization, species non equilibrium, flow and heat transfer in a stabilized arc plasma device. In this context, experimental determination of nature of arc instabilities using tools of non-linear dynamics, theoretical model formulation, prediction of instability behavior under given operating conditions and possible control methods for the observed instabilities in arcs are reviewed. Space selective probing of the zones inside arc plasma devices without disturbing the system is probably the best way to identify the originating zone of instabilities inside such devices. Existence of extremely high temperature and inaccessibility to direct experimentations due to mechanical obstructions make this task extremely difficult. Probing instabilities in otherwise inaccessible inner regions of the torches, using binary gas mixture as plasma gas is a novel technique that primarily rests on a process known as demixing in arcs. Once a binary gas mixture enters the constricted plasma column, the demixing process sets in causing spatial variations for each of the constituent gases depending on the diffusion coefficients and the gradient of the existing temperature field. By varying concentrations of the constituent gases in the feeding line, it is possible to obtain spatial variations of the plasma composition in a desired manner, enabling spatial probing of the associated zones. Detailed compositional description of different zones inside the torch may be
Nonlinear Rayleigh--Taylor instability of the cylindrical fluid flow with mass and heat transfer
Indian Academy of Sciences (India)
ALY R SEADAWY; K EL-RASHIDY
2016-08-01
The nonlinear Rayleigh--Taylor stability of the cylindrical interface between the vapour and liquid phases of a fluid is studied. The phases enclosed between two cylindrical surfaces coaxial with mass and heat transfer is derived from nonlinear Ginzburg--Landau equation. The F-expansion method is used to get exactsolutions for a nonlinear Ginzburg--Landau equation. The region of solutions is displayed graphically.
A Weakly Nonlinear Model for Kelvin-Helmholtz Instability in Incompressible Fluids
Institute of Scientific and Technical Information of China (English)
WANG Li-Feng; YE Wen-Hua; FAN Zheng-Feng; XUE Chuang; LI Ying-Jun
2009-01-01
A weakly nonlinear model is proposed for the Kelvin-Helmholtz instability in two-dimensional incompressible fluids by expanding the perturbation velocity potential to third order. The third-order harmonic generation effects of single-mode perturbation are analyzed, as well as the nonlinear correction to the exponential growth of the fundamental modulation. The weakly nonlinear results are supported by numerical simulations. Density and resonance effects exist in the development of mode coupling.
The Nonlinear Landau Damping Rate of a Driven Plasma Wave
Energy Technology Data Exchange (ETDEWEB)
Benisti, D; Strozzi, D J; Gremillet, L; Morice, O
2009-08-04
In this Letter, we discuss the concept of the nonlinear Landau damping rate, {nu}, of a driven electron plasma wave, and provide a very simple, practical, analytic formula for {nu} which agrees very well with results inferred from Vlasov simulations of stimulated Raman scattering. {nu} actually is more complicated an operator than a plain damping rate, and it may only be seen as such because it assumes almost constant values before abruptly dropping to 0. The decrease of {nu} to 0 is moreover shown to occur later when the wave amplitude varies in the direction transverse to its propagation.
Contributions of plasma physics to chaos and nonlinear dynamics
Escande, D. F.
2016-11-01
This topical review focusses on the contributions of plasma physics to chaos and nonlinear dynamics bringing new methods which are or can be used in other scientific domains. It starts with the development of the theory of Hamiltonian chaos, and then deals with order or quasi order, for instance adiabatic and soliton theories. It ends with a shorter account of dissipative and high dimensional Hamiltonian dynamics, and of quantum chaos. Most of these contributions are a spin-off of the research on thermonuclear fusion by magnetic confinement, which started in the fifties. Their presentation is both exhaustive and compact. [15 April 2016
Energy Technology Data Exchange (ETDEWEB)
Sentman, L.H.; Nayfeh, M.H.
1983-12-01
This research is an integrated theoretical and experimental investigation of the nonlinear interactions which may occur between the chemical kinetics, the fluid dynamics and the unstable resonator of a continuous wave fluid flow laser. The objectives of this grant were to measure the frequency and amplitude of the time dependent pulsations in the power spectral output which have been predicted to occur in cw chemical lasers employing unstable resonators to extract power.
Nonlinear electromagnetic gyrokinetic equation for plasmas with large mean flows
Energy Technology Data Exchange (ETDEWEB)
Sugama, H. [National Inst. for Fusion Science, Toki, Gifu (Japan); Horton, W.
1998-02-01
A new nonlinear electromagnetic gyrokinetic equation is derived for plasmas with large flow velocities on the order of the ion thermal speed. The gyrokinetic equation derived here is given in the form which is valid for general magnetic geometries including the slab, cylindrical and toroidal configurations. The source term for the anomalous viscosity arising through the Reynolds stress is identified in the gyrokinetic equation. For the toroidally rotating plasma, particle, energy and momentum balance equations as well as the detailed definitions of the anomalous transport fluxes and the anomalous entropy production are shown. The quasilinear anomalous transport matrix connecting the conjugate pairs of the anomalous fluxes and the forces satisfies the Onsager symmetry. (author)
Shahmansouri, M.; Misra, A. P.
2016-12-01
The modulational instability (MI) and the evolution of weakly nonlinear two-dimensional (2D) Langmuir wave (LW) packets are studied in an unmagnetized collisionless plasma with weakly relativistic electron flow. By using a 2D self-consistent relativistic fluid model and employing the standard multiple-scale technique, a coupled set of Davey-Stewartson (DS)-like equations is derived, which governs the slow modulation and the evolution of LW packets in relativistic plasmas. It is found that the relativistic effects favor the instability of LW envelopes in the k - θ plane, where k is the wave number and θ ( 0 ≤ θ ≤ π ) the angle of modulation. It is also found that as the electron thermal velocity or θ increases, the growth rate of MI increases with cutoffs at higher wave numbers of modulation. Furthermore, in the nonlinear evolution of the DS-like equations, it is seen that with an effect of the relativistic flow, a Gaussian wave beam collapses in a finite time, and the collapse can be arrested when the effect of the thermal pressure or the relativistic flow is slightly relaxed. The present results may be useful to the MI and the formation of localized LW envelopes in cosmic plasmas with a relativistic flow of electrons.
Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations
Energy Technology Data Exchange (ETDEWEB)
Orain, F.; Bécoulet, M.; Dif-Pradalier, G.; Nardon, E.; Passeron, C.; Latu, G.; Grandgirard, V.; Fil, A.; Ratnani, A. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Huijsmans, G. [ITER Organization, Route de Vinon, F-13115 Saint-Paul-Lez-Durance (France); Pamela, S. [IIFS-PIIM. Aix Marseille Université - CNRS, 13397 Marseille Cedex20 (France); Chapman, I.; Kirk, A.; Thornton, A. [EURATOM/CCFE Fusion Association, Culham Science Centre, Oxon OX14 3DB (United Kingdom); Hoelzl, M. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (Germany); Cahyna, P. [Association EURATOM/IPP.CR, Prague (Czech Republic)
2013-10-15
The interaction of static Resonant Magnetic Perturbations (RMPs) with the plasma flows is modeled in toroidal geometry, using the non-linear resistive MHD code JOREK, which includes the X-point and the scrape-off-layer. Two-fluid diamagnetic effects, the neoclassical poloidal friction and a source of toroidal rotation are introduced in the model to describe realistic plasma flows. RMP penetration is studied taking self-consistently into account the effects of these flows and the radial electric field evolution. JET-like, MAST, and ITER parameters are used in modeling. For JET-like parameters, three regimes of plasma response are found depending on the plasma resistivity and the diamagnetic rotation: at high resistivity and slow rotation, the islands generated by the RMPs at the edge resonant surfaces rotate in the ion diamagnetic direction and their size oscillates. At faster rotation, the generated islands are static and are more screened by the plasma. An intermediate regime with static islands which slightly oscillate is found at lower resistivity. In ITER simulations, the RMPs generate static islands, which forms an ergodic layer at the very edge (ψ≥0.96) characterized by lobe structures near the X-point and results in a small strike point splitting on the divertor targets. In MAST Double Null Divertor geometry, lobes are also found near the X-point and the 3D-deformation of the density and temperature profiles is observed.
Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations
Orain, F.; Bécoulet, M.; Dif-Pradalier, G.; Huijsmans, G.; Pamela, S.; Nardon, E.; Passeron, C.; Latu, G.; Grandgirard, V.; Fil, A.; Ratnani, A.; Chapman, I.; Kirk, A.; Thornton, A.; Hoelzl, M.; Cahyna, P.
2013-10-01
The interaction of static Resonant Magnetic Perturbations (RMPs) with the plasma flows is modeled in toroidal geometry, using the non-linear resistive MHD code JOREK, which includes the X-point and the scrape-off-layer. Two-fluid diamagnetic effects, the neoclassical poloidal friction and a source of toroidal rotation are introduced in the model to describe realistic plasma flows. RMP penetration is studied taking self-consistently into account the effects of these flows and the radial electric field evolution. JET-like, MAST, and ITER parameters are used in modeling. For JET-like parameters, three regimes of plasma response are found depending on the plasma resistivity and the diamagnetic rotation: at high resistivity and slow rotation, the islands generated by the RMPs at the edge resonant surfaces rotate in the ion diamagnetic direction and their size oscillates. At faster rotation, the generated islands are static and are more screened by the plasma. An intermediate regime with static islands which slightly oscillate is found at lower resistivity. In ITER simulations, the RMPs generate static islands, which forms an ergodic layer at the very edge (ψ ≥0.96) characterized by lobe structures near the X-point and results in a small strike point splitting on the divertor targets. In MAST Double Null Divertor geometry, lobes are also found near the X-point and the 3D-deformation of the density and temperature profiles is observed.
DEFF Research Database (Denmark)
Rasmussen, Anders Rønne; Sørensen, Mads Peter; Gaididei, Yuri Borisovich
2010-01-01
A wave equation, that governs finite amplitude acoustic disturbances in a thermoviscous Newtonian fluid, and includes nonlinear terms up to second order, is proposed. The equation preserves the Hamiltonian structure of the fundamental fluid dynamical equations in the non dissipative limit. An exact...
Compound waves in a higher order nonlinear model of thermoviscous fluids
DEFF Research Database (Denmark)
Rønne Rasmussen, Anders; Sørensen, Mads Peter; Gaididei, Yuri B.
2016-01-01
A generalized traveling wave ansatz is used to investigate compound shock waves in a higher order nonlinear model of a thermoviscous fluid. The fluid velocity potential is written as a traveling wave plus a linear function of space and time. The latter offers the possibility of predicting...
Nonlinear Simulation of Plasma Response to the NSTX Error Field
Breslau, J. A.; Park, J. K.; Boozer, A. H.; Park, W.
2008-11-01
In order to better understand the effects of the time-varying error field in NSTX on rotation braking, which impedes RWM stabilization, we model the plasma response to an applied low-n external field perturbation using the resistive MHD model in the M3D code. As an initial benchmark, we apply an m=2, n=1 perturbation to the flux at the boundary of a non-rotating model equilibrium and compare the resulting steady-state island sizes with those predicted by the ideal linear code IPEC. For sufficiently small perturbations, the codes agree; for larger perturbations, the nonlinear correction yields an upper limit on the island width beyond which stochasticity sets in. We also present results of scaling studies showing the effects of finite resistivity on island size in NSTX, and of time-dependent studies of the interaction between these islands and plasma rotation. The M3D-C1 code is also being evaluated as a tool for this analysis; first results will be shown. J.E. Menard, et al., Nucl. Fus. 47, S645 (2007). W. Park, et al., Phys. Plasmas 6, 1796 (1999). J.K. Park, et al., Phys. Plasmas 14, 052110 (2007). S.C. Jardin, et al., J. Comp. Phys. 226, 2146 (2007).
Fluid description of multi-component solar partially ionized plasma
Khomenko, Elena; Diaz, Antonio; Vitas, Nikola
2014-01-01
We derive self-consistent formalism for the description of multi-component partially ionized solar plasma, by means of the coupled equations for the charged and neutral components for an arbitrary number of chemical species, and the radiation field. All approximations and assumptions are carefully considered. Generalized Ohm's law is derived for the single-fluid and two-fluid formalism. Our approach is analytical with some order-of-magnitude support calculations. After general equations are developed we particularize to some frequently considered cases as for the interaction of matter and radiation.
Fluid description of multi-component solar partially ionized plasma
Energy Technology Data Exchange (ETDEWEB)
Khomenko, E., E-mail: khomenko@iac.es; Collados, M.; Vitas, N. [Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife (Spain); Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife (Spain); Díaz, A. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)
2014-09-15
We derive self-consistent formalism for the description of multi-component partially ionized solar plasma, by means of the coupled equations for the charged and neutral components for an arbitrary number of chemical species, and the radiation field. All approximations and assumptions are carefully considered. Generalized Ohm's law is derived for the single-fluid and two-fluid formalism. Our approach is analytical with some order-of-magnitude support calculations. After general equations are developed, we particularize to some frequently considered cases as for the interaction of matter and radiation.
Effects of Plasma Shaping on Nonlinear Gyrokinetic Turbulence
Energy Technology Data Exchange (ETDEWEB)
Belli, E. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Hammett, G. W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Dorland, W. [Univ. of Maryland, College Park, MD (United States)
2008-08-01
The effects of flux surface shape on the gyrokinetic stability and transport of tokamak plasmas are studied using the GS2 code [M. Kotschenreuther, G. Rewoldt, and W.M. Tang, Comput. Phys. Commun. 88, 128 (1995); W. Dorland, F. Jenko, M. Kotschenreuther, and B.N. Rogers, Phys. Rev. Lett. 85, 5579 (2000)]. Studies of the scaling of nonlinear turbulence with shaping parameters are performed using analytic equilibria based on interpolations of representative shapes of the Joint European Torus (JET) [P.H. Rebut and B.E. Keen, Fusion Technol. 11, 13 (1987)]. High shaping is found to be a stabilizing influence on both the linear ion-temperature-gradient (ITG) instability and the nonlinear ITG turbulence. For the parameter regime studied here, a scaling of the heat flux with elongation of χ ~ κ^{-1.5} or κ^{-2.0}, depending on the triangularity, is observed at fixed average temperature gradient. While this is not as strong as empirical elongation scalings, it is also found that high shaping results in a larger Dimits upshift of the nonlinear critical temperature gradient due to an enhancement of the Rosenbluth-Hinton residual zonal flows.
Casson fluid flow and heat transfer over a nonlinearly stretching surface
Institute of Scientific and Technical Information of China (English)
Swati Mukhopadhyay
2013-01-01
A boundary layer analysis is presented for non-Newtonian fluid flow and heat transfer over a nonlinearly stretching surface.The Casson fluid model is used to characterize the non-Newtonian fluid behavior.By using suitable transformations,the governing partial differential equations corresponding to the momentum and energy equations are converted into non-linear ordinary differential equations.Numerical solutions of these equations are obtained with the shooting method.The effect of increasing Casson parameter is to suppress the velocity field.However the temperature is enhanced with the increasing Casson parameter.
Theoretical study of nonlinear waves and shock-like phenomena in hot plasmas
Fried, B. D.; Banos, A., Jr.; Kennel, C. F.
1973-01-01
Summaries are presented of research in basic plasma physics. Nonlinear waves and shock-like phenomena were studied which are pertinent to space physics applications, and include specific problems of magnetospheric and solar wind plasma physics.
Algorithm Development for the Two-Fluid Plasma Model
2009-02-17
of m=0 sausage instabilities in an axisymmetric Z-pinch", Physics of Plasmas 13, 082310 (2006). • A. Hakim and U. Shumlak, "Two-fluid physics and...accurate as the solution variables. The high-order representation of the solution variables satisfies the accuracy requirement to preserve the...here. [2] It also illustrates the dispersive nature of the waves which makes capturing the effect difficult in MHD algorithms. The electromagnetic
A plasma polymerization technique to overcome cerebrospinal fluid shunt infections.
Cökeliler, D; Caner, H; Zemek, J; Choukourov, A; Biederman, H; Mutlu, M
2007-03-01
Prosthetic devices, mainly shunts, are frequently used for temporary or permanent drainage of cerebrospinal fluid. The pathogenesis of shunt infection is a very important problem in modern medicine and generally this is characterized by staphylococcal adhesion to the cerebrospinal fluid shunt surfaces. In this paper, the prevention of the attachment of test microorganism Staphylococcus epidermidis on the cerebrospinal fluid shunt surfaces by 2-hydroxyethylmethacrylate (HEMA) precursor modification in the plasma polymerization system, is reported. Different plasma polymerization conditions (RF discharge power 10-20-30 W, exposure time 5-10-15 min) were employed during the surface modification. The surface chemistry and topology of unmodified and modified shunts was characterized by x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also, static contact angle measurements were performed to state the change of surface hydrophilicity. All samples were tested in vitro with Staphylococcus epidermidis. A plasma-polymerized HEMA film (PP HEMA) was found to be an alternative simple method to decrease the microorganism attachment and create bacterial anti-fouling surfaces. The attachment of the model microorganism Staphylococcus epidermidis on the shunt surface modified by PP HEMA at 20 W and 15 min was reduced 62.3% if compared to the unmodified control surface of the shunt.
A plasma polymerization technique to overcome cerebrospinal fluid shunt infections
Energy Technology Data Exchange (ETDEWEB)
Coekeliler, D [Plasma Aided Bioengineering and Biotechnology Research Laboratory, Engineering Faculty, Hacettepe University, 06532, Ankara (Turkey); Caner, H [Department of Neurosurgery, School of Medicine, Baskent University, 06610, Ankara (Turkey); Zemek, J [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53, Prague, Czech Republic (Czech Republic); Choukourov, A [Department of Macromolecular Physics, Charles University, V Holesovickach 2, 18000 Prague (Czech Republic); Biederman, H [Department of Macromolecular Physics, Charles University, V Holesovickach 2, 18000 Prague (Czech Republic); Mutlu, M [Plasma Aided Bioengineering and Biotechnology Research Laboratory, Engineering Faculty, Hacettepe University, 06532, Ankara (Turkey)
2007-03-01
Prosthetic devices, mainly shunts, are frequently used for temporary or permanent drainage of cerebrospinal fluid. The pathogenesis of shunt infection is a very important problem in modern medicine and generally this is characterized by staphylococcal adhesion to the cerebrospinal fluid shunt surfaces. In this paper, the prevention of the attachment of test microorganism Staphylococcus epidermidis on the cerebrospinal fluid shunt surfaces by 2-hydroxyethylmethacrylate (HEMA) precursor modification in the plasma polymerization system, is reported. Different plasma polymerization conditions (RF discharge power 10-20-30 W, exposure time 5-10-15 min) were employed during the surface modification. The surface chemistry and topology of unmodified and modified shunts was characterized by x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also, static contact angle measurements were performed to state the change of surface hydrophilicity. All samples were tested in vitro with Staphylococcus epidermidis. A plasma-polymerized HEMA film (PP HEMA) was found to be an alternative simple method to decrease the microorganism attachment and create bacterial anti-fouling surfaces. The attachment of the model microorganism Staphylococcus epidermidis on the shunt surface modified by PP HEMA at 20 W and 15 min was reduced 62.3% if compared to the unmodified control surface of the shunt.
Fluid Modes of a Spherically Confined Yukawa Plasma
Kählert, H
2010-01-01
The normal modes of a three-dimensional Yukawa plasma in an isotropic, harmonic confinement are investigated by solving the linearized cold fluid equations. The eigenmodes are found analytically and expressed in terms of hypergeometric functions. It is found that the mode frequencies solely depend on the dimensionless plasma parameter $\\xi=\\kappa R$, where $R$ is the plasma radius and $\\kappa$ the inverse screening length. The eigenfrequencies increase monotonically with $\\xi$ and saturate in the limit $\\xi\\to\\infty$. Compared with the results in the Coulomb limit~[D. H. E. Dubin, Phys. Rev. Lett. \\textbf{66}, 2076 (1991)], we find a new class of modes characterized by the number $n$ which determines the number of radial nodes in the perturbed potential. These modes originate from the degenerate bulk modes of the Coulomb system. Analytical formulas for the eigenfrequencies are derived for limiting cases.
Fluid-plasma interaction in compressible unstable flows
Massa, Luca
2014-11-01
The receptivity of the boundary layer discrete modes to dielectric barrier discharge (DBD) actuation is studied to improve the understanding of the interaction between non-equilibrium plasma and fluid in convectively amplified vortical layers. The momentum transfer induced by a DBD patch at various Reynolds numbers is evaluated using an adaptive mesh refinement computational solver in the Mach number regime 0.8-2.0. The energy of the induced modal perturbation is determined by weighting such a source term with the corresponding adjoint eigenfunctions. Conditions of maximum overlapping between the adjoint and the source term define the regimes of maximum receptivity and the locations of optimal placement of the DBD patch at different Mach and Reynolds numbers. The interaction between non-equilibrium plasma and the jet in cross flow is also being studied to determine the ability of DBD patches to influence mixing in the compressible regime, thus improving flame-holding in plasma assisted ignition and combustion.
Modeling and Optimization of Vehicle Suspension Employing a Nonlinear Fluid Inerter
Directory of Open Access Journals (Sweden)
Yujie Shen
2016-01-01
Full Text Available An ideal inerter has been applied to various vibration engineering fields because of its superior vibration isolation performance. This paper proposes a new type of fluid inerter and analyzes the nonlinearities including friction and nonlinear damping force caused by the viscosity of fluid. The nonlinear model of fluid inerter is demonstrated by the experiments analysis. Furthermore, the full-car dynamic model involving the nonlinear fluid inerter is established. It has been detected that the performance of the vehicle suspension may be influenced by the nonlinearities of inerter. So, parameters of the suspension system including the spring stiffness and the damping coefficient are optimized by means of QGA (quantum genetic algorithm, which combines the genetic algorithm and quantum computing. Results indicate that, compared with the original nonlinear suspension system, the RMS (root-mean-square of vertical body acceleration of optimized suspension has decreased by 9.0%, the RMS of pitch angular acceleration has decreased by 19.9%, and the RMS of roll angular acceleration has decreased by 9.6%.
Shahmansouri, M
2016-01-01
The modulational instability (MI) and the evolution of weakly nonlinear two-dimensional (2D) Langmuir wave (LW) packets are studied in an unmagnetized collisionless plasma with weakly relativistic electron flow. By using a 2D self-consistent relativistic fluid model and employing the standard multiple-scale technique, a coupled set of Davey-Stewartson (DS)-like equations is derived which governs the slow modulation and the evolution of LW packets in relativistic plasmas. It is found that the relativistic effects favor the instability of LW envelopes in the k{\\theta} plane, where k is the wave number and {\\theta} the angle of modulation. It is also found that as the electron thermal velocity or {\\theta} increases, the growth rate of MI increases with cutoffs at higher wave numbers of modulation. Furthermore, in the nonlinear evolution of the DS-like equations, it is seen that with an effect of the relativistic flow, a Gaussian wave beam collapses in a finite time, and the collapse can be arrested when the effe...
Moment fluid equations for ions in weakly-ionized plasma
Semenov, I L
2016-01-01
A new one-dimensional fluid model for ions in weakly-ionized plasma is proposed. The model differs from the existing ones in two aspects. First, a more accurate approximation of the collision terms in the fluid equations is suggested. For this purpose, the results obtained using the Monte-Carlo kinetic model of the ion swarm experiments are considered. Second, the ion energy equation is taken into account. The fluid equations are closed using a simple model of the ion velocity distribution function. The accuracy of the fluid model is examined by comparing with the results of particle-in-cell/Monte Carlo simulations. In particular, several test problems are considered using a parallel plate model of the capacitively coupled radio-frequency discharge. It is shown that the results obtained using the proposed fluid model are in good agreement with those obtained from the simulations over a wide range of discharge conditions. An approximation of the ion velocity distribution function for the problem under consider...
Saha, Asit
2017-03-01
Positron acoustic shock waves (PASHWs) in unmagnetized electron-positron-ion (e-p-i) plasmas consisting of mobile cold positrons, immobile positive ions, q-nonextensive distributed electrons, and hot positrons are studied. The cold positron kinematic viscosity is considered and the reductive perturbation technique is used to derive the Burgers equation. Applying traveling wave transformation, the Burgers equation is transformed to a one dimensional dynamical system. All possible vector fields corresponding to the dynamical system are presented. We have analyzed the dynamical system with the help of potential energy, which helps to identify the stability and instability of the equilibrium points. It is found that the viscous force acting on cold mobile positron fluid is a source of dissipation and is responsible for the formation of the PASHWs. Furthermore, fully nonlinear arbitrary amplitude positron acoustic waves are also studied applying the theory of planar dynamical systems. It is also observed that the fundamental features of the small amplitude and arbitrary amplitude PASHWs are significantly affected by the effect of the physical parameters q e , q h , μ e , μ h , σ , η , and U. This work can be useful to understand the qualitative changes in the dynamics of nonlinear small amplitude and fully nonlinear arbitrary amplitude PASHWs in solar wind, ionosphere, lower part of magnetosphere, and auroral acceleration regions.
Nonlinear effects in the bounded dust-vortex flow in plasma
Laishram, Modhuchandra; Sharma, Devendra; Chattopdhyay, Prabal K.; Kaw, Predhiman K.
2017-03-01
The vortex structures in a cloud of electrically suspended dust in a streaming plasma constitutes a driven system with a rich nonlinear flow regime. Experimentally recovered toroidal formations of this system have motivated study of its volumetrically driven-dissipative vortex flow dynamics using two-dimensional hydrodynamics in the incompressible Navier-Stokes regime. Nonlinear equilibrium solutions are obtained for this system where a nonuniformly driven two-dimensional dust flow exhibits distinct regions of localized accelerations and strong friction caused by stationary fluids at the confining boundaries resisting the dust flow. In agreement with observations in experiments, it is demonstrated that the nonlinear effects appear in the limit of small viscosity, where the primary vortices form scaling with the most dominant spatial scales of the domain topology and develop separated virtual boundaries along their periphery. This separation is triggered beyond a critical dust viscosity that signifies a structural bifurcation. Emergence of uniform vorticity core and secondary vortices with a newer level of identical dynamics highlights the applicability of the studied dynamics to gigantic vortex flows, such as the Jovian great red spot, to microscopic biophysical intracellular activity.
Homogenization of a Class of Nonlinear Variational Inequalities with Applications in Fluid Film Flow
Institute of Scientific and Technical Information of China (English)
Dag LUKKASSEN; Annette MEIDELL; Peter WALL
2011-01-01
The authors consider the homogenization of a class of nonlinear variational inequalities, which include rapid oscillations with respect to a parameter. The homogenization of the corresponding class of differential equations is also studied. The results are applied to some models for the pressure in a thin fluid film fluid between two surfaces which are in relative motion. This is an important problem in the lubrication theory. In particular, the analysis includes the effects of surface roughness on both faces and the phenomenon of cavitation. Moreover, the fluid can be modeled as Newtonian or non-Newtonian by using a Rabinowitsch fluid model.
Two-fluid sub-grid-scale viscosity in nonlinear simulation of ballooning modes in a heliotron device
Miura, H.; Hamba, F.; Ito, A.
2017-07-01
A large eddy simulation (LES) approach is introduced to enable the study of the nonlinear growth of ballooning modes in a heliotron-type device, by solving fully 3D two-fluid magnetohydrodynamic (MHD) equations numerically over a wide range of parameter space, keeping computational costs as low as possible. A model to substitute the influence of scales smaller than the grid size, at sub-grid scale (SGS), and at the scales larger than it—grid scale (GS)—has been developed for LES. The LESs of two-fluid MHD equations with SGS models have successfully reproduced the growth of the ballooning modes in the GS and nonlinear saturation. The numerical results show the importance of SGS effects on the GS components, or the effects of turbulent fluctuation at small scales in low-wavenumber unstable modes, over the course of the nonlinear saturation process. The results also show the usefulness of the LES approach in studying instability in a heliotron device. It is shown through a parameter survey over many SGS model coefficients that turbulent small-scale components in experiments can contribute to keeping the plasma core pressure from totally collapsing.
Instability and dynamics of two nonlinearly coupled laser beams in a plasma
Shukla, P K; Marklund, M; Stenflo, L; Kourakis, I; Parviainen, M; Dieckmann, M E
2006-01-01
We investigate the nonlinear interaction between two laser beams in a plasma in the weakly nonlinear and relativistic regime. The evolution of the laser beams is governed by two nonlinear Schroedinger equations that are coupled with the slow plasma density response. We study the growth rates of the Raman forward and backward scattering instabilities as well of the Brillouin and self-focusing/modulational instabilities. The nonlinear evolution of the instabilities is investigated by means of direct simulations of the time-dependent system of nonlinear equations.
Nonlinear evolution of tidally forced inertial waves in rotating fluid bodies
Favier, B; Baruteau, C; Ogilvie, G I
2014-01-01
We perform one of the first studies into the nonlinear evolution of tidally excited inertial waves in a uniformly rotating fluid body, exploring a simplified model of the fluid envelope of a planet (or the convective envelope of a solar-type star) subject to the gravitational tidal perturbations of an orbiting companion. Our model contains a perfectly rigid spherical core, which is surrounded by an envelope of incompressible uniform density fluid. The corresponding linear problem was studied in previous papers which this work extends into the nonlinear regime, at moderate Ekman numbers (the ratio of viscous to Coriolis accelerations). By performing high-resolution numerical simulations, using a combination of pseudo-spectral and spectral element methods, we investigate the effects of nonlinearities, which lead to time-dependence of the flow and the corresponding dissipation rate. Angular momentum is deposited non-uniformly, leading to the generation of significant differential rotation in the initially unifor...
Plasma interfacial mixing layers: Comparisons of fluid and kinetic models
Vold, Erik; Yin, Lin; Taitano, William; Albright, B. J.; Chacon, Luis; Simakov, Andrei; Molvig, Kim
2016-10-01
We examine plasma transport across an initial discontinuity between two species by comparing fluid and kinetic models. The fluid model employs a kinetic theory approximation for plasma transport in the limit of small Knudsen number. The kinetic simulations include explicit particle-in-cell simulations (VPIC) and a new implicit Vlasov-Fokker-Planck code, iFP. The two kinetic methods are shown to be in close agreement for many aspects of the mixing dynamics at early times (to several hundred collision times). The fluid model captures some of the earliest time dynamic behavior seen in the kinetic results, and also generally agrees with iFP at late times when the total pressure gradient relaxes and the species transport is dominated by slow diffusive processes. The results show three distinct phases of the mixing: a pressure discontinuity forms across the initial interface (on times of a few collisions), the pressure perturbations propagate away from the interfacial mixing region (on time scales of an acoustic transit) and at late times the pressure relaxes in the mix region leaving a non-zero center of mass flow velocity. The center of mass velocity associated with the outward propagating pressure waves is required to conserve momentum in the rest frame. Work performed under the auspices of the U.S. DOE by the LANS, LLC, Los Alamos National Laboratory under Contract No. DE-AC52-06NA25396. Funding provided by the Advanced Simulation and Computing (ASC) Program.
Nonlinear waves in electron–positron–ion plasmas including charge separation
Indian Academy of Sciences (India)
A MUGEMANA; S MOOLLA; I J LAZARUS
2017-02-01
Nonlinear low-frequency electrostatic waves in a magnetized, three-component plasma consisting of hot electrons, hot positrons and warm ions have been investigated. The electrons and positrons are assumed to have Boltzmann density distributions while the motion of the ions are governed by fluid equations. The system is closed with the Poisson equation. This set of equations is numerically solved for the electric field. The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are sinusoidal, sawtooth andspiky. The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E0 was reduced. The results are compared with satellite observations.
Stretch flow of confined non-Newtonian fluids: nonlinear fingering dynamics.
Brandão, Rodolfo; Fontana, João V; Miranda, José A
2013-12-01
We employ a weakly nonlinear perturbative scheme to investigate the stretch flow of a non-Newtonian fluid confined in Hele-Shaw cell for which the upper plate is lifted. A generalized Darcy's law is utilized to model interfacial fingering formation in both the weak shear-thinning and weak shear-thickening limits. Within this context, we analyze how the interfacial finger shapes and the nonlinear competition dynamics among fingers are affected by the non-Newtonian nature of the stretched fluid.
Energy Technology Data Exchange (ETDEWEB)
Kok Yan Chan, G.; Sclavounos, P. D.; Jonkman, J.; Hayman, G.
2015-04-02
A hydrodynamics computer module was developed for the evaluation of the linear and nonlinear loads on floating wind turbines using a new fluid-impulse formulation for coupling with the FAST program. The recently developed formulation allows the computation of linear and nonlinear loads on floating bodies in the time domain and avoids the computationally intensive evaluation of temporal and nonlinear free-surface problems and efficient methods are derived for its computation. The body instantaneous wetted surface is approximated by a panel mesh and the discretization of the free surface is circumvented by using the Green function. The evaluation of the nonlinear loads is based on explicit expressions derived by the fluid-impulse theory, which can be computed efficiently. Computations are presented of the linear and nonlinear loads on the MIT/NREL tension-leg platform. Comparisons were carried out with frequency-domain linear and second-order methods. Emphasis was placed on modeling accuracy of the magnitude of nonlinear low- and high-frequency wave loads in a sea state. Although fluid-impulse theory is applied to floating wind turbines in this paper, the theory is applicable to other offshore platforms as well.
Fully non-linear cosmological perturbations of multicomponent fluid and field systems
Hwang, Jai-chan; Noh, Hyerim; Park, Chan-Gyung
2016-09-01
We present fully non-linear and exact cosmological perturbation equations in the presence of multiple components of fluids and minimally coupled scalar fields. We ignore the tensor-type perturbation. The equations are presented without taking the temporal gauge condition in the Friedmann background with general curvature and the cosmological constant. We include the anisotropic stress. Even in the absence of anisotropic stress of individual component, the multiple component nature introduces the anisotropic stress in the collective fluid quantities. We prove the Newtonian limit of multiple fluids in the zero-shear gauge and the uniform-expansion gauge conditions, present the Newtonian hydrodynamic equations in the presence of general relativistic pressure in the zero-shear gauge, and present the fully non-linear equations and the third-order perturbation equations of the non-relativistic pressure fluids in the CDM-comoving gauge.
Role of Density Profiles for the Nonlinear Propagation of Intense Laser Beam through Plasma Channel
Sonu Sen; Meenu Asthana Varshney; Dinesh Varshney
2014-01-01
In this work role of density profiles for the nonlinear propagation of intense laser beam through plasma channel is analyzed. By employing the expression for the dielectric function of different density profile plasma, a differential equation for beamwidth parameter is derived under WKB and paraxial approximation. The laser induces modifications of the dielectric function through nonlinearities. It is found that density profiles play vital role in laser-plasma interaction studies. To have num...
Massimo, F.; Atzeni, S.; Marocchino, A.
2016-12-01
Architect, a time explicit hybrid code designed to perform quick simulations for electron driven plasma wakefield acceleration, is described. In order to obtain beam quality acceptable for applications, control of the beam-plasma-dynamics is necessary. Particle in Cell (PIC) codes represent the state-of-the-art technique to investigate the underlying physics and possible experimental scenarios; however PIC codes demand the necessity of heavy computational resources. Architect code substantially reduces the need for computational resources by using a hybrid approach: relativistic electron bunches are treated kinetically as in a PIC code and the background plasma as a fluid. Cylindrical symmetry is assumed for the solution of the electromagnetic fields and fluid equations. In this paper both the underlying algorithms as well as a comparison with a fully three dimensional particle in cell code are reported. The comparison highlights the good agreement between the two models up to the weakly non-linear regimes. In highly non-linear regimes the two models only disagree in a localized region, where the plasma electrons expelled by the bunch close up at the end of the first plasma oscillation.
Application of optimal homotopy asymptotic method to nonlinear Bingham fluid dampers
Marinca, Vasile; Bereteu, Liviu
2015-01-01
Magnetorheological fluids (MR) are stable suspensions of magnetizable microparticles, characterized by the property to change the rheological characteristics when subjected to the action of magnetic field. Together with another class of materials that change their rheological characteristics in the presence of an electric field, called electrorheological materials are known in the literature as the smart materials or controlled materials. In the absence of a magnetic field the particles in MR fluid are dispersed in the base fluid and its flow through the apertures is behaves as a Newtonian fluid having a constant shear stress. When the magnetic field is applying a MR fluid behavior change, and behaves like a Bingham fluid with a variable shear stress. Dynamic response time is an important characteristic for determining the performance of MR dampers in practical civil engineering applications. The purpose of this paper is to show how to use the Optimal Homotopy Asymptotic Method (OHAM) to solve the nonlinear d...
Colombeau, J. F.
2007-01-01
We present numerical techniques based on generalized functions adapted to nonlinear calculations. They concern main numerical engineering problems ruled by-or issued from-nonlinear equations of continuum mechanics. The aim of this text is to invite the readers in applying these techniques in their own work without significant prerequisites by presenting their use on a sample of elementary applications from engineering. Pure mathematicians can read it easily since the numerical techniques are ...
Vitamin B6 in plasma and cerebrospinal fluid of children.
Directory of Open Access Journals (Sweden)
Monique Albersen
Full Text Available Over the past years, the essential role of vitamin B6 in brain development and functioning has been recognized and genetic metabolic disorders resulting in functional vitamin B6 deficiency have been identified. However, data on B6 vitamers in children are scarce.B6 vitamer concentrations in simultaneously sampled plasma and cerebrospinal fluid (CSF of 70 children with intellectual disability were determined by ultra performance liquid chromatography-tandem mass spectrometry. For ethical reasons, CSF samples could not be obtained from healthy children. The influence of sex, age, epilepsy and treatment with anti-epileptic drugs, were investigated.The B6 vitamer composition of plasma (pyridoxal phosphate (PLP > pyridoxic acid > pyridoxal (PL differed from that of CSF (PL > PLP > pyridoxic acid > pyridoxamine. Strong correlations were found for B6 vitamers in and between plasma and CSF. Treatment with anti-epileptic drugs resulted in decreased concentrations of PL and PLP in CSF.We provide concentrations of all B6 vitamers in plasma and CSF of children with intellectual disability (±epilepsy, which can be used in the investigation of known and novel disorders associated with vitamin B6 metabolism as well as in monitoring of the biochemical effects of treatment with vitamin B6.
Nonlinear wave breaking in self-gravitating viscoelastic quantum fluid
Energy Technology Data Exchange (ETDEWEB)
Mitra, Aniruddha, E-mail: anibabun@gmail.com [Center for Plasma Studies, Department of Instrumentation Science, Jadavpur University, Kolkata, 700 032 (India); Roychoudhury, Rajkumar, E-mail: rajdaju@rediffmail.com [Advanced Centre for Nonlinear and Complex Phenomena, 1175 Survey Park, Kolkata 700075 (India); Department of Mathematics, Bethune College, Kolkata 700006 (India); Bhar, Radhaballav [Center for Plasma Studies, Department of Instrumentation Science, Jadavpur University, Kolkata, 700 032 (India); Khan, Manoranjan, E-mail: mkhan.ju@gmail.com [Center for Plasma Studies, Department of Instrumentation Science, Jadavpur University, Kolkata, 700 032 (India)
2017-02-12
The stability of a viscoelastic self-gravitating quantum fluid has been studied. Symmetry breaking instability of solitary wave has been observed through ‘viscosity modified Ostrovsky equation’ in weak gravity limit. In presence of strong gravitational field, the solitary wave breaks into shock waves. Response to a Gaussian perturbation, the system produces quasi-periodic short waves, which in terns predicts the existence of gravito-acoustic quasi-periodic short waves in lower solar corona region. Stability analysis of this dynamical system predicts gravity has the most prominent effect on the phase portraits, therefore, on the stability of the system. The non-existence of chaotic solution has also been observed at long wavelength perturbation through index value theorem. - Highlights: • In weak gravitational field, viscoelastic quantum fluid exhibits symmetry breaking instability. • Gaussian perturbation produces quasi-periodic gravito-acoustic waves into the system. • There exists no chaotic state of the system against long wavelength perturbations.
Klimachkov, D. A.; Petrosyan, A. S.
2016-09-01
Shallow water magnetohydrodynamic (MHD) theory describing incompressible flows of plasma is generalized to the case of compressible flows. A system of MHD equations is obtained that describes the flow of a thin layer of compressible rotating plasma in a gravitational field in the shallow water approximation. The system of quasilinear hyperbolic equations obtained admits a complete simple wave analysis and a solution to the initial discontinuity decay problem in the simplest version of nonrotating flows. In the new equations, sound waves are filtered out, and the dependence of density on pressure on large scales is taken into account that describes static compressibility phenomena. In the equations obtained, the mass conservation law is formulated for a variable that nontrivially depends on the shape of the lower boundary, the characteristic vertical scale of the flow, and the scale of heights at which the variation of density becomes significant. A simple wave theory is developed for the system of equations obtained. All self-similar discontinuous solutions and all continuous centered self-similar solutions of the system are obtained. The initial discontinuity decay problem is solved explicitly for compressible MHD equations in the shallow water approximation. It is shown that there exist five different configurations that provide a solution to the initial discontinuity decay problem. For each configuration, conditions are found that are necessary and sufficient for its implementation. Differences between incompressible and compressible cases are analyzed. In spite of the formal similarity between the solutions in the classical case of MHD flows of an incompressible and compressible fluids, the nonlinear dynamics described by the solutions are essentially different due to the difference in the expressions for the squared propagation velocity of weak perturbations. In addition, the solutions obtained describe new physical phenomena related to the dependence of the
Rosin, M S; Rincon, F; Cowley, S C
2010-01-01
Plasmas have a natural tendency to develop pressure anisotropies with respect to the local direction of the magnetic field. These anisotropies trigger plasma instabilities at scales just above the ion Larmor radius with growth rates of a fraction of the ion cyclotron frequency - much faster than either the global dynamics or local turbulence. The instabilities can dramatically modify the macroscopic dynamics of the plasma. Nonlinear evolution of these instabilities is expected to drive pressure anisotropies towards marginal stability values, controlled by the plasma beta. This nonlinear evolution is worked out in an ab initio kinetic calculation for the simplest analytically tractable example - the parallel firehose instability in a high-beta plasma. A closed nonlinear equation for the firehose turbulence is derived and solved. In the nonlinear regime, the instability leads to secular (~t) growth of magnetic fluctuations. The fluctuations develop a k^{-3} spectrum, extending from scales somewhat larger than r...
Asymptotic Analysis to Two Nonlinear Equations in Fluid Mechanics by Homotopy Renormalisation Method
Guan, Jiang; Kai, Yue
2016-09-01
By the homotopy renormalisation method, the global approximate solutions to Falkner-Skan equation and Von Kármá's problem of a rotating disk in an infinite viscous fluid are obtained. The homotopy renormalisation method is simple and powerful for finding global approximate solutions to nonlinear perturbed differential equations arising in mathematical physics.
AMABILI, M.; PELLICANO, F.; PAÏDOUSSIS, M. P.
1999-08-01
The study presented is an investigation of the non-linear dynamics and stability of simply supported, circular cylindrical shells containing inviscid incompressible fluid flow. Non-linearities due to large-amplitude shell motion are considered by using the non-linear Donnell's shallow shell theory, with account taken of the effect of viscous structural damping. Linear potential flow theory is applied to describe the fluid-structure interaction. The system is discretiszd by Galerkin's method, and is investigated by using a model involving seven degrees of freedom, allowing for travelling wave response of the shell and shell axisymmetric contraction. Two different boundary conditions are applied to the fluid flow beyond the shell, corresponding to: (i) infinite baffles (rigid extensions of the shell), and (ii) connection with a flexible wall of infinite extent in the longitudinal direction, permitting solution by separation of variables; they give two different kinds of dynamical behaviour of the system, as a consequence of the fact that axisymmetric contraction, responsible for the softening non-linear dynamical behaviour of shells, is not allowed if the fluid flow beyond the shell is constrained by rigid baffles. Results show that the system loses stability by divergence.
Nonlinear low-frequency electrostatic wave dynamics in a two-dimensional quantum plasma
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Samiran, E-mail: sran_g@yahoo.com [Department of Applied Mathematics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009 (India); Chakrabarti, Nikhil, E-mail: nikhil.chakrabarti@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700064 (India)
2016-08-15
The problem of two-dimensional arbitrary amplitude low-frequency electrostatic oscillation in a quasi-neutral quantum plasma is solved exactly by elementary means. In such quantum plasmas we have treated electrons quantum mechanically and ions classically. The exact analytical solution of the nonlinear system exhibits the formation of dark and black solitons. Numerical simulation also predicts the possible periodic solution of the nonlinear system. Nonlinear analysis reveals that the system does have a bifurcation at a critical Mach number that depends on the angle of propagation of the wave. The small-amplitude limit leads to the formation of weakly nonlinear Kadomstev–Petviashvili solitons.
Nonlinear nonlocal vibration of embedded DWCNT conveying fluid using shell model
Energy Technology Data Exchange (ETDEWEB)
Ghorbanpour Arani, A., E-mail: aghorban@kashanu.ac.ir [Faculty of Mechanical Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Zarei, M.Sh.; Amir, S.; Khoddami Maraghi, Z. [Faculty of Mechanical Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)
2013-02-01
In this work nonlinear vibration of double-walled carbon nanotube (DWCNT) embedded in an elastic medium and subjected to an axial fluid flow (incompressible and non-viscose) is investigated. The elastic medium is simulated using Pasternak foundation in which adjacent layer interactions are assumed to have been coupled by van der Waals (VdW) force. The higher-order equation of motion is derived using Hamilton's principle and nonlocal-nonlinear shell theory. Galerkin and averaging methods are adopted to solve the higher-order governing equations. Elastic medium, small scale parameter, velocity and fluid density are taken into account to calculate the effects of axial and circumferential wave numbers in this study. Results reveal that increasing circumferential wave number, leads to enhanced nonlinearity. Critical flow velocities of DWCNT are inversely related to the non-local parameter (e{sub 0}a), so that increase in the later lead to reduced critical flow velocities.
Nonlinear Acoustics and Shock Formation in Lossless Barotropic Green--Naghdi Fluids
Christov, Ivan C
2016-01-01
The equations of motion of lossless compressible nonclassical fluids under the so-called Green--Naghdi theory are considered for two classes of barotropic fluids: (\\textit{i}) perfect gases and (\\textit{ii}) liquids obeying a quadratic equation of state. An exact reduction in terms of a scalar acoustic potential and the (scalar) thermal displacement is achieved. Properties and simplifications of these model nonlinear acoustic equations for unidirectional flows are noted. Specifically, the requirement that the governing system of equations for such flows remain hyperbolic is shown to lead to restrictions on the physical parameters and/or applicability of the model. A weakly nonlinear model is proposed on the basis of neglecting only terms proportional to the square of the Mach number in the governing equations, without any further approximation or modification of the nonlinear terms. Shock formation via acceleration wave blowup is studied numerically in a one-dimensional context using a high-resolution Godunov...
Flow-Induced Vibration of A Nonlinearly Restrained Curved Pipe Conveying Fluid
Institute of Scientific and Technical Information of China (English)
王琳; 倪樵; 黄玉盈
2004-01-01
Investigated in this study is the flow-induced vibration of a nonlinearly restrained curved pipe conveying fluid. The nonlinear equation of motion is derived by equilibrium of forces on microelement of the system under consideration. The spatial coordinate of the system is discretized by DQM (differential quadrature method). On the basis of the boundary conditions, the dynamic equation is solved by the Newton-Raphson iteration method. The numerical solutions reveal several complex dynamic motions for the variation of the fluid velocity parameter, such as limit cycle motion, buckling and so on. The result obtained also shows that the sub parameter regions corresponding to the several motions may change with the variation of some parameters of the curved pipe. The present study supplies a new reference for investigating the nonlinear dynamic response of some other structures.
NONLINEAR FLUID DAMPING IN STRUCTURE-WAKE OSCILLATORS IN MODELING VORTEX-INDUCED VIBRATIONS
Institute of Scientific and Technical Information of China (English)
LIN Li-ming; LING Guo-can; WU Ying-xiang; ZENG Xiao-hui
2009-01-01
A Nonlinear Fluid Damping(NFD)in the form of the square-velocity is applied in the response analysis of Vortex-Induced Vibrations(VIV).Its nonlinear hydrodynamic effects on the coupled wake and structure oscillators are investigated.A comparison between the coupled systems with the linear and nonlinear fluid dampings and experiments shows that the NFD model can well describe response characteristics,such as the amplification of body displacement at lock-in and frequency lock-in,both at high and low mass ratios.Particularly,the predicted peak amplitude of the body in the Griffin plot is in good agreement with experimental data and empirical equation,indicating the significant effect of the NFD on the structure motion.
Boundary layer flow and heat transfer to Carreau fluid over a nonlinear stretching sheet
Directory of Open Access Journals (Sweden)
Masood Khan
2015-10-01
Full Text Available This article studies the Carreau viscosity model (which is a generalized Newtonian model and then use it to obtain a formulation for the boundary layer equations of the Carreau fluid. The boundary layer flow and heat transfer to a Carreau model over a nonlinear stretching surface is discussed. The Carreau model, adequate for many non-Newtonian fluids, is used to characterize the behavior of the fluids having shear thinning properties and fluids with shear thickening properties for numerical values of the power law exponent n. The modeled boundary layer conservation equations are converted to non-linear coupled ordinary differential equations by a suitable transformation. Numerical solution of the resulting equations are obtained by using the Runge-Kutta Fehlberg method along with shooting technique. This analysis reveals many important physical aspects of flow and heat transfer. Computations are performed for different values of the stretching parameter (m, the Weissenberg number (We and the Prandtl number (Pr. The obtained results show that for shear thinning fluid the fluid velocity is depressed by the Weissenberg number while opposite behavior for the shear thickening fluid is observed. A comparison with previously published data in limiting cases is performed and they are in excellent agreement.
Nonlinear Characteristics of an Intense Laser Pulse Propagating in Partially Stripped Plasmas
Institute of Scientific and Technical Information of China (English)
HU Qiang-Lin; LIU Shi-Bing; CHEN Tao; JIANG Yi-Jian
2005-01-01
The nonlinear optic characteristics of an intense laser pulse propagating in partially stripped plasmas are investigated analytically. The phase and group velocity of the laser pulse propagation as well as the three general expressions governing the nonlinear optic behavior, based on the photon number conservation, are obtained by considering the partially stripped plasma as a nonlinear optic medium. The numerical result shows that the presence of the bound electrons in partially stripped plasma can significantly change the propagating property of the intense laser pulse.
Rognlien, Thomas; Rensink, Marvin
2016-10-01
Transport simulations for the edge plasma of tokamaks and other magnetic fusion devices requires the coupling of plasma and recycling or injected neutral gas. There are various neutral models used for this purpose, e.g., atomic fluid model, a Monte Carlo particle models, transition/escape probability methods, and semi-analytic models. While the Monte Carlo method is generally viewed as the most accurate, it is time consuming, which becomes even more demanding for device simulations of high densities and size typical of fusion power plants because the neutral collisional mean-free path becomes very small. Here we examine the behavior of an extended fluid neutral model for hydrogen that includes both atoms and molecules, which easily includes nonlinear neutral-neutral collision effects. In addition to the strong charge-exchange between hydrogen atoms and ions, elastic scattering is included among all species. Comparisons are made with the DEGAS 2 Monte Carlo code. Work performed for U.S. DoE by LLNL under Contract DE-AC52-07NA27344.
The Blended Finite Element Method for Multi-fluid Plasma Modeling
2016-07-01
Briefing Charts 3. DATES COVERED (From - To) 07 June 2016 - 01 July 2016 4. TITLE AND SUBTITLE The Blended Finite Element Method for Multi-fluid Plasma ...BLENDED FINITE ELEMENT METHOD FOR MULTI-FLUID PLASMA MODELING Éder M. Sousa1, Uri Shumlak2 1ERC INC., IN-SPACE PROPULSION BRANCH (RQRS) AIR FORCE RESEARCH...MULTI-FLUID PLASMA MODEL 2 BLENDED FINITE ELEMENT METHOD Blended Finite Element Method Nodal Continuous Galerkin Modal Discontinuous Galerkin Model
Application of nonlinear methods to the study of ionospheric plasma
Chernyshov, A. A.; Mogilevsky, M. M.; Kozelov, B. V.
2015-01-01
Most of the processes taking place in the auroral region of Earth's ionosphere are reflected in a variety of dynamic forms of the aurora borealis. In order to study these processes it is necessary to consider temporary and spatial variations of the characteristics of ionospheric plasma. Most traditional methods of classical physics are applicable mainly for stationary or quasi-stationary phenomena, but dynamic regimes, transients, fluctuations, selfsimilar scaling could be considered using the methods of nonlinear dynamics. Special interest is the development of the methods for describing the spatial structure and the temporal dynamics of auroral ionosphere based on the ideas of percolation theory and fractal geometry. The fractal characteristics (the Hausdorff fractal dimension and the index of connectivity) of Hall and Pedersen conductivities are used to the description of fractal patterns in the ionosphere. To obtain the self-consistent estimates of the parameters the Hausdorff fractal dimension and the index of connectivity in the auroral zone, an additional relation describing universal behavior of the fractal geometry of percolation at the critical threshold is applied. Also, it is shown that Tsallis statistics can be used to study auroral ionosphere
Nonlinear associations between plasma cholesterol levels and neuropsychological function.
Wendell, Carrington R; Zonderman, Alan B; Katzel, Leslie I; Rosenberger, William F; Plamadeala, Victoria V; Hosey, Megan M; Waldstein, Shari R
2016-11-01
Although both high and low levels of total and low-density lipoprotein (LDL) cholesterol have been associated with poor neuropsychological function, little research has examined nonlinear effects. We examined quadratic relations of cholesterol to performance on a comprehensive neuropsychological battery. Participants were 190 older adults (53% men, ages 54-83) free of major medical, neurologic, and psychiatric disease. Measures of fasting plasma total and high-density lipoprotein (HDL) cholesterol were assayed, and LDL cholesterol was calculated. Participants completed neuropsychological measures of attention, executive function, memory, visuospatial judgment, and manual speed and dexterity. Multiple regression analyses examined cholesterol levels as quadratic predictors of each measure of cognitive performance, with age (dichotomized as quadratic effect of Total Cholesterol² × Age was identified for Logical Memory II (b = -.0013, p = .039), such that the 70+ group performed best at high and low levels of total cholesterol than at midrange total cholesterol (U-shaped) and the Quadratic associations between HDL cholesterol and cognitive performance were nonsignificant. Results indicate differential associations between cholesterol and neuropsychological function across different ages and domains of function. High and low total and LDL cholesterol may confer both risk and benefit for suboptimal cognitive function at different ages. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
Soliton solutions for a variable-coefficient Korteweg-de Vries equation in fluids and plasmas
Jiang, Yan; Tian, Bo; Liu, Wen-Jun; Sun, Kun; Qu, Qi-Xing
2010-11-01
In this paper, we investigate a variable-coefficient Korteweg-de Vries (vc-KdV) equation, which can be used to describe the propagation of nonlinear waves in fluids, plasmas and other fields. Through the rational transformation and Hirota method, new soliton solutions to the vc-KdV equation are derived. On the basis of those soliton solutions, three types of collisions are obtained: overtaking collision between two unidirectional solitons, head-on collision between two bidirectional ones and collision between moving and stationary solitons. These collisions are proved to be elastic through asymptotic analysis, and figures are plotted which show that they are indeed elastic except for a phase shift.
The global nonlinear stability of self-gravitating irrotational Chaplygin fluids in a FRW geometry
LeFloch, Philippe G
2015-01-01
We analyze the global nonlinear stability of FRW (Friedmann-Robertson-Walker) spacetimes in presence of an irrotational perfect fluid. We assume that the fluid is governed by the so-called (generalized) Chaplygin equation of state relating the pressure to the mass-energy density. We express the Einstein equations in wave gauge as a systems of coupled nonlinear wave equations and by performing a suitable conformal transformation, we are able to analyze the global behavior of solutions in future timelike directions. We establish that the (3+1)-spacetime metric and the mass density and velocity vector describing the evolution of the fluid remain globally close to a reference FRW solution, under small initial data perturbations. Our analysis provides also the precise asymptotic behavior of the perturbed solutions in the future directions.
BOUT++: a framework for parallel plasma fluid simulations
Dudson, B D; Xu, X Q; Snyder, P B; Wilson, H R
2008-01-01
A new modular code called BOUT++ is presented, which simulates 3D fluid equations in curvilinear coordinates. Although aimed at simulating Edge Localised Modes (ELMs) in tokamak X-point geometry, the code is able to simulate a wide range of fluid models (magnetised and unmagnetised) involving an arbitrary number of scalar and vector fields, in a wide range of geometries. Time evolution is fully implicit, and 3rd-order WENO schemes are implemented. Benchmarks are presented for linear and non-linear problems (the Orszag-Tang vortex) showing good agreement. Performance of the code is tested by scaling with problem size and processor number, showing efficient scaling to thousands of processors. Linear initial-value simulations of ELMs using reduced ideal MHD are presented, and the results compared to the ELITE linear MHD eigenvalue code. The resulting mode-structures and growth-rate are found to be in good agreement (BOUT++ = 0.245, ELITE = 0.239). To our knowledge, this is the first time dissipationless, initial...
Nonlinear wave breaking in self-gravitating viscoelastic quantum fluid
Mitra, Aniruddha; Roychoudhury, Rajkumar; Bhar, Radhaballav; Khan, Manoranjan
2017-02-01
The stability of a viscoelastic self-gravitating quantum fluid has been studied. Symmetry breaking instability of solitary wave has been observed through 'viscosity modified Ostrovsky equation' in weak gravity limit. In presence of strong gravitational field, the solitary wave breaks into shock waves. Response to a Gaussian perturbation, the system produces quasi-periodic short waves, which in terns predicts the existence of gravito-acoustic quasi-periodic short waves in lower solar corona region. Stability analysis of this dynamical system predicts gravity has the most prominent effect on the phase portraits, therefore, on the stability of the system. The non-existence of chaotic solution has also been observed at long wavelength perturbation through index value theorem.
Tsurutani, Bruce T.
1995-01-01
As the lead-off presentation for the topic of nonlinear waves and their evolution, we will illustrate some prominent examples of waves in space plasmas. We will describe recent observations detected within planetary foreshocks, near comets and in interplanetary space. It is believed that the nonlinear LF plasma wave features discussed here are part of and may be basic to the development of plasma turbulence. In this sense, this is one area of space plasma physics that is fundamental, with applications to fusion physics and astrophysics as well. It is hoped that the reader(s) will be stimulated to study nonlinear wave development themselves, if he/she is not already involved.
Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse
Energy Technology Data Exchange (ETDEWEB)
Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)
2017-03-15
Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron–ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.
Linear vs. nonlinear acceleration in plasma turbulence. I. Global versus local measures
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Sanjoy [Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723 (United States); Parashar, Tulasi N. [University of Delaware, Newark, Delaware 19716 (United States)
2015-04-15
Magnetized turbulent plasmas are generally characterized as strongly or weakly turbulent based on the average relative strengths of the linear and nonlinear terms. While this description is useful, it does not represent the full picture and can be misleading. We study the variation of linear and nonlinear accelerations in the Fourier space of a magnetohydrodynamic system with a mean magnetic field and broad selection of initial states and plasma parameters. We show that the local picture can show significant departures from what is expected from the general global picture. We find that high cross helicity systems that are traditionally believed to have relatively weaker nonlinearities, compared to low cross helicity systems, can show strong nonlinearities in parts of the Fourier space that are orthogonal to the mean magnetic field direction. In some cases, these nonlinearities can exceed in strength the level of nonlinearities recovered from low cross helicity systems.
Nonlinear Gyrokinetics: A Powerful Tool for the Description of Microturbulence in Magnetized Plasmas
Energy Technology Data Exchange (ETDEWEB)
John E. Krommes
2010-09-27
Gyrokinetics is the description of low-frequency dynamics in magnetized plasmas. In magnetic-confinement fusion, it provides the most fundamental basis for numerical simulations of microturbulence; there are astrophysical applications as well. In this tutorial, a sketch of the derivation of the novel dynamical system comprising the nonlinear gyrokinetic (GK) equation (GKE) and the coupled electrostatic GK Poisson equation will be given by using modern Lagrangian and Lie perturbation methods. No background in plasma physics is required in order to appreciate the logical development. The GKE describes the evolution of an ensemble of gyrocenters moving in a weakly inhomogeneous background magnetic field and in the presence of electromagnetic perturbations with wavelength of the order of the ion gyroradius. Gyrocenters move with effective drifts, which may be obtained by an averaging procedure that systematically, order by order, removes gyrophase dependence. To that end, the use of the Lagrangian differential one-form as well as the content and advantages of Lie perturbation theory will be explained. The electromagnetic fields follow via Maxwell's equations from the charge and current density of the particles. Particle and gyrocenter densities differ by an important polarization effect. That is calculated formally by a "pull-back" (a concept from differential geometry) of the gyrocenter distribution to the laboratory coordinate system. A natural truncation then leads to the closed GK dynamical system. Important properties such as GK energy conservation and fluctuation noise will be mentioned briefly, as will the possibility (and diffculties) of deriving nonlinear gyro fluid equations suitable for rapid numerical solution -- although it is probably best to directly simulate the GKE. By the end of the tutorial, students should appreciate the GKE as an extremely powerful tool and will be prepared for later lectures describing its applications to physical problems.
Data Analysis Techniques for Resolving Nonlinear Processes in Plasmas : a Review
de Wit, T. Dudok
1996-01-01
The growing need for a better understanding of nonlinear processes in plasma physics has in the last decades stimulated the development of new and more advanced data analysis techniques. This review lists some of the basic properties one may wish to infer from a data set and then presents appropriate analysis techniques with some recent applications. The emphasis is put on the investigation of nonlinear wave phenomena and turbulence in space plasmas.
Latyshev, A V
2015-01-01
The analysis of nonlinear interaction of transversal electromagnetic field with collisionless plasma is carried out. Formulas for calculation electric current in collisionless plasma with arbitrary degree of degeneration of electronic gas are deduced. It has appeared, that the nonlinearity account leads to occurrence of the longitudinal electric current directed along a wave vector. This second current is orthogonal to the known transversal current, received at the classical linear analysis.
Nonlinear vibrations and imperfection sensitivity of a cylindrical shell containing axial fluid flow
del Prado, Z.; Gonçalves, P. B.; Païdoussis, M. P.
2009-10-01
The high imperfection sensitivity of cylindrical shells under static compressive axial loads is a well-known phenomenon in structural stability. On the other hand, less is known of the influence of imperfections on the nonlinear vibrations of these shells under harmonic axial loads. The aim of this work is to study the simultaneous influence of geometric imperfections and an axial fluid flow on the nonlinear vibrations and instabilities of simply supported circular cylindrical shells under axial load. The fluid is assumed to be non-viscous and incompressible and the flow to be isentropic and irrotational. The behavior of the thin-walled shell is modeled by Donnell's nonlinear shallow-shell equations. It is subjected to a static uniform compressive axial pre-load plus a harmonic axial load. A low-dimensional modal expansion, which satisfies the relevant boundary and continuity conditions, and takes into account all relevant nonlinear modal interactions observed in the past in the nonlinear vibrations of cylindrical shells with and without flow is used together with the Galerkin method to derive a set of eight coupled nonlinear ordinary differential equations of motion which are, in turn, solved by the Runge-Kutta method. The shell is considered to be initially at rest, in a position corresponding to a pre-buckling configuration. Then, a harmonic excitation is applied and conditions for parametric instability and dynamic snap-through are sought. The results clarify the marked influence of geometric imperfections and fluid flow on the dynamic stability boundaries, bifurcations and basins of attraction.
Nonlinear acoustic waves in a collisional self-gravitating dusty plasma
Institute of Scientific and Technical Information of China (English)
Guo Zhi-Rong; Yang Zeng-Qiang; Yin Bao-Xiang; Sun Mao-Zhu
2010-01-01
Using the reductive perturbation method,we investigate the small amplitude nonlinear acoustic wave in a collisional self-gravitating dusty plasma.The result shows that the small amplitude dust acoustic wave can be expressed by a modified Korteweg-de Vries equation,and the nonlinear wave is instable because of the collisions between the neutral gas molecules and the charged particles.
Charge exchange in fluid description of partially ionized plasmas
Vranjes, J; Luna, M
2015-01-01
The effects of charge exchange on waves propagating in weakly ionized plasmas are discussed. It is shown that for low-frequency processes, ions and neutrals should be treated as a single fluid with some effective charge on all of them. We have derived a new momentum equation which should be used in such an environment. As a result, the low-frequency magnetic waves can propagate even if particles are not magnetized, which is entirely due to the charge exchange and the fact that it is not possible to separate particles into two different populations as charged and neutral species. So there can be no friction force between ions and neutrals in the usual sense. The mean force per particle is proportional to the ionization ratio $n_i/(n_i+ n_n)$. Regarding the application of the theory to the Alfven wave propagation in the lower solar atmosphere, the results predict that the plane of displacement of the fluid must change by 90 degrees when an Alfven wave propagates from the area where particles are un-magnetized (...
Source formulation for electron-impact ionization for fluid plasma simulations
DEFF Research Database (Denmark)
Müller, S.H.; Holland, C.; Tynan, G.R.;
2009-01-01
The derivation of the correct functional form of source terms in plasma fluid theory is revisited. The relation between the fluid source terms and atomic physics differential cross sections is established for particle-impact ionization. It is shown that the interface between atomic and plasma...
Soliton-plasma nonlinear dynamics in mid-IR gas-filled hollow-core fibers
DEFF Research Database (Denmark)
Habib, Selim; Markos, Christos; Bang, Ole
2017-01-01
We investigate numerically soliton-plasma interaction in a noble-gas-filled silica hollow-core anti-resonant fiber pumped in the mid-IR at 3.0 mu m. We observe multiple soliton self-compression stages due to distinct stages where either the self-focusing or the self-defocusing nonlinearity...... dominates. Specifically, the parameters may be tuned so the competing plasma self-defocusing nonlinearity only dominates over the Kerr self-focusing nonlinearity around the soliton self-compression stage, where the increasing peak intensity on the leading pulse edge initiates a competing self...
Small amplitude nonlinear electron acoustic solitary waves in weakly magnetized plasma
Energy Technology Data Exchange (ETDEWEB)
Dutta, Manjistha; Khan, Manoranjan [Department of Instrumentation Science, Jadavpur University, Kolkata-700 032 (India); Ghosh, Samiran [Department of Applied Mathematics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009 (India); Roychoudhury, Rajkumar [Indian Statistical Institute, Kolkata-700 108 (India); Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar Kolkata-700 064 (India)
2013-01-15
Nonlinear propagation of electron acoustic waves in homogeneous, dispersive plasma medium with two temperature electron species is studied in presence of externally applied magnetic field. The linear dispersion relation is found to be modified by the externally applied magnetic field. Lagrangian transformation technique is applied to carry out nonlinear analysis. For small amplitude limit, a modified KdV equation is obtained, the modification arising due to presence of magnetic field. For weakly magnetized plasma, the modified KdV equation possesses stable solitary solutions with speed and amplitude increasing temporally. The solutions are valid upto some finite time period beyond which the nonlinear wave tends to wave breaking.
Ertel's vorticity theorem and new flux surfaces in multi-fluid plasmas
Hameiri, Elie
2013-10-01
Based on an extension to plasmas of Ertel's classical vorticity theorem in fluid dynamics, it is shown that for each species in a multi-fluid plasma there exists a set of nested surfaces that have this species' fluid particles confined within them. Variational formulations for the plasma evolution and its equilibrium states are developed, based on the new surfaces and all of the dynamical conservation laws associated with them. It is shown that in the general equilibrium case, the energy principle lacks a minimum and cannot be used as a stability criterion. A special limit of the variational principle yields single-fluid magnetohydrodynamic plasma equilibria and can be used to approximate the equilibrium state of a two-fluid plasma in a perturbative way. Work supported by USDOE under grant no. DE-FG02-86ER53223.
Nonlinear Electromagnetic Waves and Spherical Arc-Polarized Waves in Space Plasmas
Tsurutani, B.; Ho, Christian M.; Arballo, John K.; Lakhina, Gurbax S.; Glassmeier, Karl-Heinz; Neubauer, Fritz M.
1997-01-01
We review observations of nonlinear plasma waves detected by interplanetary spacecraft. For this paper we will focus primarily on the phase-steepened properties of such waves. Plasma waves at comet Giacobini-Zinner measured by the International Cometary Explorer (ICE), at comets Halley and Grigg-Skjellerup measured by Giotto, and interplanetary Alfven waves measured by Ulysses, will be discussed and intercompared.
A Nonlinear Dynamic Characterization of The Universal Scrape-off Layer Plasma Fluctuations
Mekkaoui, A
2012-01-01
A stochastic differential equation of plasma density dynamic is derived, consistent with the experimentally measured pdf and the theoretical quadratic nonlinearity. The plasma density evolves on the turbulence correlation time scale and is driven by a stochastic white noise proportional to the turbulence fluctuations amplitude, while the linear growth is quadratically damped by the fluctuation level $n_e(t)/\\bar{n}_e$.
Least-Squares, Continuous Sensitivity Analysis for Nonlinear Fluid-Structure Interaction
2009-08-20
Lecture notes in mathematics ; 606, Springer-Verlag, Berlin ; New York, 1977, pp. 362. [56] Gel’fand, I.M., Fomin, S.V., and Silverman, R.A...computational fluid dynamics and electromagnetics, Scientific computation, Springer, Berlin ; New York, 1998. [70] Karniadakis, G., and Sherwin, S.J...Aeroelasticity,” Journal of Aircraft, Vol. 40, No. 6, 2003, pp. 1066-1092. [78] Lucia , D.J., “The SensorCraft Configurations: A Non-Linear
Weakly Nonlinear Stability Analysis of a Thin Magnetic Fluid during Spin Coating
Directory of Open Access Journals (Sweden)
Cha'o-Kuang Chen
2010-01-01
Full Text Available This paper investigates the stability of a thin electrically conductive fluid under an applied uniform magnetic filed during spin coating. A generalized nonlinear kinematic model is derived by the long-wave perturbation method to represent the physical system. After linearizing the nonlinear evolution equation, the method of normal mode is applied to study the linear stability. Weakly nonlinear dynamics of film flow is studied by the multiple scales method. The Ginzburg-Landau equation is determined to discuss the necessary conditions of the various critical flow states, namely, subcritical stability, subcritical instability, supercritical stability, and supercritical explosion. The study reveals that the rotation number and the radius of the rotating circular disk generate similar destabilizing effects but the Hartmann number gives a stabilizing effect. Moreover, the optimum conditions can be found to alter stability of the film flow by controlling the applied magnetic field.
A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures
Directory of Open Access Journals (Sweden)
Liyuan Yu
2017-01-01
Full Text Available Selecting appropriate governing equations for fluid flow in fractured rock masses is of special importance for estimating the permeability of rock fracture networks. When the flow velocity is small, the flow is in the linear regime and obeys the cubic law, whereas when the flow velocity is large, the flow is in the nonlinear regime and should be simulated by solving the complex Navier-Stokes equations. The critical conditions such as critical Reynolds number and critical hydraulic gradient are commonly defined in the previous works to quantify the onset of nonlinear fluid flow. This study reviews the simplifications of governing equations from the Navier-Stokes equations, Stokes equation, and Reynold equation to the cubic law and reviews the evolutions of critical Reynolds number and critical hydraulic gradient for fluid flow in rock fractures and fracture networks, considering the influences of shear displacement, normal stress and/or confining pressure, fracture surface roughness, aperture, and number of intersections. This review provides a reference for the engineers and hydrogeologists especially the beginners to thoroughly understand the nonlinear flow regimes/mechanisms within complex fractured rock masses.
Directory of Open Access Journals (Sweden)
Yan-Lei Zhang
2016-01-01
Full Text Available Nonlinear vibration of a fluid-conveying pipe subjected to a transverse external harmonic excitation is investigated in the case with two-to-one internal resonance. The excitation amplitude is in the same magnitude of the transverse displacement. The fluid in the pipes flows in the speed larger than the critical speed so that the straight configuration becomes an unstable equilibrium and two curved configurations bifurcate as stable equilibriums. The motion measured from each of curved equilibrium configurations is governed by a nonlinear integro-partial-differential equation with variable coefficients. The Galerkin method is employed to discretize the governing equation into a gyroscopic system consisting of a set of coupled nonlinear ordinary differential equations. The method of multiple scales is applied to analyze approximately the gyroscopic system. A set of first-order ordinary differential equations governing the modulations of the amplitude and the phase are derived via the method. In the supercritical regime, the subharmonic, superharmonic, and combination resonances are examined in the presence of the 2 : 1 internal resonance. The steady-state responses and their stabilities are determined. The various jump phenomena in the amplitude-frequency response curves are demonstrated. The effects of the viscosity, the excitation amplitude, the nonlinearity, and the flow speed are observed. The analytical results are supported by the numerical integration.
Viriato: A Fourier-Hermite spectral code for strongly magnetized fluid-kinetic plasma dynamics
Loureiro, N. F.; Dorland, W.; Fazendeiro, L.; Kanekar, A.; Mallet, A.; Vilelas, M. S.; Zocco, A.
2016-09-01
We report on the algorithms and numerical methods used in Viriato, a novel fluid-kinetic code that solves two distinct sets of equations: (i) the Kinetic Reduced Electron Heating Model (KREHM) equations (Zocco and Schekochihin, 2011) (which reduce to the standard Reduced-MHD equations in the appropriate limit) and (ii) the kinetic reduced MHD (KRMHD) equations (Schekochihin et al., 2009). Two main applications of these equations are magnetized (Alfvénic) plasma turbulence and magnetic reconnection. Viriato uses operator splitting (Strang or Godunov) to separate the dynamics parallel and perpendicular to the ambient magnetic field (assumed strong). Along the magnetic field, Viriato allows for either a second-order accurate MacCormack method or, for higher accuracy, a spectral-like scheme composed of the combination of a total variation diminishing (TVD) third order Runge-Kutta method for the time derivative with a 7th order upwind scheme for the fluxes. Perpendicular to the field Viriato is pseudo-spectral, and the time integration is performed by means of an iterative predictor-corrector scheme. In addition, a distinctive feature of Viriato is its spectral representation of the parallel velocity-space dependence, achieved by means of a Hermite representation of the perturbed distribution function. A series of linear and nonlinear benchmarks and tests are presented, including a detailed analysis of 2D and 3D Orszag-Tang-type decaying turbulence, both in fluid and kinetic regimes.
Energy Technology Data Exchange (ETDEWEB)
Eliasson, B., E-mail: bengt.eliasson@strath.ac.uk [SUPA, Physics Department, John Anderson Building, Strathclyde University, Glasgow G4 0NG, Scotland (United Kingdom); Lazar, M., E-mail: mlazar@tp4.rub.de [Centre for Mathematical Plasma Astrophysics, Celestijnenlaan 200B, 3001 Leuven (Belgium); Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum (Germany)
2015-06-15
This paper presents a numerical study of the linear and nonlinear evolution of the electromagnetic electron-cyclotron (EMEC) instability in a bi-Kappa distributed plasma. Distributions with high energy tails described by the Kappa power-laws are often observed in collision-less plasmas (e.g., solar wind and accelerators), where wave-particle interactions control the plasma thermodynamics and keep the particle distributions out of Maxwellian equilibrium. Under certain conditions, the anisotropic bi-Kappa distribution gives rise to plasma instabilities creating low-frequency EMEC waves in the whistler branch. The instability saturates nonlinearly by reducing the temperature anisotropy until marginal stability is reached. Numerical simulations of the Vlasov-Maxwell system of equations show excellent agreement with the growth-rate and real frequency of the unstable modes predicted by linear theory. The wave-amplitude of the EMEC waves at nonlinear saturation is consistent with magnetic trapping of the electrons.
Clack, C
2009-01-01
The nonlinear theory of driven magnetohydrodynamics (MHD) waves in strongly anisotropic and dispersive plasmas, developed for slow resonance by Clack and Ballai [Phys. Plasmas, 15, 2310 (2008)] and Alfv\\'en resonance by Clack \\emph{et al.} [A&A,494, 317 (2009)], is used to study the weakly nonlinear interaction of fast magnetoacoustic (FMA) waves in a one-dimensional planar plasma. The magnetic configuration consists of an inhomogeneous magnetic slab sandwiched between two regions of semi-infinite homogeneous magnetic plasmas. Laterally driven FMA waves penetrate the inhomogeneous slab interacting with the localized slow or Alfv\\'{e}n dissipative layer and are partly reflected, dissipated and transmitted by this region. The nonlinearity parameter defined by Clack and Ballai (2008) is assumed to be small and a regular perturbation method is used to obtain analytical solutions in the slow dissipative layer. The effect of dispersion in the slow dissipative layer is to further decrease the coefficient of ener...
Schlieren High Speed Imaging on Fluid Flow in Liquid Induced by Plasma-driven Interfacial Forces
Lai, Janis; Foster, John
2016-10-01
Effective plasma-based water purification depends heavily on the transport of plasma-derived reactive species from the plasma into the liquid. Plasma interactions at the liquid-gas boundary are known to drive circulation in the bulk liquid. This forced circulation is not well understood. A 2-D plasma- in-liquid water apparatus is currently being investigated as a means to study the plasma-liquid interface to understand not only reactive species flows but to also understand plasma- driven fluid dynamic effects in the bulk fluid. Using Schlieren high speed imaging, plasma-induced density gradients near the interfacial region and into the bulk solution are measured to investigate the nature of these interfacial forces. Plasma-induced flow was also measured using particle imaging velocimetry. NSF CBET 1336375 and DOE DE-SC0001939.
Steady-State Flows in Two-Fluid Models of NSTX and DIII-D Plasmas
Ferraro, N. M.; Jardin, S. C.; Chen, J.
2009-05-01
Accurate axisymmetric steady-states of a comprehensive two-fluid model are calculated for plasmas in diverted NSTX and DIII-D geometries using the M3D-C^1 code [1]. It is found that gyroviscosity may have a significant effect on the flows in steady-state when a localized density source is present. The model implemented in M3D-C^1 self-consistently includes the effects of flows, anisotropic viscosity, anisotropic thermal conductivity, and resistivity. Results for ohmically driven plasmas are presented. New capabilities of M3D-C^1 allow the three-dimensional linear stability of axisymmetric equilibria to be calculated; these capabilities and preliminary stability results are discussed. Also discussed are recent and future extensions to M3D-C^1, including heuristic bootstrap current models, coupling to a physics-based transport model, and nonlinear non-axisymmetric capability. 3pt[1] S. C. Jardin, J. Breslau, N. Ferraro, J. Comput. Phys, 226 (2007) 2146
Institute of Scientific and Technical Information of China (English)
Cai-Wan Chang-Jian; Her-Terng Yau
2007-01-01
This study performs a dynamic analysis of a rotor supported by two squeeze couple stress fluid film journal bearings with nonlinear suspension. The numerical results show that the stability of the system varies with the non-dimensional speed ratios and the dimensionless parameter l*. It is found that the system is more stable with higher dimensionless parameter l*.Thus it can conclude that the rotor-bearing system lubricated with the couple stress fluid is more stable than that with the conventional Newtonian fluid. The modeling results thus obtained by using the method proposed in this paper can be used to predict the stability of the rotor-bearing system and the undesirable behavior of the rotor and bearing center can be avoided.
Dust-ion acoustic cnoidal waves and associated nonlinear ion flux in a nonthermal dusty plasma
Ur-Rehman, Hafeez; Mahmood, S.
2016-09-01
The dust-ion acoustic nonlinear periodic (cnoidal) waves and solitons are investigated in a dusty plasma containing dynamic cold ions, superthermal kappa distributed electrons and static charged dust particles. The massive dust particles can have positive or negative charge depending on the plasma environment. Using reductive perturbation method (RPM) with appropriate periodic boundary conditions, the evolution equations for the first and second order nonlinear potentials are derived. The first order potential is determined through Korteweg-de Vries (KdV) equation which gives dust-ion acoustic cnoidal waves and solitons structures. The solution of second order nonlinear potential is obtained through an inhomogeneous differential equation derived from collecting higher order terms of dynamic equations, which is linear for second order electrostatic potential. The nonlinear ion flux associated with the cnoidal waves is also found out numerically. The numerical plots of the dust-ion acoustic cnoidal wave and soliton structures for both positively and negatively charged dust particles cases and nonthermal electrons are also presented for illustration. It is found that only compressive nonlinear electrostatic structures are formed in case of positively dust charged particles while both compressive and rarefactive nonlinear structures are obtained in case of negatively charged particles depending on the negatively charged dust density in a nonthermal dusty plasma. The numerical results are obtained using data of the ionospheric region containing dusty plasma exist in the literature.
Two-fluid plasma Richtmyer-Meshkov instability
Wheatley, Vincent; Bond, Daryl; Pullin, Dale; Samtaney, Ravi
2016-11-01
The Richtmyer-Meshkov instability of a shock accelerated perturbed density interface is computationally investigated in the context of ideal two-fluid plasmas. This is accomplished by numerically solving separate sets of conservation equations for the ions and electrons, coupled to the full Maxwell's equations. We focus on cases without an imposed magnetic field and with Debye lengths ranging from a thousandth to a tenth of the interface perturbation wavelength. For all cases investigated, the behavior of the flow is substantially different from that predicted by the Euler or ideal magnetohydrodynamics equations. Electric fields generated by charge separation cause interface oscillations, particularly in the electrons, that drive a secondary high-wavenumber instability. Consequently, the density interface is substantially more unstable than predicted by the Euler equations for all cases investigated. Self-generated magnetic fields are predicted within our simulations, but their orientation is such that they do not dampen the Richtmyer-Meshkov instability. This work was partially supported by the KAUST Office of Sponsored Research under Award URF/1/2162-01.
Koup, J R; Thomas, D; Tucker, E; Black, A; Ruderman, M; Dixon, J A; Kinkel, A
1988-01-01
We have measured plasma and synovial fluid concentrations of meclofenamic acid at 2, 4, 8, and 12 h during steady-state administration (100 mg three times daily for 4-7 days). Paired plasma and synovial samples were obtained pre-treatment and at one of the above times in twelve patients with a diagnosis of rheumatoid arthritis. In addition, the extent of protein binding of meclofenamic acid was assessed in vitro in the pre-treatment plasma and synovial fluid specimens. Peak total concentrations of 1.73 and 0.86 micrograms.ml-1 were observed in plasma (at 2 h) and synovial fluid (at 4 h) respectively. The extent of protein binding was 99.7 and 99.6% (not significantly different) in plasma and synovial fluid respectively. The results of this study are compared to those from similar reported studies of other nonsteroidal anti-inflamatory compounds.
Nonlinear propagation of positron-acoustic waves in a four component space plasma
Shah, M. G.; Hossen, M. R.; Mamun, A. A.
2015-10-01
> The nonlinear propagation of positron-acoustic waves (PAWs) in an unmagnetized, collisionless, four component, dense plasma system (containing non-relativistic inertial cold positrons, relativistic degenerate electron and hot positron fluids as well as positively charged immobile ions) has been investigated theoretically. The Korteweg-de Vries (K-dV), modified K-dV (mK-dV) and further mK-dV (fmK-dV) equations have been derived by using reductive perturbation technique. Their solitary wave solutions have been numerically analysed in order to understand the localized electrostatic disturbances. It is observed that the relativistic effect plays a pivotal role on the propagation of positron-acoustic solitary waves (PASW). It is also observed that the effects of degenerate pressure and the number density of inertial cold positrons, hot positrons, electrons and positively charged static ions significantly modify the fundamental features of PASW. The basic features and the underlying physics of PASW, which are relevant to some astrophysical compact objects (such as white dwarfs, neutron stars etc.), are concisely discussed.
Phase mixing vs. nonlinear advection in drift-kinetic plasma turbulence
Schekochihin, A A; Highcock, E G; Dellar, P J; Dorland, W; Hammett, G W
2015-01-01
A scaling theory of long-wavelength electrostatic turbulence in a magnetised, weakly collisional plasma (e.g., drift-wave turbulence driven by temperature gradients) is proposed, with account taken both of the nonlinear advection of the perturbed particle distribution by fluctuating ExB flows and of its phase mixing, which is caused by the streaming of the particles along the mean magnetic field and, in a linear problem, would lead to Landau damping. A consistent theory is constructed in which very little free energy leaks into high velocity moments of the distribution, rendering the turbulent cascade in the energetically relevant part of the wave-number space essentially fluid-like. The velocity-space spectra of free energy expressed in terms of Hermite-moment orders are steep power laws and so the free-energy content of the phase space does not diverge at infinitesimal collisionality (while it does for a linear problem); collisional heating due to long-wavelength perturbations vanishes in this limit (also i...
Nonlinear Transport Processes in Tokamak Plasmas. Part I: The Collisional Regimes
Sonnino, Giorgio
2008-01-01
An application of the thermodynamic field theory (TFT) to transport processes in L-mode tokamak plasmas is presented. The nonlinear corrections to the linear (Onsager) transport coefficients in the collisional regimes are derived. A quite encouraging result is the appearance of an asymmetry between the Pfirsch-Schlueter (P-S) ion and electron transport coefficients: the latter presents a nonlinear correction, which is absent for the ions, and makes the radial electron coefficients much larger than the former. Explicit calculations and comparisons between the neoclassical results and the TFT predictions for JET plasmas are also reported. We found that the nonlinear electron P-S transport coefficients exceed the values provided by neoclassical theory by a factor, which may be of the order 100. The nonlinear classical coefficients exceed the neoclassical ones by a factor, which may be of order 2. The expressions of the ion transport coefficients, determined by the neoclassical theory in these two regimes, remain...
Nonlinear Alfvén Waves in a Vlasov Plasma
DEFF Research Database (Denmark)
Bell, T.F.
1965-01-01
Stationary solutions to the nonlinear Vlasov—Boltzmann equations are considered which represent one-dimensional electromagnetic waves in a hot magnetoplasma. These solutions appear in arbitrary reference frames as circularly polarized, sinusoidal waves of unlimited amplitude, i.e., as nonlinear...... Alfvén waves. Solutions are found implicitly by deriving a set of integral dispersion relations which link the wave characteristics with the particle distribution functions. A physical discussion is given of the way in which the Alfvén waves can trap particles, and it is shown that the presence...
Shahmohammadi Beni, Mehrdad; Yu, K N
2015-12-14
A promising application of plasma medicine is to treat living cells and tissues with cold plasma. In cold plasmas, the fraction of neutrals dominates, so the carrier gas could be considered the main component. In many realistic situations, the treated cells are covered by a fluid. The present paper developed models to determine the temperature of the fluid at the positions of the treated cells. Specifically, the authors developed a three-phase-interaction model which was coupled with heat transfer to examine the injection of the helium carrier gas into water and to investigate both the fluid dynamics and heat transfer output variables, such as temperature, in three phases, i.e., air, helium gas, and water. Our objective was to develop a model to perform complete fluid dynamics and heat transfer computations to determine the temperature at the surface of living cells. Different velocities and plasma temperatures were also investigated using finite element method, and the model was built using the comsol multiphysics software. Using the current model to simulate plasma injection into such systems, the authors were able to investigate the temperature distributions in the domain, as well as the surface and bottom boundary of the medium in which cells were cultured. The temperature variations were computed at small time intervals to analyze the temperature increase in cell targets that could be highly temperature sensisitve. Furthermore, the authors were able to investigate the volume of the plasma plume and its effects on the average temperature of the medium layer/domain. Variables such as temperature and velocity at the cell layer could be computed, and the variations due to different plume sizes could be determined. The current models would be very useful for future design of plasma medicine devices and procedures involving cold plasmas.
Nonlinear propagation of weakly relativistic ion-acoustic waves in electron–positron–ion plasma
Indian Academy of Sciences (India)
M G HAFEZ; M R TALUKDER; M HOSSAIN ALI
2016-11-01
This work presents theoretical and numerical discussion on the dynamics of ion-acoustic solitary wave for weakly relativistic regime in unmagnetized plasma comprising non-extensive electrons, Boltzmann positrons and relativistic ions. In order to analyse the nonlinear propagation phenomena, the Korteweg–de Vries(KdV) equation is derived using the well-known reductive perturbation method. The integration of the derived equation is carried out using the ansatz method and the generalized Riccati equation mapping method. The influenceof plasma parameters on the amplitude and width of the soliton and the electrostatic nonlinear propagation of weakly relativistic ion-acoustic solitary waves are described. The obtained results of the nonlinear low-frequencywaves in such plasmas may be helpful to understand various phenomena in astrophysical compact object and space physics.
DEFF Research Database (Denmark)
Rasmussen, Anders Rønne; Sørensen, Mads Peter; Gaididei, Yuri Borisovich
2011-01-01
A wave equation including nonlinear terms up to the second order for a thermoviscous Newtonian fluid is proposed. In the lossless case this equation results from an expansion to third order of the Lagrangian for the fundamental non-dissipative fluid dynamical equations. Thus it preserves...
Rudin, Sergey; Rupper, Greg
2012-02-01
The non-linear electron plasma response to electromagnetic signal applied to a gated graphene conduction channel can be used to make a graphene based Dyakonov-Shur terahertz detector. The hydrodynamic model predicts a resonance response to electromagnetic radiation at the plasma oscillation frequency. With less damping and higher mobility, the graphene conduction channels may provide higher quality plasma response than possible with semiconductor channels. Our analysis of plasma oscillations in a graphene channel is based on the hydrodynamic equations which we derive from the Boltzmann equation accounting for both electrons and holes, and including the effects of viscosity and finite mobility.
Directory of Open Access Journals (Sweden)
Cha'o-Kuang Chen
2009-01-01
Full Text Available The main object of this paper is to study the weakly nonlinear hydrodynamic stability of the thin Newtonian fluid flowing on a rotating circular disk. A long-wave perturbation method is used to derive the nonlinear evolution equation for the film flow. The linear behaviors of the spreading wave are investigated by normal mode approach, and its weakly nonlinear behaviors are explored by the method of multiple scales. The Ginzburg-Landau equation is determined to discuss the necessary condition for the existence of such flow pattern. The results indicate that the superctitical instability region increases, and the subcritical stability region decreases with the increase of the rotation number or the radius of circular disk. It is found that the rotation number and the radius of circular disk not only play the significant roles in destabilizing the flow in the linear stability analysis but also shrink the area of supercritical stability region at high Reynolds number in the weakly nonlinear stability analysis.
Numerical Studies of Two-Fluid Axisymmetric Steady-States with Flow in Ohmic NSTX-like Plasmas
Ferraro, Nathaniel; Jardin, Stephen
2008-11-01
Axisymmetric steady-states of the resistive two-fluid equations, including flow and gyroviscosity, are obtained by evolving these nonlinear equations from an initial ideal MHD equilibrium using the code M3D-C^1 [1], which has now been extended to toroidal geometry. Steady-states for high-β, inductively driven discharges in diverted NSTX geometries are studied. Excellent agreement with theoretical predictions of cross-surface Pfirsch-Schlüter flows in the axisymmetric steady-states is found. The dependence of flow velocities with resistivity is explored. It is found that in the two-fluid model, the statistical steady-state may be a fixed point, a limit cycle, or chaotic, depending on the parameters. Two-fluid terms lead to a preferred direction of toroidal rotation. The inclusion of gyroviscosity is observed to alter the character of the steady-state. The three-dimensional linear stability of simple equilibria in this two-fluid model are also explored using M3D-C^1 [2]. [1] N. Ferraro, S. Jardin. Phys. Plasmas 13:092101 (2006). [2] S. Jardin, N. Ferraro, J. Breslau, J. Chen, and M. Chance. Initial results for linear 3D Toroidal Two-Fluid stability using M3D-C1. APS DPP Conference, Dallas, TX (2008).
Modeling Granular Materials as Compressible Non-Linear Fluids: Heat Transfer Boundary Value Problems
Energy Technology Data Exchange (ETDEWEB)
Massoudi, M.C.; Tran, P.X.
2006-01-01
We discuss three boundary value problems in the flow and heat transfer analysis in flowing granular materials: (i) the flow down an inclined plane with radiation effects at the free surface; (ii) the natural convection flow between two heated vertical walls; (iii) the shearing motion between two horizontal flat plates with heat conduction. It is assumed that the material behaves like a continuum, similar to a compressible nonlinear fluid where the effects of density gradients are incorporated in the stress tensor. For a fully developed flow the equations are simplified to a system of three nonlinear ordinary differential equations. The equations are made dimensionless and a parametric study is performed where the effects of various dimensionless numbers representing the effects of heat conduction, viscous dissipation, radiation, and so forth are presented.
Nonlinear radiative heat transfer to stagnation-point flow of Sisko fluid past a stretching cylinder
Energy Technology Data Exchange (ETDEWEB)
Khan, Masood [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan); Malik, Rabia, E-mail: rabiamalik.qau@gmail.com [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan); Department of Mathematics and Statistics, International Islamic University Islamabad 44000 (Pakistan); Hussain, M. [Department of Sciences and Humanities, National University of Computer and Emerging Sciences, Islamabad 44000 (Pakistan)
2016-05-15
In the present paper, we endeavor to perform a numerical analysis in connection with the nonlinear radiative stagnation-point flow and heat transfer to Sisko fluid past a stretching cylinder in the presence of convective boundary conditions. The influence of thermal radiation using nonlinear Rosseland approximation is explored. The numerical solutions of transformed governing equations are calculated through forth order Runge-Kutta method using shooting technique. With the help of graphs and tables, the influence of non-dimensional parameters on velocity and temperature along with the local skin friction and Nusselt number is discussed. The results reveal that the temperature increases however, heat transfer from the surface of cylinder decreases with the increasing values of thermal radiation and temperature ratio parameters. Moreover, the authenticity of numerical solutions is validated by finding their good agreement with the HAM solutions.
Final Report: Experimental Investigation of Nonlinear Plasma Wake-Fields
Energy Technology Data Exchange (ETDEWEB)
Rosenzweig, J.
1997-10-31
We discuss the exploration of the newly proposed blowout regime of the plasma wakefield accelerator and advanced photoinjector technology for linear collider applications. The plasma wakefield experiment at ANL produced several ground-breaking results in the physics of the blowout regime. The photoinjector R and D effort produced breakthroughs in theoretical, computational, and experimental methods in high brightness beam physics. Results have been published.
Final Report: Experimental Investigation of Nonlinear Plasma Wake-Fields
Energy Technology Data Exchange (ETDEWEB)
Rosenzweig, J.
1997-10-31
We discuss the exploration of the newly proposed blowout regime of the plasma wakefield accelerator and advanced photoinjector technology for linear collider applications. The plasma wakefield experiment at ANL produced several ground-breaking results in the physics of the blowout regime. The photoinjector R and D effort produced breakthroughs in theoretical, computational, and experimental methods in high brightness beam physics. Results have been published.
Fluid-structure interaction for nonlinear response of shells conveying pulsatile flow
Tubaldi, Eleonora; Amabili, Marco; Païdoussis, Michael P.
2016-06-01
Circular cylindrical shells with flexible boundary conditions conveying pulsatile flow and subjected to pulsatile pressure are investigated. The equations of motion are obtained based on the nonlinear Novozhilov shell theory via Lagrangian approach. The flow is set in motion by a pulsatile pressure gradient. The fluid is modeled as a Newtonian pulsatile flow and it is formulated using a hybrid model that contains the unsteady effects obtained from the linear potential flow theory and the pulsatile viscous effects obtained from the unsteady time-averaged Navier-Stokes equations. A numerical bifurcation analysis employs a refined reduced order model to investigate the dynamic behavior. The case of shells containing quiescent fluid subjected to the action of a pulsatile transmural pressure is also addressed. Geometrically nonlinear vibration response to pulsatile flow and transmural pressure are here presented via frequency-response curves and time histories. The vibrations involving both a driven mode and a companion mode, which appear due to the axial symmetry, are also investigated. This theoretical framework represents a pioneering study that could be of great interest for biomedical applications. In particular, in the future, a more refined model of the one here presented will possibly be applied to reproduce the dynamic behavior of vascular prostheses used for repairing and replacing damaged and diseased thoracic aorta in cases of aneurysm, dissection or coarctation. For this purpose, a pulsatile time-dependent blood flow model is here considered by applying physiological waveforms of velocity and pressure during the heart beating period. This study provides, for the first time in literature, a fully coupled fluid-structure interaction model with deep insights in the nonlinear vibrations of circular cylindrical shells subjected to pulsatile pressure and pulsatile flow.
Nonlinear wave collapse, shock, and breather formation in an electron magnetohydrodynamic plasma.
Ghosh, Samiran; Chakrabarti, Nikhil
2014-12-01
Low-frequency nonlinear wave dynamics is investigated in a two-dimensional inhomogeneous electron magnetohydrodynamic (EMHD) plasma in the presence of electron viscosity. In the long-wavelength limit, the dynamics of the wave is found to be governed by a novel nonlinear equation. The result of the moving-frame nonlinear analysis is noteworthy, which shows that this nonlinear equation does have a breather solution and electron viscosity is responsible for the breather. A breather is a nonlinear wave in which energy accumulates in a localized and oscillatory manner. Analytical solution and time-dependent numerical simulation of this novel equation reveal the collapse of a soliton (localized pulse) into a weak noise shelf and formation of shocklike structures.
Integral Invariance and Non-linearity Reduction for Proliferating Vorticity Scales in Fluid Dynamics
Lam, F
2013-01-01
A vorticity theory for incompressible fluid flows in the absence of solid boundaries is proposed. Some apriori bounds are established. They are used in an interpolation theory to show the well-posedness of the vorticity Cauchy problem. A non-linear integral equation for vorticity is derived and its solution is expressed in an expansion. Interpretations of flow evolutions starting from given initial data are given and elaborated. The kinetic theory for Maxwellian molecules with cut-off is revisited in order to link microscopic properties to flow characters on the continuum.
ALE Fractional Step Finite Element Method for Fluid-Structure Nonlinear Interaction Problem
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A computational procedure is developed to solve the problems of coupled motion of a structure and a viscous incompressible fluid. In order to incorporate the effect of the moving surface of the structure as well as the free surface motion, the arbitrary Lagrangian-Eulerian formulation is employed as the basis of the finite element spatial discretization. For numerical integration in time, the fraction step method is used. This method is useful because one can use the same linear interpolation function for both velocity and pressure. The method is applied to the nonlinear interaction of a structure and a tuned liquid damper. All computations are performed with a personal computer.
MHD flow of a viscous fluid on a nonlinear porous shrinking sheet with homotopy analysis method
Institute of Scientific and Technical Information of China (English)
S. Nadeem; Anwar Hussain
2009-01-01
The present paper investigates the magnetohydrodynamic (MHD) flow of a viscous fluid towards a nonlinear porous shrinking sheet. The governing equations are simplified by similarity transformations. The reduced problem is then solved by the homotopy analysis method. The pertinent parameters appearing in the problem are discussed graphically and presented in tables. It is found that the shrinking solutions exist in the presence of MHD. It is also observed from the tables that the solutions for f"(0) with different values of parameters are convergent.
Nonlinear behavior of saturated porous crust under the influence of internal fluid source
Suetnova, Elena; Cherniavski, Vladimir
2010-05-01
We consider the effective stress evolution inside high porosity fault zone as a result of local dehydration due to heating. The rock is assumed to be a two-velocity medium; it consists of a deformable porous matrix (with Maxwell's rheology) and a Newtonian liquid that saturates this matrix. Nonlinear behavior of liquid saturated porous media in gravity filed under the influence of internal fluid source is modeled. The elaborated non-isothermal mathematical model is a thermodynamically consistent and closed model. The original scheme was used for computer simulation; the method implies numerical simulation for effective stress, deformation and flux time- space evolution. Deformation spreading through the saturated porous matrix occurs with pressure distortions. Calculations show that the peculiarity of effective stress evolution is dependent not only upon the volume of supplementary fluids, but upon the viscosity and elastic modules of matrix.
A Fluid Dynamics Approach for the Computation of Non-linear Force-Free Magnetic Field
Institute of Scientific and Technical Information of China (English)
Jing-Qun Li; Jing-Xiu Wang; Feng-Si Wei
2003-01-01
Inspired by the analogy between the magnetic field and velocity fieldof incompressible fluid flow, we propose a fluid dynamics approach for comput-ing nonlinear force-free magnetic fields. This method has the advantage that thedivergence-free condition is automatically satisfied, which is a sticky issue for manyother algorithms, and we can take advantage of modern high resolution algorithmsto process the force-free magnetic field. Several tests have been made based on thewell-known analytic solution proposed by Low & Lou. The numerical results arein satisfactory agreement with the analytic ones. It is suggested that the newlyproposed method is promising in extrapolating the active region or the whole sunmagnetic fields in the solar atmosphere based on the observed vector magnetic fieldon the photosphere.
Self-mapping the longitudinal field structure of a nonlinear plasma accelerator cavity.
Clayton, C E; Adli, E; Allen, J; An, W; Clarke, C I; Corde, S; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Litos, M; Lu, W; Marsh, K A; Mori, W B; Vafaei-Najafabadi, N; Xu, X; Yakimenko, V
2016-08-16
The preservation of emittance of the accelerating beam is the next challenge for plasma-based accelerators envisioned for future light sources and colliders. The field structure of a highly nonlinear plasma wake is potentially suitable for this purpose but has not been yet measured. Here we show that the longitudinal variation of the fields in a nonlinear plasma wakefield accelerator cavity produced by a relativistic electron bunch can be mapped using the bunch itself as a probe. We find that, for much of the cavity that is devoid of plasma electrons, the transverse force is constant longitudinally to within ±3% (r.m.s.). Moreover, comparison of experimental data and simulations has resulted in mapping of the longitudinal electric field of the unloaded wake up to 83 GV m(-1) to a similar degree of accuracy. These results bode well for high-gradient, high-efficiency acceleration of electron bunches while preserving their emittance in such a cavity.
Latyshev, A V
2014-01-01
The analysis of nonlinear interaction of transversal electromagnetic field with quantum collisionless plasma is carried out. Formulas for calculation electric current in quantum collisionless plasma at any temperature are deduced. It has appeared, that the nonlinearity account leads to occurrence of the longitudinal electric current directed along a wave vector. This second current is orthogonal to the known transversal classical current, received at the classical linear analysis. The case of degenerate electronic plasma is considered. The concept of longitudinal-transversal conductivity is entered. The graphic analysis of the real and imaginary parts of dimensionless coefficient of longitudinal-transversal conductivity is made. It is shown, that for degenerate plasmas the electric current is calculated under the formula, not containing quadratures. In this formula we have allocated known Kohn's singularities (W. Kohn, 1959).
Hafez, M. G.; Talukder, M. R.; Hossain Ali, M.
2017-04-01
The Burgers equation is obtained to study the characteristics of nonlinear propagation of ionacoustic shock, singular kink, and periodic waves in weakly relativistic plasmas containing relativistic thermal ions, nonextensive distributed electrons, Boltzmann distributed positrons, and kinematic viscosity of ions using the well-known reductive perturbation technique. This equation is solved by employing the ( G'/ G)-expansion method taking unperturbed positron-to-electron concentration ratio, electron-to-positron temperature ratio, strength of electrons nonextensivity, ion kinematic viscosity, and weakly relativistic streaming factor. The influences of plasma parameters on nonlinear propagation of ion-acoustic shock, periodic, and singular kink waves are displayed graphically and the relevant physical explanations are described. It is found that these parameters extensively modify the shock structures excitation. The obtained results may be useful in understanding the features of small but finite amplitude localized relativistic ion-acoustic shock waves in an unmagnetized plasma system for some astrophysical compact objects and space plasmas.
Numerical simulation of nonlinear processes in a beam-plasma system
Energy Technology Data Exchange (ETDEWEB)
Efimova, A. A., E-mail: anna.an.efimova@gmail.com; Berendeev, E. A.; Vshivkov, V. A. [Institute of Computational Mathematics and Mathematical Geophysics SB RAS 6 Acad. Lavrentyev Ave., Novosibirsk 630090 (Russian Federation); Dudnikova, G. I. [University of Maryland, College Park, MD 20742 (United States); Institute of Computational Technologies SB RAS, 6 Acad. Lavrentyev Ave., Novosibirsk 630090 (Russian Federation)
2015-10-28
In the present paper we consider the efficiency of the electromagnetic radiation generation due to various nonlinear processes in the beam-plasma system. The beam and plasma parameters were chosen close to the parameters in the experiment on the GOL-3 facility (BINP SB RAS). The model of the collisionless plasma is described by system of the Vlasov-Maxwell equations with periodic boundary conditions. The parallel numerical algorithm is based on the particles-in-cell method (PIC) with mixed Euler-Lagrangian domain decomposition. Various scenarios of nonlinear evolution in the beam-plasma system under the influence of an external magnetic field in case of a low density beam were studied. The energy transfer from one unstable mode to the others modes was observed.
Self-mapping the longitudinal field structure of a nonlinear plasma accelerator cavity
Clayton, C. E.; Adli, E.; Allen, J.; An, W.; Clarke, C. I.; Corde, S.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Xu, X.; Yakimenko, V.
2016-08-01
The preservation of emittance of the accelerating beam is the next challenge for plasma-based accelerators envisioned for future light sources and colliders. The field structure of a highly nonlinear plasma wake is potentially suitable for this purpose but has not been yet measured. Here we show that the longitudinal variation of the fields in a nonlinear plasma wakefield accelerator cavity produced by a relativistic electron bunch can be mapped using the bunch itself as a probe. We find that, for much of the cavity that is devoid of plasma electrons, the transverse force is constant longitudinally to within +/-3% (r.m.s.). Moreover, comparison of experimental data and simulations has resulted in mapping of the longitudinal electric field of the unloaded wake up to 83 GV m-1 to a similar degree of accuracy. These results bode well for high-gradient, high-efficiency acceleration of electron bunches while preserving their emittance in such a cavity.
Singh, Navpreet; Gupta, Naveen; Singh, Arvinder
2016-12-01
This paper investigates second harmonic generation (SHG) of an intense Cosh-Gaussian (ChG) laser beam propagating through a preformed underdense collisional plasma with nonlinear absorption. Nonuniform heating of plasma electrons takes place due to the nonuniform irradiance of intensity along the wavefront of laser beam. This nonuniform heating of plasma leads to the self-focusing of the laser beam and thus produces strong density gradients in the transverse direction. The density gradients so generated excite an electron plasma wave (EPW) at pump frequency that interacts with the pump beam to produce its second harmonics. To envision the propagation dynamics of the ChG laser beam, moment theory in Wentzel-Kramers-Brillouin (W.K.B) approximation has been invoked. The effects of nonlinear absorption on self-focusing of the laser beam as well as on the conversion efficiency of its second harmonics have been theoretically investigated.
A nonlinear plasma retroreflector for single pulse Compton backscattering
Palastro, J P; Gordon, D; Hafizi, B; Helle, M; Penano, J; Ting, A
2014-01-01
Compton scattered x-rays can be generated using a configuration consisting of a single, ultra-intense laser pulse, and a shaped gas target. The gas target incorporates a hydrodynamically formed density spike, which nonlinearly scatters the incident pump radiation, to produce a counter-propagating electromagnetic wiggler. This self-generated wiggler field Compton scatters from electrons accelerated in the laser wakefield of the pump radiation. The nonlinear scattering mechanism in the density spike is examined theoretically and numerically in order to optimize the Compton scattered radiation. It is found that narrow-band x-rays are produced by moderate intensity pump radiation incident on the quarter-critical surface of the density spike, while high fluence, broadband x-rays are produced by high intensity pump radiation reflected near the critical surface.
Nonlinear frequency shift in Raman backscattering and its implications for plasma diagnostics
Kaganovich, D.; Hafizi, B.; Palastro, J. P.; Ting, A.; Helle, M. H.; Chen, Y.-H.; Jones, T. G.; Gordon, D. F.
2016-12-01
Raman backscattered radiation of intense laser pulses in plasmas is investigated for a wide range of intensities relevant to laser wakefield acceleration. The weakly nonlinear dispersion relation for Raman backscattering predicts an intensity and density dependent frequency shift that is opposite to that suggested by a simple relativistic consideration. This observation has been benchmarked against experimental results, providing a novel diagnostic for laser-plasma interactions.
Nonlinear Frequency Shift in Raman Backscattering and its Implications for Plasma Diagnostics
Kaganovich, D; Palastro, J P; Ting, A; Helle, M H; Chen, Y -H; Jones, T G; Gordon, D F
2016-01-01
Raman backscattered radiation of intense laser pulses in plasma is investigated for a wide range of intensities relevant to laser wakefield acceleration. The weakly nonlinear dispersion relation for Raman backscattering predicts an intensity and density dependent frequency shift that is opposite to that suggested by a simple relativistic consideration. This observation has been benchmarked against experimental results, providing a novel diagnostic for laser-plasma interactions.
Excitation of nonlinear ion acoustic waves in CH plasmas
Feng, Q S; Liu, Z J; Xiao, C Z; Wang, Q; He, X T
2016-01-01
Excitation of nonlinear ion acoustic wave (IAW) by an external electric field is demonstrated by Vlasov simulation. The frequency calculated by the dispersion relation with no damping is verified much closer to the resonance frequency of the small-amplitude nonlinear IAW than that calculated by the linear dispersion relation. When the wave number $ k\\lambda_{De} $ increases, the linear Landau damping of the fast mode (its phase velocity is greater than any ion's thermal velocity) increases obviously in the region of $ T_i/T_e < 0.2 $ in which the fast mode is weakly damped mode. As a result, the deviation between the frequency calculated by the linear dispersion relation and that by the dispersion relation with no damping becomes larger with $k\\lambda_{De}$ increasing. When $k\\lambda_{De}$ is not large, such as $k\\lambda_{De}=0.1, 0.3, 0.5$, the nonlinear IAW can be excited by the driver with the linear frequency of the modes. However, when $k\\lambda_{De}$ is large, such as $k\\lambda_{De}=0.7$, the linear ...
Comparison of apoprotein B of low density lipoproteins of human interstitial fluid and plasma.
Hong, J L; Pflug, J; Reichl, D
1984-08-15
Virtually all apoprotein B (apoB)-containing lipoproteins of the peripheral interstitial fluid of subjects with primary lymphoedema float in the ultracentrifugal field in the density interval 1.019-1.063 g/ml; in this respect they are similar to plasma low-density lipoproteins (LDL). 2. Virtually all apo-B-containing lipoproteins of interstitial fluid migrate in the electrophoretic field with pre-beta mobility; in this respect they are similar to plasma very-low-density lipoproteins. 3. The apoB of lipoproteins of interstitial fluid does not differ in terms of Mr from apoB-100 of human plasma [Kane, Hardman & Paulus (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 2465-2469] as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 4. Both apoB of interstitial fluid and plasma are heterogenous in terms of their charge as determined by isoelectric focusing of their complexes with the nonionic detergent Nonidet P40. ApoB of plasma LDL focuses between pH5.9 and 6.65, and that of interstitial fluid LDL between pH 5.9 and 6.1. Thus the overall charge of apoB of interstitial fluid is more negative than that of its plasma LDL counterpart.
Magnetohydrodynamic motion of a two-fluid plasma
Burby, J. W.
2017-08-01
The two-fluid Maxwell system couples frictionless electrons and ion fluids via Maxwell's equations. When the frequencies of light waves, Langmuir waves, and single-particle cyclotron motion are scaled to be asymptotically large, the two-fluid Maxwell system becomes a fast-slow dynamical system. This fast-slow system admits a formally exact single-fluid closure that may be computed systematically with any desired order of accuracy through the use of a functional partial differential equation. In the leading order approximation, the closure reproduces magnetohydrodynamics (MHD). Higher order truncations of the closure give an infinite hierarchy of extended MHD models that allow for arbitrary mass ratio, as well as perturbative deviations from charge neutrality. The closure is interpreted geometrically as an invariant slow manifold in the infinite-dimensional two-fluid phase space, on which two-fluid motions are free of high-frequency oscillations. This perspective shows that the full closure inherits a Hamiltonian structure from the two-fluid theory. By employing infinite-dimensional Lie transforms, the Poisson bracket for the all-order closure may be obtained in the closed form. Thus, conservative truncations of the single-fluid closure may be obtained by simply truncating the single-fluid Hamiltonian. Moreover, the closed-form expression for the all-order bracket gives explicit expressions for a number of the full closure's conservation laws. Notably, the full closure, as well as any of its Hamiltonian truncations, admits a pair of independent circulation invariants.
Larson, John Philip
Smart material electro-hydraulic actuators (EHAs) utilize fluid rectification via one-way check valves to amplify the small, high-frequency vibrations of certain smart materials into large motions of a hydraulic cylinder. Although the concept has been demonstrated in previously, the operating frequency of smart material EHA systems has been limited to a small fraction of the available bandwidth of the driver materials. The focus of this work is to characterize and model the mechanical performance of a magnetostrictive EHA considering key system components: rectification valves, smart material driver, and fluid-system components, leading to an improved actuator design relative to prior work. The one-way valves were modeled using 3-D finite element analysis, and their behavior was characterized experimentally by static and dynamic experimental measurement. Taking into account the effect of the fluid and mechanical conditions applied to the valves within the pump, the dynamic response of the valve was quantified and applied to determine rectification bandwidth of different valve configurations. A novel miniature reed valve, designed for a frequency response above 10~kHz, was fabricated and tested within a magnetostrictive EHA. The nonlinear response of the magnetostrictive driver, including saturation and hysteresis effects, was modeled using the Jiles-Atherton approach to calculate the magnetization and the resulting magnetostriction based on the applied field calculated within the rod from Maxwell's equations. The dynamic pressure response of the fluid system components (pumping chamber, hydraulic cylinder, and connecting passages) was measured over a range of input frequencies. For the magnetostrictive EHA tested, the peak performance frequency was found to be limited by the fluid resonances within the system. A lumped-parameter modeling approach was applied to model the overall behavior of a magnetostrictive EHA, incorporating models for the reed valve response
Viriato: a Fourier-Hermite spectral code for strongly magnetised fluid-kinetic plasma dynamics
Loureiro, Nuno; Dorland, William; Fazendeiro, Luis; Kanekar, Anjor; Mallet, Alfred; Zocco, Alessandro
2015-11-01
We report on the algorithms and numerical methods used in Viriato, a novel fluid-kinetic code that solves two distinct sets of equations: (i) the Kinetic Reduced Electron Heating Model equations [Zocco & Schekochihin, 2011] and (ii) the kinetic reduced MHD (KRMHD) equations [Schekochihin et al., 2009]. Two main applications of these equations are magnetised (Alfvnénic) plasma turbulence and magnetic reconnection. Viriato uses operator splitting to separate the dynamics parallel and perpendicular to the ambient magnetic field (assumed strong). Along the magnetic field, Viriato allows for either a second-order accurate MacCormack method or, for higher accuracy, a spectral-like scheme. Perpendicular to the field Viriato is pseudo-spectral, and the time integration is performed by means of an iterative predictor-corrector scheme. In addition, a distinctive feature of Viriato is its spectral representation of the parallel velocity-space dependence, achieved by means of a Hermite representation of the perturbed distribution function. A series of linear and nonlinear benchmarks and tests are presented, with focus on 3D decaying kinetic turbulence. Work partially supported by Fundação para a Ciência e Tecnologia via Grants UID/FIS/50010/2013 and IF/00530/2013.
Electron vortex magnetic holes: A nonlinear coherent plasma structure
Haynes, Christopher T.; Burgess, David; Camporeale, Enrico; Sundberg, Torbjorn
2015-01-01
We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas.
Electron vortex magnetic holes: A nonlinear coherent plasma structure
Energy Technology Data Exchange (ETDEWEB)
Haynes, Christopher T., E-mail: c.t.haynes@qmul.ac.uk; Burgess, David; Sundberg, Torbjorn [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Camporeale, Enrico [Multiscale Dynamics, Centrum Wiskunde and Informatica (CWI), Amsterdam (Netherlands)
2015-01-15
We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas.
Chatterjee, Debjani; Misra, A P
2015-12-01
The nonlinear theory of amplitude modulation of electrostatic wave envelopes in a collisionless electron-positron (EP) pair plasma is studied by using a set of Vlasov-Poisson equations in the context of Tsallis' q-nonextensive statistics. In particular, the previous linear theory of Langmuir oscillations in EP plasmas [Saberian and Esfandyari-Kalejahi, Phys. Rev. E 87, 053112 (2013)] is rectified and modified. Applying the multiple scale technique (MST), it is shown that the evolution of electrostatic wave envelopes is governed by a nonlinear Schrödinger (NLS) equation with a nonlocal nonlinear term ∝P∫|ϕ(ξ',τ)|(2)dξ'ϕ/(ξ-ξ') [where P denotes the Cauchy principal value, ϕ is the small-amplitude electrostatic (complex) potential, and ξ and τ are the stretched coordinates in MST], which appears due to the wave-particle resonance. It is found that a subregion 1/3Landau damping) due to the nonlocal nonlinearity in the NLS equation. Furthermore, the effect of the nonlinear Landau damping is to slow down the amplitude of the wave envelope, and the corresponding decay rate can be faster the larger is the number of superthermal particles in pair plasmas.
Kerswell, R R; Willis, A P
2014-01-01
This article introduces, and reviews recent work using, a simple optimisation technique for analysing the nonlinear stability of a state in a dynamical system. The technique can be used to identify the most efficient way to disturb a system such that it transits from one stable state to another. The key idea is introduced within the framework of a finite-dimensional set of ordinary differential equations (ODEs) and then illustrated for a very simple system of 2 ODEs which possesses bistability. Then the transition to turbulence problem in fluid mechanics is used to show how the technique can be formulated for a spatially-extended system described by a partial differential equation (the well-known Navier-Stokes equation). Within that context, the optimisation technique bridges the gap between (linear) optimal perturbation theory and the (nonlinear) dynamical systems approach to fluid flows. The fact that the technique has now been recently shown to work in this very high dimensional setting augurs well for its...
Kerswell, R R; Pringle, C C T; Willis, A P
2014-08-01
This article introduces and reviews recent work using a simple optimization technique for analysing the nonlinear stability of a state in a dynamical system. The technique can be used to identify the most efficient way to disturb a system such that it transits from one stable state to another. The key idea is introduced within the framework of a finite-dimensional set of ordinary differential equations (ODEs) and then illustrated for a very simple system of two ODEs which possesses bistability. Then the transition to turbulence problem in fluid mechanics is used to show how the technique can be formulated for a spatially-extended system described by a set of partial differential equations (the well-known Navier-Stokes equations). Within that context, the optimization technique bridges the gap between (linear) optimal perturbation theory and the (nonlinear) dynamical systems approach to fluid flows. The fact that the technique has now been recently shown to work in this very high dimensional setting augurs well for its utility in other physical systems.
Munir, Asif; Shahzad, Azeem; Khan, Masood
2014-01-01
The major focus of this article is to analyze the forced convective heat transfer in a steady boundary layer flow of Sisko fluid over a nonlinear stretching sheet. Two cases are studied, namely (i) the sheet with variable temperature (PST case) and (ii) the sheet with variable heat flux (PHF case). The heat transfer aspects are investigated for both integer and non-integer values of the power-law index. The governing partial differential equations are reduced to a system of nonlinear ordinary differential equations using appropriate similarity variables and solved numerically. The numerical results are obtained by the shooting method using adaptive Runge Kutta method with Broyden's method in the domain[Formula: see text]. The numerical results for the temperature field are found to be strongly dependent upon the power-law index, stretching parameter, wall temperature parameter, material parameter of the Sisko fluid and Prandtl number. In addition, the local Nusselt number versus wall temperature parameter is also graphed and tabulated for different values of pertaining parameters. Further, numerical results are validated by comparison with exact solutions as well as previously published results in the literature.
Munir, Asif; Shahzad, Azeem; Khan, Masood
2014-01-01
The major focus of this article is to analyze the forced convective heat transfer in a steady boundary layer flow of Sisko fluid over a nonlinear stretching sheet. Two cases are studied, namely (i) the sheet with variable temperature (PST case) and (ii) the sheet with variable heat flux (PHF case). The heat transfer aspects are investigated for both integer and non-integer values of the power-law index. The governing partial differential equations are reduced to a system of nonlinear ordinary differential equations using appropriate similarity variables and solved numerically. The numerical results are obtained by the shooting method using adaptive Runge Kutta method with Broyden’s method in the domain. The numerical results for the temperature field are found to be strongly dependent upon the power-law index, stretching parameter, wall temperature parameter, material parameter of the Sisko fluid and Prandtl number. In addition, the local Nusselt number versus wall temperature parameter is also graphed and tabulated for different values of pertaining parameters. Further, numerical results are validated by comparison with exact solutions as well as previously published results in the literature. PMID:24949738
Nonlinear plasma processes and the formation of electron kappa distribution
Yoon, Peter
2016-07-01
The goal of nonequilibrium statistical mechanics is to establish fundamental relationship between the time irreversible macroscopic dynamics and the underlying time reversible behavior of microscopic system. The paradigm of achieving this seemingly paradoxical goal is through the concept of probability. For classical systems Boltzmann accomplished this through his H theorem and his kinetic equation for dilute gas. Boltzmann's H function is the same as classical extensive entropy aside from the minus sign, and his kinetic equation is applicable for short-range molecular interaction. For plasmas, the long-range electromagnetic force dictates the inter-particular interaction, and the underlying entropy is expected to exhibit non-extensive, or non-additive behavior. Among potential models for the non-additive entropy, the celebrated Tsallis entropy is the most well known. One of the most useful fundamental kinetic equations that governs the long-range plasma interaction is that of weak turbulence kinetic theory. At present, however, there is no clear-cut connection between the Tsallis entropy and the kinetic equations that govern plasma behavior. This can be contrasted to Boltzmann's H theorem, which is built upon his kinetic equation. The best one can do is to show that the consequences of Tsallis entropy and plasma kinetic equation are the same, that is, they both imply kappa distribution. This presentation will overview the physics of electron acceleration by beam-generated Langmuir turbulence, and discuss the asymptotic solution that rigorously can be shown to correspond to the kappa distribution. Such a finding is a strong evidence, if not water-tight proof, that there must be profound inter-relatioship between the Tsallis thermostatistical theory and the plasma kinetic theory.
Generation of zonal flows in rotating fluids and magnetized plasmas
DEFF Research Database (Denmark)
Juul Rasmussen, J.; Garcia, O.E.; Naulin, V.
2006-01-01
contribution the generation of zonal flows will be illustrated in a simple fluid experiment performed in a rotating container with radial symmetric bottom topography. An effective mixing that homogenizes the potential vorticity in the fluid layer will lead to the replacement of the high-potential vorticity...
A nonlinear model for magnetoacoustic waves in dense dissipative plasmas with degenerate electrons
Energy Technology Data Exchange (ETDEWEB)
Masood, W. [COMSATS Institute of Information Technology, Islamabad (Pakistan); National Centre for Physics (NCP), Shahdra Valley Road, Islamabad (Pakistan); Jahangir, R.; Siddiq, M. [National Centre for Physics (NCP), Shahdra Valley Road, Islamabad (Pakistan); Eliasson, B. [SUPA, Physics Department, University of Strathclyde, Glasgow (United Kingdom)
2014-10-15
The properties of nonlinear fast magnetoacoustic waves in dense dissipative plasmas with degenerate electrons are studied theoretically in the framework of the Zabolotskaya-Khokhlov (ZK) equation for small but finite amplitude excitations. Shock-like solutions of the ZK equation are obtained and are applied to parameters relevant to white dwarf stars.
Alffenaar, J. W. C.; van Altena, R.; Bokkerink, H. J.; Luijckx, G. J.; van Soolingen, D.; Aarnoutse, R. E.; van der Werf, T. S.
2009-01-01
Moxifloxacin cerebrospinal fluid (CSF) penetration was evaluated by obtaining full plasma and CSF time concentration curves for 4 patients with tuberculous meningitis. The geometric mean ratio of the areas under the curve for CSF to plasma were 0.82 (range, 0.70-0.94) at 400 mg once per day and 0.71
Bhattacharjee, Amitava
2012-01-01
To celebrate Professor Robert Dewar's 65th birthday, a Symposium was held on 31 October 2009 in Atlanta, Georgia, just before the 51st Annual Meeting of the Division of Plasma Physics of the American Physical Society. The Symposium was attended by many of Bob's colleagues, friends, postdoctoral colleagues and students (present and former). Boyd Blackwell, Anthony Cooper, Chris Hegna, Stuart Hudson, John Krommes, Alexander Pletzer, Ellen Zweibel, and I gave talks that covered various aspects of Bob's wide-ranging scholarship, and his leadership in the Australian and the US fusion program. At the Symposium, Bob gave an insightful talk, published in this issue as a paper with D Leykam. This paper makes available for the first time unpublished results from Bob's M Sc Thesis on a general method for calculating the potential around a `dressed' test particle in an isotropic and collisionless plasma. The paper is interesting not only because it provides a glimpse of the type of elegant applied mathematics that we have come to associate with Bob, but also because he discusses some leitmotifs in his intellectual evolution since the time he was a graduate student at the University of Melbourne and Princeton University. Through his early encounter with quantum field theory, Bob appreciated the power of Lagrangian and Hamiltonian formalisms, which he used with great effectiveness in nonlinear dynamics and plasma physics. A question that animates much of his work is one that underlies the `dressed' particle problem: if one is given a Hamiltonian with an unperturbed (or `bare') part and an interaction part, how is one to obtain a canonical transformation to `the oscillation centre' thatwould reduce the interaction part to an irreducible residual part while incorporating the rest in a renormalized zeroth-order Hamiltonian? One summer in Princeton, I worked with Bob on a possible variational formulation for this problem, and failed. I was daunted enough by my failure that I turned
Maglio, Dana; Teng, Renli; Thyrum, Per T.; Nightingale, Charles H.; Nicolau, David P.
2003-01-01
The pharmacokinetic disposition of meropenem, administered at 500 mg every 8 h, in plasma and cantharidin-induced blister fluid is described. Peak meropenem concentrations in blister fluid lagged behind peak meropenem concentrations in plasma, while a lower elimination rate from blister fluid was also noted. The mean penetration of meropenem into blister fluid was 67%. The pharmacokinetic profile of meropenem in blister fluid supports the utility of this dose in the management of skin and sof...
Maglio, Dana; Teng, Renli; Thyrum, Per T; Nightingale, Charles H; Nicolau, David P
2003-05-01
The pharmacokinetic disposition of meropenem, administered at 500 mg every 8 h, in plasma and cantharidin-induced blister fluid is described. Peak meropenem concentrations in blister fluid lagged behind peak meropenem concentrations in plasma, while a lower elimination rate from blister fluid was also noted. The mean penetration of meropenem into blister fluid was 67%. The pharmacokinetic profile of meropenem in blister fluid supports the utility of this dose in the management of skin and soft tissue infections.
Nonlinear Langmuir Wave Modulation in Weakly Magnetized Plasmas
DEFF Research Database (Denmark)
Dysthe, K. B.; Pécseli, Hans
1978-01-01
influence on the modulation stability of plane Langmuir waves. As in the unmagnetized case, kinetic results were found to deviate considerably from those obtained by using a fluid description for the ion dynamics. With particular attention to ionospheric phenomena, the effect is included of the spatially...... varying electron heating in the amplitude modulated Langmuir wave. For modulations travelling almost perpendicular to the magnetic field, this effect has a profound influence on a modulational instability...
Kinetic treatment of nonlinear magnetized plasma motions - General geometry and parallel waves
Khabibrakhmanov, I. KH.; Galinskii, V. L.; Verheest, F.
1992-01-01
The expansion of kinetic equations in the limit of a strong magnetic field is presented. This gives a natural description of the motions of magnetized plasmas, which are slow compared to the particle gyroperiods and gyroradii. Although the approach is 3D, this very general result is used only to focus on the parallel propagation of nonlinear Alfven waves. The derivative nonlinear Schroedinger-like equation is obtained. Two new terms occur compared to earlier treatments, a nonlinear term proportional to the heat flux along the magnetic field line and a higher-order dispersive term. It is shown that kinetic description avoids the singularities occurring in magnetohydrodynamic or multifluid approaches, which correspond to the degenerate case of sound speeds equal to the Alfven speed, and that parallel heat fluxes cannot be neglected, not even in the case of low parallel plasma beta. A truly stationary soliton solution is derived.
Nonlinear effects of inertial Alfvén wave in low beta plasmas
Energy Technology Data Exchange (ETDEWEB)
Rinawa, M. L., E-mail: motilal.rinawa@gmail.com; Gaur, Nidhi, E-mail: nidhiphysics@gmail.com; Sharma, R. P., E-mail: rpsharma@ces.iitd.ac.in [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India)
2015-02-15
This paper is devoted to the study of the nonlinear interaction and propagation of high frequency pump inertial Alfvén wave (IAW) with comparatively low frequency IAW with emphasis on nonlinear effects and applications within space plasma and astrophysics for low β-plasma (β≪m{sub e}/m{sub i}). We have developed a set of dimensionless equations in the presence of ponderomotive nonlinearity due to high frequency pump IAW in the dynamics of comparatively low frequency IAW. Stability analysis and numerical simulation have been carried out for the coupled system comprising of pump IAW and low frequency IAW to study the localization and turbulent spectra, applicable to auroral region. The result reveals that localized structures become more complex and intense in nature at the quasi steady state. From the obtained result, we found that the present model may be useful to study the turbulent fluctuations in accordance with the observations of FAST/THEMIS spacecraft.
Role of nonlinear localized structures and turbulence in magnetized plasma
Pathak, Neha; Yadav, Nitin; Uma, R.; Sharma, R. P.
2016-09-01
In the present study, we have analyzed the field localization of kinetic Alfvén wave (KAW) due to the presence of background density perturbation, which are assumed to be originated by the three dimensionally propagating low frequency KAW. These localized structures play an important role for energy transportation at smaller scales in the dispersion range of magnetic power spectrum. For the present model, governing dynamic equations of high frequency pump KAW and low frequency KAW has been derived by considering ponderomotive nonlinearity. Further, these coupled equations have been numerically solved to analyze the resulting localized structures of pump KAW and magnetic power spectrum in the magnetopause regime. Numerically calculated spectrum exhibits inertial range having spectral index of -3/2 followed by steeper scaling; this steepening in the turbulent spectrum is a signature of energy transportation from larger to smaller scales. In this way, the proposed mechanism, which is based on nonlinear wave-wave interaction, may be useful for understanding the particle acceleration and turbulence in magnetopause.
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%.
Electron vortex magnetic holes: a nonlinear coherent plasma structure
Haynes, Christopher T; Camporeale, Enrico; Sundberg, Torbjorn
2014-01-01
We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional PIC simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is ...
Multi-fluid studies of plasma shocks relevant to inertial confinement fusion
Srinivasan, B.; Kagan, G.; Adams, C. S.
2016-05-01
Results from inertial confinement fusion (ICF) experiments performed at the Omega laser facility suggest the potential role of kinetic effects in plasmas during implosion. Recent theoretical and numerical work has indicated the importance of diffusion effects in the presence of multiple ion species as well as the importance of ion viscosity. This provides the motivation to adequately develop multi-fluid plasma models capable of capturing kinetic physics including concentration diffusion and ion species separation driven by the ion concentration gradient, the ion pressure gradient, the electron and ion temperature gradients, and the electric field. Benchmarks between the newly developed code and analytical results are presented for multi-fluid plasma shocks.
Role of Density Profiles for the Nonlinear Propagation of Intense Laser Beam through Plasma Channel
Directory of Open Access Journals (Sweden)
Sonu Sen
2014-01-01
Full Text Available In this work role of density profiles for the nonlinear propagation of intense laser beam through plasma channel is analyzed. By employing the expression for the dielectric function of different density profile plasma, a differential equation for beamwidth parameter is derived under WKB and paraxial approximation. The laser induces modifications of the dielectric function through nonlinearities. It is found that density profiles play vital role in laser-plasma interaction studies. To have numerical appreciation of the results the propagation equation for plasma is solved using the fourth order Runge-Kutta method for the initial plane wave front of the beam, using boundary conditions. The spot size of the laser beam decreases as the beam penetrates into the plasma and significantly adds self-focusing in plasma. This causes the laser beam to become more focused by reduction of diffraction effect, which is an important phenomenon in inertial confinement fusion and also for the understanding of self-focusing of laser pulses. Numerical computations are presented and discussed in the form of graphs for typical parameters of laser-plasma interaction.
Nonlinear dynamics of phase space zonal structures and energetic particle physics in fusion plasmas
Zonca, Fulvio; Briguglio, Sergio; Fogaccia, Giuliana; Vlad, Gregorio; Wang, Xin
2014-01-01
A general theoretical framework for investigating nonlinear dynamics of phase space zonal structures is presented in this work. It is then, more specifically, applied to the limit where the nonlinear evolution time scale is smaller or comparable to the wave-particle trapping period. In this limit, both theoretical and numerical simulation studies show that non-adiabatic frequency chirping and phase locking could lead to secular resonant particle transport on meso- or macro-scales. The interplay between mode structures and resonant particles then provides the crucial ingredient to properly understand and analyze the nonlinear dynamics of Alfv\\'en wave instabilities excited by non-perturbative energetic particles in burning fusion plasmas. Analogies with autoresonance in nonlinear dynamics and with superradiance in free electron lasers are also briefly discussed.
Directory of Open Access Journals (Sweden)
Renlong Zhou
2014-01-01
Full Text Available We have studied the excitation second-order nonlinearity through a triangular lattice perforated gold film instead of square lattice in many papers. Under the excitation of surface plasmas resonance effect, the second order nonlinearity exists in the noncentrosymmetric split-ring resonators arrays. Reflection of fundamental frequency wave through a triangular lattice perforated gold film is obtained. We also described the second harmonic conversion efficiencies in the second order nonlinear optical process with the spectra. Moreover, the electric field distributions of fundamental frequency above the gold film region are calculated. The light propagation through the holes results in the enhancement of the second order nonlinearity including second harmonic generation as well as the sum (difference frequency generation.
Intermittency, nonlinear dynamics and dissipation in the solar wind and astrophysical plasmas.
Matthaeus, W H; Wan, Minping; Servidio, S; Greco, A; Osman, K T; Oughton, S; Dmitruk, P
2015-05-13
An overview is given of important properties of spatial and temporal intermittency, including evidence of its appearance in fluids, magnetofluids and plasmas, and its implications for understanding of heliospheric plasmas. Spatial intermittency is generally associated with formation of sharp gradients and coherent structures. The basic physics of structure generation is ideal, but when dissipation is present it is usually concentrated in regions of strong gradients. This essential feature of spatial intermittency in fluids has been shown recently to carry over to the realm of kinetic plasma, where the dissipation function is not known from first principles. Spatial structures produced in intermittent plasma influence dissipation, heating, and transport and acceleration of charged particles. Temporal intermittency can give rise to very long time correlations or a delayed approach to steady-state conditions, and has been associated with inverse cascade or quasi-inverse cascade systems, with possible implications for heliospheric prediction.
Weakly nonlinear ion-acoustic excitations in a relativistic model for dense quantum plasma.
Behery, E E; Haas, F; Kourakis, I
2016-02-01
The dynamics of linear and nonlinear ionic-scale electrostatic excitations propagating in a magnetized relativistic quantum plasma is studied. A quantum-hydrodynamic model is adopted and degenerate statistics for the electrons is taken into account. The dispersion properties of linear ion acoustic waves are examined in detail. A modified characteristic charge screening length and "sound speed" are introduced, for relativistic quantum plasmas. By employing the reductive perturbation technique, a Zakharov-Kuznetzov-type equation is derived. Using the small-k expansion method, the stability profile of weakly nonlinear slightly supersonic electrostatic pulses is also discussed. The effect of electron degeneracy on the basic characteristics of electrostatic excitations is investigated. The entire analysis is valid in a three-dimensional as well as in two-dimensional geometry. A brief discussion of possible applications in laboratory and space plasmas is included.
Linear and nonlinear dynamics of current-driven waves in dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Ahmad, Ali [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Ali Shan, S.; Haque, Q. [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Saleem, H. [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan)
2012-09-15
The linear and nonlinear dynamics of a recently proposed plasma mode of dusty plasma is studied using kappa distribution for electrons. This electrostatic wave can propagate in the plasma due to the sheared flow of electrons and ions parallel to the external magnetic field in the presence of stationary dust. The coupling of this wave with the usual drift wave and ion acoustic wave is investigated. D'Angelo's mode is also modified in the presence of superthermal electrons. In the nonlinear regime, the wave can give rise to dipolar vortex structures if the shear in flow is weaker and tripolar vortices if the flow has steeper gradient. The results have been applied to Saturn's magnetosphere corresponding to negatively charged dust grains. But the theoretical model is applicable for positively charged dust as well. This work will be useful for future observations and studies of dusty environments of planets and comets.
The Fluid-Kinetic Particle-in-Cell Solver for Plasma Simulations
Markidis, Stefano; Lapenta, Giovanni; Ronnmark, Kjell; Hamrin, Maria; Meliani, Zakaria; Laure, Erwin
2013-01-01
A new method that solves concurrently the multi-fluid and Maxwell's equations has been developed for plasma simulations. By calculating the stress tensor in the multi-fluid momentum equation by means of computational particles moving in a self-consistent electromagnetic field, the kinetic effects are retained while solving the multi-fluid equations. The Maxwell's and multi-fluid equations are discretized implicitly in time enabling kinetic simulations over time scales typical of the fluid simulations. The fluid-kinetic Particle-in-Cell solver has been implemented in a three-dimensional electromagnetic code, and tested against the ion cyclotron resonance and magnetic reconnection problems. The new method is a promising approach for coupling fluid and kinetic methods in a unified framework.
Institute of Scientific and Technical Information of China (English)
LIN Chang; ZHANG Xiu-Lian
2005-01-01
The nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation is analytically investigated by using the formally variable separation approach. New analytical solutions for the governing equation of this system have been obtained for dust acoustic waves in a dust plasma for the first time. We derive exact analytical expressions for the general case of the nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation.
Swanson, DG
1989-01-01
Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th
Energy Technology Data Exchange (ETDEWEB)
Savel' ev, Sergey; Yampol' skii, V A; Rakhmanov, A L; Nori, Franco [Advanced Science Institute, Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama 351-0198 (Japan)
2010-02-15
The recent growing interest in terahertz (THz) and sub-THz science and technology is due to its many important applications in physics, astronomy, chemistry, biology and medicine, including THz imaging, spectroscopy, tomography, medical diagnosis, health monitoring, environmental control, as well as chemical and biological identification. We review the problem of linear and nonlinear THz and sub-THz Josephson plasma waves in layered superconductors and their excitations produced by moving Josephson vortices. We start by discussing the coupled sine-Gordon equations for the gauge-invariant phase difference of the order parameter in the junctions, taking into account the effect of breaking the charge neutrality, and deriving the spectrum of Josephson plasma waves. We also review surface and waveguide Josephson plasma waves. The spectrum of these waves is presented, and their excitation is discussed. We review the propagation of weakly nonlinear Josephson plasma waves below the plasma frequency, {omega}{sub J}, which is very unusual for plasma-like excitations. In close analogy to nonlinear optics, these waves exhibit numerous remarkable features, including a self-focusing effect and the pumping of weaker waves by a stronger one. In addition, an unusual stop-light phenomenon, when {partial_derivative}{omega}/{partial_derivative}k {approx} 0, caused by both nonlinearity and dissipation, can be observed in the Josephson plasma waves. At frequencies above {omega}{sub J}, the current-phase nonlinearity can be used for transforming continuous sub-THz radiation into short, strongly amplified, pulses. We also present quantum effects in layered superconductors, specifically, the problem of quantum tunneling of fluxons through stacks of Josephson junctions. Moreover, the nonlocal sine-Gordon equation for Josephson vortices is reviewed. We discuss the Cherenkov and transition radiations of the Josephson plasma waves produced by moving Josephson vortices, either in a single
Multidimensional Plasma Wake Excitation in the Non-linear Blowout Regime
Vieira, J; Silva, L O
2016-01-01
Plasma accelerators can sustain very high acceleration gradients. They are promising candidates for future generations of particle accelerators for sev- eral scientific, medical and technological applications. Current plasma based acceleration experiments operate in the relativistic regime, where the plasma response is strongly non-linear. We outline some of the key properties of wake- field excitation in these regimes. We outline a multidimensional theory for the excitation of plasma wakefields in connection with current experiments. We then use these results and provide design guidelines for the choice of laser and plasma parameters ensuring a stable laser wakefield accelerator that maximizes the quality of the accelerated electrons. We also mention some of the future challenges associated with this technology.
Improved energy confinement with nonlinear isotope effects in magnetically confined plasmas
Garcia, J; Jenko, F
2016-01-01
The efficient production of electricity from nuclear fusion in magnetically confined plasmas relies on a good confinement of the thermal energy. For more than thirty years, the observation that such confinement depends on the mass of the plasma isotope and its interaction with apparently unrelated plasma conditions has remained largely unexplained and it has become one of the main unsolved issues. By means of numerical studies based on the gyrokinetic theory, we quantitatively show how the plasma microturbulence depends on the isotope mass through nonlinear multiscale microturbulence effects involving the interplay between zonal flows, electromagnetic effects and the torque applied. This finding has crucial consequences for the design of future reactors since, in spite of the fact that they will be composed by multiple ion species, their extrapolation from present day experiments heavily relies on the knowledge obtained from a long experimental tradition based in single isotope plasmas.
Two-fluid biasing simulations of the large plasma device
Fisher, Dustin M.; Rogers, Barrett N.
2017-02-01
External biasing of the Large Plasma Device (LAPD) and its impact on plasma flows and turbulence are explored for the first time in 3D simulations using the Global Braginskii Solver code. Without external biasing, the LAPD plasma spontaneously rotates in the ion diamagnetic direction. The application of a positive bias increases the plasma rotation in the simulations, which show the emergence of a coherent Kelvin Helmholtz (KH) mode outside of the cathode edge with poloidal mode number m ≃6 . Negative biasing reduces the rotation in the simulations, which exhibit KH turbulence modestly weaker than but otherwise similar to unbiased simulations. Biasing either way, but especially positively, forces the plasma potential inside the cathode edge to a spatially constant, KH-stable profile, leading to a more quiescent core plasma than the unbiased case. A moderate increase in plasma confinement and an associated steepening of the profiles are seen in the biasing runs. The simulations thus show that the application of external biasing can improve confinement while also driving a Kelvin-Helmholtz instability. Ion-neutral collisions have only a weak effect in the biased or unbiased simulations.
Development Of Sputtering Models For Fluids-Based Plasma Simulation Codes
Veitzer, Seth; Beckwith, Kristian; Stoltz, Peter
2015-09-01
Rf-driven plasma devices such as ion sources and plasma processing devices for many industrial and research applications benefit from detailed numerical modeling. Simulation of these devices using explicit PIC codes is difficult due to inherent separations of time and spatial scales. One alternative type of model is fluid-based codes coupled with electromagnetics, that are applicable to modeling higher-density plasmas in the time domain, but can relax time step requirements. To accurately model plasma-surface processes, such as physical sputtering and secondary electron emission, kinetic particle models have been developed, where particles are emitted from a material surface due to plasma ion bombardment. In fluid models plasma properties are defined on a cell-by-cell basis, and distributions for individual particle properties are assumed. This adds a complexity to surface process modeling, which we describe here. We describe the implementation of sputtering models into the hydrodynamic plasma simulation code USim, as well as methods to improve the accuracy of fluids-based simulation of plasmas-surface interactions by better modeling of heat fluxes. This work was performed under the auspices of the Department of Energy, Office of Basic Energy Sciences Award #DE-SC0009585.
Directory of Open Access Journals (Sweden)
Taha Aziz
2013-01-01
Full Text Available This study is based upon constructing a new class of closed-form shock wave solutions for some nonlinear problems arising in the study of a third grade fluid model. The Lie symmetry reduction technique has been employed to reduce the governing nonlinear partial differential equations into nonlinear ordinary differential equations. The reduced equations are then solved analytically, and the shock wave solutions are constructed. The conditions on the physical parameters of the flow problems also fall out naturally in the process of the derivation of the solutions.
Directory of Open Access Journals (Sweden)
Kim Gaik Tay
2010-04-01
Full Text Available In the present work, by considering the artery as a prestressed thin-walled elastic tube with a symmetrical stenosis and the blood as an incompressible viscous fluid, we have studied the amplitude modulation of nonlinear waves in such a composite medium through the use of the reductive perturbation method [23]. The governing evolutions can be reduced to the dissipative non-linear Schrodinger (NLS equation with variable coefficient. The progressive wave solution to the above non-linear evolution equation is then sought.
Credille, B C; Giguère, S; Vickroy, T W; Fishman, H J; Jones, A L; Mason, M E; DiPietro, R O; Ensley, D T
2015-08-01
The objective of this study was to determine the disposition of ampicillin in plasma, uterine tissue, lochial fluid, and milk of postpartum dairy cattle. Ampicillin trihydrate was administered by intramuscular (i.m.) injection at a dose of 11 mg/kg of body weight every 24 h (n = 6, total of 3 doses) or every 12 h (n = 6, total of 5 doses) for 3 days. Concentrations of ampicillin were measured in plasma, uterine tissue, lochial fluid, and milk using HPLC with ultraviolet absorption. Quantifiable ampicillin concentrations were found in plasma, milk, and lochial fluid of all cattle within 30 min, 4 h, and 4 h of administration of ampicillin trihydrate, respectively. There was no significant effect of dosing interval (every 12 vs. every 24 h) and no significant interactions between dosing interval and sampling site on the pharmacokinetic variable measured or calculated. Median peak ampicillin concentration at steady-state was significantly higher in lochial fluid (5.27 μg/mL after q 24 h dosing) than other body fluids or tissues and significantly higher in plasma (3.11 μg/mL) compared to milk (0.49 μg/mL) or endometrial tissue (1.55 μg/mL). Ampicillin trihydrate administered once daily by the i.m. route at the label dose of 11 mg/kg of body weight achieves therapeutic concentrations in the milk, lochial fluid, and endometrial tissue of healthy postpartum dairy cattle.
Nonlinear Alfvén wave propagating in ideal MHD plasmas
Zheng, Jugao; Chen, Yinhua; Yu, Mingyang
2016-01-01
The behavior of nonlinear Alfvén waves propagating in ideal MHD plasmas is investigated numerically. It is found that in a one-dimensional weakly nonlinear system an Alfvén wave train can excite two longitudinal disturbances, namely an acoustic wave and a ponderomotively driven disturbance, which behave differently for β \\gt 1 and β \\lt 1, where β is the ratio of plasma-to-magnetic pressures. In a strongly nonlinear system, the Alfvén wave train is modulated and can steepen to form shocks, leading to significant dissipation due to appearance of current sheets at magnetic-pressure minima. For periodic boundary condition, we find that the Alfvén wave transfers its energy to the plasma and heats it during the shock formation. In two-dimensional systems, fast magneto-acoustic wave generation due to Alfvén wave phase mixing is considered. It is found that the process depends on the amplitude and frequency of the Alfvén waves, as well as their speed gradients and the pressure of the background plasma.
Institute of Scientific and Technical Information of China (English)
Zhang Li-Ping; Xue Ju-Kui; Li Yan-Long
2011-01-01
Both linear and nonlinear excitation in dusty plasmas have been investigated including the nonadiabatic dust charge fluctuation and Gaussian size distribution dust particles.A linear dispersion relation and a Korteweg-de VriesBurgers equation governing the dust acoustic shock waves are obtained.The relevance of the instability of wave and the wave evolution to the dust size distribution and nonadiabatic dust charge fluctuation is illustrated both analytically and numerically.The numerical results show that the Gaussian size distribution of dust particles and the nonadiabatic dust charge fluctuation have strong common influence on the propagation of both linear and nonlinear excitations.
Reduction of the equation for lower hybrid waves in a plasma to a nonlinear Schroedinger equation
Karney, C. F. F.
1977-01-01
Equations describing the nonlinear propagation of waves in an anisotropic plasma are rarely exactly soluble. However it is often possible to make approximations that reduce the exact equations into a simpler equation. The use of MACSYMA to make such approximations, and so reduce the equation describing lower hybrid waves into the nonlinear Schrodinger equation which is soluble by the inverse scattering method is demonstrated. MACSYMA is used at several stages in the calculation only because there is a natural division between calculations that are easiest done by hand, and those that are easiest done by machine.
Nonlinear dynamic analysis of cantilever tube conveying fluid with system identification
Energy Technology Data Exchange (ETDEWEB)
Lim, Jae Hoon; Choi, Yeon Sun [Sungkyunkwan Univ., Suwon (Korea, Republic of); Jung, Goo Choong [Daelim Industrial Co., Ltd., Seoul (Korea, Republic of)
2003-12-01
The vibration of a flexible cantilever tube with nonlinear constraints when it is subjected to flow internally with fluids is examined by experimental and theoretical analysis. These kinds of studies have been performed to find the existence of chaotic motion. In this paper, the important parameters of the system leading to such a chaotic motion such as Young's modulus and the coefficient of viscoelastic damping are discussed. The parameters are investigated by means of system identification so that comparisons are made between numerical analysis using the design parameters and the experimental results. The chaotic region led by several period-doubling bifurcations beyond the Hopf bifurcation is also re-established with phase portraits, bifurcation diagram and Lyapunov exponent so that one can define optimal parameters for system design.
Helical waves and non-linear dynamics of fluid/structure interactions in a tube row
Energy Technology Data Exchange (ETDEWEB)
Moon, F.C.; Thothadri, M. [Cornell Univ., Ithaca, NY (United States)
1997-12-31
The goal of this study has been to investigate low-dimensional models for fluid-structure dynamics of flow across a row of cylindrical tubes. Four principle results of this experimental-theoretical study are discussed. (i) Experimental evidence has shown that the dynamic instability of the tube row is a subcritical Hopf bifurcation. (ii) The critical flow velocity decreases as the number of flexible cylinders increases. (iii) The linear model exhibits coupled helical wave solutions in the tube dynamics. (iv) A nonlinear model of the tube motions shows a complex subcritical Hopf bifurcation with a secondary bifurcation to a torus or quasi-periodic oscillation. In this analysis the tools of center manifolds, normal forms and numerical simulation are used.
Current-vortex filament model of nonlinear Alfven perturbations in a finite-pressure plasma
Lakhin, V. P.; Schep, T. J.; Westerhof, E.
1998-01-01
A low-beta, two-fluid model is shown to possess solutions in the form of current-vortex filaments. The model can be viewed as that of reduced magnetohydrodynamics, extended with electron inertia, the Hall term and parallel electron pressure. These drift-Alfven filaments are the plasma analogs of poi
Selection principles and pattern formation in fluid mechanics and nonlinear shell theory
Sather, Duane P.
1987-01-01
Research accomplishments are summarized and publications generated under the contract are listed. The general purpose of the research was to investigate various symmetry breaking problems in fluid mechanics by the use of structure parameters and selection principles. Although all of the nonlinear problems studied involved systems of partial differential equations, many of these problems led to the study of a single nonlinear operator equation of the form F(w, lambda, gamma) = 0, (w is an element of H), (lambda is an element of R1), (gamma is an element of R1). Instead of varying only the load parameter lambda, as is often done in the study of such equations, one of the main ideas used was to vary the structure parameter gamma in such a way that stable solutions were obtained. In this way one determines detailed stability results by making use of the structure of the model equations and the known physical parameters of the problem. The approach was carried out successfully for Benard-type convection problems, Taylor-like problems for short cylinders, rotating Couette-Poiseuille channel flows, and plane Couette flows. The main focus of the research was on wave theory of vortex breakdown in a tube. A number of preliminary results for inviscid axisymmetric flows were obtained.
Classical fluid aspects of nonlinear SchrÃƒÂ¶dinger equations and solitons
Directory of Open Access Journals (Sweden)
James G. Gilson
1987-01-01
Full Text Available The author extends his alternative theory for SchrÃƒÂ¶dinger quantum mechanics by introducing the idea of energy reference strata over configuration space. It is then shown that the view from various such strata defines, the content of the system of interest and enables a variety of different descriptions of events in the same space time region. Thus according to Ã‚Â“the point of viewÃ‚Â” or energy stratum chosen so the type of SchrÃƒÂ¶dinger equation, linear or otherwise, appropriate to describe the system is determined. A nonlinear information channel between two dimensional fluid action in hyperspace into two dimensional energy hyperspace is shown to exist generally as a background to nonlinear SchrÃƒÂ¶dinger structures. In addition it is shown how soliton solutions of the one dimensional SchrÃƒÂ¶dinger equation are related to two dimensional vortex fields in hyperspace.
The effect of nonlinear thermo-fluid-dynamic terms on free-piston Stirling machine stability
Energy Technology Data Exchange (ETDEWEB)
Benvenuto, G. [Univ. of Genoa (Italy). Dipt. di Ingegneria Navale; Monte, F. de [Univ. of L`Aquila (Italy). Dipt. de Energetica
1996-12-31
In this work a new linearization technique of the dynamic balance equations of a free-piston Stirling machine is developed. It takes into account the nonlinear thermo-fluid-dynamic terms inherent in the machine, although keeping the linearity of the differential dynamic equations. This allows the equations of motion to be solved still analytically and, therefore, useful algebraic relations (already established by the authors in past studies) linking together the various machine parameters to be used. The advantages related to the proposed linearization methodology are the following: (1) it gives a right interpretation of the machine working when the operational parameters vary, because the considered nonlinear terms have a stabilizing effect; (2) it can be used to predict the machine performance not only with more accuracy, but especially in a more exhaustive way, allowing to estimate also the piston stroke and, therefore, the delivered power; (3) it enables to design the machine in such a way to enhance its stability, thus eliminating the necessity of power control systems.
Nonlinear dynamics of beam-plasma instability in a finite magnetic field
Bogdankevich, I. L.; Goncharov, P. Yu.; Gusein-zade, N. G.; Ignatov, A. M.
2017-06-01
The nonlinear dynamics of beam-plasma instability in a finite magnetic field is investigated numerically. In particular, it is shown that decay instability can develop. Special attention is paid to the influence of the beam-plasma coupling factor on the spectral characteristics of a plasma relativistic microwave accelerator (PRMA) at different values of the magnetic field. It is shown that two qualitatively different physical regimes take place at two values of the external magnetic field: B 0 = 4.5 kG (Ω ω B p ) and 20 kG (Ω B ≫ ωp). For B 0 = 4.5 kG, close to the actual experimental value, there exists an optimal value of the gap length between the relativistic electron beam and the plasma (and, accordingly, an optimal value of the coupling factor) at which the PRMA output power increases appreciably, while the noise level decreases.
Tanjia, Fatema; Fedele, Renato; Shukla, P K; Jovanovic, Dusan
2011-01-01
A numerical analysis of the self-interaction induced by a relativistic electron/positron beam in the presence of an intense external longitudinal magnetic field in plasmas is carried out. Within the context of the Plasma Wake Field theory in the overdense regime, the transverse beam-plasma dynamics is described by a quantumlike Zakharov system of equations in the long beam limit provided by the Thermal Wave Model. In the limiting case of beam spot size much larger than the plasma wavelength, the Zakharov system is reduced to a 2D Gross-Pitaevskii-type equation, where the trap potential well is due to the external magnetic field. Vortices, "beam halos" and nonlinear coherent states (2D solitons) are predicted.
Nonlinear ion-acoustic waves in a degenerate plasma with nuclei of heavy elements
Energy Technology Data Exchange (ETDEWEB)
Hossen, M. A., E-mail: armanplasma@gmail.com; Mamun, A. A., E-mail: mamun-phys@yahoo.co.uk [Department of Physics, Jahangirnagar University, Savar, Dhaka-1342 (Bangladesh)
2015-10-15
The ion-acoustic (IA) solitary waves propagating in a fully relativistic degenerate dense plasma (containing relativistic degenerate electron and ion fluids, and immobile nuclei of heavy elements) have been theoretically investigated. The relativistic hydrodynamic model is used to derive the Korteweg-de Vries (K-dV) equation by the reductive perturbation method. The stationary solitary wave solution of this K-dV equation is obtained to characterize the basic features of the IA solitary structures that are found to exist in such a degenerate plasma. It is found that the effects of electron dynamics, relativistic degeneracy of the plasma fluids, stationary nuclei of heavy elements, etc., significantly modify the basic properties of the IA solitary structures. The implications of this results in astrophysical compact objects like white dwarfs are briefly discussed.
Non-linear Dynamics in ETG Mode Saturation and Beam-Plasma Instabilities
Tokluoglu, Erinc K.
Non-linear mechanisms arise frequently in plasmas and beam-plasma systems resulting in dynamics not predicted by linear theory. The non-linear mechanisms can influence the time evolution of plasma instabilities and can be used to describe their saturation. Furthermore time and space averaged non-linear fields generated by instabilities can lead to collisionless transport and plasma heating. In the case of beam-plasma systems counter-intuitive beam defocusing and scaling behavior which are interesting areas of study for both Low-Temperature and High Energy Density physics. The non-linear mode interactions in form of phase coupling can describe energy transfer to other modes and can be used to describe the saturation of plasma instabilities. In the first part of this thesis, a theoretical model was formulated to explain the saturation mechanism of Slab Electron Temperature Gradient (ETG) mode observed in the Columbia Linear Machine (CLM), based on experimental time-series data collected through probe diagnostics [1]. ETG modes are considered to be a major player in the unexplained high levels of electron transport observed in tokamak fusion experiments and the saturation mechanism of these modes is still an active area of investigation. The data in the frequency space indicated phase coupling between 3 modes, through a higher order spectral correlation coefficient known as bicoherence. The resulting model is similar to [2], which was a treatment for ITG modes observed in the CLM and correctly predicts the observed saturation level of the ETG turbulence. The scenario is further supported by the fact that the observed mode frequencies are in close alignment with those predicted theoretical dispersion relations. Non-linear effects arise frequently in beam-plasma systems and can be important for both low temperature plasma devices commonly used for material processing as well as High Energy Density applications relevant to inertial fusion. The non-linear time averaged
Remigius, W. Dheelibun; Sarkar, Sunetra; Gupta, Sayan
2017-03-01
Use of heavy gases in centrifugal compressors for enhanced oil extraction have made the impellers susceptible to failures through acousto-elastic instabilities. This study focusses on understanding the dynamical behavior of such systems by considering the effects of the bounded fluid housed in a casing on a rotating disc. First, a mathematical model is developed that incorporates the interaction between the rotating impeller - modelled as a flexible disc - and the bounded compressible fluid medium in which it is immersed. The nonlinear effects arising due to large deformations of the disc have been included in the formulation so as to capture the post flutter behavior. A bifurcation analysis is carried out with the disc rotational speed as the bifurcation parameter to investigate the dynamical behavior of the coupled system and estimate the stability boundaries. Parametric studies reveal that the relative strengths of the various dissipation mechanisms in the coupled system play a significant role that affect the bifurcation route and the post flutter behavior in the acousto-elastic system.
Capturing nonlinear dynamics of two-fluid Couette flows with asymptotic models
Papageorgiou, Demetrios; Cimpeanu, Radu; Kalogirou, Anna; Keaveny, Eric
2016-11-01
The nonlinear stability of two-fluid Couette flows is studied using a novel evolution equation whose dynamics are validated by direct numerical simulations (DNS). The evolution equation incorporates inertial effects at arbitrary Reynolds numbers through a nonlocal term arising from the coupling between the two fluid regions, and is valid when one of the layers is thin. The equation predicts asymmetric solutions and exhibits bistability as seen in experiments. Related low-inertia models have been used in qualitative predictions using ad hoc modifications rather than the direct comparisons carried out here. Comparisons between model solutions and DNS show excellent agreement at Reynolds numbers of O (103) found in experiments. Direct comparisons are also made with the available experimental results of Barthelet et al. (1995) when the thin layer occupies 1 / 5 of the channel height. Pointwise comparisons of the travelling wave shapes are carried out and once again the agreement is very good. EPSRC Grant Numbers EP/K041134 and EP/L020564.
Nonlinear propagation of ion-acoustic waves in a degenerate dense plasma
Indian Academy of Sciences (India)
M M Masud; A A Mamun
2013-07-01
Nonlinear propagation of ion-acoustic (IA) waves in a degenerate dense plasma (with all the constituents being degenerate, for both the non-relativistic or ultrarelativistic cases) have been investigated by the reductive perturbation method. The linear dispersion relation and Korteweg de Vries (KdV) equation have been derived, and the numerical solutions of KdV equation have been analysed to identify the basic features of electrostatic solitary structures that may form in such a degenerate dense plasma. The implications of our results in compact astrophysical objects, particularly, in white dwarfs and neutron stars, have been briefly discussed.
Electrostatic Nonlinear Structures in Dissipative Electron-Positron-Ion Quantum Plasmas
Institute of Scientific and Technical Information of China (English)
S. A. Khan; Q. Haque
2008-01-01
@@ Low frequency (in comparison to ion plasma frequency) ion-acoustic shocks and solitons in superdense electron-positron-ion quantum plasmas are studied.The quantum hydrodynamic model is used incorporating quantum Bohm forces and Fermi-Dirac statistical corrections to derive the deformed Korteweg de Vries-Burgers (dKdVB) equation in weakly nonlinear limit.The travelling wave solution of dKdVB equation is presented and results are discussed in different limits.It is found that shock height increases with increase of quantum pressure, positron concentration and dissipation.Further, it is seen that the width of soliton decreases with increase of quantum pressure.
Effect of nonlinear wave collapse on line shapes in a plasma
Hannachi, I.; Stamm, R.; Rosato, J.; Marandet, Y.
2016-04-01
The nonlinear interaction of waves can change the structural and radiative properties of plasmas. We describe the main features of a fully ionized unmagnetized plasma affected by strong Langmuir turbulence characterized by nonlinear wave collapse, and propose a simple model for evaluating the changes expected on a hydrogen line shape affected by such conditions. Our model is based on a stochastic renewal model using an exponential waiting time distribution and a half-normal probability density function for the electric-field magnitude of the turbulent wave packet. The first results obtained with a simulation calculation of the hydrogen \\text{L}α line show that strong Langmuir turbulence can provide an additional broadening to a Stark profile.
Miwadinou, C H; Monwanou, A V; Orou, J B Chabi
2013-01-01
This paper considers nonlinear dynamics of plasma oscillations modeled by a forced modified Van der Pol-Duffing oscillator. These plasma oscillations are described by a nonlinear differential equation of the form $ \\ddot{x}+ \\epsilon (1 +{x}^{2}){\\dot{x}} + x+ \\alpha \\epsilon{x}{\\dot{x}} + {\\beta}x^{2}+\\gamma x^{3}= F\\cos{\\Omega t}.$ The amplitudes of the forced harmonic, superharmonic and subharmonic oscillatory states are obtained using the harmonic balance technique and the multiple time scales methods. Bifurcation sequences displayed by the model for each type of oscillatory states are performed numerically through the fourth order Runge- Kutta scheme. The influences of the differents parameters and of amplitude of external forced have been found.
Indian Academy of Sciences (India)
Tarsem Singh Gill; Harvinder Kaur
2000-11-01
The effects of nonthermal ion distribution and ﬁnite dust temperature are incorporated in the investigation of nonlinear dust acoustic waves in an unmagnetized dusty plasma. Sagdeev pseudopotential method which takes into account the full nonlinearity of plasma equations, is used here to study solitary wave solutions. Possibility of co-existence of refractive and compressive solitons as a function of Mach number, dust temperature and concentration of nonthermal ions, is considered. For the ﬁxed value of nonthermal ions, it is found that the effect of increase in dust temperature is to reduce the range of co-existence of compressive and refractive solitons. Particular concentration of nonthermal ions results in disappearance of refractive solitons while the decrease in dust temperature, at this concentration restores the lost refractive solitons.
Analytical Predictions of Field and Plasma Dynamics during Nonlinear Weibel-Mediated Flow Collisions
Ruyer, C.; Gremillet, L.; Bonnaud, G.; Riconda, C.
2016-08-01
The formation of collisionless shocks mediated by the ion Weibel instability is addressed theoretically and numerically in the nonrelativistic limit. First, the model developed in C. Ruyer et al., Phys. Plasmas 22, 032102 (2015) for the weakly nonlinear ion Weibel instability in a symmetric two-stream system is shown to be consistent with recent experimental and simulation results. Large-scale kinetic simulations are then performed to clarify the spatiotemporal evolution of the magnetic-field and plasma properties in the subsequent strongly nonlinear phase leading to shock formation. A simple analytical model is proposed which captures the simulation results up to a point close to ion isotropization. Electron screening effects are found important in the instability dynamics, so that numerical simulations using a nonphysical electron mass should be considered with caution.
Relativistic nonlinearity and wave-guide propagation of rippled laser beam in plasma
Indian Academy of Sciences (India)
R K Khanna; K Baheti
2001-06-01
In the present paper we have investigated the self-focusing behaviour of radially symmetrical rippled Gaussian laser beam propagating in a plasma. Considering the nonlinearity to arise from relativistic phenomena and following the approach of Akhmanov et al, which is based on the WKB and paraxial-ray approximation, the self-focusing behaviour has been investigated in some detail. The effect of the position and width of the ripple on the self-focusing of laser beam has been studied for arbitrary large magnitude of nonlinearity. Results indicate that the medium behaves as an oscillatory wave-guide. The self-focusing is found to depend on the position parameter of ripple as well as on the beam width. Values of critical power has been calculated for different values of the position parameter of ripple. Effects of axially and radially inhomogeneous plasma on self-focusing behaviour have been investigated and presented here.
Analytical solitons for Langmuir waves in plasma physics with cubic nonlinearity and perturbations
Energy Technology Data Exchange (ETDEWEB)
Zhou, Qin [Wuhan Donghu Univ. (China). School of Electronics and Information Engineering; Mirzazadeh, M. [Guilan Univ. (Iran, Islamic Republic of). Dept. of Engineering Sciences
2016-07-01
We presented an analytical study on dynamics of solitons for Langmuir waves in plasma physics. The mathematical model is given by the perturbed nonlinear Schroedinger equation with full nonlinearity and Kerr law nonlinearity. There are three techniques of integrability were employed to extract exact solutions along with the integrability conditions. The topological 1-soliton solutions, singular 1-soliton solutions, and plane wave solution were reported by Ricatti equation expansion approach and then the bright 1-soliton solution, singular 1-soliton solution, periodic singular solutions, and plane wave solution were derived with the help of trial solution method. Finally, based on the G'/G-expansion scheme, we obtained the hyperbolic function travelling wave solution, trigonometric function travelling wave solution, and plane wave solution.
Analytical Solitons for Langmuir Waves in Plasma Physics with Cubic Nonlinearity and Perturbations
Zhou, Qin; Mirzazadeh, M.
2016-09-01
We presented an analytical study on dynamics of solitons for Langmuir waves in plasma physics. The mathematical model is given by the perturbed nonlinear Schrödinger equation with full nonlinearity and Kerr law nonlinearity. There are three techniques of integrability were employed to extract exact solutions along with the integrability conditions. The topological 1-soliton solutions, singular 1-soliton solutions, and plane wave solution were reported by Ricatti equation expansion approach and then the bright 1-soliton solution, singular 1-soliton solution, periodic singular solutions, and plane wave solution were derived with the help of trial solution method. Finally, based on the G'/G-expansion scheme, we obtained the hyperbolic function travelling wave solution, trigonometric function travelling wave solution, and plane wave solution.
Nonlinear regime of the mode-coupling instability in 2D plasma crystals
Röcker, T B; Zhdanov, S K; Nosenko, V; Ivlev, A V; Thomas, H M; Morfill, G E
2014-01-01
The transition between linear and nonlinear regimes of the mode-coupling instability (MCI) operating in a monolayer plasma crystal is studied. The mode coupling is triggered at the centre of the crystal and a melting front is formed, which travels through the crystal. At the nonlinear stage, the mode coupling results in synchronisation of the particle motion and the kinetic temperature of the particles grows exponentially. After melting of the crystalline structure, the mean kinetic energy of the particles continued to grow further, preventing recrystallisation of the melted phase. The effect could not be reproduced in simulations employing a simple point-like wake model. This shows that at the nonlinear stage of the MCI a heating mechanism is working which was not considered so far.
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
Nonlinear wave evolution in VLASOV plasma: a lie-transform analysis
Energy Technology Data Exchange (ETDEWEB)
Cary, J.R.
1979-08-01
Nonlinear wave evolution in Vlasov plasma is analyzed using the Lie transform, a powerful mathematical tool which is applicable to Hamiltonian systems. The first part of this thesis is an exposition of the Lie transform. Dewar's general Lie transform theory is explained and is used to construct Deprit's Lie transform perturbation technique. The basic theory is illustrated by simple examples.
How to assess the plasma delivery of RONS into tissue fluid and tissue
Oh, Jun-Seok; Szili, Endre J.; Gaur, Nishtha; Hong, Sung-Ha; Furuta, Hiroshi; Kurita, Hirofumi; Mizuno, Akira; Hatta, Akimitsu; Short, Robert D.
2016-08-01
The efficacy of helium (He) and argon (Ar) plasma jets are being investigated for different healthcare applications including wound and cancer therapy, sterilisation and surface disinfections. Current research points to a potential link between the generation of reactive oxygen and nitrogen species (RONS) and outcomes in a range of biological and medical applications. As new data accrue, further strengthening this link, it becomes important to understand the controlled delivery of RONS into solutions, tissue fluids and tissues. This paper investigates the use of He and Ar plasma jets to deliver three RONS (hydrogen peroxide—H2O2, nitrite—\\text{NO}2- and nitrate—\\text{NO}3- ) and molecular oxygen (O2) directly into deionised (DI) water, or indirectly into DI water through an agarose target. The DI water is used in place of tissue fluid and the agarose target serves as a surrogate of tissue. Direct plasma jet treatments deliver more RONS and O2 than the through-agarose treatments for equivalent treatments times. The former only deliver RONS whilst the plasma jets are ignited; the latter continues to deliver RONS into the DI water long after the plasmas are extinguished. The He plasma jet is more effective at delivering H2O2 and \\text{NO}2- directly into DI water, but the Ar plasma jet is more effective at nitrating the DI water in both direct and through-agarose treatments. DI water directly treated with the plasma jets is deoxygenated, with the He plasma jet purging more O2 than the Ar plasma jet. This effect is known as ‘sparging’. In contrast, for through-agarose treatments both jets oxygenated the DI water. These results indicate that in the context of direct and indirect plasma jet treatments of real tissue fluids and tissue, the choice of process gas (He or Ar) could have a profound effect on the concentrations of RONS and O2. Irrespective of operating gas, sparging of tissue fluid (in an open wound) for long prolonged periods during direct plasma
RamReddy, Ch.; Pradeepa, T.
2016-09-01
The significance of nonlinear temperaturedependent density relation and convective boundary condition on natural convection flow of an incompressible micropolar fluid with homogeneous-heterogeneous reactions is analyzed. In spite of the complicated nonlinear structure of the present setup and to allow all the essential features, the representation of similarity transformations for the system of non-dimensional fluid flow equations is attained through Lie group transformations and hence the governing similarity equations are worked out by a numerical approach known as spectral quasi-linearization method. It is noticed that in the presence of the nonlinear convection parameter enhance the velocity, species concentration, heat transfer rate, skin friction, but decreases the temperature and wall couple stress.
Kumar, Rakesh
2015-01-01
This investigation deals with the analysis of stagnation point heat transfer and corresponding flow features of hydromagnetic viscous incompressible fluid over a vertical shrinking sheet. The considered sheet is assumed to be permeable and subject to addition of stagnation point to control the generated vorticity in the boundary layer. The sheet is placed on the right side of the fluid saturated porous medium which is having permeability of specified form. Nonlinear convection waves in the flow field are realized due to the envisaged nonlinear relation between density and temperature. The equations governing the nonlinear convection boundary layer flow are modeled and simplified using similarity transformations. The economized equations are solved for numerical solutions by employing the implicit finite difference scheme also known as Keller-box method. The influence of the associated parameters of the problem on velocity and temperature distributions, skin friction and rate of heat transfer are presented thr...
Institute of Scientific and Technical Information of China (English)
邓英尔; 刘慈群
2003-01-01
A mathematical model of two-phase fluid nonlinear flow in the direction ofnormal of ellipse through low-permeability porous media was established according to anonlinear flow law expressed in a continuous function with three parameters, a massconservation law and a concept of turbulent ellipses. A solution to the model was obtainedby using a finite difference method and an extrapolation method. Formulas of calculatingdevelopment index not only before but also after water breaks through an oil well in thecondition of two-phase fluid nonlinear flow in the media were derived. An example wasdiscussed. Water saturation distribution was presented. The moving law of drainage frontwas found. Laws of change of pressure difference with time were recognized. Results showthat there is much difference of water saturation distribution between nonlinear flow andlinear flow; that drainage front by water moves faster, water breaks through sooner and theindex gets worse because of the nonlinear flow ; and that dimensionless pressure differencegets larger at the same dimensionless time and difficulty of oil development becomes biggerby the nonlinear flow . Thus, it is necessary that influence of nonlinear flow on developmentindexes of the oil fields be taken into account. The results provide water-floodingdevelopment of the oil fields with scientific basis.
Directory of Open Access Journals (Sweden)
M. A. Daha
2012-02-01
Full Text Available The evolution of temperature profiles and weld pool geometry during dissimilar welding between 2205 duplex stainless steel and A36 low carbon steel using keyhole plasma arc welding has been simulated using a three dimensional numerical heat transfer and fluid flow model. An adaptive heat source is proposed as a heat source model for performing a non-linear transient thermal analysis, based on the configuration feature of keyhole plasma arc welds. Temperature profiles and solidified weld pool geometry are presented for three different welding heat input. The reversed bugle shape parameters (width of fusion zone at both top and bottom surfaces of the weld pool geometry features for a dissimilar 2205–A36 weld joint are summarized to successfully explain the observations. The model was also applied to keyhole plasma welding of 6.8 mm thick similar 2205 duplex stainless steel joint for validation. The simulation results were compared with independently obtained experimental data and good agreements have been obtained.
Energy Technology Data Exchange (ETDEWEB)
Sahai, A. A.; Katsouleas, T. C.; Gessner, S.; Hogan, M.; Joshi, C.; Mori, W. B. [Electrical and Computer Engineering, Duke University, Durham, NC 27708 (United States); SLAC National Accelerator Laboratory, Menlo Park, CA 90309 (United States); University of California Los Angeles, Los Angeles, CA 90095 (United States)
2012-12-21
We study the various physical processes and their timescales involved in the excitation of wakefields in relativistically hot plasma. This has relevance to the design of a high repetition-rate plasma wakefield collider in which the plasma has not had time to cool between bunches in addition to understanding the physics of cosmic jets in relativistically hot astrophysical plasmas. When the plasma is relativistically hot (plasma temperature near m{sub e}c{sup 2}), the thermal pressure competes with the restoring force of ion space charge and can reduce or even eliminate the accelerating field of a wake. We will investigate explicitly the case where the hot plasma is created by a preceding Wakefield drive bunch 10's of picoseconds to many nanoseconds ahead of the next drive bunch. The relativistically hot plasma is created when the excess energy (not coupled to the driven e{sup -} bunch) in the wake driven by the drive e{sup -} bunch is eventually converted into thermal energy on 10's of picosecond timescale. We will investigate the thermalization and diffusion processes of this non-equilibrium plasma on longer time scales, including the effects of ambi-polar diffusion of ions driven by hot electron expansion, possible Columbic explosion of ions producing higher ionization states and ionization of surrounding neutral atoms via collisions with hot electrons. Preliminary results of the transverse and longitudinal wakefields at different timescales of separation between a first and second bunch are presented and a possible experiment to study this topic at the FACET facility is described.
Energy Technology Data Exchange (ETDEWEB)
Choi, W.; Camassa, R.
1998-12-31
The authors derive model equations that govern the evolution of internal gravity waves at the interface of two immiscible fluids. These models follow from the original Euler equations under the sole assumption that the waves are long compared to the undisturbed thickness of one of the fluid layers. No smallness assumption on the wave amplitude is made. Here the shallow water configuration is first considered, whereby the waves are taken to be long with respect to the total undisturbed thickness of the fluids. In part 2, the authors derive models for the configuration in which one of the two fluids has a thickness much larger than the wavelength. The fully nonlinear models contain the Korteweg-de Vries (KdV) equation and the intermediate-long-wave (ILW) equation, for shallow and deep water configurations respectively, as special cases in the limit of weak nonlinearity and unidirectional wave propagation. In particular, for a solitary wave of given amplitude, the characteristic wavelength is larger and the wave speed smaller than their counterparts for solitary wave solutions of the weakly nonlinear equations. These features are compared and found in overall good agreement with available experimental data for solitary waves of large amplitude in two-fluid systems.
Physics-Based Computational Algorithm for the Multi-Fluid Plasma Model
2014-06-30
Riemann solver for the two-fluid plasma model. Journal of Computational Physics , 187(2):620–638, 2003. [23] Jeffrey P. Freidberg. Ideal...Computational Physics , 141(2):199–224, 1998. [52] P. L. Roe. Approximate Riemann solvers, parameter vectors and difference schemes. Journal of...AFRL-OSR-VA-TR-2014-0310 PHYSICS -BASED COMPUTATIONAL ALGORITHM FOR THE MULTIFLUID PLASMA MODEL Uri Shumlak UNIVERSITY OF WASHINGTON Final Report 10
Sengupta, Prabuddha; Baird, Barbara; Holowka, David
2007-01-01
Novel biophysical approaches combined with modeling and new biochemical data have helped to recharge the lipid raft field and have contributed to the generation of a refined model of plasma membrane organization. In this review, we summarize new information in the context of previous literature to provide new insights into the spatial organization and dynamics of lipids and proteins in the plasma membrane of live cells. Recent findings of large-scale separation of liquid-ordered and liquid-di...
Shukla, P. K.; Bingham, R.; Stenflo, L.; Dawson, J. M.
1996-01-01
Starting in 1989 we have created a forum at the International Centre for Theoretical Physics, Trieste, where scientists from different parts of the world can meet and exchange information in the frontier areas of physics. In the three previous meetings, we focused on large amplitude waves and fields in plasmas, the physics of dusty plasmas, and wave-particle interactions and energization in plasmas. In 1995, we came up with a fresh idea of organizing somewhat enlarged but still well focused research topics that are cross-disciplinary. Thus, the usual 'fourth-week activity' of the Plasma Physics College at the ICTP was replaced by an International Topical Workshop on Plasma Physics: Coherent Processes in Nonlinear Media, which was held at the ICTP during the period 16-20 October, 1995. This provided us an opportunity to draw eminent speakers from many closely related fields such as plasma physics, fluid dynamics, nonlinear optics, and astrophysics. The Workshop was attended by 82 delegates from 34 countries, and the participation from the industrial and the developing countries was about half each. The programme included 4 review and 29 topical invited lectures. In addition, about 30 contributed papers were presented as posters in two sessions. The latter were created in order to give opportunities to younger physicists for displaying the results of their recent work and to obtain constructive comments from the other participants. During the five days at the ICTP, we focused on almost all the various aspects of nonlinear phenomena that are common in different branches of science. The review and topical lectures as well as the posters dealt with the most recent advances in coherent nonlinear processes in space and astrophysical plasmas, in fluids and optics, in low temperature dusty plasmas, as well as in laser produced and magnetically confined laboratory plasmas. The focus was on the physics of various types of waves and their generation mechanisms, the development
Sui, Jize; Zhao, Peng; Cheng, Zhengdong; Zheng, Liancun; Zhang, Xinxin
2017-02-01
The rheological and heat-conduction constitutive models of micropolar fluids (MFs), which are important non-Newtonian fluids, have been, until now, characterized by simple linear expressions, and as a consequence, the non-Newtonian performance of such fluids could not be effectively captured. Here, we establish the novel nonlinear constitutive models of a micropolar fluid and apply them to boundary layer flow and heat transfer problems. The nonlinear power law function of angular velocity is represented in the new models by employing generalized "n-diffusion theory," which has successfully described the characteristics of non-Newtonian fluids, such as shear-thinning and shear-thickening fluids. These novel models may offer a new approach to the theoretical understanding of shear-thinning behavior and anomalous heat transfer caused by the collective micro-rotation effects in a MF with shear flow according to recent experiments. The nonlinear similarity equations with a power law form are derived and the approximate analytical solutions are obtained by the homotopy analysis method, which is in good agreement with the numerical solutions. The results indicate that non-Newtonian behaviors involving a MF depend substantially on the power exponent n and the modified material parameter K 0 introduced by us. Furthermore, the relations of the engineering interest parameters, including local boundary layer thickness, local skin friction, and Nusselt number are found to be fitted by a quadratic polynomial to n with high precision, which enables the extraction of the rapid predictions from a complex nonlinear boundary-layer transport system.
Characterization of the porcine synovial fluid proteome and a comparison to the plasma proteome
DEFF Research Database (Denmark)
Bennike, Tue Bjerg; Barnaby, Omar; Steen, Hanno;
2015-01-01
Synovial fluid is present in all joint cavities, and protects the articular cartilage surfaces in large by lubricating the joint, thus reducing friction. Several studies have described changes in the protein composition of synovial fluid in patients with joint disease. However, the protein...... concentration, content, and synovial fluid volume change dramatically during active joint diseases and inflammation, and the proteome composition of healthy synovial fluid is incompletely characterized. We performed a normative proteomics analysis of porcine synovial fluid, and report data from optimizing...... data used in the method optimization, human plasma proteomics data, and search results, have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD000935....
Nonlinear interaction of intense hypergeometric Gaussian subfamily laser beams in plasma
Sobhani, H.; Vaziri (Khamedi), M.; Rooholamininejad, H.; Bahrampour, A. R.
2016-07-01
Propagation of Hypergeometric-Gaussian laser beam in a nonlinear plasma medium is investigated by considering the Source Dependent Expansion method. A subfamily of Hypergeometric-Gaussian beams with a non-negative, even and integer radial index, can be expressed as the linear superposition of finite number of Laguerre-Gaussian functions. Propagation of Hypergeometric-Gaussian beams in a nonlinear plasma medium depends on the value of radial index. The bright rings' number of these beams is changed during the propagation in plasma medium. The effect of beam vortex charge number l and initial (input) beam intensity on the self-focusing of Hypergeometric-Gaussian beams is explored. Also, by choosing the suitable initial conditions, Hypergeometric-Gaussian subfamily beams can be converted to one or more mode components that a typical of mode conversion may be occurred. The self-focusing of these winding beams can be used to control the focusing force and improve the electron bunch quality in laser plasma accelerators.
Energy Technology Data Exchange (ETDEWEB)
Khorashadizadeh, S. M.; Rastbood, E.; Zeinaddini Meymand, H. [Physics Department, University of Birjand, Birjand (Iran, Islamic Republic of); Niknam, A. R. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)
2013-08-15
The nonlinear coupling between circularly polarized electromagnetic (CPEM) waves and acoustic-like waves in a magnetoactive electron-positron-ion (e-p-i) plasma is studied, taking into account the relativistic motion of electrons and positrons. The possibility of modulational instability and its growth rate as well as the envelope soliton formation and its characteristics in such plasmas are investigated. It is found that the growth rate of modulation instability increases in the case that ω{sub c}/ω<1 (ω{sub c} and ω are the electron gyrofrequency and the CPEM wave frequency, respectively) and decreases in the case that ω{sub c}/ω>1. It is also shown that in a magnetoactive e-p-i plasma, the width of bright soliton increases/decreases in case of (ω{sub c}/ω)<1/(ω{sub c}/ω)>1 by increasing the magnetic field strength.
Matda, Y.; Crawford, F. W.
1974-01-01
An economical low noise plasma simulation model is applied to a series of problems associated with electrostatic wave propagation in a one-dimensional, collisionless, Maxwellian plasma, in the absence of magnetic field. The model is described and tested, first in the absence of an applied signal, and then with a small amplitude perturbation, to establish the low noise features and to verify the theoretical linear dispersion relation at wave energy levels as low as 0.000,001 of the plasma thermal energy. The method is then used to study propagation of an essentially monochromatic plane wave. Results on amplitude oscillation and nonlinear frequency shift are compared with available theories. The additional phenomena of sideband instability and satellite growth, stimulated by large amplitude wave propagation and the resulting particle trapping, are described.
Latyshev, A V
2015-01-01
Kinetic Vlasov-Boltzmann equation for degenerate collisional plasmas with integral of collisions of relaxation type BGK (Bhatnagar, Gross and Krook) is used. Square-law expansion on size of intensity of electric field for kinetic equation, Lorentz's force and integral of collisions is considered. It is shown, that nonlinearity leads to generation of the longitudinal electric current directed along a wave vector. Longitudinal current is perpendicular to the known transversal classical current received at the linear analysis. The case of small values of wave number is considered. When frequency of collisions tends to the zero, all received results for collisional pass plasmas in corresponding results for collisionless plasmas. Graphic research of the real and imaginary part current density is carried out.
Impact of nonlinear absorption on propagation of microwave in a plasma filled rectangular waveguide
Sobhani, H.; Vaziri, M.; Rooholamininejad, H.; Bahrampour, A. R.
2016-07-01
In collisional and ponderomotive predominant regimes, the propagation of microwave in rectangular waveguide filled with collisional plasma is investigated numerically. The dominant mode is excited through an evacuated waveguide and then enters a similar and co-axis waveguide filled with plasma. In collisional predominant regime, the amplitude of electric field is oscillated along propagation path; outset of propagation path due to the electron-ion collision, the intensity oscillations are reduced. Afterward, under competition between the collisional nonlinearity and absorption, the intensity is increased, so the electron density peak is created in middle of waveguide. In ponderomotive predominant regime, the intensity is slowly decreased due to collision, so the electron density is ramped. Control parameters, like the frequency, input power, collision frequency, and background electron density are surveyed that can be used to control propagation characteristics of microwave. This method can be used to control heating of fusion plasma and accelerate charged particle.
Indian Academy of Sciences (India)
P K Karmakar
2007-04-01
Application of inertia-induced acoustic excitation theory offers a new resonant excitation source channel of acoustic turbulence in the transonic domain of plasma flow. In bi-ion plasmas like colloidal plasma, two well-defined transonic points exist corresponding to the parent ion and the dust grain-associated acoustic modes. As usual, the modified ion acoustic mode (also known as dust ion-acoustic (DIA) wave) dynamics associated with parent ion inertia is excitable for both nanoscale- and micronscale-sized dust grains. It is found that the so-called (ion) acoustic mode (also known as dust-acoustic (DA) wave) associated with nanoscale dust grain inertia is indeed resonantly excitable through the active role of weak but finite parent ion inertia. It is interestingly conjectured that the same excitation physics, as in the case of normal plasma sound mode, operates through the active inertial role of plasma thermal species. Details of the nonlinear acoustic mode analyses of current interest in transonic domains of such impure plasmas in hydrodynamic flow are presented.
Travelling wave analysis and jump relations for a fluid model of quasineutral plasma
Energy Technology Data Exchange (ETDEWEB)
Cordier, S. (Ecole Polytechnique, 91 - Palaiseau (France)); Degond, P. (Toulouse-3 Univ., 31 (France)); Markowich, P. (Technische Univ. Berlin (Germany)); Schmeiser, C. (Technische Univ., Vienna (Austria))
1994-05-01
A 1-D fluid model for a plasma is presented. In the quasineutral limit, this model leads to a non conservative hyperbolic system for which the jump relations are a-priority not well defined. The problem can be solved for sufficiently strong shocks via a travelling wave analysis. (authors). 5 refs.
Ertel's vorticity theorem and new flux surfaces in multi-fluid plasmas
Energy Technology Data Exchange (ETDEWEB)
Hameiri, Eliezer [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)
2013-09-15
Dedicated to Professor Harold Weitzner on the occasion of his retirement“Say to wisdom ‘you are my sister,’ and to insight ‘you are my relative.’”—Proverbs 7:4Based on an extension to plasmas of Ertel's classical vorticity theorem in fluid dynamics, it is shown that for each species in a multi-fluid plasma there can be constructed a set of nested surfaces that have this species' fluid particles confined within them. Variational formulations for the plasma evolution and its equilibrium states are developed, based on the new surfaces and all of the dynamical conservation laws associated with them. It is shown that in the general equilibrium case, the energy principle lacks a minimum and cannot be used as a stability criterion. A limit of the variational integral yields the two-fluid Hall-magnetohydrodynamic (MHD) model. A further special limit yields MHD equilibria and can be used to approximate the equilibrium state of a Hall-MHD plasma in a perturbative way.
Numerical Construction of Magnetosphere with Relativistic Two-fluid Plasma Flows
Kojima, Yasufumi
2009-01-01
We present a numerical model in which a cold pair plasma is ejected with relativistic speed through a polar cap region and flows almost radially outside the light cylinder. Stationary axisymmetric structures of electromagnetic fields and plasma flows are self-consistently calculated. In our model, motions of positively and negatively charged particles are assumed to be determined by electromagnetic forces and inertial terms, without pair creation and annihilation or radiation loss. The global electromagnetic fields are calculated by the Maxwell's equations for the plasma density and velocity, without using ideal MHD condition. Numerical result demonstrates the acceleration and deceleration of plasma due to parallel component of the electric fields. Numerical model is successfully constructed for weak magnetic fields or highly relativistic fluid velocity, i.e, kinetic energy dominated outflow. It is found that appropriate choices of boundary conditions and plasma injection model at the polar cap should be expl...
Effect of nitazoxanide on albendazole pharmacokinetics in cerebrospinal fluid and plasma in rats.
Ruiz-Olmedo, María Isabel; González-Hernández, Iliana; Palomares-Alonso, Francisca; Franco-Pérez, Javier; González F, María de Lourdes; Jung-Cook, Helgi
2017-03-01
Background: Although albendazole is the drug-of-choice for the treatment of neurocysticercosis, its efficacy is limited due to its low bioavailability. An alternative for optimizing pharmacological treatment is through drug combinations. In vitro studies have shown that nitazoxanide and tizoxanide (the active metabolite of nitazoxanide) exhibit cysticidal activity and that the combination of tizoxanide with albendazole sulfoxide (the active metabolite of albendazole) produced an additive effect. Objectives: (1) To assess the concentration profile of tizoxanide in plasma and in cerebrospinal fluid; and (2) to evaluate the influence of nitazoxanide on the pharmacokinetics of albendazole in plasma and in cerebrospinal fluid. Methods: Two different studies were conducted. In study 1, 10 male Sprague-Dawley rats received a single oral dose of 7.5 mg/kg of nitazoxanide and serial blood and cerebrospinal fluid samples were collected over a period of 4 h. In study 2, 38 healthy male Sprague-Dawley rats were randomly divided into two groups: one of these received a single dose of albendazole (15 mg/kg) and, in the other group, albendazole (15 mg/kg) was co-administered with nitazoxanide (7.5 mg/kg). Plasma and cerebrospinal fluid samples were collected from 0 to 16 h after administration. Albendazole sulfoxide and tizoxanide levels were assayed by using HPLC or LC/MS techniques. Results: In study 1, tizoxanide reached a maximum plasma concentration of 244.42 ± 31.98 ng/mL at 0.25 h; however, in cerebrospinal fluid, this could be detected only at 0.5 h, and levels were below the quantification limit (10 ng/mL). These data indicate low permeation of tizoxanide into the blood brain barrier. In study 2, Cmax, the area under the curve, and the mean residence time of albendazole sulfoxide in plasma and cerebrospinal fluid were not affected by co-administration with nitazoxanide. Conclusion: The results of the present study indicate that in rats at the applied doses
Adams, Allan; Schaefer, Thomas; Steinberg, Peter; Thomas, John E
2012-01-01
Strongly correlated quantum fluids are phases of matter that are intrinsically quantum mechanical, and that do not have a simple description in terms of weakly interacting quasi-particles. Two systems that have recently attracted a great deal of interest are the quark-gluon plasma, a plasma of strongly interacting quarks and gluons produced in relativistic heavy ion collisions, and ultracold atomic Fermi gases, very dilute clouds of atomic gases confined in optical or magnetic traps. These systems differ by more than 20 orders of magnitude in temperature, but they were shown to exhibit very similar hydrodynamic flow. In particular, both fluids exhibit a robustly low shear viscosity to entropy density ratio which is characteristic of quantum fluids described by holographic duality, a mapping from strongly correlated quantum field theories to weakly curved higher dimensional classical gravity. This review explores the connection between these fields, and it also serves as an introduction to the Focus Issue of N...
Nonlinear evolution of multi-helicity neo-classical tearing modes in rotating tokamak plasmas
Wei, Lai; Wang, Zheng-Xiong; Wang, Jialei; Yang, Xuefeng
2016-10-01
Plasma perturbations from the core and/or boundary regions of tokamaks can provide seed islands for the excitation of neo-classical tearing modes (NTMs) with negative {{ Δ }\\prime} , where {{ Δ }\\prime} is the linear instability parameter of the classical tearing mode. In this work, by means of reduced magnetohydrodynamic simulations, we numerically investigate the nonlinear evolution of multi-helicity NTMs in rotating tokamak plasmas with these two types of plasma perturbations with different boundary conditions. In the first case of initial plasma perturbations from the core region with a zero boundary condition, the meta-stable property of seed-island triggered NTM with negative {{ Δ }\\prime} is verified in the single helicity simulation. Nevertheless in the multiple helicity simulation, this seed-island triggered NTM with negative {{ Δ }\\prime} can be suppressed by a spontaneous NTM with positive {{ Δ }\\prime} through the competitive interaction between NTMs with different helicities. If a fixed poloidal rotation is taken into account in the first case, two different helicity NTMs could coexist in the saturation stage, which is different qualitatively from the process without plasma rotation. In the second case of initial plasma perturbations from the boundary region with a nonzero boundary condition, as the amplitude of plasma perturbations on the boundary increases, the mode with negative {{ Δ }\\prime} gradually changes from the driven-reconnection state to the NTM state, accompanied by an enhancement of magnetic island width in the single helicity simulation. Nevertheless in the multi-helicity simulation, the spontaneous NTM with positive {{ Δ }\\prime} can make the driven-reconnection triggered NTM with negative {{ Δ }\\prime} transfer from the NTM state back to the driven-reconnection state again. The underlying mechanism behind these transitions is analyzed step by step. Effects of fixed and unfixed poloidal rotations on the nonlinear
Zonal Flows and Turbulence in Fluids and Plasmas
Parker, Jeffrey B
2015-01-01
In geophysical and plasma contexts, zonal flows are well known to arise out of turbulence. We elucidate the transition from statistically homogeneous turbulence without zonal flows to statistically inhomogeneous turbulence with steady zonal flows. Starting from the Hasegawa--Mima equation, we employ both the quasilinear approximation and a statistical average, which retains a great deal of the qualitative behavior of the full system. Within the resulting framework known as CE2, we extend recent understanding of the symmetry-breaking `zonostrophic instability'. Zonostrophic instability can be understood in a very general way as the instability of some turbulent background spectrum to a zonally symmetric coherent mode. As a special case, the background spectrum can consist of only a single mode. We find that in this case the dispersion relation of zonostrophic instability from the CE2 formalism reduces exactly to that of the 4-mode truncation of generalized modulational instability. We then show that zonal flow...
Three-fluid plasmas in star formation I. Magneto-hydrodynamic equations
Pinto, Cecilia; Bacciotti, Francesca
2008-01-01
Interstellar magnetic fields influence all stages of the process of star formation, from the collapse of molecular cloud cores to the formation of protostellar jets. This requires us to have a full understanding of the physical properties of magnetized plasmas of different degrees of ionization for a wide range of densities and temperatures. We derive general equations governing the magneto-hydrodynamic evolution of a three-fluid medium of arbitrary ionization, also including the possibility of charged dust grains as the main charge carriers. In a companion paper (Pinto & Galli 2007), we complement this analysis computing accurate expressions of the collisional coupling coefficients. Over spatial and temporal scales larger than the so-called large-scale plasma limit and the collision-dominated plasma limit, and for non-relativistic fluid speeds, we obtain an advection-diffusion for the magnetic field. We derive the general expressions for the resistivities, the diffusion time scales and the heating rates ...
Fluid approach to evaluate sound velocity in Yukawa systems (complex plasmas)
Khrapak, Sergey
2015-01-01
The conventional fluid description of multi-component plasma, supplemented by an appropriate equation of state for the macroparticle component, is used to evaluate the longitudinal sound velocity of Yukawa fluids. The obtained results are in very good agreement with those obtained earlier employing the quasi-localized charge approximation and molecular dynamics simulations in a rather broad parameter regime. Thus, a simple yet accurate tool to estimate the sound velocity across coupling regimes is proposed, which can be particularly helpful in estimating the dust-acoustic velocity in strongly coupled dusty (complex) plasmas. It is shown that, within the present approach, the sound velocity is completely determined by particle-particle correlations and the neutralizing medium (plasma), apart from providing screening of the Coulomb interaction, has no other effect on the sound propagation. The ratio of the actual sound velocity to its "ideal gas" (weak coupling) scale only weakly depends on the coupling strengt...
Ellahi, Rahmat; Wang, Xinil; Hameed, Muhammad
2014-02-01
This article is concerned with the study of heat transfer and nonlinear slip effects on the Couette flow of a third-grade fluid. Numerical solutions are obtained by solving nonlinear differential equations using the higher-order Chebyshev spectral method. The results for no slip and no thermal slip become special cases of this study. Moreover, the results for Poiseuille flow can be obtained as a special case from the generalized Couette flow analysis by setting the plate velocity to zero. Graphical results for involved pertinent parameters are sketched and examined.
Oblique non-neutral solitary Alfven modes in weakly nonlinear pair plasmas
Energy Technology Data Exchange (ETDEWEB)
Verheest, Frank [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B-9000 Gent (Belgium); School of Physics, Howard College Campus, University of KwaZulu-Natal, Durban 4041 (South Africa); Lakhina, G S [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410218 (India); Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)
2005-04-01
The equal charge-to-mass ratio for both species in pair plasmas induces a decoupling of the linear eigenmodes between waves that are charge neutral or non-neutral, also at oblique propagation with respect to a static magnetic field. While the charge-neutral linear modes have been studied in greater detail, including their weakly and strongly nonlinear counterparts, the non-neutral mode has received less attention. Here the nonlinear evolution of a solitary non-neutral mode at oblique propagation is investigated in an electron-positron plasma. Employing the framework of reductive perturbation analysis, a modified Korteweg-de Vries equation (with cubic nonlinearity) for the lowest-order wave magnetic field is obtained. In the linear approximation, the non-neutral mode has its magnetic component orthogonal to the plane spanned by the directions of wave propagation and of the static magnetic field. The linear polarization is not maintained at higher orders. The results may be relevant to the microstructure in pulsar radiation or to the subpulses.
Chatterjee, D
2015-01-01
The nonlinear theory of amplitude modulation of electrostatic wave envelopes in a collisionless electron-positron (EP) pair plasma is studied by using a set of Vlasov-Poisson equations in the context of Tsallis' $q$-nonextensive statistics. In particular, the previous linear theory of Langmuir oscillations in EP plasmas [Phys. Rev. E {\\bf87}, 053112 (2013)] is rectified and modified. Applying the multiple scale technique (MST), it is shown that the evolution of electrostatic wave envelopes is governed by a nonlinear Schr{\\"o}dinger (NLS) equation with a nonlocal nonlinear term $\\propto {\\cal{P}}\\int|\\phi(\\xi',\\tau)|^2d\\xi'\\phi/(\\xi-\\xi') $ [where ${\\cal P}$ denotes the Cauchy principal value, $\\phi$ is the small-amplitude electrostatic (complex) potential, and $\\xi$ and $\\tau$ are the stretched coordinates in MST] which appears due to the wave-particle resonance. It is found that a subregion $1/3
Dynamic Thomson Scattering from Nonlinear Electron Plasma Waves in a Raman Plasma Amplifier
Davies, A.; Katz, J.; Bucht, S.; Haberberger, D.; Bromage, J.; Zuegel, J. D.; Froula, D. H.; Trines, R.; Bingham, R.; Sadler, J.; Norreys, P. A.
2016-10-01
Electron plasma waves (EPW's) can be used to transfer significant energy from a long-pulse laser to a short-pulse seed laser through the Raman scattering instability. Successful implementation of Raman amplification could open an avenue to producing high-intensity pulses beyond the capabilities of current laser technology ( 1022 W / cm 2). This three-wave interaction takes advantage of the plasma's ability to sustain large-amplitude plasma waves. Having complete knowledge of the EPW amplitude is essential to establishing optimal parameters for high-efficiency Raman amplification. A dynamic Thomson-scattering diagnostic is being developed to spatially and temporally resolve the amplitude of the driven and thermal EPW's. By imaging the scattered probe light onto a novel pulse-front tilt compensated streaked optical spectrometer, the diffraction efficiency of this plasma wave can be measured as a function of space and time. These data will be used in conjunction with particle-in-cell simulations to determine the EPW's spatial and temporal profile. This will allow the effect of the EPW profile on Raman scattering to be experimentally determined. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.
Modeling of plasma and thermo-fluid transport in hybrid welding
Ribic, Brandon D.
Hybrid welding combines a laser beam and electrical arc in order to join metals within a single pass at welding speeds on the order of 1 m min -1. Neither autonomous laser nor arc welding can achieve the weld geometry obtained from hybrid welding for the same process parameters. Depending upon the process parameters, hybrid weld depth and width can each be on the order of 5 mm. The ability to produce a wide weld bead increases gap tolerance for square joints which can reduce machining costs and joint fitting difficulty. The weld geometry and fast welding speed of hybrid welding make it a good choice for application in ship, pipeline, and aerospace welding. Heat transfer and fluid flow influence weld metal mixing, cooling rates, and weld bead geometry. Cooling rate affects weld microstructure and subsequent weld mechanical properties. Fluid flow and heat transfer in the liquid weld pool are affected by laser and arc energy absorption. The laser and arc generate plasmas which can influence arc and laser energy absorption. Metal vapors introduced from the keyhole, a vapor filled cavity formed near the laser focal point, influence arc plasma light emission and energy absorption. However, hybrid welding plasma properties near the opening of the keyhole are not known nor is the influence of arc power and heat source separation understood. A sound understanding of these processes is important to consistently achieving sound weldments. By varying process parameters during welding, it is possible to better understand their influence on temperature profiles, weld metal mixing, cooling rates, and plasma properties. The current literature has shown that important process parameters for hybrid welding include: arc power, laser power, and heat source separation distance. However, their influence on weld temperatures, fluid flow, cooling rates, and plasma properties are not well understood. Modeling has shown to be a successful means of better understanding the influence of
Kinetic treatment of nonlinear ion-acoustic waves in multi-ion plasma
Ahmad, Zulfiqar; Ahmad, Mushtaq; Qamar, A.
2017-09-01
By applying the kinetic theory of the Valsove-Poisson model and the reductive perturbation technique, a Korteweg-de Vries (KdV) equation is derived for small but finite amplitude ion acoustic waves in multi-ion plasma composed of positive and negative ions along with the fraction of electrons. A correspondent equation is also derived from the basic set of fluid equations of adiabatic ions and isothermal electrons. Both kinetic and fluid KdV equations are stationary solved with different nature of coefficients. Their differences are discussed both analytically and numerically. The criteria of the fluid approach as a limiting case of kinetic theory are also discussed. The presence of negative ion makes some modification in the solitary structure that has also been discussed with its implication at the laboratory level.
Helfrich, Karl R.
2006-08-01
The nonlinear evolution of a localized layer of buoyant, uniform potential vorticity fluid with depth H, width w and length L released adjacent to a wall in a rotating system is studied using reduced-gravity shallow-water theory and numerical modeling. In the interior, far from the two ends of the layer, the initial adjustment gives, after ignoring inertia-gravity waves, a geostrophic flow of width w and layer velocities parallel to the wall directed in the downstream direction (defined by Kelvin wave propagation). This steady geostrophic flow serves as the initial condition for a semigeostrophic solution using the method of characteristics. At the downstream end, the theory shows that the fluid intrudes along the wall as rarefaction terminating at a nose of vanishing width and depth. However, in a real fluid the presence of the lower layer leads to a blunt gravity current head. The theory is amended by introducing a gravity current head condition that has a blunt bore joined to the rarefaction by a uniform gravity current. The upstream termination of the initial layer produces a Kelvin rarefaction that propagates downstream, decreasing the layer depth along the wall, and initiating upstream flow adjacent to the wall. The theoretical solution compares favorably to numerical solutions of the reduced-gravity shallow-water equations. The agreement between theory and numerical solutions occurs regardless of whether the numerical runs are initiated with an adjusted geostrophic solution or with the release of a stagnant layer. The latter case excites inertia-gravity waves that, despite their large amplitude and breaking, do not significantly affect the evolution of the geostrophic flow. At times beyond the validity of the semigeostrophic theory, the numerical solutions evolve into a stationary array of vortices. The vortex formation can be interpreted as the finite-amplitude manifestation of a linear instability of the new flow established by the passage of the Kelvin
Fully Nonlinear Simulation for Fluid/Structure Impact:A Review
Institute of Scientific and Technical Information of China (English)
Shili Sun; Guoxiong Wu
2014-01-01
This paper presents a review of the work on fluid/structure impact based on inviscid and imcompressible liquid and irrotational flow. The focus is on the velocity potential theory together with boundary element method (BEM). Fully nonlinear boundary conditions are imposed on the unknown free surface and the wetted surface of the moving body. The review includes (1) vertical and oblique water entry of a body at constant or a prescribed varying speed, as well as free fall motion, (2) liquid droplets or column impact as well as wave impact on a body, (3) similarity solution of an expanding body. It covers two dimensional (2D), axisymmetric and three dimensional (3D) cases. Key techniques used in the numerical simulation are outlined, including mesh generation on the multivalued free surface, the stretched coordinate system for expanding domain, the auxiliary function method for decoupling the mutual dependence of the pressure and the body motion, and treatment for the jet or the thin liquid film developed during impact.
Markowich, Peter
2010-06-01
We study the system ct + u · ∇c = ∇c -nf(c) nt + u · ∇n = ∇n m - ∇ · (n×(c) ∇c) ut + u·∇u + ∇P - η∇u + n∇φ/ = 0 ∇·u = 0. arising in the modelling of the motion of swimming bacteria under the effect of diffusion, oxygen-taxis and transport through an incompressible fluid. The novelty with respect to previous papers in the literature lies in the presence of nonlinear porous-medium-like diffusion in the equation for the density n of the bacteria, motivated by a finite size effect. We prove that, under the constraint m ε (3/2, 2] for the adiabatic exponent, such system features global in time solutions in two space dimensions for large data. Moreover, in the case m = 2 we prove that solutions converge to constant states in the large-time limit. The proofs rely on standard energy methods and on a basic entropy estimate which cannot be achieved in the case m = 1. The case m = 2 is very special as we can provide a Lyapounov functional. We generalize our results to the three-dimensional case and obtain a smaller range of exponents m ε (m*, 2] with m* > 3/2, due to the use of classical Sobolev inequalities.
DEFF Research Database (Denmark)
Fuglsang, Stefan; Henriksen, Ulrik L; Hansen, Hanne Boskov
2016-01-01
In patients with fluid retention, the plasma clearance of (51) Cr-EDTA (Clexp obtained by multiexponential fit) may overestimate the glomerular filtration rate (GFR). The present study was undertaken to compare a gamma-variate plasma clearance (Clgv) with the urinary plasma clearance of (51) Cr......-EDTA (Clu ) in patients with cirrhosis with and without fluid retention. A total of 81 patients with cirrhosis (22 without fluid retention, 59 with ascites) received a quantitative intravenous injection of (51) Cr-EDTA followed by plasma and quantitative urinary samples for 5 h. Clgv was determined from...... the injected dose relative to the plasma concentration-time area, obtained by a gamma-variate iterative fit. Clexp and Clu were determined by standard technique. In patients without fluid retention, Clgv , Clexp and Clu were closely similar. The difference between Clgv and Clu (Clgv - Clu = ΔCl) was mean -0...
Two-dimensional nonlinear dynamics of bidirectional beam-plasma instability
Pavan, J.; Ziebell, L. F.; Gaelzer, R.; Yoon, P. H.
2009-01-01
Solar wind electrons near 1 AU feature wide-ranging asymmetries in the superthermal tail distribution. Gaelzer et al. (2008) recently demonstrated that a wide variety of asymmetric distributions results if one considers a pair of counterstreaming electron beams interacting with the core solar wind electrons. However, the nonlinear dynamics was investigated under the simplifying assumption of one dimensionality. In the present paper, this problem is revisited by extending the analysis to two dimensions. The classic bump-on-tail instability involves a single electron beam interacting with the background population. The bidirectional or counterstreaming beams excite Langmuir turbulence initially propagating in opposite directions. It is found that the nonlinear mode coupling leads to the redistribution of wave moments along concentric arcs in wave number space, somewhat similar to the earlier findings by Ziebell et al. (2008) in the case of one beam-plasma instability. However, the present result also shows distinctive features. The similarities and differences in the nonlinear wave dynamics are discussed. It is also found that the initial bidirectional beams undergo plateau formation and broadening in perpendicular velocity space. However, the anisotropy persists in the nonlinear stage, implying that an additional pitch angle scattering by transverse electromagnetic fluctuations is necessary in order to bring the system to a truly isotropic state.
Energy Technology Data Exchange (ETDEWEB)
Ahmad, Ali [National Centre for Physics, Shahdara Valley Road, Islamabad (Pakistan); Masood, W. [National Centre for Physics, Shahdara Valley Road, Islamabad (Pakistan); COMSATS Institute of Information Technology, Park Road, Chak Shahzad, Islamabad (Pakistan)
2016-05-15
Linear and nonlinear electrostatic ion acoustic waves in a weakly relativistic magnetorotating plasma in the presence of non-Maxwellian electrons and warm ions have been examined. The system under consideration has yielded two solutions, namely, the fast and slow acoustic modes which have been observed to depend on the streaming velocity, ion to electron temperature ratio, and the nonthermality parameter of the non-Maxwellian electrons. Using the multiple time scale analysis, we have derived the three dimensional nonlinear Zakharov–Kuznetsov equation and also presented its solution. Both compressive and rarefactive solitary structures have been found in consonance with the satellite observations. It has been observed that although the linear dispersion relation gives both fast and slow ion acoustic waves, the solitary structures form only for the fast acoustic mode. The dependence of the characteristics of the solitary structures on several plasma parameters has also been explored. The present investigation may be beneficial to understanding the rotating plasma environments such as those found in the planetary magnetospheres of Saturn and Jupiter.
Nonlinear phenomena in RF wave propagation in magnetized plasma: A review
Energy Technology Data Exchange (ETDEWEB)
Porkolab, Miklos
2015-12-10
Nonlinear phenomena in RF wave propagation has been observed from the earliest days in basic laboratory experiments going back to the 1960s [1], followed by observations of parametric instability (PDI) phenomena in large scale RF heating experiments in magnetized fusion plasmas in the 1970s and beyond [2]. Although not discussed here, the importance of PDI phenomena has also been central to understanding anomalous absorption in laser-fusion experiments (ICF) [3]. In this review I shall discuss the fundamentals of nonlinear interactions among waves and particles, and in particular, their role in PDIs. This phenomenon is distinct from quasi-linear phenomena that are often invoked in calculating absorption of RF power in wave heating experiments in the core of magnetically confined plasmas [4]. Indeed, PDIs are most likely to occur in the edge of magnetized fusion plasmas where the electron temperature is modest and hence the oscillating quiver velocity of charged particles can be comparable to their thermal speeds. Specifically, I will review important aspects of PDI theory and give examples from past experiments in the ECH/EBW, lower hybrid (LHCD) and ICRF/IBW frequency regimes. Importantly, PDI is likely to play a fundamental role in determining the so-called “density limit” in lower hybrid experiments that has persisted over the decades and still central to understanding present day experiments [5-7].
Simulation of plasma discharge in liquids: A detailed two-phase fluid approach
Charchi Aghdam, Ali; Farouk, Tanvir; Reacting Systems; Advanced Energy Research Laboratory Team
2015-09-01
Plasma discharge in liquids has gained great attention recently due to its applications in biomedical engineering, fuel processing, and water treatment and so on. Despite the tremendous interest, a comprehensive understanding of the underlying physics still remains limited. In the current work, an attempt is made to present a mathematical multi-physics model to describe the discharge of plasma in liquids. An in-house modeling platform is developed for simulating plasma formation in multiphase fluids. The model resolves a detailed two-phase fluid including viscous effects, surface tension, gravitational forces and electrical body force. All the governing equations are solved for gas and liquid phases. Electric field and charged species equations along with the plasma reaction kinetics are solved to get the charge distribution in the different phases as well as at the gas-liquid interface to obtain the electric body force acting at the interface. By coupling the above sub-models, a comprehensive multi-physics model for plasma discharge in liquids is constructed which is able to capture several physical aspects of the phenomena especially the role of the bubble, its motion and distortion on plasma characteristics.
Fluid Simulation of the Ion Temperature Effects on a Collisional Magnetized Sheath of a Dusty Plasma
Directory of Open Access Journals (Sweden)
I Driouch
2013-01-01
Full Text Available The properties of magnetized dusty plasma sheath with finite ion temperature are studied using a fluid model. Hot electrons, fluid ions, neutral particles and cold fluid dust grains are taken into account in this system. Considering the cross section for collisions between the dust and neutrals has a power law dependence on the dust flow velocity, the fluid model is then solved numerically to obtain detailed sheath information under different ion temperatures. A significant change is observed in the quantities characterizing the sheath with respect to the cold ion assumption. In addition, the result reveals that the effect of ion temperature is more obvious on the dust dynamics in collisional sheath with constant cross section.
Energy Technology Data Exchange (ETDEWEB)
Khorashadizadeh, S. M., E-mail: smkhorashadi@birjand.ac.ir; Taheri Boroujeni, S. [Physics Department, University of Birjand, Birjand (Iran, Islamic Republic of); Niknam, A. R. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)
2015-11-15
In this paper, we have investigated the nonlinear interaction between high-frequency surface plasmons and low-frequency ion oscillations in a semi-bounded collisional quantum plasma. By coupling the nonlinear Schrodinger equation and quantum hydrodynamic model, and taking into account the ponderomotive force, the dispersion equation is obtained. By solving this equation, it is shown that there is a modulational instability in the system, and collisions and quantum forces play significant roles on this instability. The quantum tunneling increases the phase and group velocities of the modulated waves and collisions increase the growth rate of the modulational instability. It is also shown that the effect of quantum forces and collisions is more significant in high modulated wavenumber regions.
Solitonic and chaotic behaviors for the nonlinear dust-acoustic waves in a magnetized dusty plasma
Zhen, Hui-Ling; Tian, Bo; Xie, Xi-Yang; Wu, Xiao-Yu; Wen, Xiao-Yong
2016-05-01
A model for the nonlinear dust-ion-acoustic waves in a two-ion-temperature, magnetized dusty plasma is studied in this paper. Via the symbolic computation, one-, two- and N-soliton solutions are obtained. It is found that when √{μeμi }parallel during the propagation on the x - y, x - t, and y - t planes, where x, y, and z are the scaled spacial coordinates, and t is the retarded time. Upon the introduction of the driving force Γ(t ) , both the developed and weak chaotic motions as well as the effect of Γ(t ) are explored. Via the phase projections and power spectra, we find the difference between the two chaotic motions roots in the relative magnitude of nonlinearity and external force. Increasing the frequency of the external force or the strength of the damped term can weaken the chaotic motions of such a forced model.
A blended continuous-discontinuous finite element method for solving the multi-fluid plasma model
Sousa, E. M.; Shumlak, U.
2016-12-01
The multi-fluid plasma model represents electrons, multiple ion species, and multiple neutral species as separate fluids that interact through short-range collisions and long-range electromagnetic fields. The model spans a large range of temporal and spatial scales, which renders the model stiff and presents numerical challenges. To address the large range of timescales, a blended continuous and discontinuous Galerkin method is proposed, where the massive ion and neutral species are modeled using an explicit discontinuous Galerkin method while the electrons and electromagnetic fields are modeled using an implicit continuous Galerkin method. This approach is able to capture large-gradient ion and neutral physics like shock formation, while resolving high-frequency electron dynamics in a computationally efficient manner. The details of the Blended Finite Element Method (BFEM) are presented. The numerical method is benchmarked for accuracy and tested using two-fluid one-dimensional soliton problem and electromagnetic shock problem. The results are compared to conventional finite volume and finite element methods, and demonstrate that the BFEM is particularly effective in resolving physics in stiff problems involving realistic physical parameters, including realistic electron mass and speed of light. The benefit is illustrated by computing a three-fluid plasma application that demonstrates species separation in multi-component plasmas.
Effect of a seed magnetic field on two-fluid plasma Richtmyer-Meshkov instability
Bond, Daryl; Wheatley, Vincent; Samtaney, Ravi; Pullin, Dale
2016-11-01
We investigate the effect of a uniform seed magnetic field on the plasma Richtmyer-Meshkov instability (RMI) using two-fluid simulations. These couple sets of conservation equations for the ions and electrons to the full Maxwell's equations. We consider cases where the seed magnetic field is normal to the interface and where the reference Debye length and Larmor radius range from a tenth to a thousandth of the interface perturbation wavelength. In ideal magnetohydrodynamics (MHD), it has been shown that in the presence of such a seed magnetic field, the growth of the RMI is suppressed by the transport of vorticity from the interface by MHD shocks. Our two-fluid plasma simulations reveal that while the RMI is suppressed in the presence of the seed field, the suppression mechanism varies depending on the plasma length-scales. Two-fluid plasma RMI simulations also reveal a secondary, high-wavenumber, electron-driven interface instability. This is not suppressed by the presence of the seed field. This work was partially supported by the KAUST Office of Sponsored Research under Award URF/1/2162-01.
CENTORI: a global toroidal electromagnetic two-fluid plasma turbulence code
Knight, P J; Edwards, T D; Hein, J; Romanelli, M; McClements, K G
2011-01-01
A new global two-fluid electromagnetic turbulence code, CENTORI, has been developed for the purpose of studying magnetically-confined fusion plasmas. This code is used to evolve the combined system of electron and ion fluid equations and Maxwell equations in fully toroidal geometry, and is applicable to tokamaks of arbitrary aspect ratio and high plasma beta. A predictor corrector, semi-implicit finite difference scheme is used to compute the time evolution of fluid quantities and fields. Vector operations and the evaluation of flux surface averages are speeded up by choosing the Jacobian of the transformation from laboratory to plasma coordinates to be a function of the equilibrium poloidal magnetic flux. A subroutine, GRASS, is used to co-evolve the plasma equilibrium by computing the steady-state solutions of a diffusion equation with a pseudo-time derivative. The code is written in Fortran 95 and is efficiently parallelized using Message Passing Interface (MPI). Illustrative examples of output from a simu...
Cortisol in plasma and cerebrospinal fluid of patients with brain ischemia
Directory of Open Access Journals (Sweden)
Selaković Vesna M.
2004-01-01
Full Text Available Introduction One of the reactions to ischemia is increased release of glucocorticoid hormones, included in regulation of effects of numerous mediators/modulators that could be released in the acute phase of brain ischemia. The aim of our investigation was to define temporal dynamics of cortisol concentrations in plasma and cerebrospinal fluid of patients with different types of ischemic brain disease. Material and methods The study included 263 patients of both sexes, aged 55-68 years. History, clinical examination and cerebral computerized tomography were performed to establish the diagnosis. 97 patients had brain infarction, 66 had a reversible ischemic attack, 66 had a transient ischemic attack, and 34 patients had chronic encephalopathy. The control group included 22 age- and sex- matched patients, subjected to diagnostic lumbar radiculography, without disturbances in the cerebrospinal fluid passage. Cortisol concentrations were measured by direct radioimmunoassay. Results and discussion Results obtained in this research showed that in acute brain ischemic period there was a significant increase of cortisol concentration in plasma and cerebrospinal fluid. The increase was highest in patients with brain infarction, somewhat lower in reversible ischemic attack, and the lowest in transient ischemic attack compared to controls (331.7±92.8 pmol/ml of plasma and 2.5±1.1 pmol/ml of cerebrospinal fluid. Maximum concentrations were found during the first two days after insult. The main potentially protective effects of increased cortisol concentrations in patients with acute stroke could be the decrease of effects of deleterious reactions induced by ischemia. This mechanism might be an attempt of organism to compensate for disturbed homeostasis. Conclusion Measurement of cortisol in plasma and cerebrospinal fluid in patients with acute stroke is significant for monitoring the intensity of response of an organism to acute brain damage.
Experimental study of nonlinear dust acoustic solitary waves in a dusty plasma
Bandyopadhyay, P; Sen, A; Kaw, P K
2008-01-01
The excitation and propagation of finite amplitude low frequency solitary waves are investigated in an Argon plasma impregnated with kaolin dust particles. A nonlinear longitudinal dust acoustic solitary wave is excited by pulse modulating the discharge voltage with a negative potential. It is found that the velocity of the solitary wave increases and the width decreases with the increase of the modulating voltage, but the product of the solitary wave amplitude and the square of the width remains nearly constant. The experimental findings are compared with analytic soliton solutions of a model Kortweg-de Vries equation.
Nonlinear ion dynamics in Hall thruster plasma source by ion transit-time instability
Lim, Youbong; Choe, Wonho; Mazouffre, Stéphane; Park, Jae Sun; Kim, Holak; Seon, Jongho; Garrigues, L.
2017-03-01
High-energy tail formation in an ion energy distribution function (IEDF) is explained in a Hall thruster plasma with the stationary crossed electric and magnetic fields whose discharge current is oscillated at the ion transit-time scale with a frequency of 360 kHz. Among ions in different charge states, singly charged Xe ions (Xe+) have an IEDF that is significantly broadened and shifted toward the high-energy side, which contributes to tail formation in the entire IEDF. Analytical and numerical investigations confirm that the IEDF tail is due to nonlinear ion dynamics in the ion transit-time oscillation.
Kinetics of HIV-1 in cerebrospinal fluid and plasma in cryptococcal meningitis
Directory of Open Access Journals (Sweden)
Jorge A. Benetucci
2012-04-01
Full Text Available In order to determine HIV-1 kinetics in cerebrospinal fluid (CSF and plasma in patients with cryptococcal meningitis (CM, we undertook a prospective collection of paired CSF/plasma samples from antiretroviral therapy- free HIV-infected patients with CM. Samples were obtained at baseline (S1 and at the second (S2 and third (S3 weeks of antifungal therapy. HIV-1 CSF concentrations were significantly lower in both S2 and S3 with respect to S1. Plasma concentrations remained stable. HIV-1 concentrations were higher in plasma than CSF in all cases. Patients who survived the episode of CM (but not those who died showed a decrease in CSF viral load, what suggests different viral kinetics of HIV-1 in the CSF according to the clinical course of this opportunistic disease.
Kinetics of HIV-1 in cerebrospinal fluid and plasma in cryptococcal meningitis
Cecchini, Diego M.; Cañizal, Ana M.; Rojas, Haroldo; Arechavala, Alicia; Negroni, Ricardo; Bouzas, María B.; Benetucci, Jorge A.
2012-01-01
In order to determine HIV-1 kinetics in cerebrospinal fluid (CSF) and plasma in patients with cryptococcal meningitis (CM), we undertook a prospective collection of paired CSF/plasma samples from antiretroviral therapy-free HIV-infected patients with CM. Samples were obtained at baseline (S1) and at the second (S2) and third (S3) weeks of antifungal therapy. HIV-1 CSF concentrations were significantly lower in both S2 and S3 with respect to S1. Plasma concentrations remained stable. HIV-1 concentrations were higher in plasma than CSF in all cases. Patients who survived the episode of CM (but not those who died) showed a decrease in CSF viral load, what suggests different viral kinetics of HIV-1 in the CSF according to the clinical course of this opportunistic disease. PMID:24470944
Kinetics of HIV-1 in cerebrospinal fluid and plasma in cryptococcal meningitis.
Cecchini, Diego M; Cañizal, Ana M; Rojas, Haroldo; Arechavala, Alicia; Negroni, Ricardo; Bouzas, María B; Benetucci, Jorge A
2012-04-27
In order to determine HIV-1 kinetics in cerebrospinal fluid (CSF) and plasma in patients with cryptococcal meningitis (CM), we undertook a prospective collection of paired CSF/plasma samples from antiretroviral therapy-free HIV-infected patients with CM. Samples were obtained at baseline (S1) and at the second (S2) and third (S3) weeks of antifungal therapy. HIV-1 CSF concentrations were significantly lower in both S2 and S3 with respect to S1. Plasma concentrations remained stable. HIV-1 concentrations were higher in plasma than CSF in all cases. Patients who survived the episode of CM (but not those who died) showed a decrease in CSF viral load, what suggests different viral kinetics of HIV-1 in the CSF according to the clinical course of this opportunistic disease.
Improvement of Plasma Gun Performance using Comprehensive Fluid Element Modeling: Part I
Muggli, Felix A.; Molz, Ronald J.; McCullough, Richard; Hawley, Dave
2007-12-01
The use of computational fluid dynamics (CFD) to model the operation of thermal-spray processes has gained interest in the thermal-spray community, able to provide an understanding as to how a process functions, and better how to make a process work better. Advancements to the science of modeling now permits the ability to create a comprehensive model of a plasma gun that not only simulates the dynamics of the gas, but also the mechanics of arcs (plasma), thermodynamics, and entrained particulates to form a nearly complete model of a working thermal-spray process. Work presented includes the methods and procedures used to validate the model to a Sulzer Metco TriplexProTM-200 plasma gun and exploration of the operating regime to give an in depth and insightful look into the physics behind the operation of a triple-arc cascaded plasma gun.
Energy Technology Data Exchange (ETDEWEB)
Khan, Masood [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan); Hashim, E-mail: hashim_alik@yahoo.com [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan); Hussain, M. [Department of Sciences and Humanities, National University of Computer and Emerging Sciences, Islamabad 44000 (Pakistan); Azam, M. [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan)
2016-08-15
This paper presents a study of the magnetohydrodynamic (MHD) boundary layer flow of a non-Newtonian Carreau fluid over a convectively heated surface. The analysis of heat transfer is further performed in the presence of non-linear thermal radiation. The appropriate transformations are employed to bring the governing equations into dimensionless form. The numerical solutions of the partially coupled non-linear ordinary differential equations are obtained by using the Runge-Kutta Fehlberg integration scheme. The influence of non-dimensional governing parameters on the velocity, temperature, local skin friction coefficient and local Nusselt number is studied and discussed with the help of graphs and tables. Results proved that there is significant decrease in the velocity and the corresponding momentum boundary layer thickness with the growth in the magnetic parameter. However, a quite the opposite is true for the temperature and the corresponding thermal boundary layer thickness. - Highlights: • We investigated the Magnetohydrodynamic flow of Carreau constitutive fluid model. • Impact of non-linear thermal radiation is further taken into account. • Runge-Kutta Fehlberg method is employed to obtain the numerical solutions. • Fluid velocity is higher in case of hydromagnetic flow in comparison with hydrodynamic flow. • The local Nusselt number is a decreasing function of the thermal radiation parameter.
Non-linear plasma effects on laser-induced terahertz emission from the atmosphere
Shin, J.-H.; Zhidkov, A.; Jin, Z.; Hosokai, T.; Kodama, R.
2012-02-01
Power, spectral characteristics, and angle distribution of terahertz (THz) radiation from air irradiated by a single (ω) or coupled (ω, 2ω) femtosecond laser pulses are analyzed for higher intensities, for which non-linear plasma effects on the pulse propagation become essential, by means of multidimensional particle-in-cell simulations exploiting the self-consistent plasma kinetics. THz radiation is shown to be a result of beat waves generated at ionization front with fundamental and second harmonic waves. At lower intensities, the THz power growth is far faster than the linear; at pulse intensities over I > 1015 W/cm2, the power increases slower than the linear. Along with the forward emission, strong power in around 30o angles occurs at high intensities. Ionization of air results in poor focusing of laser pulses and, therefore, lower efficiency of THz emission.
Plasma wakefields in the quasi-nonlinear regime: Experiments at ATF
Rosenzweig, J. B.; Andonian, G.; Barber, S.; Ferrario, M.; Muggli, P.; O'Shea, B.; Sakai, Y.; Valloni, A.; Williams, O.; Xi, Y.; Yakimenko, V.
2012-12-01
In this work we present details of planned experiments to investigate certain aspects of the quasi non linear regime (QNL) of plasma wakefield acceleration (PWFA). In the QNL regime it is, in principal, possible to combine the benefits of both nonlinear and linear PWFA. That is, beams of high quality can be maintained through acceleration due to the complete ejection of plasma electrons from beam occupied region, while large energy gains can be achieved through use of transformer ratio increasing schemes, such as ramped bunch trains. With the addition of an short focal length PMQ triplet capable of focusing beams to the few micron scale and the ability to generate tunable bunch trains, the Accelerator Test Facility (ATF) at Brookhaven National Lab offers the unique capabilities to probe these characteristics of the QNL regime.
Plasma pro-atrial natriuretic peptide to indicate fluid balance during cystectomy
DEFF Research Database (Denmark)
Rasmussen, Kirsten C; Højskov, Michael; Ruhnau, Birgitte
2016-01-01
: One university/tertiary centre. PARTICIPANTS: The study included patients who underwent radical cystectomy. Plasma for determination of proANP was obtained before surgery, after resection of the bladder, and at the end of surgery for 20 robotic-assisted radical cystectomy (RARC) and 20 open radical......OBJECTIVES: During surgery the volume of administered fluid is debated. Pro-atrial natriuretic peptide (proANP) is released by atrial distension, and we evaluated the relationship between changes in proANP associated with perioperative fluid balance. DESIGN: Prospective observational study. SETTING...
Navier-Stokes Neutral and Plasma Fluid Modelling in 3D
Energy Technology Data Exchange (ETDEWEB)
Riemann, J; Borchardt, M; Schneider, R; Mutzke, A; Rognlien, T; Umansky, M
2004-05-17
The 3D finite volume transport code BoRiS is applied to a system of coupled plasma and neutral fluid equations in a slab. Demonstrating easy implementation of new equations, a new parallel BoRiS version is tested on three different models for the neutral fluid - diffusive, parallel Navier-Stokes and full Navier-Stokes - and the results are compared to each other. Typical effects like density enhancement by ionization of recycled neutrals in front of a target plate can be seen and differences are linked to the neutral models in use.
Georgievskii, D. V.
2007-06-01
Material functions are necessary element of the constitutive relations determining any model of continuum. These functions can be defined as a collection of objects from which the operator of constitutive relations can be reconstructed completely. The material functions are found in test experiments and show the differences between a given medium and other media in the framework of the same model [1]. The "test experiment theory" is an important part of modern experimental mechanics. Just as in any experiment, from determining the viscosity coefficient by using the rotational viscosimeters to constructing the yield surface by using machines combined loading, the material functions are determined with an unavoidable error. For example, experimenters know that, in experiments with arbitrary accuracy, the moduli of elasticity can only be measured with an unimprovable tolerance of about 7%. Starting already from [2], the investigators' attention has been repeatedly drawn to the fact that it is necessary to take into account this tolerance in determining the material constants, functions, and functionals in problems of mechanics and especially in analyzing the stability of deformation processes. Mathematically, this means that problems of stability under perturbations of the initial data, external constantly acting forces, domain boundaries, etc. should be supplemented with the assumption that the material functions have unknown perturbations of a certain class [3]. The variations of material functions in the framework of the linearized stability theory were considered in [2, 4, 5]. In what follows, we study isotropic tensor functions in the most general case of scalar and tensor nonlinearity. These functions are assigned the meaning of constitutive relations between the stress and strain rate tensors in continuum. These constitutive relations contain scalar material functions of invariants on which, as follows from the above, some variations proportional to a small
Solitons and rogue waves for a nonlinear system in the geophysical fluid
Xie, Xi-Yang; Tian, Bo; Liu, Lei; Wu, Xiao-Yu; Jiang, Yan
2016-12-01
In this paper, we investigate a nonlinear system, which describes the marginally unstable baroclinic wave packets in the geophysical fluid. Based on the symbolic computation and Hirota method, bright one- and two-soliton solutions for such a system are derived. Propagation and collisions of the solitons are graphically shown and discussed with β, which reflects the collision between the wave packet and mean flow, α, which measures the state of the basic flow, and group velocity γ. γ is observed to affect the amplitudes of the solitons, and α can influence the solitons’ traveling directions. By virtue of the generalized Darboux transformation, the first- and second-order rogue-wave solutions are derived. Properties of the first- and second-order rogue waves are graphically presented and analyzed: The first-order rogue waves are shown in the figures. α has no effects on A, which is the amplitude of the wave packet, but with the increase of α, amplitude of B, which is a quantity measuring the correction of the basic flow, decreases. When β is chosen differently, A and B do not keep their shapes invariant. With the value of γ increasing, amplitudes of A and B become larger. The second-order rogue wave is presented, from which we observe that with α increasing, amplitude of B decreases, but α has no effects on A. Collision features of A and B alter with the value of β changing. When we make the value of γ larger, amplitudes of A and B increase.
Waves in General Relativistic Two-fluid Plasma around a Schwarzschild Black Hole
Rahman, M Atiqur
2010-01-01
Waves propagating in the relativistic electron-positron or ions plasma are investigated in a frame of two-fluid equations using the 3+1 formalism of general relativity developed by Thorne, Price and Macdonald (TPM). The plasma is assumed to be freefalling in the radial direction toward the event horizon due to the strong gravitational field of a Schwarzschild black hole. The local dispersion relations for transverse and longitudinal waves have been derived, in analogy with the special relativistic formulation as explained in an earlier paper, to take account of relativistic effects due to the event horizon using WKB approximation
Dispersion Relations and Polarizations of Low-frequency Waves in Two-fluid Plasmas
Zhao, Jinsong
2015-01-01
Analytical expressions for the dispersion relations and polarizations of low-frequency waves in magnetized plasmas based on two-fluid model are obtained. The properties of waves propagating at different angles (to the ambient magnetic field $\\mathbf{B}_{0}$) and \\beta (the ratio of the plasma to magnetic pressures) values are investigated. It is shown that two linearly polarized waves, namely the fast and Alfv\\'{e}n modes in the low-\\beta $\\left( \\beta \\ll 1\\right)$ plasmas, the fast and slow modes in the \\beta \\sim 1 plasmas, and the Alfv\\'{e}n and slow modes in the high-\\beta $\\left( \\beta \\gg 1\\right)$ plasmas, become circularly polarized at the near-parallel (to $\\mathbf{B}_{0}$) propagation. The negative magnetic-helicity of the Alfv\\'{e}n mode occurs only at small or moderate angles in the low-\\beta plasmas, and the ion cross-helicity of the slow mode is nearly the same as that of the Alfv\\'{e}n mode in the high-\\beta plasmas. It also shown the electric polarization $\\delta E_{z}/\\delta E_{y}$ decreases...
Predator-prey dynamics stabilised by nonlinearity explain oscillations in dust-forming plasmas
Ross, A. E.; McKenzie, D. R.
2016-04-01
Dust-forming plasmas are ionised gases that generate particles from a precursor. In nature, dust-forming plasmas are found in flames, the interstellar medium and comet tails. In the laboratory, they are valuable in generating nanoparticles for medicine and electronics. Dust-forming plasmas exhibit a bizarre, even puzzling behaviour in which they oscillate with timescales of seconds to minutes. Here we show how the problem of understanding these oscillations may be cast as a predator-prey problem, with electrons as prey and particles as predators. The addition of a nonlinear loss term to the classic Lotka-Volterra equations used for describing the predator-prey problem in ecology not only stabilises the oscillations in the solutions for the populations of electrons and particles in the plasma but also explains the behaviour in more detail. The model explains the relative phase difference of the two populations, the way in which the frequency of the oscillations varies with the concentration of the precursor gas, and the oscillations of the light emission, determined by the populations of both species. Our results demonstrate the value of adopting an approach to a complex physical science problem that has been found successful in ecology, where complexity is always present.
Kwon, Deuk-Chul; Song, Mi-Young; Yoon, Jung-Sik
2014-10-01
It is well known that the dielectric relaxation scheme (DRS) can efficiently overcome the limitation on the simulation time step for fluid transport simulations of high density plasma discharges. By imitating a realistic and physical shielding process of electric field perturbation, the DRS overcomes the dielectric limitation on time step. However, the electric field was obtained with assuming the drift-diffusion approximation. Although the drift-diffusion expressions are good approximations for both the electrons and ions at high pressure, the inertial term cannot be neglected in the ion momentum equation for low pressure. Therefore, in this work, we developed the extended DRS by introducing an effective electric field. To compare the extended DRS with the previous method, two-dimensional fluid simulations for inductively coupled plasma discharges were performed. This work was supported by the Industrial Strategic Technology Development Program (10041637, Development of Dry Etch System for 10 nm class SADP Process) funded by the Ministry of Knowledge Economy (MKE, Korea).
Directory of Open Access Journals (Sweden)
M. M. Becker
2013-01-01
Full Text Available Common fluid models used for the description of electron transport in nonthermal discharge plasmas are subject to substantial restrictions if the electron energy transport significantly influences the discharge behaviour. A drift-diffusion approach is presented which is based on a multiterm approximation of the electron velocity distribution function and overcomes some of these restrictions. It is validated using a benchmark model and applied for the analysis of argon discharge plasmas at low and atmospheric pressure. The results are compared to those of common drift-diffusion models as well as to experimental data. It is pointed out that fluid models are able to describe nonlocal phenomena caused by electron energy transport, if the energy transport is consistently described. Numerical difficulties that frequently occur when the conventional drift-diffusion model is consistently applied are avoided by the proposed method.
DEFF Research Database (Denmark)
Strandby, Rune Broni; Ambrus, Rikard; Secher, Niels H
2017-01-01
BACKGROUND: It remains debated how much fluid should be administered during surgery. The atrial natriuretic peptide precursor proANP is released by atrial distension and deviations in plasma proANP are reported associated with perioperative fluid balance. We hypothesized that plasma proANP would...... decrease when the central blood volume is compromised during the abdominal part of robot-assisted hybrid (RE) esophagectomy and that a positive fluid balance would be required to maintain plasma proANP. METHODS: Patients undergoing RE (n = 25) or open (OE; n = 25) esophagectomy for gastroesophageal cancer...
Directory of Open Access Journals (Sweden)
Mustapha Lahmar
2015-04-01
Full Text Available On the basis of the V. K. Stokes micro-continuum theory, the effects of couple stresses on the nonlinear dynamic response of the unbalanced Jeffcott’s flexible rotor supported by layered hydrodynamic journal bearings is presented in this paper. A nonlinear transient modified Reynolds’ equation is derived and discretized by the finite element method to obtain the fluid-film pressure field as well as the film thickness by means of the implicit Euler method. The nonlinear orbits of the rotor center are determined by solving the nonlinear differential equations of motion with the explicit Euler’s scheme taking into account the flexibility of rotor. According to the obtained results, the combined effects of couple stresses due to the presence of polymer additives in lubricant and the pressure dependent viscosity on the nonlinear dynamic response of the rotor-bearing system are significant and cannot be ignored or overlooked. As expected, these effects are more noticeable for polymers characterized by higher length molecular chains.
Directory of Open Access Journals (Sweden)
Amelia eGreig
2015-01-01
Full Text Available Computational fluid dynamics (CFD simulations of a radio-frequency (13.56 MHz electro-thermal capacitively coupled plasma (CCP micro-thruster have been performed using the commercial CFD-ACE+ package. Standard operating conditions of a 10 W, 1.5 Torr argon discharge were used to compare with previously obtained experimental results for validation. Results show that the driving force behind plasma production within the thruster is ion-induced secondary electrons ejected from the surface of the discharge tube, accelerated through the sheath to electron temperatures up to 33.5 eV. The secondary electron coefficient was varied to determine the effect on the discharge, with results showing that full breakdown of the discharge did not occur for coefficients coefficients less than or equal to 0.01.
Optics and Fluid Dynamics Department annual progress report for 1995
Energy Technology Data Exchange (ETDEWEB)
Hanson, S.G.; Lading, L.; Lynov, J.P.; Skaarup, B. [eds.
1996-01-01
Research in the Optics and Fluid Dynamics Department has been performed within the following two programme areas: (1) optical diagnostics and information processing and (2) plasma and fluid dynamics. The optical activities are concentrated on optical materials, diagnostics and sensors. The plasma and fluid dynamics activities are concentrated on nonlinear dynamics in fluids, plasmas and optics as well as on plasma and fluid diagnostics. Scientific computing is an integral part of the work. The activities are supported by several EU programmes, including EURATOM, by research councils and by industry. A summary of the activities in 1995 is presented. (au) 36 ills., 166 refs.
Dahl, V.; Gisslen, M.; Hagberg, L.; Peterson, J.; Shao, W.; Spudich, S.; Price, RW; Palmer, S.
2014-01-01
We sequenced the genome of human immunodeficiency virus type 1 (HIV-1) recovered from 70 cerebrospinal fluid (CSF) specimens and 29 plasma samples and corresponding samples obtained before treatment initiation from 17 subjects receiving suppressive therapy. More CSF sequences than plasma sequences were hypermutants. We determined CSF sequences and plasma sequences in specimens obtained from 2 subjects after treatment initiation. In one subject, we found genetically distinct CSF and plasma seq...
Effect of Rehydration Fluid Osmolality on Plasma Volume and Vasopressin in Resting Dehydrated Men
Geelen, Ghislaine; Greenleaf, J. E.; Keil, L. C.; Wade, Charles E. (Technical Monitor)
1994-01-01
Elevated plasma vasopressin concentration [PVP], which may act as a dipsogen, decreases promptly following the ingestion of fluids in many mammals including humans. The purpose for this study was to determine whether fluids of varied electrolyte and carbohydrate composition and osmolality (Osm] would modify post-drinking decreases in [PVP] which could be attributed to interaction with plasma volume (PV)- or fluid-electrolyte interactive hormones. Five men (23-41 yr, 78.0 +/- SD 8.2 kg), water deprived for 24 h, drank six fluids (12 ml/kg, at 16.5C in 4.0-6.2 min): water (30 m0sm/kg), NaCl (70 mOsm/kg), NaCl + NaCitrate (270 mOsm/kg), NaCl + 9.7% glucose (650 mOsm/kg), and two commercial drinks containing various ionic and carbohydrate contents (380 and 390 mOsm/kg). Blood (20 ml/sample) was drawn at -5 min before and at +3, +9, +15, +30, and +70 min after drinking. Heart rate, blood pressures, and plasma renin activity, {Na+], [K+], [Osm], aldosterone, atrial natriuretic peptide, and epinephrine concentrations were unchanged after drinking. Post-drinking [PVP] decreased from 1.7 - 3.7 pg/ml within 3 min with all fluids independently of their composition, [Osm], or delta PV; with maximal depression to 0.1-0.7 pg/ml (pplasma (Osm] but 1.8-7.6% increases (pplasma norepinephrine concentrations [PNE] at 15 min correlated -0.70 (P<0.10) suggesting that about half the variability in [PVP I I depression was associated with [PNE]. Thus, part of the mechanism for post-drinking [PVP] depression may involve a drinking stimulated norepinephrine (neural) factor.
Nonlinear plasma experiments in geospace with gigawatts of RF power at HAARP
Sheerin, J. P.; Cohen, Morris B.
2015-12-01
The ionosphere is the ionized uppermost layer of our atmosphere (from 70 - 500 km altitude) where free electron densities yield peak critical frequencies in the HF (3 - 30 MHz) range. The ionosphere thus provides a quiescent plasma target, stable on timescales of minutes, for a whole host of active plasma experiments. High power RF experiments on ionospheric plasma conducted in the U.S. have been reported since 1970. The largest HF transmitter built to date is the HAARP phased-array HF transmitter near Gakona, Alaska which can deliver up to 3.6 Gigawatts (ERP) of CW RF power in the range of 2.8 - 10 MHz to the ionosphere with microsecond pointing, power modulation, and frequency agility. With an ionospheric background thermal energy in the range of only 0.1 eV, this amount of power gives access to the highest regimes of the nonlinearity (RF intensity to thermal pressure) ratio. HAARP's unique features have enabled the conduct of a number of unique nonlinear plasma experiments in the interaction region of overdense ionospheric plasma including generation of artificial aurorae, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, parametric instabilities, stimulated electromagnetic emissions (SEE), strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and telescopes and cameras for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the HF-enhanced plasma line, and production of suprathermal electrons. One of the primary missions of HAARP, has been the generation of ELF (300 - 3000 Hz) and VLF (3 - 30 kHz) radio waves which are guided to global distances in the Earth-ionosphere waveguide. We review
Nonlinear plasma experiments in geospace with gigawatts of RF power at HAARP
Energy Technology Data Exchange (ETDEWEB)
Sheerin, J. P., E-mail: jsheerin@emich.edu [Physics and Astronomy, Eastern Michigan Univ., Ypsilanti, MI 48197 (United States); Cohen, Morris B., E-mail: mcohen@gatech.edu [Electrical and Computer Engineering, Georgia Tech, Atlanta, GA 30332-0250 (United States)
2015-12-10
The ionosphere is the ionized uppermost layer of our atmosphere (from 70 – 500 km altitude) where free electron densities yield peak critical frequencies in the HF (3 – 30 MHz) range. The ionosphere thus provides a quiescent plasma target, stable on timescales of minutes, for a whole host of active plasma experiments. High power RF experiments on ionospheric plasma conducted in the U.S. have been reported since 1970. The largest HF transmitter built to date is the HAARP phased-array HF transmitter near Gakona, Alaska which can deliver up to 3.6 Gigawatts (ERP) of CW RF power in the range of 2.8 – 10 MHz to the ionosphere with microsecond pointing, power modulation, and frequency agility. With an ionospheric background thermal energy in the range of only 0.1 eV, this amount of power gives access to the highest regimes of the nonlinearity (RF intensity to thermal pressure) ratio. HAARP’s unique features have enabled the conduct of a number of unique nonlinear plasma experiments in the interaction region of overdense ionospheric plasma including generation of artificial aurorae, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, parametric instabilities, stimulated electromagnetic emissions (SEE), strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and telescopes and cameras for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the HF-enhanced plasma line, and production of suprathermal electrons. One of the primary missions of HAARP, has been the generation of ELF (300 – 3000 Hz) and VLF (3 – 30 kHz) radio waves which are guided to global distances in the Earth
Comparisons of linear and nonlinear plasma response models for non-axisymmetric perturbations
Energy Technology Data Exchange (ETDEWEB)
Turnbull, A. D.; Ferraro, N. M.; Lao, L. L.; Lanctot, M. J. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Izzo, V. A. [University of California-San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Lazarus, E. A.; Hirshman, S. P. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States); Park, J.-K.; Lazerson, S.; Reiman, A. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Cooper, W. A. [Association Euratom-Confederation Suisse, Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland); Liu, Y. Q. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Turco, F. [Columbia University, 116th St and Broadway, New York, New York 10027 (United States)
2013-05-15
With the installation of non-axisymmetric coil systems on major tokamaks for the purpose of studying the prospects of ELM-free operation, understanding the plasma response to the applied fields is a crucial issue. Application of different response models, using standard tools, to DIII-D discharges with applied non-axisymmetric fields from internal coils, is shown to yield qualitatively different results. The plasma response can be treated as an initial value problem, following the system dynamically from an initial unperturbed state, or from a nearby perturbed equilibrium approach, and using both linear and nonlinear models [A. D. Turnbull, Nucl. Fusion 52, 054016 (2012)]. Criteria are discussed under which each of the approaches can yield a valid response. In the DIII-D cases studied, these criteria show a breakdown in the linear theory despite the small 10{sup −3} relative magnitude of the applied magnetic field perturbations in this case. For nonlinear dynamical evolution simulations to reach a saturated nonlinear steady state, appropriate damping mechanisms need to be provided for each normal mode comprising the response. Other issues arise in the technical construction of perturbed flux surfaces from a displacement and from the presence of near nullspace normal modes. For the nearby equilibrium approach, in the absence of a full 3D equilibrium reconstruction with a controlled comparison, constraints relating the 2D system profiles to the final profiles in the 3D system also need to be imposed to assure accessibility. The magnetic helicity profile has been proposed as an appropriate input to a 3D equilibrium calculation and tests of this show the anticipated qualitative behavior.
Directory of Open Access Journals (Sweden)
Selaković Vesna M.
2003-01-01
Full Text Available The objective of this research was to determine the dynamics of change of neuron-specific enolase concentration in patients with acute ischemic brain disease in cerebrospinal fluid and plasma. The study included 103 patients, their mean age 58-66 years. The control group consisted of 16 patients, of matching age and sex, with radicular lesions of discal origin, subjected to diagnostic radiculography. Concentration of neuron-specific enolase was measured by a flouroimmunometric method. The results showed that the concentration of neuron-specific enolase in cerebrospinal fluid and plasma of patients with brain ischemic disease within first seven days significantly increased compared to the control. The highest increase of concentration was established in brain infarction, somewhat lower in reversible ischemic attack, and the lowest in transient ischemic attack. Maximal concentration was established on the 3rd-4th day upon the brain infarction. Neuron-specific enolase concentration in cerebrospinal fluid and plasma may be an indicator of pathophysiological processes in the acute phase of brain ischemia and is significant in early diagnostics and therapy of the disease.
Maternal Plasma and Amniotic Fluid Chemokines Screening in Fetal Down Syndrome
Directory of Open Access Journals (Sweden)
Piotr Laudanski
2014-01-01
Full Text Available Objective. Chemokines exert different inflammatory responses which can potentially be related to certain fetal chromosomal abnormalities. The aim of the study was to determine the concentration of selected chemokines in plasma and amniotic fluid of women with fetal Down syndrome. Method. Out of 171 amniocentesis, we had 7 patients with confirmed fetal Down syndrome (15th–18th weeks of gestation. For the purpose of our control, we chose 14 women without confirmed chromosomal aberration. To assess the concentration of chemokines in the blood plasma and amniotic fluid, we used a protein macroarray, which allows the simultaneous determination of 40 chemokines per sample. Results. We showed significant decrease in the concentration of 4 chemokines, HCC-4, IL-28A, IL-31, and MCP-2, and increase in the concentration of CXCL7 (NAP-2 in plasma of women with fetal Down syndrome. Furthermore, we showed decrease in concentration of 3 chemokines, ITAC, MCP-3, MIF, and increase in concentration of 4 chemokines, IP-10, MPIF-1, CXCL7, and 6Ckine, in amniotic fluid of women with fetal Down syndrome. Conclusion. On the basis of our findings, our hypothesis is that the chemokines may play role in the pathogenesis of Down syndrome. Defining their potential as biochemical markers of Down syndrome requires further investigation on larger group of patients.
Gulino, Daniel A.; Coles, Carolyn E.
1987-01-01
The Liquid Droplet Radiator is one of several radiator systems currently under investigation by NASA Lewis Research Center. It involves the direct exposure of the radiator working fluid to the space environment. An area of concern is the potential harmful effects of the low-Earth-orbit atomic oxygen environment on the radiator working fluid. To address this issue, seven candidate fluids were exposed to an oxygen plasma environment in a laboratory plasma asher. The fluids studied included Dow Corning 705 Diffusion Pump Fluid, polymethylphenylsiloxane and polydimethylsiloxane, both of which are experimental fluids made by Dow Corning, Fomblin Z25, made by Montedison, and three fluids from the Krytox family of fluids, Krytox 143AB, 1502, and 16256, which are made by DuPont. The fluids were characterized by noting changes in visual appearance, physical state, mass, and infrared spectra. Of the fluids tested, the Fomblin and the three Krytoxes were the least affected by the oxygen plasma. The only effect noted was a change in mass, which was most likely due to an oxygen-catalyzed depolymerization of the fluid molecule.
Vlasov fluid stability of a 2-D plasma with a linear magnetic field null
Energy Technology Data Exchange (ETDEWEB)
Kim, J.S.
1984-01-01
Vlasov fluid stability of a 2-dimensional plasma near an O type magnetic null is investigated. Specifically, an elongated Z-pinch is considered, and applied to Field Reversed Configurations at Los Alamos National Laboratory by making a cylindrical approximation of the compact torus. The orbits near an elliptical O type null are found to be very complicated; the orbits are large and some are stochastic. The kinetic corrections to magnetohydrodynamics (MHD) are investigated by evaluating the expectation values of the growth rates of a Vlasov fluid dispersion functional by using set of trial functions based on ideal MHD. The dispersion functional involves fluid parts and orbit dependent parts. The latter involves phase integral of two time correlations. The phase integral is replaced by the time integral both for the regular and for the stochastic orbits. Two trial functions are used; one has a large displacement near the null and the other away from the null.
Vlasov Fluid stability of a 2-D plasma with a linear magnetic field null
Energy Technology Data Exchange (ETDEWEB)
Kim, J.S.
1984-01-01
Vlasov Fluid stability of a 2-dimensional plasma near an O type magnetic null is investigated. Specifically, an elongated Z-pinch is considered, and applied to Field Reversed Configurations at Los Alamos National Laboratory by making a cylindrical approximation of the compact torus. The orbits near an elliptical O type null are found to be very complicated; the orbits are large and some are stochastic. The kinetic corrections to magnetohydrodynamics (MHD) are investigated by evaluating the expectation values of the growth rates of a Vlasov Fluid dispersion functional by using a set of trial functions based on ideal MHD. The dispersion functional involves fluid parts and orbit dependent parts. The latter involves phase integral of two time correlations. The phase integral is replaced by the time integral both for the regular and for the stochastic orbits. Two trial functions are used; one has a large displacement near the null and the other away from the null.
Adams, Allan; Carr, Lincoln D.; Schäfer, Thomas; Steinberg, Peter; Thomas, John E.
2012-11-01
Strongly correlated quantum fluids are phases of matter that are intrinsically quantum mechanical and that do not have a simple description in terms of weakly interacting quasiparticles. Two systems that have recently attracted a great deal of interest are the quark-gluon plasma, a plasma of strongly interacting quarks and gluons produced in relativistic heavy ion collisions, and ultracold atomic Fermi gases, very dilute clouds of atomic gases confined in optical or magnetic traps. These systems differ by 19 orders of magnitude in temperature, but were shown to exhibit very similar hydrodynamic flows. In particular, both fluids exhibit a robustly low shear viscosity to entropy density ratio, which is characteristic of quantum fluids described by holographic duality, a mapping from strongly correlated quantum field theories to weakly curved higher dimensional classical gravity. This review explores the connection between these fields, and also serves as an introduction to the focus issue of New Journal of Physics on ‘Strongly Correlated Quantum Fluids: From Ultracold Quantum Gases to Quantum Chromodynamic Plasmas’. The presentation is accessible to the general physics reader and includes discussions of the latest research developments in all three areas.
Energy Technology Data Exchange (ETDEWEB)
Ali Shan, S. [Theoretical Plasma Physics Division, PINSTECH, Nilore, 44000 Islamabad (Pakistan); National Centre For Physics (NCP), Shahdra Valley Road, 44000 Islamabad (Pakistan); Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad (Pakistan); El-Tantawy, S. A.; Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt)
2013-08-15
Arbitrary amplitude ion-acoustic waves in an unmagnetized plasma consisting of cold positive ions, superthermal electrons, and positrons beam are reported. The basic set of fluid equations is reduced to an energy-balance like equation. The latter is numerically analyzed to examine the existence regions for solitary and shock waves. It is found that only solitary waves can propagate, however, the model cannot support shocks. The effects of superthermality and beam parameters (via, positrons concentration and streaming velocity) on the existence region, as well as solitary wave profile have been discussed.
Tiwary, PremPyari; Sharma, Swati; Sharma, Prachi; Singh, Ram Kishor; Uma, R.; Sharma, R. P.
2016-12-01
This paper presents the spatio-temporal evolution of magnetic field due to the nonlinear coupling between fast magnetosonic wave (FMSW) and low frequency slow Alfvén wave (SAW). The dynamical equations of finite frequency FMSW and SAW in the presence of ponderomotive force of FMSW (pump wave) has been presented. Numerical simulation has been carried out for the nonlinear coupled equations of finite frequency FMSW and SAW. A systematic scan of the nonlinear behavior/evolution of the pump FMSW has been done for one of the set of parameters chosen in this paper, using the coupled dynamical equations. Filamentation of fast magnetosonic wave has been considered to be responsible for the magnetic turbulence during the laser plasma interaction. The results show that the formation and growth of localized structures depend on the background magnetic field but the order of amplification does not get affected by the magnitude of the background magnetic field. In this paper, we have shown the relevance of our model for two different parameters used in laboratory and astrophysical phenomenon. We have used one set of parameters pertaining to experimental observations in the study of fast ignition of laser fusion and hence studied the turbulent structures in stellar environment. The other set corresponds to the study of magnetic field amplification in the clumpy medium surrounding the supernova remnant Cassiopeia A. The results indicate considerable randomness in the spatial structure of the magnetic field profile in both the cases and gives a sufficient indication of turbulence. The turbulent spectra have been studied and the break point has been found around k which is consistent with the observations in both the cases. The nonlinear wave-wave interaction presented in this paper may be important in understanding the turbulence in the laboratory as well as the astrophysical phenomenon.
Enhanced nonlinear iterative techniques applied to a non-equilibrium plasma flow
Energy Technology Data Exchange (ETDEWEB)
Knoll, D.A.; McHugh, P.R. [Idaho National Engineering Lab., Idaho Falls, ID (United States)
1996-12-31
We study the application of enhanced nonlinear iterative methods to the steady-state solution of a system of two-dimensional convection-diffusion-reaction partial differential equations that describe the partially-ionized plasma flow in the boundary layer of a tokamak fusion reactor. This system of equations is characterized by multiple time and spatial scales, and contains highly anisotropic transport coefficients due to a strong imposed magnetic field. We use Newton`s method to linearize the nonlinear system of equations resulting from an implicit, finite volume discretization of the governing partial differential equations, on a staggered Cartesian mesh. The resulting linear systems are neither symmetric nor positive definite, and are poorly conditioned. Preconditioned Krylov iterative techniques are employed to solve these linear systems. We investigate both a modified and a matrix-free Newton-Krylov implementation, with the goal of reducing CPU cost associated with the numerical formation of the Jacobian. A combination of a damped iteration, one-way multigrid and a pseudo-transient continuation technique are used to enhance global nonlinear convergence and CPU efficiency. GMRES is employed as the Krylov method with Incomplete Lower-Upper(ILU) factorization preconditioning. The goal is to construct a combination of nonlinear and linear iterative techniques for this complex physical problem that optimizes trade-offs between robustness, CPU time, memory requirements, and code complexity. It is shown that a one-way multigrid implementation provides significant CPU savings for fine grid calculations. Performance comparisons of the modified Newton-Krylov and matrix-free Newton-Krylov algorithms will be presented.
Progranulin Levels in Plasma and Cerebrospinal Fluid in Granulin Mutation Carriers
Meeter, Lieke H.H.; Patzke, Holger; Loewen, Gordon; Dopper, Elise G.P.; Pijnenburg, Yolande A.L.; van Minkelen, Rick; van Swieten, John C.
2016-01-01
Background Pathogenic mutations in the granulin gene (GRN) are causative in 5-10% of patients with frontotemporal dementia (FTD), mostly leading to reduced progranulin protein (PGRN) levels. Upcoming therapeutic trials focus on enhancing PGRN levels. Methods Fluctuations in plasma PGRN (n = 41) and its relationship with cerebrospinal fluid (CSF, n = 32) and specific single nucleotide polymorphisms were investigated in pre- and symptomatic GRN mutation carriers and controls. Results Plasma PGRN levels were lower in carriers than in controls and showed a mean coefficient of variation of 5.3% in carriers over 1 week. Although plasma PGRN correlated with CSF PGRN in carriers (r = 0.54, p = 0.02), plasma only explained 29% of the variability in CSF PGRN. rs5848, rs646776 and rs1990622 genotypes only partly explained the variability of PGRN levels between subjects. Conclusions Plasma PGRN is relatively stable over 1 week and therefore seems suitable for treatment monitoring of PGRN-enhancing agents. Since plasma PGRN only moderately correlated with CSF PGRN, CSF sampling will additionally be needed in therapeutic trials. PMID:27703466
Energy Technology Data Exchange (ETDEWEB)
Gupta, Naveen, E-mail: naveens222@rediffmail.com; Singh, Arvinder, E-mail: arvinder6@lycos.com [Department of Physics, National Institute of Technology Jalandhar (India); Singh, Navpreet, E-mail: navpreet.nit@gmail.com [Guru Nanak Dev University College, Kapurthala, Punjab (India)
2015-11-15
This paper presents a scheme for second harmonic generation of an intense q-Gaussian laser beam in a preformed parabolic plasma channel, where collisional nonlinearity is operative with nonlinear absorption. Due to nonuniform irradiance of intensity along the wavefront of the laser beam, nonuniform Ohmic heating of plasma electrons takes place. Due to this nonuniform heating of plasma, the laser beam gets self-focused and produces strong density gradients in the transverse direction. The generated density gradients excite an electron plasma wave at pump frequency that interacts with the pump beam to produce its second harmonics. The formulation is based on a numerical solution of the nonlinear Schrodinger wave equation in WKB approximation followed by moment theory approach. A second order nonlinear differential equation governing the propagation dynamics of the laser beam with distance of propagation has been obtained and is solved numerically by Runge Kutta fourth order technique. The effect of nonlinear absorption on self-focusing of the laser beam and conversion efficiency of its second harmonics has been investigated.
Directory of Open Access Journals (Sweden)
Melissa A McAlexander
2013-05-01
Full Text Available Interest in extracellular RNA has intensified as evidence accumulates that these molecules may be useful as indicators of a wide variety of biological conditions. To establish specific extracellular RNA molecules as clinically relevant biomarkers, reproducible recovery from biological samples and reliable measurements of the isolated RNA are paramount. Towards these ends, careful and rigorous comparisons of technical procedures are needed at all steps from sample handling to RNA isolation to RNA measurement protocols. In the investigations described in this methods paper, RT-qPCR was used to examine the apparent recovery of specific endogenous miRNAs and a spiked-in synthetic RNA from blood plasma samples. RNA was isolated using several widely used RNA isolation kits, with or without the addition of glycogen as a carrier. Kits examined included total RNA isolation systems that have been commercially available for several years and commonly adapted for extraction of biofluid RNA, as well as more recently introduced biofluids-specific RNA methods. Our conclusions include the following: some RNA isolation methods appear to be superior to others for the recovery of RNA from biological fluids; addition of a carrier molecule seems to be beneficial for some but not all isolation methods; and partially or fully quantitative recovery of RNA is observed from increasing volumes of plasma and cerebrospinal fluid.
Energy Technology Data Exchange (ETDEWEB)
Hong Qin and Ronald C. Davidson
2011-07-19
In a linear trap confining a one-component nonneutral plasma, the external focusing force is a linear function of the configuration coordinates and/or the velocity coordinates. Linear traps include the classical Paul trap and the Penning trap, as well as the newly proposed rotating-radio- frequency traps and the Mobius accelerator. This paper describes a class of self-similar nonlinear solutions of nonneutral plasma in general time-dependent linear focusing devices, with self-consistent electrostatic field. This class of nonlinear solutions includes many known solutions as special cases.
Kumar, Naveen; Hatsagortsyan, Karen Z; Keitel, Christoph H
2013-09-06
Stimulated Raman scattering of an ultraintense laser pulse in plasmas is studied by perturbatively including the leading order term of the Landau-Lifshitz radiation reaction force in the equation of motion for plasma electrons. In this approximation, the radiation reaction force causes a phase shift in nonlinear current densities that drive the two Raman sidebands (anti-Stokes and Stokes waves), manifesting itself into the nonlinear mixing of two sidebands. This mixing results in a strong enhancement in the growth of the forward Raman scattering instability.
Crunch-in regime - Non-linearly driven hollow-channel plasma
Sahai, Aakash A
2016-01-01
Plasma wakefields driven inside a hollow-channel plasma are significantly different from those driven in a homogeneous plasma. This work investigates the scaling laws of the accelerating and focusing fields in the "crunch-in" regime. This regime is excited due to the collapse of the electron-rings from the channel walls onto the propagation axis of the energy-source, in its wake. This regime is thus the non-linearly driven hollow channel, since the electron-ring displacement is of the order of the channel radius. We present the properties of the coherent structures in the "crunch-in" regime where the channel radius is matched to the beam properties such that channel-edge to on-axis collapse time has a direct correspondence to the energy source intensity. We also investigate the physical mechanisms that underlie the "crunch-in" wakefields by tuning the channel radius. Using a theoretical framework and results from PIC simulations the possible applications of the "crunch-in" regime for acceleration of positron ...
Schneider, Kai
2015-01-01
Immersed boundary methods for computing confined fluid and plasma flows in complex geometries are reviewed. The mathematical principle of the volume penalization technique is described and simple examples for imposing Dirichlet and Neumann boundary conditions in one dimension are given. Applications for fluid and plasma turbulence in two and three space dimensions illustrate the applicability and the efficiency of the method in computing flows in complex geometries, for example in toroidal geometries with asymmetric poloidal cross-sections.
The ''phase velocity'' of nonlinear plasma waves in the laser beat-wave accelerator
Energy Technology Data Exchange (ETDEWEB)
Spence, W.L.
1985-04-01
A calculational scheme for beat-wave accelerators is introduced that includes all orders in velocity and in plasma density, and additionally accounts for the influence of plasma nonlinearities on the wave's phase velocity. The main assumption is that the laser frequencies are very large compared to the plasma frequency - under which it is possible to sum up all orders of forward Raman scattering. It is found that the nonlinear plasma wave does not have simply a single phase velocity, but that the beat-wave which drives it is usefully described by a non-local ''effective phase velocity'' function. A time-space domain approach is followed. (LEW)
Benefits of fresh-frozen plasma as a replacement fluid to neutralize ABO antibodies.
Won, Dong Il; Ham, Ji Yeon; Kim, Chan Duck; Suh, Jang Soo; Kim, Byung Chang
2015-10-01
ABO-incompatible organ transplantation requires pre-transplant conditioning to reduce ABO antibody levels in the recipients. With respect to replacement fluids used in plasma exchange, we intended to verify whether fresh-frozen plasma (FFP) containing soluble ABO substance (SAS) is more effective than albumin solution in reducing ABO IgG antibody levels. Apheresis data were retrospectively studied for in vivo effects, and in vitro plasma mixing studies were prospectively performed. The amount of ABO IgG antibodies bound to red cells was measured as the mean fluorescence intensity (MFI) using flow cytometry. Neutralization of ABO antibodies in the recipientst plasma by an ABO-incompatible donornc plasma was measured using the inhibition assay principle. The MFI value of the unneutralized control tube was divided by that of the neutralized test tube (neutralizing-capacity index, NCI). The plasma exchange procedures replaced with group AB FFP showed a significantly greater decreased titer than those replaced with albumin (P = 0.010). The in vitro plasma mixing study simulating plasma exchange also produced consistent results. When the pooled group O plasma was neutralized for anti-A by individual group AB plasmas (AB-to-O, N = 30), the NCI was 12.8 ± 5.4 (6.5-29.5). When this group O plasma was neutralized by pooled group AB or A plasma, the repeatedly measured NCI (N = 5) of A-to-O (11.4 ± 1.4) was not significantly different from that of AB-to-O (9.7 ± 1.3, P = 0.074). ABO antibody levels are reduced more effectively by group AB FFP than by albumin. Either group AB or donor type (group A or B) FFP can be infused to group O recipients. FFP units with higher SAS levels can be selected from multiple available candidate units using our protocol for measuring the neutralizing-capacity. © 2014 Wiley Periodicals, Inc.
Adams, Allan; Carr, Lincoln D.; Schaefer, Thomas; Steinberg, Peter; Thomas, John E.
2013-04-01
The last few years have witnessed a dramatic convergence of three distinct lines of research concerned with different kinds of extreme quantum matter. Two of these involve new quantum fluids that can be studied in the laboratory, ultracold quantum gases and quantum chromodynamics (QCD) plasmas. Even though these systems involve vastly different energy scales, the physical properties of the two quantum fluids are remarkably similar. The third line of research is based on the discovery of a new theoretical tool for investigating the properties of extreme quantum matter, holographic dualties. The main goal of this focus issue is to foster communication and understanding between these three fields. We proceed to describe each in more detail. Ultracold quantum gases offer a new paradigm for the study of nonperturbative quantum many-body physics. With widely tunable interaction strength, spin composition, and temperature, using different hyperfine states one can model spin-1/2 fermions, spin-3/2 fermions, and many other spin structures of bosons, fermions, and mixtures thereof. Such systems have produced a revolution in the study of strongly interacting Fermi systems, for example in the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) crossover region, where a close collaboration between experimentalists and theorists—typical in this field—enabled ground-breaking studies in an area spanning several decades. Half-way through this crossover, when the scattering length characterizing low-energy collisions diverges, one obtains a unitary quantum gas, which is universal and scale invariant. The unitary gas has close parallels in the hydrodynamics of QCD plasmas, where the ratio of viscosity to entropy density is extremely low and comparable to the minimum viscosity conjecture, an important prediction of AdS/CFT (see below). Exciting developments in the thermodynamic and transport properties of strongly interacting Fermi gases are of broad
Integrable, oblique travelling waves in quasi-charge-neutral two-fluid plasmas
Directory of Open Access Journals (Sweden)
G. M. Webb
2008-02-01
Full Text Available A Hamiltonian description of oblique travelling waves in a two-fluid, charge-neutral, electron-proton plasma reveals that the transverse momentum equations for the electron and proton fluids are exactly integrable in cases where the total transverse momentum flux integrals, P_{y}^{(d} and P_{z}^{(d}, are both zero in the de Hoffman Teller (dHT frame. In this frame, the transverse electric fields are zero, which simplifies the transverse momentum equations for the two fluids. The integrable travelling waves for the case P_{y}^{(d}=P_{z}^{(d}=0, are investigated based on the Hamiltonian trajectories in phase space, and also on the longitudinal structure equation for the common longitudinal fluid velocity component u_{x} of the electron and proton fluids. Numerical examples of a variety of travelling waves in a cold plasma, including oscillitons, are used to illustrate the physics. The transverse, electron and proton velocity components u_{jy} and u_{jz} (j=e, p of the waves exhibit complex, rosette type patterns over several periods for u_{x}. The role of separatrices in the phase space, the rotational integral and the longitudinal structure equation on the different wave forms are discussed.
Energy Technology Data Exchange (ETDEWEB)
Sahu, Biswajit, E-mail: biswajit-sahu@yahoo.co.in [Department of Mathematics, West Bengal State University, Barasat, Kolkata 700126 (India); Sinha, Anjana, E-mail: sinha.anjana@gmail.com [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Roychoudhury, Rajkumar, E-mail: rroychoudhury123@gmail.com [Department of Mathematics, Visva-Bharati, Santiniketan - 731 204, India and Advanced Centre for Nonlinear and Complex Phenomena, 1175 Survey Park, Kolkata 700 075 (India)
2015-09-15
A numerical study is presented of the nonlinear dynamics of a magnetized, cold, non-relativistic plasma, in the presence of electron-ion collisions. The ions are considered to be immobile while the electrons move with non-relativistic velocities. The primary interest is to study the effects of the collision parameter, external magnetic field strength, and the initial electromagnetic polarization on the evolution of the plasma system.
Directory of Open Access Journals (Sweden)
Khairy Zaimi
2014-01-01
Full Text Available This paper considers the problem of a steady two-dimensional stagnation-point flow and heat transfer of an incompressible micropolar fluid over a nonlinearly stretching/shrinking sheet. A similarity transformation is employed to convert the partial differential equations into nonlinear ordinary ones which are then solved numerically using a shooting method. Numerical results obtained are presented graphically, showing the effects of the micropolar or material parameter and the stretching/shrinking parameter on the flow field and heat transfer characteristics. The dual solutions are found to exist in a limited range of the stretching/shrinking parameter for the shrinking case, while unique solutions are possible for all positive values of the stretching/shrinking parameter (stretching case. It is also observed that the skin friction coefficient and the magnitude of the local Nusselt number increase as the material parameter increases.
Herbert, Eric; Mordant, Nicolas; Falcon, Eric
2010-10-01
We report experiments on gravity-capillary wave turbulence on the surface of a fluid. The wave amplitudes are measured simultaneously in time and space by using an optical method. The full space-time power spectrum shows that the wave energy is localized on several branches in the wave-vector-frequency space. The number of branches depends on the power injected within the waves. The measurement of the nonlinear dispersion relation is found to be well described by a law suggesting that the energy transfer mechanisms involved in wave turbulence are restricted not only to purely resonant interaction between nonlinear waves. The power-law scaling of the spatial spectrum and the probability distribution of the wave amplitudes at a given wave number are also measured and compared to the theoretical predictions.
Simplified Model of Nonlinear Landau Damping
Energy Technology Data Exchange (ETDEWEB)
N. A. Yampolsky and N. J. Fisch
2009-07-16
The nonlinear interaction of a plasma wave with resonant electrons results in a plateau in the electron distribution function close to the phase velocity of the plasma wave. As a result, Landau damping of the plasma wave vanishes and the resonant frequency of the plasma wave downshifts. However, this simple picture is invalid when the external driving force changes the plasma wave fast enough so that the plateau cannot be fully developed. A new model to describe amplification of the plasma wave including the saturation of Landau damping and the nonlinear frequency shift is proposed. The proposed model takes into account the change of the plasma wave amplitude and describes saturation of the Landau damping rate in terms of a single fluid equation, which simplifies the description of the inherently kinetic nature of Landau damping. A proposed fluid model, incorporating these simplifications, is verified numerically using a kinetic Vlasov code.
Energy Technology Data Exchange (ETDEWEB)
Banks, J.W., E-mail: banksj3@rpi.edu; Henshaw, W.D., E-mail: henshw@rpi.edu; Kapila, A.K., E-mail: kapila@rpi.edu; Schwendeman, D.W., E-mail: schwed@rpi.edu
2016-01-15
We describe an added-mass partitioned (AMP) algorithm for solving fluid–structure interaction (FSI) problems involving inviscid compressible fluids interacting with nonlinear solids that undergo large rotations and displacements. The computational approach is a mixed Eulerian–Lagrangian scheme that makes use of deforming composite grids (DCG) to treat large changes in the geometry in an accurate, flexible, and robust manner. The current work extends the AMP algorithm developed in Banks et al. [1] for linearly elasticity to the case of nonlinear solids. To ensure stability for the case of light solids, the new AMP algorithm embeds an approximate solution of a nonlinear fluid–solid Riemann (FSR) problem into the interface treatment. The solution to the FSR problem is derived and shown to be of a similar form to that derived for linear solids: the state on the interface being fundamentally an impedance-weighted average of the fluid and solid states. Numerical simulations demonstrate that the AMP algorithm is stable even for light solids when added-mass effects are large. The accuracy and stability of the AMP scheme is verified by comparison to an exact solution using the method of analytical solutions and to a semi-analytical solution that is obtained for a rotating solid disk immersed in a fluid. The scheme is applied to the simulation of a planar shock impacting a light elliptical-shaped solid, and comparisons are made between solutions of the FSI problem for a neo-Hookean solid, a linearly elastic solid, and a rigid solid. The ability of the approach to handle large deformations is demonstrated for a problem of a high-speed flow past a light, thin, and flexible solid beam.
Non-linear modeling of the plasma response to RMPs in ASDEX Upgrade
Orain, F; Viezzer, E; Dunne, M; Becoulet, M; Cahyna, P; Huijsmans, G T A; Morales, J; Willensdorfer, M; Suttrop, W; Kirk, A; Pamela, S; Strumberger, E; Guenter, S; Lessig, A
2016-01-01
The plasma response to Resonant Magnetic Perturbations (RMPs) in ASDEX Upgrade is modeled with the non-linear resistive MHD code JOREK, using input profiles that match those of the experiments as closely as possible. The RMP configuration for which Edge Localized Modes are best mitigated in experiments is related to the largest edge kink response observed near the X-point in modeling. On the edge resonant surfaces q = m=n, the coupling between the m + 2 kink component and the m resonant component is found to induce the amplification of the resonant magnetic perturbation. The ergodicity and the 3D-displacement near the X-point induced by the resonant ampli?cation can only partly explain the density pumpout observed in experiments.
Analytical approximations for a conservative nonlinear singular oscillator in plasma physics
Directory of Open Access Journals (Sweden)
A. Mirzabeigy
2012-10-01
Full Text Available A modified variational approach and the coupled homotopy perturbation method with variational formulation are exerted to obtain periodic solutions of a conservative nonlinear singular oscillator in plasma physics. The frequency–amplitude relations for the oscillator which the restoring force is inversely proportional to the dependent variable are achieved analytically. The approximate frequency obtained using the coupled method is more accurate than the modified variational approach and ones obtained using other approximate methods and the discrepancy between the approximate frequency using this coupled method and the exact one is lower than 0.31% for the whole range of values of oscillation amplitude. The coupled method provides a very good accuracy and is a promising technique to a lot of practical engineering and physical problems.
Non-linear modeling of the plasma response to RMPs in ASDEX Upgrade
Orain, F.; Hölzl, M.; Viezzer, E.; Dunne, M.; Bécoulet, M.; Cahyna, P.; Huijsmans, G. T. A.; Morales, J.; Willensdorfer, M.; Suttrop, W.; Kirk, A.; Pamela, S.; Günter, S.; Lackner, K.; Strumberger, E.; Lessig, A.; the ASDEX Upgrade Team; the EUROfusion MST1 Team
2017-02-01
The plasma response to resonant magnetic perturbations (RMPs) in ASDEX Upgrade is modeled with the non-linear resistive MHD code JOREK, using input profiles that match those of the experiments as closely as possible. The RMP configuration for which edge localized modes are best mitigated in experiments is related to the largest edge kink response observed near the X-point in modeling. On the edge resonant surfaces q = m/n, the coupling between the kink component (m > nq) and the m resonant component is found to induce the amplification of the resonant magnetic perturbation. The ergodicity and the 3D-displacement near the X-point induced by the resonant amplification can only partly explain the density pumpout observed in experiments.
Nonlinear physics and energetic particle transport features of the beam-plasma instability
Carlevaro, Nakia; Montani, Giovanni; Zonca, Fulvio
2015-01-01
In this paper, we study transport features of a one-dimensional beam-plasma system in the presence of multiple resonances. As a model description of the general problem of a warm energetic particle beam, we assume $n$ cold supra-thermal beams and investigate the self-consistent evolution in the presence of the complete spectrum of nearly degenerate Langmuir modes. A qualitative transport estimation is obtained by computing the Lagrangian Coherent Structures of the system on given temporal scales. This leads to the splitting of the phase space into regions where the local transport processes are relatively faster. The general theoretical framework is applied to the case of the nonlinear dynamics of two cold beams, for which numerical simulation results are illustrated and analyzed.
The Effect of Nonlinear Landau Damping on Ultrarelativistic Beam Plasma Instabilities
Chang, Philip; Lamberts, Astrid
2014-01-01
Very-high energy gamma-rays from extragalactic sources pair-produce off of the extragalactic background light, yielding an electron-positron pair beam. This pair beam is unstable to various plasma instabilities, especially the "oblique" instability, which can be the dominant cooling mechanism for the beam. However, recently, it has been claimed that nonlinear Landau damping renders it physically irrelevant by reducing the effective damping rate to a low level. Here, we show with numerical calculations that the effective damping rate is $8\\times 10^{-4}$ of the growth rate of the linear instability, which is sufficient for the "oblique" instability to be the dominant cooling mechanism of these pair beams. In particular, we show that previous estimates of this rate ignored the exponential cutoff in the scattering amplitude at large wavenumber and assumed that the damping of scattered waves entirely depends on collisions, ignoring collisionless processes. We find that the total wave energy eventually grows to ap...
Nonlinear features of ion acoustic shock waves in dissipative magnetized dusty plasma
Sahu, Biswajit; Sinha, Anjana; Roychoudhury, Rajkumar
2014-10-01
The nonlinear propagation of small as well as arbitrary amplitude shocks is investigated in a magnetized dusty plasma consisting of inertia-less Boltzmann distributed electrons, inertial viscous cold ions, and stationary dust grains without dust-charge fluctuations. The effects of dissipation due to viscosity of ions and external magnetic field, on the properties of ion acoustic shock structure, are investigated. It is found that for small amplitude waves, the Korteweg-de Vries-Burgers (KdVB) equation, derived using Reductive Perturbation Method, gives a qualitative behaviour of the transition from oscillatory wave to shock structure. The exact numerical solution for arbitrary amplitude wave differs somehow in the details from the results obtained from KdVB equation. However, the qualitative nature of the two solutions is similar in the sense that a gradual transition from KdV oscillation to shock structure is observed with the increase of the dissipative parameter.
Nonlinear features of ion acoustic shock waves in dissipative magnetized dusty plasma
Energy Technology Data Exchange (ETDEWEB)
Sahu, Biswajit, E-mail: biswajit-sahu@yahoo.co.in [Department of Mathematics, West Bengal State University, Barasat, Kolkata 700126 (India); Sinha, Anjana, E-mail: sinha.anjana@gmail.com [Department of Instrumentation Science, Jadavpur University, Kolkata 700032 (India); Roychoudhury, Rajkumar, E-mail: rroychoudhury123@gmail.com [Department of Mathematics, Visva-Bharati, Santiniketan 731204, India and Advanced Centre for Nonlinear and Complex Phenomena, 1175 Survey Park, Kolkata 700075 (India)
2014-10-15
The nonlinear propagation of small as well as arbitrary amplitude shocks is investigated in a magnetized dusty plasma consisting of inertia-less Boltzmann distributed electrons, inertial viscous cold ions, and stationary dust grains without dust-charge fluctuations. The effects of dissipation due to viscosity of ions and external magnetic field, on the properties of ion acoustic shock structure, are investigated. It is found that for small amplitude waves, the Korteweg-de Vries-Burgers (KdVB) equation, derived using Reductive Perturbation Method, gives a qualitative behaviour of the transition from oscillatory wave to shock structure. The exact numerical solution for arbitrary amplitude wave differs somehow in the details from the results obtained from KdVB equation. However, the qualitative nature of the two solutions is similar in the sense that a gradual transition from KdV oscillation to shock structure is observed with the increase of the dissipative parameter.
Modeling Plasmas with Strong Anisotropy, Neutral Fluid Effects, and Open Boundaries
Meier, Eric T.
Three computational plasma science topics are addressed in this research: the challenge of modeling strongly anisotropic thermal conduction, capturing neutral fluid effects in collisional plasmas, and modeling open boundaries in dissipative plasmas. The research efforts on these three topics contribute to a common objective: the improvement and extension of existing magnetohydrodynamic modeling capability. Modeling magnetically confined fusion-related plasmas is the focus of the research, but broader relevance is recognized and discussed. Code development is central to this work, and has been carried out within the flexible physics framework of the highly parallel HiFi implicit spectral element code. In magnetic plasma confinement, heat conduction perpendicular to the magnetic field is extremely slow compared to conduction parallel to the field. The anisotropy in heat conduction can be many orders of magnitude, and the inaccuracy of low-order representations can allow parallel heat transport to "leak" into the perpendicular direction, resulting in numerical perpendicular transport. If the computational grid is aligned to the magnetic field, this numerical error can be eliminated, even for low-order representations. However, grid alignment is possible only in idealized problems. In realistic applications, magnetic topology is chaotic. A general approach for accurately modeling the extreme anisotropy of fusion plasmas is to use high-order representations which do not require grid alignment for sufficient resolution. This research provides a comprehensive assessment of spectral element representation of anisotropy, in terms of dependence of accuracy on grid alignment, polynomial degree, and grid cell size, and gives results for two- and three-dimensional cases. Truncating large physical domains to concentrate computational resources is often necessary or desirable in simulating natural and man-made plasmas. A novel open boundary condition (BC) treatment for such
Directory of Open Access Journals (Sweden)
D. E. Panayotounakos
1996-01-01
Full Text Available We develop a new unique technique in constructing closed-form solutions for several nonlinear partial differential systems appearing in fluid mechanics and gas dynamics. The obtained solutions include fewer arbitrary functions than needed for general solutions, fact that permits us to specify them according to the initial state, or the geometry, of each specific problem under consideration. In order to apply the before mentioned technique we construct closed-form solutions concerning the gas-dynamic equations with constant pressure, the dynamic equations of an ideal gas in isentropic flow, and the two-dimensional incompressible boundary layer flow.
Aziz, Taha; Mahomed, F M
2014-01-01
In this communication, we utilize some basic symmetry reductions to transform the governing nonlinear partial differential equations arising in the study of third-grade fluid flows into ordinary differential equations. We obtain some simple closed-form steady-state solutions of these reduced equations. Our solutions are valid for the whole domain [0,∞) and also satisfy the physical boundary conditions. We also present the numerical solutions for some of the underlying equations. The graphs corresponding to the essential physical parameters of the flow are presented and discussed.
Directory of Open Access Journals (Sweden)
Panayotounakos D. E.
1996-01-01
Full Text Available We develop a new unique technique in constructing closed-form solutions for several nonlinear partial differential systems appearing in fluid mechanics and gas dynamics. The obtained solutions include fewer arbitrary functions than needed for general solutions, fact that permits us to specify them according to the initial state, or the geometry, of each specific problem under consideration. In order to apply the before mentioned technique we construct closed-form solutions concerning the gas-dynamic equations with constant pressure, the dynamic equations of an ideal gas in isentropic flow, and the two-dimensional incompressible boundary layer flow.
Energy Technology Data Exchange (ETDEWEB)
Abbas, Z.; Naveed, M., E-mail: rana.m.naveed@gmail.com [Department of Mathematics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Sajid, M. [Theoretical Physics Division, PINSTECH, P.O. Nilore, Islamabad 44000 (Pakistan)
2015-10-15
In this paper, effects of Hall currents and nonlinear radiative heat transfer in a viscous fluid passing through a semi-porous curved channel coiled in a circle of radius R are analyzed. A curvilinear coordinate system is used to develop the mathematical model of the considered problem in the form partial differential equations. Similarity solutions of the governing boundary value problems are obtained numerically using shooting method. The results are also validated with the well-known finite difference technique known as the Keller-Box method. The analysis of the involved pertinent parameters on the velocity and temperature distributions is presented through graphs and tables.
Institute of Scientific and Technical Information of China (English)
Yirang YUAN
2006-01-01
For nonlinear coupled system of multilayer dynamics of fluids in porous media, the second order and first order upwind finite difference fractional steps schemes applicable to parallel arithmetic are put forward, and two-dimensional and three-dimensional schemes are used to form a complete set. Some techniques, such as calculus of variations, multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates, are adopted. Optimal order estimates in L2 norm are derived to determine the error in the second order approximate solution.This method has already been applied to the numerical simulation of migration-accumulation of oil resources.
Directory of Open Access Journals (Sweden)
Taha Aziz
2012-01-01
Full Text Available The unsteady unidirectional flow of an incompressible fourth grade fluid bounded by a suddenly moved rigid plate is studied. The governing nonlinear higher order partial differential equation for this flow in a semiinfinite domain is modelled. Translational symmetries in variables and are employed to construct two different classes of closed-form travelling wave solutions of the model equation. A conditional symmetry solution of the model equation is also obtained. The physical behavior and the properties of various interesting flow parameters on the structure of the velocity are presented and discussed. In particular, the significance of the rheological effects are mentioned.
Theoretical analysis on nonlinear vibration of fluid flow in single-walled carbon nanotube
Valipour, P.; Ghasemi, S. E.; Khosravani, Mohammad Reza; Ganji, D. D.
2016-09-01
In this study, the concept of nonlocal continuum theory is used to characterize the nonlinear vibration of an embedded single-walled carbon nanotube. The Pasternak-type model is employed to simulate the interaction of the SWNTs. The parameterized perturbation method is used to solve the corresponding nonlinear differential equation. The effects of the vibration amplitude, flow velocity, nonlocal parameter, and stiffness of the medium on the nonlinear frequency variation are presented. The result shows that by increasing the Winkler constant, the nonlinear frequency decreases, especially for low vibration amplitudes. In addition, it is resulted that influence of the nonlocal parameter is greater at higher flow velocities in comparison with lower flow velocities.
MicroRNAs in plasma and cerebrospinal fluid as potential markers for Alzheimer's disease.
Kiko, Takehiro; Nakagawa, Kiyotaka; Tsuduki, Tsuyoshi; Furukawa, Katsutoshi; Arai, Hiroyuki; Miyazawa, Teruo
2014-01-01
The development of Alzheimer's disease (AD) biomarkers remains an unmet challenge, and new approaches that can improve current AD biomarker strategies are needed. Recent reports suggested that microRNA (miRNA) profiling of biological fluids has emerged as a diagnostic tool for several pathologic conditions. In this study, we measured six candidate miRNAs (miR-9, miR-29a, miR-29b, miR-34a, miR-125b, and miR-146a) in plasma and cerebrospinal fluid (CSF) of AD and normal subjects by using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) to evaluate their potential usability as AD biomarkers. The qRT-PCR results showed that plasma miR-34a and miR-146a levels, and CSF miR-34a, miR-125b, and miR-146a levels in AD patients were significantly lower than in control subjects. On the other hand, CSF miR-29a and miR-29b levels were significantly higher than in control subjects. Our results provide a possibility that miRNAs detected in plasma and CSF can serve as biomarkers for AD.
Fructose levels are markedly elevated in cerebrospinal fluid compared to plasma in pregnant women.
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Janice J Hwang
Full Text Available Fructose, unlike glucose, promotes feeding behavior in rodents and its ingestion exerts differential effects in the human brain. However, plasma fructose is typically 1/1000 th of glucose levels and it is unclear to what extent fructose crosses the blood-brain barrier. We investigated whether local endogenous central nervous system (CNS fructose production from glucose via the polyol pathway (glucose → sorbitol → fructose contributes to brain exposure to fructose.In this observational study, fasting glucose, sorbitol and fructose concentrations were measured using gas-chromatography-liquid mass spectroscopy in cerebrospinal fluid (CSF, maternal plasma, and venous cord blood collected from 25 pregnant women (6 lean, 10 overweight/obese, and 9 T2DM/gestational DM undergoing spinal anesthesia and elective cesarean section.As expected, CSF glucose was ~ 60% of plasma glucose levels. In contrast, fructose was nearly 20-fold higher in CSF than in plasma (p < 0.001, and CSF sorbitol was ~ 9-times higher than plasma levels (p < 0.001. Moreover, CSF fructose correlated positively with CSF glucose (ρ 0.45, p = 0.02 and sorbitol levels (ρ 0.75, p < 0.001. Cord blood sorbitol was also ~ 7-fold higher than maternal plasma sorbitol levels (p = 0.001. There were no differences in plasma, CSF, and cord blood glucose, fructose, or sorbitol levels between groups.These data raise the possibility that fructose may be produced endogenously in the human brain and that the effects of fructose in the human brain and placenta may extend beyond its dietary consumption.
Bhatti, M. M.; Zeeshan, A.; Ellahi, R.
2016-09-01
In this article, heat transfer with nonlinear thermal radiation on sinusoidal motion of magnetic solid particles in a dust Jeffrey fluid has been studied. The effects of Magnetohydrodynamic (MHD) and hall current are also taken under consideration. The governing equation of motion and energy equation are modelled with help of Ohms law for fluid and dust phases. The solutions of the resulting ordinary coupled partial differential equations are solved analytically. The impact of all the physical parameters of interest such as Hartmann number, slip parameter, Hall parameter, radiation parameter, Prandtl number, Eckert number and particle volume fraction are demonstrated mathematically and graphically. Trapping mechanism is also discussed in detail by drawing contour lines. The present analysis affirms many interesting behaviours, which permit further study on solid particles motion with heat and mass transfer.
The extreme nonlinear optics of gases and femtosecond optical/plasma filamentation
Milchberg, Howard
2013-10-01
Under certain conditions, powerful ultrashort laser pulses can form greatly extended filaments of concentrated high intensity in gases, leaving behind a very long trail of plasma. Such filaments can be much longer than the longitudinal scale over which a laser beam typically diverges by diffraction. Applications range from laser-guided electrical discharges to remote sensing. Air is a medium of particular interest for applications, and as a mostly molecular gas it is interesting from a physics perspective as well. I will work through the fundamentals of filamentation and give an overview of the field. Understanding in detail the microscopic processes leading to filamentation requires fundamental measurements of the strong field nonlinear response of gas phase atoms and molecules with unprecedented precision in space and time. This includes absolute, ultrafast measurements of nonlinear laser-induced polarization and high field ionization. I will describe how such measurements are done and show how they can be applied to propagation experiments. Work supported by the Air Force Office of Scientific Research, the Office of Naval Research, the National Science Foundation, and the US Dept. of Energy.
Directory of Open Access Journals (Sweden)
Ricardo Aguilar-López
2016-01-01
Full Text Available A nonlinear PI-type control strategy is designed in order to minimize the HIV concentration in blood plasma, via medical drug injection, under the framework of bounded uncertain input disturbances. For control design it is considered a simplified mathematical model of the virus infection as a benchmark. The model is based on mass balances of healthy cells, infected cells, and the virus concentrations. The proposed controller contains a nonlinear feedback PI structure of bounded functions of the regulation error. The closed-loop stability of the system is analyzed via Lyapunov technique, in which robustness against system disturbances is demonstrated. Numerical experiments show a satisfactory performance of the proposed methodology as a HIV therapy, in which the virion particles and the infected CD4+T cells are minimized and, as an interesting result, the drug dosage can be suspended, thus avoiding drug resistance from the virus. Finally, the proposed controller is compared to a standard sliding-mode and hyperbolic tangent controllers showing better performance.
Hybrid finite-volume-ROM approach to non-linear aerospace fluid-structure interaction modelling
CSIR Research Space (South Africa)
Mowat, AGB
2011-06-01
Full Text Available frame, describe the fluid domain while the structure is represented by a quadratic modal reduced order model (ROM). A Runge-Kutta dual-timestepping method is employed for the fluid solver, and three upwind schemes are considered viz. AUSM+ -up, HLLC...
Energy Technology Data Exchange (ETDEWEB)
Nariyuki, Y. [Faculty of Human Development, University of Toyama, 3190, Toyama City, Toyama 930-8555 (Japan); Hada, T. [Department of Earth System Science and Technology, Kyushu University, 6-1, Kasuga City, Fukuoka 816-8580 (Japan); Tsubouchi, K., E-mail: nariyuki@edu.u-toyama.ac.jp [Graduate School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)
2014-10-01
The damping process of field-aligned, low-frequency right-handed polarized nonlinear Alfvén waves (NAWs) in solar wind plasmas with and without proton beams is studied by using a two-dimensional ion hybrid code. The numerical results show that the obliquely propagating kinetic Alfvén waves (KAWs) excited by beam protons affect the damping of the low-frequency NAW in low beta plasmas, while the nonlinear wave-wave interaction between parallel propagating waves and nonlinear Landau damping due to the envelope modulation are the dominant damping process in high beta plasmas. The nonlinear interaction between the NAWs and KAWs does not cause effective energy transfer to the perpendicular direction. Numerical results suggest that while the collisionless damping due to the compressibility of the envelope-modulated NAW plays an important role in the damping of the field-aligned NAW, the effect of the beam instabilities may not be negligible in low beta solar wind plasmas.
Prolongation Structure of a Generalised Inhomogeneous Gardner Equation in Plasmas and Fluids
Xie, Xi-Yang; Tian, Bo; Sun, Wen-Rong; Wang, Yun-Po
2016-04-01
In this article, the prolongation structure technique is applied to a generalised inhomogeneous Gardner equation, which can be used to describe certain physical situations, such as the stratified shear flows in ocean and atmosphere, ion acoustic waves in plasmas with a negative ion, interfacial solitary waves over slowly varying topographies, and wave motion in a non-linear elastic structural element with large deflection. The Lax pairs, which are derived via the prolongation structure, are more general than the Lax pairs published before. Under the Painlevé conditions, the linear-damping coefficient equals to zero, the quadratic non-linear coefficient is proportional to the dispersive coefficient c(t), the cubic non-linear coefficient is proportional to c(t), leaving no constraints on c(t) and the dissipative coefficient d(t). We establish the prolongation structure through constructing the exterior differential system. We introduce two methods to obtain the Lax pairs: (a) based on the prolongation structure, the Lax pairs are obtained, and (b) via the Lie algebra, we can derive the Pfaffian forms and Lax pairs when certain parameters are chosen. We set d(t) as a constant to discuss the influence of c(t) on the Pfaffian forms and Lax pairs, and to discuss the influence of d(t) on the Pfaffian forms and Lax pairs, we set c(t) as another constant. Then, we get different prolongation structure, Pfaffian forms and Lax pairs.
Garai, S.; Janaki, M. S.; Chakrabarti, N.
2016-09-01
The nonlinear propagation of low frequency waves, in a collisionless, strongly coupled dusty plasma (SCDP) with a density dependent viscosity, has been studied with a proper Galilean invariant generalized hydrodynamic (GH) model. The well known reductive perturbation technique (RPT) has been employed in obtaining the solutions of the longitudinal and transverse perturbations. It has been found that the nonlinear propagation of the acoustic perturbations govern with the modified Korteweg-de Vries (KdV) equation and are decoupled from the sheared fluctuations. In the regions, where transversal gradients of the flow exists, coupling between the longitudinal and transverse perturbations occurs due to convective nonlinearity which is true for the homogeneous case also. The results, obtained here, can have relative significance to astrophysical context as well as in laboratory plasmas.
Trigger, S A; van Heijst, G J F; Litinski, D
2014-01-01
The problems of high linear conductivity in an electric field, as well as nonlinear conductivity, are considered for plasma-like systems. First, we recall several observations of nonlinear fast charge transport in dusty plasma, molecular chains, lattices, conducting polymers and semiconductor layers. Exploring the role of noise we introduce the generalized Fokker-Planck equation. Second, one-dimensional models are considered on the basis of the Fokker-Planck equation with active and passive velocity-dependent friction including an external electrical field. On this basis it is possible to find the linear and nonlinear conductivities for electrons and other charged particles in a homogeneous external field. It is shown that the velocity dependence of the friction coefficient can lead to an essential increase of the electron average velocity and the corresponding conductivity in comparison with the usual model of constant friction, which is described by the Drude-type conductivity. Applications including novel ...
Exact scaling laws for helical three-dimensional two-fluid turbulent plasmas
Andrés, Nahuel; Sahraoui, Fouad
2016-01-01
We derive exact scaling laws for a three-dimensional incompressible helical two-fluid plasma, without the assumption of isotropy. For each ideal invariant of the two-fluid model, i.e. the total energy, the electron helicity and the proton helicity, we derive simple scaling laws in terms of two-point increments correlation functions expressed in terms of the velocity field of each species and the magnetic field. These variables are appropriate for comparison with \\textit{in-situ} measurements in the solar wind at different spatial ranges and data from numerical simulations. Finally, with the exact scaling laws and dimensional analysis we predict the magnetic energy and electron helicity spectra for different ranges of scales.
Monte-Carlo fluid approaches to detached plasmas in non-axisymmetric divertor configurations
Feng, Y.; Frerichs, H.; Kobayashi, M.; Reiter, D.
2017-03-01
Fluid transport modeling in three-dimensional boundaries of toroidal confinement devices is reviewed with the emphasis on a Monte-Carlo approach to simulate detached plasmas. The loss of axisymmetry in such configurations presents a major challenge for numerical implementation of the standard fluid model widely applied to fusion experimental devices. A large-scale effort has been made to address this problem under complementary aspects including different magnetic topologies and numerical techniques. In this paper, we give a brief review of the different strategies pioneered and the challenges involved. A more detailed description is provided for the Monte-Carlo code—EMC3-Eirene, where the physics model and the basic idea behind the applied Monte-Carlo method are presented. The focus is put on its applications to detachment studies for stellarators and tokamaks. Here, major achievements and difficulties encountered are described. Model limitations and further development plans are discussed.
Koons, H. C.; Roeder, J. L.; Bauer, O. H.; Haerendel, G.; Treumann, R.
1987-01-01
Nonlinear wave decay processes have been detected in the solar wind by the plasma wave experiment aboard the Active Magnetospheric Particle Tracer Explorers (AMPTE) IRM spacecraft. The main process is the generation of ultralow-frequency ion acoustic waves from the decay of Langmuir waves near the electron plasma frequency. Frequently, this is accompanied by an enhancement of emissions near twice the plasma frequency. This enhancement is most likely due to the generation of electromagnetic waves from the coalescence of two Langmuir waves. These processes occur within the electron foreshock in front of the earth's bow shock.
Parameteric studies of nonlinear oblique magnetosonic waves in two-ion-species plasmas
Toida, Mieko; Kondo, Yuichi
2011-06-01
The study of the effects of ion composition on perpendicular magnetosonic waves in two-ion-species plasmas [M. Toida, H. Higashino, and Y. Ohsawa, J. Phys. Soc. Jpn. 76, 104052 (2007)] is extended to include oblique waves. First, the conditions necessary for KdV equations for low- and high-frequency modes to be valid are analytically obtained. The upper limit of the amplitude of the low-frequency-mode pulse is expressed as a function of the propagation angle θ, density ratio, and cyclotron frequency ratio of the two ion species. Next, with electromagnetic particle simulations, the nonlinear evolution of a long-wavelength low-frequency-mode disturbance is examined for various θs in two plasmas with different ion densities and cyclotron frequency ratios, and the theory for the low-frequency-mode pulse is confirmed. It is also shown that if the pulse amplitude exceeds the theoretical value of the upper limit of the amplitude, then shorter-wavelength low- and high-frequency-mode waves are generated.
Nonlinear instability and chaos in plasma wave-wave interactions. II. Numerical methods and results
Energy Technology Data Exchange (ETDEWEB)
Kueny, C.S.; Morrison, P.J.
1995-05-01
In Part I of this work and Physics of Plasmas, June 1995, the behavior of linearly stable, integrable systems of waves in a simple plasma model was described using a Hamiltonian formulation. It was shown that explosive instability arises from nonlinear coupling between modes of positive and negative energy, with well-defined threshold amplitudes depending on the physical parameters. In this concluding paper, the nonintegrable case is treated numerically. Several sets of waves are considered, comprising systems of two and three degrees of freedom. The time evolution is modelled with an explicit symplectic integration algorithm derived using Lie algebraic methods. When initial wave amplitudes are large enough to support two-wave decay interactions, strongly chaotic motion destroys the separatrix bounding the stable region for explosive triplets. Phase space orbits then experience diffusive growth to amplitudes that are sufficient for explosive instability, thus effectively reducing the threshold amplitude. For initial amplitudes too small to drive decay instability, small perturbations might still grow to arbitrary size via Arnold diffusion. Numerical experiments do not show diffusion in this case, although the actual diffusion rate is probably underestimated due to the simplicity of the model.
Parabola solitons for the nonautonomous KP equation in fluids and plasmas
Energy Technology Data Exchange (ETDEWEB)
Yu, Xin, E-mail: yuxin@buaa.edu.cn; Sun, Zhi-Yuan
2016-04-15
Under investigation in this paper is a nonautonomous Kadomtsev–Petviashvili (KP) equation in fluids and plasmas. The integrability of this equation is examined via the Painlevé analysis and its multi-soliton solutions are constructed. A constraint is proposed to ensure the existence of parabola solitons for such KP equation. Based on the constructed solutions, the solitonic propagation and interaction, including the elastic interaction, inelastic interaction and soliton resonance for parabola solitons, are discussed. The results might be useful for shallow water wave and rogue wave.
Studies on fluid model for numerical simulation of gas discharges in color plasma displays
Institute of Scientific and Technical Information of China (English)
HE Feng; LIU Chun-Liang
2005-01-01
The fluid models of gas discharge in alternating current plasma display panel (AC PDP) cell are discussed.From the Boltzmann equation, the hydrodynamic equations are derived, but this model consumes much computa tional time for simulation. The drift-diffusion approximation model and the local field approximation model are ob tained to simplify the numerical computation, and the approximation conditions of these two models are discussed in detail. The drift-diffusion approximation model gives more satisfactory result for PDP simulation, and the expression of energy balance equation is given completely in this model.
Lara Rodriguez, L; Sundaram, P A
2016-09-15
Plasma electrolytic oxidized (PEO) γTiAl alloy samples were electrochemically characterized by open circuit potential (OCP), cyclic polarization and electrochemical impedance spectroscopy (EIS) to evaluate their corrosion resistance in simulated body fluid (SBF) in order to gauge their potential for biomedical applications. Experimental results through OCP and cyclic polarization studies demonstrated the protective nature and the beneficial effect of the PEO coatings on γTiAl. The PEO surface increased corrosion resistance of these surface modified alloys. EIS data indicated the presence of an underlying compact oxide layer with surface pores represented by two domes in the Nyquist plots. Electrical equivalent circuits to describe the EIS results are proposed.
Sui, Jin-Ling; Bo, Wu; Hai, Zhou; Cao, Ning; Li, Mu-Sen
Two types of hydroxyapatite (HA) coatings onto carbon/carbon composite (C/C composites) substrates, deposited by plasma spraying technique, were immersed in a simulated body fluid (SBF) in order to determine their behavior in conditions similar to the human blood plasma. Calcium ion concentration, pH value, microstructure, and phase compositions were analyzed. Results demonstrated that both the crystal Ca-P phases or the amorphous HA do dissolve slightly, and the dissolution of CaO phases in SBF was evident after 1 day of soaking. The calcium-ion concentration was decreased and the pH value of SBF was increased with the increasing of the immersing time. The precipitation was mainly composed of HA, which was verified by X-ray diffraction (XRD) and electron-probe microanalyzer.
A linear dispersion relation for the hybrid kinetic-ion/fluid-electron model of plasma physics
Told, Daniel; Astfalk, Patrick; Jenko, Frank
2016-01-01
A dispersion relation for a commonly used hybrid model of plasma physics is developed, which combines fully kinetic ions and a massless-electron fluid description. Although this model and variations of it have been used to describe plasma phenomena for about 40 years, to date there exists no general dispersion relation to describe the linear wave physics contained in the model. Previous efforts along these lines are extended here to retain arbitrary wave propagation angles, temperature anisotropy effects, as well as additional terms in the generalized Ohm's law which determines the electric field. A numerical solver for the dispersion relation is developed, and linear wave physics is benchmarked against solutions of a full Vlasov-Maxwell dispersion relation solver. This work opens the door to a more accurate interpretation of existing and future wave and turbulence simulations using this type of hybrid model.
Velocity statistics in holographic fluids: magnetized quark-gluon plasma and superfluid flow
Energy Technology Data Exchange (ETDEWEB)
Areán, Daniel [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, D-80805, Munich (Germany); Zayas, Leopoldo A. Pando [The Abdus Salam International Centre for Theoretical Physics,Strada Costiera 11, 34014 Trieste (Italy); Michigan Center for Theoretical Physics, Department of Physics, University of Michigan,450 Church Street, Ann Arbor, MI 48109 (United States); Patiño, Leonardo; Villasante, Mario [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México,A.P. 70-542, México D.F. 04510 (Mexico)
2016-10-28
We study the velocity statistics distribution of an external heavy particle in holographic fluids. We argue that when the dual supergravity background has a finite temperature horizon the velocity statistics goes generically as 1/v, compatible with the jet-quenching intuition from the quark-gluon plasma. A careful analysis of the behavior of the classical string whose apparent world sheet horizon deviates from the background horizon reveals that other regimes are possible. We numerically discuss two cases: the magnetized quark-gluon plasma and a model of superfluid flow. We explore a range of parameters in these top-down supergravity solutions including, respectively, the magnetic field and the superfluid velocity. We determine that the velocity statistics goes largely as 1/v, however, as we leave the non-relativistic regime we observe some deviations.
Enhancing Understanding of High Energy Density Plasmas Using Fluid Modeling with Kinetic Closures
Hansen, David; Held, Eric; Srinivasan, Bhuvana; Masti, Robert; King, Jake
2016-10-01
This work seeks to understand possible stabilization mechanisms of the early-time electrothermal instability in the evolution of the Rayleigh-Taylor instability in MagLIF (Magnetized Liner Inertial Fusion) experiments. Such mechanisms may include electron thermal conduction, viscosity, and large magnetic fields. Experiments have shown that the high-energy density plasmas from wire-array implosions require physics modelling that goes well beyond simple models such as ideal MHD. The plan is to develop a multi-fluid extended-MHD model that includes kinetic closures for thermal conductivity, resistivity, and viscosity using codes that are easily available to the wider research community. Such an effort would provide the community with a well-benchmarked tool capable of advanced modeling of high-energy-density plasmas.
Energy Technology Data Exchange (ETDEWEB)
Guo, Shimin, E-mail: gsm861@126.com [School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an, 710049 (China); Research Group MAC, Centrum Wiskunde and Informatica, Amsterdam, 1098XG (Netherlands); Mei, Liquan, E-mail: lqmei@mail.xjtu.edu.cn [School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an, 710049 (China); Center for Computational Geosciences, Xi’an Jiaotong University, Xi’an, 710049 (China); Sun, Anbang [Research Group MAC, Centrum Wiskunde and Informatica, Amsterdam, 1098XG (Netherlands)
2013-05-15
The nonlinear propagation of planar and nonplanar (cylindrical and spherical) ion-acoustic waves in an unmagnetized electron–positron–ion–dust plasma with two-electron temperature distributions is investigated in the context of the nonextensive statistics. Using the reductive perturbation method, a modified nonlinear Schrödinger equation is derived for the potential wave amplitude. The effects of plasma parameters on the modulational instability of ion-acoustic waves are discussed in detail for planar as well as for cylindrical and spherical geometries. In addition, for the planar case, we analyze how the plasma parameters influence the nonlinear structures of the first- and second-order ion-acoustic rogue waves within the modulational instability region. The present results may be helpful in providing a good fit between the theoretical analysis and real applications in future spatial observations and laboratory plasma experiments. -- Highlights: ► Modulational instability of ion-acoustic waves in a new plasma model is discussed. ► Tsallis’s statistics is considered in the model. ► The second-order ion-acoustic rogue wave is studied for the first time.
Institute of Scientific and Technical Information of China (English)
徐会静; 赵书霞; 高飞; 张钰如; 李雪春; 王友年
2015-01-01
A new type of two-dimensional self-consistent fluid model that couples an equivalent circuit module is used to in-vestigate the mode transition characteristics and hysteresis in hydrogen inductively coupled plasmas at different pressures, by varying the series capacitance of the matching box. The variations of the electron density, temperature, and the cir-cuit electrical properties are presented. As cycling the matching capacitance, at high pressure both the discontinuity and hysteresis appear for the plasma parameters and the transferred impedances of both the inductive and capacitive discharge components, while at low pressure only the discontinuity is seen. The simulations predict that the sheath plays a determi-native role on the presence of discontinuity and hysteresis at high pressure, by influencing the inductive coupling efficiency of applied power. Moreover, the values of the plasma transferred impedances at different pressures are compared, and the larger plasma inductance at low pressure due to less collision frequency, as analyzed, is the reason why the hysteresis is not seen at low pressure, even with a wider sheath. Besides, the behaviors of the coil voltage and current parameters during the mode transitions are investigated. They both increase (decrease) at the E to H (H to E) mode transition, indicating an improved (worsened) inductive power coupling efficiency.
Directory of Open Access Journals (Sweden)
Sérgio Monteiro de Almeida
2014-07-01
Full Text Available Increased plasma lactate levels can indicate the presence of metabolic disorders in HIV infected individuals. Objective: To determine whether a portable analyzer is valid for measuring cerebrospinal fluid (CSF and plasma lactate levels in HIV infected individuals. Method: CSF and plasma were collected from 178 subjects. Samples tested by the Accutrend® portable analyzer were compared to those tested by a reference device (SYNCHRON LX® 20. Results: The portable analyzer had in plasma sensitivity of 0.95 and specificity 0.87. For CSF the specificity was 0.95; the sensitivity 0.33; the negative predictive value was 95% and the positive predictive value 33%. Conclusions: These findings support the validity of the portable analyzer in measuring lactate concentrations in CSF that fall within the normal range. The relatively poor positive predictive value indicates that a result above the reference range may represent a “false positive test”, and should be confirmed by the reference device before concluding abnormality.
Xu, Hui-Jing; Zhao, Shu-Xia; Fei, Gao; Yu-Ru, Zhang; Xue-Chun, Li; You-Nian, Wang
2015-11-01
A new type of two-dimensional self-consistent fluid model that couples an equivalent circuit module is used to investigate the mode transition characteristics and hysteresis in hydrogen inductively coupled plasmas at different pressures, by varying the series capacitance of the matching box. The variations of the electron density, temperature, and the circuit electrical properties are presented. As cycling the matching capacitance, at high pressure both the discontinuity and hysteresis appear for the plasma parameters and the transferred impedances of both the inductive and capacitive discharge components, while at low pressure only the discontinuity is seen. The simulations predict that the sheath plays a determinative role on the presence of discontinuity and hysteresis at high pressure, by influencing the inductive coupling efficiency of applied power. Moreover, the values of the plasma transferred impedances at different pressures are compared, and the larger plasma inductance at low pressure due to less collision frequency, as analyzed, is the reason why the hysteresis is not seen at low pressure, even with a wider sheath. Besides, the behaviors of the coil voltage and current parameters during the mode transitions are investigated. They both increase (decrease) at the E to H (H to E) mode transition, indicating an improved (worsened) inductive power coupling efficiency. Project supported by the National Natural Science Foundation of China (Grant Nos. 11175034, 11205025, 11305023, and 11075029).
Energy Technology Data Exchange (ETDEWEB)
Hashemabadi, S.H. [Iran Univ. of Science and Technology, Dept. of Chemical Engineering, Tehran (Iran); Etemad, S.Gh. [Isfahan Univ. of Technology, Dept. of Chemical Engineering, Isfahan (Israel); Thibault, J. [Ottawa Univ., Dept. of Chemical Engineering, Ottawa, ON (Canada)
2004-08-01
Heat transfer to viscoelastic fluids is frequently encountered in various industrial processing. In this investigation an analytical solution was obtained to predict the fully developed, steady and laminar heat transfer of viscoelastic fluids between parallel plates. One of the plates was stationary and was subjected to a constant heat flux. The other plate moved with constant velocity and was insulated. The simplified Phan-Thien-Tanner (SPTT) model, believed to be a more realistic model for viscoelastic fluids, was used to represent the rheological behavior of the fluid. The energy equation was solved for a wide range of Brinkman number, dimensionless viscoelastic group, and dimensionless pressure drop. Results highlight the strong effects of these parameters on the heat transfer rate. (Author)
Application of the DTM to Nonlinear Cases Arising in Fluid Flows with Variable Viscosity
DEFF Research Database (Denmark)
Barari, Amin; Rahimi, M; Hosseini, M.J;
2012-01-01
This paper employs the differential transformation method to investigate two nonlinear ordinary differential systems for plane coquette flow having variable viscosity and thermal conductivity. The concept of differential transformation is briefly introduced, and then differential transformation...... method is employed to derive solutions of nonlinear equation systems. The results of differential transformation method are compared with those ones obtained by Adomian decomposition method to verify the accuracy of proposed method. The results reveal that the differential transformation method can...... achieve suitable results in predicting the solution of such problems....
Schmidt, Julius J; Kielstein, Jan T
2015-06-01
Fluids play an important role in clinical nephrology.1) Temperature of dialysate fluid has recently re-attracted a lot of attention. Individualized cooling of the dialysate (0.5 °C below predialysis ear temperature) has been shown to not only prevent intradialytic hypotension but also to improve myocardial contractility and to prevent white matter changes in CKD5D.2) Access fluid in AKI is associated with an increased mortality. While Furosemide has no place in treating AKI the Furosemide stress test can help to identify patients with AKI that will eventually need renal replacement therapy.3) Components of replacement fluid for therapeutic plasma exchange (albumin or fresh frozen plasma) are high in demand. Especially the cost for albumin increases year by year. Alternative solutions such as immunoadsorption should be studied and employed for those indications where replenishment of plasma components is not necessary. Further, a seperate reimbursement of repalcement fluid seems necessary to avoid a decline in treatment quality.
Institute of Scientific and Technical Information of China (English)
Fan Yuxin; Xia Jian
2014-01-01
A fluid–structure interaction method combining a nonlinear finite element algorithm with a preconditioning finite volume method is proposed in this paper to simulate parachute tran-sient dynamics. This method uses a three-dimensional membrane–cable fabric model to represent a parachute system at a highly folded configuration. The large shape change during parachute infla-tion is computed by the nonlinear Newton–Raphson iteration and the linear system equation is solved by the generalized minimal residual (GMRES) method. A membrane wrinkling algorithm is also utilized to evaluate the special uniaxial tension state of membrane elements on the parachute canopy. In order to avoid large time expenses during structural nonlinear iteration, the implicit Hil-ber–Hughes–Taylor (HHT) time integration method is employed. For the fluid dynamic simula-tions, the Roe and HLLC (Harten–Lax–van Leer contact) scheme has been modified and extended to compute flow problems at all speeds. The lower–upper symmetric Gauss–Seidel (LU-SGS) approximate factorization is applied to accelerate the numerical convergence speed. Finally, the test model of a highly folded C-9 parachute is simulated at a prescribed speed and the results show similar characteristics compared with experimental results and previous literature.
Yu, G. Y.; Luo, E. C.; Dai, W.; Hu, J. Y.
2007-10-01
This article focuses on using computational fluid dynamics (CFD) method to study several important nonlinear phenomenon and processes of a large experimental thermoacoustic-Stirling heat engine. First, the simulated physical model was introduced, and the suitable numerical scheme and algorithm for the time-dependent compressible thermoacoustic system was determined through extensive numerical tests. Then, the simulation results of the entire evolution process of self-excited thermoacoustic oscillation and the acoustical characteristics of pressure and velocity waves were presented and analyzed. Especially, the onset temperature and the saturation process of dynamic pressure were captured by the CFD simulation. In addition, another important nonlinear phenomenon accompanying the acoustic wave, which is the steady mass flow through the traveling-wave loop inside the thermoacoustic engine, was studied. To suppress the steady mass flow numerically, a fan model was adopted in the simulation. Finally, the multidimensional effects of vortex formation in the thermal buffer tube and other components were displayed numerically. Most importantly, a substantial comparison between the simulation and experiments was made, which demonstrated well the validity and powerfulness of the CFD simulation for characterizing several complicated nonlinear phenomenon involved in the self-excited thermoacoustic heat engine.
Salamatin, A.
2016-11-01
Numerical algorithm is developed for modelling non-linear mass transfer process in supercritical fluid extraction (SFE). The ground raw material is considered as polydisperse, characterized by discrete number of effective particle fractions. Two continuous interacting counterparts separated by permeable membrane are distinguished in plant material build-up. The apoplast plays role of transport channels during extraction, and symplast contains extractable oil. The complete SFE model is non-linear as a result of non-linearity of oil dissolution kinetics. The computational scheme is based on the finite-volume approximation method and Thomas elimination procedure. The resulting system of algebraic equations is solved iteratively. Special attention is paid to polydisperse substrates, when particle scale characteristics of all fractions interact with each other through pore phase concentration on the vessel scale. Stability of the developed algorithm is demonstrated in numerical tests. Special iterative procedure guarantees a monotonic decrease of oil content in individual particles of substrate. It is also shown that in the limit of the so-called shrinking core approach the number of mesh nodes on a particle scale should be increased.
Institute of Scientific and Technical Information of China (English)
胡业民; 胡希伟
2001-01-01
Numerical analyses for the nonlinear evolutions of stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) processes are given. Various effects of the second- and third-order nonlinear susceptibilities on the SRS and SBS processes are studied. The nonlinear evolutions of SRS and SBS processes are atfected more efficiently than their linear growth rates by the nonlinear susceptibility.
Application of the DTM to Nonlinear Cases Arising in Fluid Flows with Variable Viscosity
DEFF Research Database (Denmark)
Barari, Amin; Rahimi, M; Hosseini, M.J
2012-01-01
method is employed to derive solutions of nonlinear equation systems. The results of differential transformation method are compared with those ones obtained by Adomian decomposition method to verify the accuracy of proposed method. The results reveal that the differential transformation method can...
FOKINA, Valentina M; WEST, Holly; ONCKEN, Cheryl; CLARK, Shannon M; AHMED, Mahmoud S; HANKINS, Gary DV; NANOVSKAYA, Tatiana N
2017-01-01
Background Bupropion is used for treatment of depression during pregnancy. However, its use as a smoking cessation aid for pregnant women is currently under evaluation. Objectives The aim of this opportunistic study was to investigate the transfer of bupropion and its major pharmacologically active metabolites, hydroxybupropion and threohydrobupropion, across the placenta in vivo. In addition, the concentrations of the drug and its metabolites were determined in the amniotic fluid. Methods The following samples were collected at deliveries from twenty-two women taking bupropion: maternal blood (n=22), umbilical cord venous blood (n=22), and amniotic fluid (n=9). The concentrations of the drug and its metabolites in blood plasma and amniotic fluid were determined by means of liquid chromatography-mass spectrometry. Placental passage was calculated as a ratio of umbilical cord venous plasma to maternal plasma concentrations. Results The levels of hydroxybupropion and threohydrobupropion in umbilical cord venous plasma were invariably lower than their corresponding concentrations in maternal plasma. The concentrations of bupropion in umbilical cord plasma were lower than in maternal plasma in the majority of the maternal-cord blood pairs. The median values of the umbilical cord venous plasma to maternal plasma ratios were: bupropion, 0.53 (interquartile range 0.35, n=18), hydroxybupropion, 0.21 (interquartile range 0.12, n=18), and threohydrobupropion, 0.61 (interquartile range 0.11, n=21). In umbilical cord venous plasma, the median concentration of bupropion was 5.3 ng/ml; hydroxybupropion, 103.6 ng/ml and threohydrobupropion, 59.6 ng/ml. Bupropion and its metabolites were detectable in the amniotic fluid but the concentrations of threohydrobupropion were higher than those in the corresponding umbilical cord venous plasma. Conclusion Bupropion and its active metabolites cross the placenta to the fetal circulation. The concentrations of hydroxybupropion and
Rayleigh-Taylor instability in partially ionized compressible plasmas: one fluid approach
Diaz, A J; Collados, M
2014-01-01
We study the modification of the classical criterion for the linear onset and growth rate of the Rayleigh-Taylor instability (RTI) in a partially ionized (PI) plasma in the one-fluid description, considering a generalized induction equation. The governing linear equations and appropriate boundary conditions, including gravitational terms, are derived and applied to the case of the RTI in a single interface between two partially ionized plasmas. The boundary conditions lead to an equation for the frequencies in which some of them have positive complex parts, marking the appearance of the RTI. We study the ambipolar term alone first, extending the result to the full induction equation later. We find that the configuration is always unstable because of the presence of a neutral species. In the classical stability regime the growth rate is small, since the collisions prevent the neutral fluid to fully develop the RTI. For parameters in the classical instability regime the growth rate is lowered, but for the consi...
Yazar, M; Sarban, S; Kocyigit, A; Isikan, U E
2005-08-01
In recent years, a great number of studies have investigated the possible role of trace elements in the etiology and pathogenesis of rheumatoid arthritis (RA) and osteoartritis (OA). We studied synovial fluid and plasma concentrations of selenium (Se), zinc (Zn), copper (Cu), and iron (Fe) in patients with RA and OA and compared them with sex- and age-matched healthy subjects. Plasma albumin levels were measured as an index of nutritional status. Plasma Se, Cu, and Zn concentrations were determined by atomic absorption spectrophotometry and Fe concentrations were determined by the colorimetric method. Although plasma and synovial fluid Se concentration were found to be significantly lower (p 0.05). On the other hand, synovial fluid Cu and Fe concentrations were significantly higher in patients with OA than those of healthy subjects (p < 0.05). There was a significantly positive correlation between synovial fluid Se-Cu values and Zn-Fe values in patients with RA. Our results showed that synovial fluid and plasma trace element concentrations, excluding Zn, change in inflammatory RA, but not in OA. These alterations in trace element concentrations in inflammatory RA might be a result of the changes of the immunoregulatory cytokines.
Papaseit, Esther; Farré, Magí; Graziano, Silvia; Pacifici, Roberta; Pérez-Mañá, Clara; García-Algar, Oscar; Pichini, Simona
2017-03-01
Electronic cigarettes (e-cig) known as electronic nicotine devices recently gained popularity among smokers. Despite many studies investigating their safety and toxicity, few examined the delivery of e-cig-derived nicotine and its metabolites in alternative biological fluids. We performed a randomized, crossover, and controlled clinical trial in nine healthy smokers. Nicotine (NIC), cotinine (COT), and trans-3'-hydroxycotinine (3-HCOT) were measured in plasma and oral fluid by liquid chromatography-tandem mass spectrometry after consumption of two consecutive e-cig administrations or two consecutive tobacco cigarettes. NIC and its metabolites were detected both in oral fluid and plasma following both administration conditions. Concentrations in oral fluid resulted various orders of magnitude higher than those observed in plasma. Oral fluid concentration of tobacco cigarette and e-cig-derived NIC peaked at 15 min after each administration and ranged between 1.0 and 1396 μg/L and from 0.3 to 860 μg/L; those of COT between 52.8 and 110 μg/L and from 33.8 to 94.7 μg/L; and those of 3-HCOT between 12.4 and 23.5 μg/L and from 8.5 to 24.4 μg/L. The oral fluid to plasma concentration ratio of both e-cig- and tobacco cigarette-derived NIC peaked at 15 min after both administrations and correlated with oral fluid NIC concentration. The obtained results support the measurement of NIC and metabolites in oral fluid in the assessment of intake after e-cig use and appear to be a suitable alternative to plasma when monitoring nicotine delivery from e-cig for clinical and toxicological studies.
Prasannakumara, B. C.; Shashikumar, N. S.; Venkatesh, P.
2017-09-01
An analysis has been carried out to study the effect of nonlinear thermal radiation on slip flow and heat transfer of fluid particle suspension with nanoparticles over a nonlinear stretching sheet immersed in a porous medium. Water is considered as a base fluid with dust particles along with suspended Aluminum Oxide (Al2O3) nanoparticles. Using appropriate similarity transformations, the coupled nonlinear partial differential equations are reduced into a set of coupled nonlinear ordinary differential equations. The reduced equations are then solved numerically using Runge-Kutta-Fehlberg45 order method with the help of shooting technique to investigate the impact of various pertinent parameters for the velocity and temperature fields. The obtained results are presented in tabular form as well as graphically and discussed in detail. Effect of different parameters on skin friction coefficient and Nusselt number are also discussed.
THE EFFECT OF NONLINEAR LANDAU DAMPING ON ULTRARELATIVISTIC BEAM PLASMA INSTABILITIES
Energy Technology Data Exchange (ETDEWEB)
Chang, Philip; Lamberts, Astrid [Department of Physics, University of Wisconsin-Milwaukee, 1900 E. Kenwood Boulevard, Milwaukee, WI 53211 (United States); Broderick, Avery E.; Shalaby, Mohamad [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON, N2L 2Y5 (Canada); Pfrommer, Christoph [Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Puchwein, Ewald, E-mail: chang65@uwm.edu [Institute of Astronomy and Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
2014-12-20
Very high energy gamma-rays from extragalactic sources produce pairs from the extragalactic background light, yielding an electron-positron pair beam. This pair beam is unstable to various plasma instabilities, especially the ''oblique'' instability, which can be the dominant cooling mechanism for the beam. However, recently, it has been claimed that nonlinear Landau damping renders it physically irrelevant by reducing the effective damping rate to a low level. Here we show with numerical calculations that the effective damping rate is 8 × 10{sup –4} the growth rate of the linear instability, which is sufficient for the ''oblique'' instability to be the dominant cooling mechanism of these pair beams. In particular, we show that previous estimates of this rate ignored the exponential cutoff in the scattering amplitude at large wave numbers and assumed that the damping of scattered waves entirely depends on collisions, ignoring collisionless processes. We find that the total wave energy eventually grows to approximate equipartition with the beam by increasingly depositing energy into long-wavelength modes. As we have not included the effect of nonlinear wave-wave interactions on these long-wavelength modes, this scenario represents the ''worst case'' scenario for the oblique instability. As it continues to drain energy from the beam at a faster rate than other processes, we conclude that the ''oblique'' instability is sufficiently strong to make it the physically dominant cooling mechanism for high-energy pair beams in the intergalactic medium.
Pooled population pharmacokinetic model of imipenem in plasma and the lung epithelial lining fluid
Rizk, Matthew L.; Lala, Mallika; Chavez‐Eng, Cynthia; Visser, Sandra A. G.; Kerbusch, Thomas; Danhof, Meindert; Rao, Gauri; van der Graaf, Piet H.
2016-01-01
Aims Several clinical trials have confirmed the therapeutic benefit of imipenem for treatment of lung infections. There is however no knowledge of the penetration of imipenem into the lung epithelial lining fluid (ELF), the site of action relevant for lung infections. Furthermore, although the plasma pharmacokinetics (PK) of imipenem has been widely studied, most studies have been based on selected patient groups. The aim of this analysis was to characterize imipenem plasma PK across populations and to quantify imipenem ELF penetration. Methods A population model for imipenem plasma PK was developed using data obtained from healthy volunteers, elderly subjects and subjects with renal impairment, in order to identify predictors for inter‐individual variability (IIV) of imipenem PK. Subsequently, a clinical study which measured plasma and ELF concentrations of imipenem was included in order to quantify lung penetration. Results A two compartmental model best described the plasma PK of imipenem. Creatinine clearance and body weight were included as subject characteristics predictive for IIV on clearance. Typical estimates for clearance, central and peripheral volume, and inter‐compartmental clearance were 11.5 l h–1, 9.37 l, 6.41 l, 13.7 l h–1, respectively (relative standard error (RSE) <8%). The distribution of imipenem into ELF was described using a time‐independent penetration coefficient of 0.44 (RSE 14%). Conclusion The identified lung penetration coefficient confirms the clinical relevance of imipenem for treatment of lung infections, while the population PK model provided insights into predictors of IIV for imipenem PK and may be of relevance to support dose optimization in various subject groups. PMID:26852277
Scholl-Bürgi, S; Korman, S H; Applegarth, D A; Karall, D; Lillquist, Y; Heinz-Erian, P; Davidson, A G F; Haberlandt, E; Sass, J O
2008-06-01
The characteristic elevation of plasma glycine concentrations observed in propionic acidaemia (PA) and other 'ketotic hyperglycinaemias' has been attributed to secondary inhibition of the hepatic glycine cleavage system (GCS) by accumulating CoA derivatives of branched-chain amino acid metabolites. In nonketotic hyperglycinaemia (NKH), cerebrospinal fluid (CSF) and plasma glycine levels and their ratio are increased due to primary deficiency of central nervous system (CNS) as well as hepatic GCS. Whether the GCS in the CNS is also inhibited in PA is unclear, as there are scant data available on CSF glycine levels in this disorder. We studied the relation of CSF and plasma glycine levels in 6 paired samples from 4 PA patients, including one PA patient with bacterial meningitis who underwent ventriculoperitoneal shunting and multiple CSF analyses (n = 26). In contrast to the CSF glycine levels which were generally elevated in all four PA patients, the CSF/plasma glycine concentration ratios in paired samples were normal (0.016-0.029), with the exception of a single sample (0.132) with extremely high CSF protein concentration (2010 mg/L) during the course of meningitis indicating a disturbed blood-brain barrier. This finding of normal CSF/plasma glycine ratio in PA suggests that the observed elevations of CSF glycine levels are a reflection of the concurrent hyperglycinaemia resulting from secondary inhibition of hepatic GCS, but that brain GCS is not affected, in contrast to the situation in NKH. The neurological sequelae in PA are therefore unlikely to be related to disturbed glycine metabolism.
DEFF Research Database (Denmark)
Henriksen, Ulrik Lütken; Hansen, Hanne B; Ring-Larsen, Helmer
2015-01-01
Abstract Background and aim. In patients with fluid retention, the total plasma clearance of (51)Cr-EDTA (ClP) may overestimate the glomerular filtration rate (GFR). The present study was therefore undertaken in order to compare ClP with the urinary plasma clearance of (51)Cr-EDTA (ClU) in patients...... with cirrhosis with and without fluid retention. Material and methods. A total of 136 patients with cirrhosis (24 without fluid retention, 112 with ascites) received a quantitative intravenous injection of (51)Cr-EDTA followed by plasma and quantitative urinary samples for 5 hours. ClP was determined from...... the injected dose relative to the plasma concentration-time area, extrapolated to infinity. ClU was determined as urinary excretion relative to the plasma concentration-time area up to voiding. Results. In patients without fluid retention, the difference between ClP and ClU (ClP - ClU = ClΔ) was mean 4.5 m...
Metabolomics of Human Amniotic Fluid and Maternal Plasma during Normal Pregnancy.
Orczyk-Pawilowicz, Magdalena; Jawien, Ewa; Deja, Stanislaw; Hirnle, Lidia; Zabek, Adam; Mlynarz, Piotr
2016-01-01
Metabolic profiles of amniotic fluid and maternal blood are sources of valuable information about fetus development and can be potentially useful in diagnosis of pregnancy disorders. In this study, we applied 1H NMR-based metabolic profiling to track metabolic changes occurring in amniotic fluid (AF) and plasma (PL) of healthy mothers over the course of pregnancy. AF and PL samples were collected in the 2nd (T2) and 3rd (T3) trimester, prolonged pregnancy (PP) until time of delivery (TD). A multivariate data analysis of both biofluids reviled a metabolic switch-like transition between 2nd and 3rd trimester, which was followed by metabolic stabilization throughout the rest of pregnancy probably reflecting the stabilization of fetal maturation and development. The differences were further tested using univariate statistics at α = 0.001. In plasma the progression from T2 to T3 was related to increasing levels of glycerol, choline and ketone bodies (3-hydroxybutyrate and acetoacetate) while pyruvate concentration was significantly decreased. In amniotic fluid, T2 to T3 transition was associated with decreasing levels of glucose, carnitine, amino acids (valine, leucine, isoleucine, alanine, methionine, tyrosine, and phenylalanine) and increasing levels of creatinine, succinate, pyruvate, choline, N,N-dimethylglycine and urocanate. Lactate to pyruvate ratio was decreased in AF and conversely increased in PL. The results of our study, show that metabolomics profiling can be used to better understand physiological changes of the complex interdependencies of the mother, the placenta and the fetus during pregnancy. In the future, these results might be a useful reference point for analysis of complicated pregnancies.
Divergence-free Approximate Riemann Solver for the Quasi-neutral Two-fluid Plasma Model
Amano, Takanobu
2015-01-01
A numerical method for the quasi-neutral two-fluid (QNTF) plasma model is described. The basic equations are ion and electron fluid equations and the Maxwell equations without displacement current. The neglect of displacement current is consistent with the assumption of charge neutrality. It thus reduces to the ideal magnetohydrodynamic (MHD) equations in the long wavelength limit, but the two-fluid effect appearing at ion and electron inertial scales is fully taken into account. It is shown that the basic equations may be rewritten in a form that has formally the same structure as the MHD equations. The total mass, momentum, and energy are all written in the conservative form. A new three-dimensional numerical simulation code has been developed for the QNTF equations. The HLL (Harten-Lax-van Leer) approximate Riemann solver combined with the upwind constrained transport (UCT) scheme is applied. The method was originally developed for MHD (Londrillo & Del Zanna, 2004), but works quite well for the present...
Fuller, C J; Ghosh, P; Barr, A R S
2002-01-01
Results from in vitro studies have indicated that calcium pentosan polysulphate (CaPPS) may be of therapeutic value in osteoarthritis (OA) in the horse. However, no controlled clinical trials using this drug in equine OA have yet been reported. If CaPPS is to be developed for such use, the relationship between the proposed i.m. dose of CaPPS to be used and the concentrations of drug attained in plasma and synovial fluid of the target joint should first be established. An investigation was undertaken to determine these concentrations after a single 2 mg/kg i.m. injection of CaPPS. Blood and synovial fluid samples were taken from 6 healthy, sound horses following i.m. CaPPS administration. Concentrations of CaPPS measured in the synovial fluid were, on the basis of published studies, sufficient to elicit a potential therapeutic effect on synoviocyte metabolism, and possibly also to stimulate proteoglycan synthesis and reduce matrix metalloproteinase activities in articular cartilage. It would therefore seem justified to investigate further the therapeutic effect of CaPPS in OA in the horse.
Energy Technology Data Exchange (ETDEWEB)
El-Hanbaly, A. M.; Sallah, M., E-mail: msallahd@mans.edu.eg [Mansoura University, Physics Department, Faculty of Science (Egypt); El-Shewy, E. K. [Taibah University Al-Madinah Al-Munawarah, Department of Physics (Saudi Arabia); Darweesh, H. F. [Mansoura University, Physics Department, Faculty of Science (Egypt)
2015-10-15
Linear and nonlinear dust-acoustic (DA) waves are studied in a collisionless, unmagnetized and dissipative dusty plasma consisting of negatively charged dust grains, Boltzmann-distributed electrons, and nonthermal ions. The normal mode analysis is used to obtain a linear dispersion relation illustrating the dependence of the wave damping rate on the carrier wave number, the dust viscosity coefficient, the ratio of the ion temperature to the electron temperatures, and the nonthermal parameter. The plasma system is analyzed nonlinearly via the reductive perturbation method that gives the KdV-Burgers equation. Some interesting physical solutions are obtained to study the nonlinear waves. These solutions are related to soliton, a combination between a shock and a soliton, and monotonic and oscillatory shock waves. Their behaviors are illustrated and shown graphically. The characteristics of the DA solitary and shock waves are significantly modified by the presence of nonthermal (fast) ions, the ratio of the ion temperature to the electron temperature, and the dust kinematic viscosity. The topology of the phase portrait and the potential diagram of the KdV-Burgers equation is illustrated, whose advantage is the ability to predict different classes of traveling wave solutions according to different phase orbits. The energy of the soliton wave and the electric field are calculated. The results in this paper can be generalized to analyze the nature of plasma waves in both space and laboratory plasma systems.
Three-fluid plasmas in star formation II. Momentum transfer rate coefficients
Pinto, Cecilia
2008-01-01
The charged component of the insterstellar medium consists of atomic and molecular ions, electrons, and charged dust grains, coupled to the local Galactic magnetic field. Collisions between neutral particles (mostly atomic or molecular hydrogen) and charged species, and between the charged species themselves, affect the magnetohydrodynamical behaviour of the medium and the dissipation of electric currents. The friction force due to elastic collisions between particles of different species in the multi-component interstellar plasma is a nonlinear function of the temperature of each species and the Mach number of the relative drift velocity. The aim of this paper is to provide an accurate and, as far as possible, complete set of momentum transfer rate coefficients for magnetohydrodynamical studies of the interstellar medium. Momentum transfer rates are derived from available experimental data and theoretical calculations of cross sections within the classic approach developed by Boltzmann and Langevin for a wid...
A Theoretical Analysis of Nonlinear Effects on the Flutter and Divergence of a Tube Conveying Fluid,
1977-08-02
Dugundji (1). To predict the large .1! 3.._ _ • .amplitude periodic motion after the threshold of instability is exceeded, nonlinearities have to be...John Dugundji (1). Although the approaches used are significantly different, the two results are p. ,0 found to be in very close agreement. They are...very flexible, the gravity term should not be neglected. -°- 0"%". 4 ! 0.° References 1. Greenwald, A.S., and Dugundji , J., "Static and Dynamic
Przekwas, A. J.; Yang, H. Q.
1989-01-01
The capability of accurate nonlinear flow analysis of resonance systems is essential in many problems, including combustion instability. Classical numerical schemes are either too diffusive or too dispersive especially for transient problems. In the last few years, significant progress has been made in the numerical methods for flows with shocks. The objective was to assess advanced shock capturing schemes on transient flows. Several numerical schemes were tested including TVD, MUSCL, ENO, FCT, and Riemann Solver Godunov type schemes. A systematic assessment was performed on scalar transport, Burgers' and gas dynamic problems. Several shock capturing schemes are compared on fast transient resonant pipe flow problems. A system of 1-D nonlinear hyperbolic gas dynamics equations is solved to predict propagation of finite amplitude waves, the wave steepening, formation, propagation, and reflection of shocks for several hundred wave cycles. It is shown that high accuracy schemes can be used for direct, exact nonlinear analysis of combustion instability problems, preserving high harmonic energy content for long periods of time.
Nonlinear dynamics aspects of subcritical transitions and singular flows in viscoelastic fluids
Becherer, Paul
2008-01-01
Recently, there has been a renewed interest in theoretical aspects of flows of viscoelastic fluids (such as dilute polymer solutions). This thesis addresses two distinct issues related to such flows. Motivated by the possible occurrence of subcritical (finite-amplitude) instabilities in parallel flo
Energy Technology Data Exchange (ETDEWEB)
Archambeau, C.B. [Univ. of Colorado, Boulder, CO (United States)
1994-01-01
A fractured solid under stress loading (or unloading) can be viewed as behaving macroscopically as a medium with internal, hidden, degrees of freedom, wherein changes in fracture geometry (i.e. opening, closing and extension) and flow of fluid and gas within fractures will produce major changes in stresses and strains within the solid. Likewise, the flow process within fractures will be strongly coupled to deformation within the solid through boundary conditions on the fracture surfaces. The effects in the solid can, in part, be phenomenologically represented as inelastic or plastic processes in the macroscopic view. However, there are clearly phenomena associated with fracture growth and open fracture fluid flows that produce effects that can not be described using ordinary inelastic phenomenology. This is evident from the fact that a variety of energy release phenomena can occur, including seismic emissions of previously stored strain energy due to fracture growth, release of disolved gas from fluids in the fractures resulting in enhanced buoyancy and subsequent energetic flows of gas and fluids through the fracture system which can produce raid extension of old fractures and the creation of new ones. Additionally, the flows will be modulated by the opening and closing of fractures due to deformation in the solid, so that the flow process is strongly coupled to dynamical processes in the surrounding solid matrix, some of which are induced by the flow itself.
Liu, Yu-Ping; Gao, Yi-Tian; Wei, Guang-Mei
2012-02-01
The inhomogeneous nonlinear Schrödinger-type (NLS) model from certain plasmas and optical fibers is investigated with symbolic computation. An improved Γ-Riccati Bäcklund transformation (Γ-R BT) is presented, which can generate successively a hierarchy of solutions through algebraic manipulations. Based on the improved Γ-R BT, the Darboux transformation is obtained, the analytic one/two-soliton-like solutions are presented, and the physical characteristics of the influences of the coefficient parameters on the propagation of the soliton pulses are discussed graphically.
Ponalagusamy, R.
2016-08-01
The present article concerns the problem of blood flow through an artery with an axially asymmetric stenosis (constriction). The two-layered macroscopic model consisting of a cell-rich core of suspension of all the erythrocytes described as a particle-fluid suspension (Jeffrey fluid) and a peripheral zone of cell-free plasma (Newtonian fluid). The analytical expressions for flow characteristics such as fluid phase and particle phase velocities, flow rate, wall shear stress, and resistive force are obtained. It is of interest to mention that the magnitudes of wall shear stress and flow resistance increase with red cell concentration but the flow resistance decreases with increasing shape parameter. One of the important observations is that when blood behaves like a Jeffrey fluid, the flowing blood experiences lesser wall shear stress and flow resistance than in the case of blood being characterized as a Newtonian fluid in both the particle-fluid suspension and particle- free flow studies. The rheology of blood as Jeffrey fluid and the introduction of plasma layer thickness cause significant reduction in the magnitudes of the flow characteristics.
Towards a non-linear theory for fluid pressure and osmosis in shales
Droghei, Riccardo; Salusti, Ettore
2015-04-01
In exploiting deep hydrocarbon reservoirs, often injections of fluid and/or solute are used. To control and avoid troubles as fluid and gas unexpected diffusions, a reservoir characterization can be obtained also from observations of space and time evolution of micro-earthquake clouds resulting from such injections. This is important since several among the processes caused by fluid injections can modify the deep matrix. Information about the evolution of such micro-seismicity clouds therefore plays a realistic role in the reservoir analyses. To reach a better insight about such processes, and obtain a better system control, we here analyze the initial stress necessary to originate strong non linear transients of combined fluid pressure and solute density (osmosis) in a porous matrix. All this can indeed perturb in a mild (i.e. a linear diffusion) or dramatic non linear way the rock structure, till inducing rock deformations, micro-earthquakes or fractures. I more detail we here assume first a linear Hooke law relating strain, stress, solute density and fluid pressure, and analyze their effect in the porous rock dynamics. Then we analyze its generalization, i.e. the further non linear effect of a stronger external pressure, also in presence of a trend of pressure or solute in the whole region. We moreover characterize the zones where a sudden arrival of such a front can cause micro-earthquakes or fractures. All this allows to reach a novel, more realistic insight about the control of rock evolution in presence of strong pressure fronts. We thus obtain a more efficient reservoir control to avoid large geological perturbations. It is of interest that our results are very similar to those found by Shapiro et al.(2013) with a different approach.
Huang, Z.; Toth, G.; Gombosi, T. I.; Jia, X.; Rubin, M.; Hansen, K. C.; Fougere, N.; Bieler, A. M.; Shou, Y.; Altwegg, K.; Combi, M. R.; Tenishev, V.
2015-12-01
The neutral and plasma environment is critical in understanding the interaction of comet Churyumov-Gerasimenko (CG), the target of the Rosetta mission, and the solar wind. To serve this need and support the Rosetta mission, we develop a 3-D four fluid model, which is based on BATS-R-US within the SWMF (Space Weather Modeling Framework) that solves the governing multi-fluid MHD equations and the Euler equations for the neutral gas fluid. These equations describe the behavior and interactions of the cometary heavy ions, the solar wind protons, the electrons, and the neutrals. This model incorporates different mass loading processes, including photo and electron impact ionization, charge exchange, dissociative ion-electron recombination, and collisional interactions between different fluids. We simulate the near nucleus plasma and neutral gas environment near perihelion with a realistic shape model of CG and compare our simulation results with Rosetta observations.
Energy Technology Data Exchange (ETDEWEB)
Bonnaud, G.; Dussy, S.; Lefebvre, E. [CEA Bruyeres-le-Chatel, 91 (France). Dept. de Physique Theorique et Appliquee; Bouchut, F. [Orleans Univ., 45 (France). Dept. de Mathematiques, UMR CNRS
1998-12-31
This report presents a numerical model to simulate the electromagnetic processes involved by electrically-charged relativistic fluids. The physical model is first given. Second, the numerical methods are explained with the various packages of the code RHEA, with indication methods are explained with the various packages of the code RHEA, with indication of its performances, within a 1.5.- dimensional framework. Results from test-simulations are shown to validate the use of the code, for both academic situations and realistic context of laser-plasma interaction, for which the code has been designed: the non-linear phenomena in the context of inertial confinement fusion and the ultra-intense laser pulses. (author) 25 refs.
Energy Technology Data Exchange (ETDEWEB)
Bonnaud, G.; Dussy, S.; Lefebvre, E. [CEA Bruyeres-le-Chatel, 91 (France). Dept. de Physique Theorique et Appliquee; Bouchut, F. [Orleans Univ., 45 (France). Dept. de Mathematiques, UMR CNRS
1998-12-31
This report presents a numerical model to simulate the electromagnetic processes involved by electrically-charged relativistic fluids. The physical model is first given. Second, the numerical methods are explained with the various packages of the code RHEA, with indication methods are explained with the various packages of the code RHEA, with indication of its performances, within a 1.5.- dimensional framework. Results from test-simulations are shown to validate the use of the code, for both academic situations and realistic context of laser-plasma interaction, for which the code has been designed: the non-linear phenomena in the context of inertial confinement fusion and the ultra-intense laser pulses. (author) 25 refs.
Kinetic plasma turbulence during the nonlinear stage of the Kelvin-Helmholtz instability
Kemel, Koen; Lapenta, Giovanni; Califano, Francesco; Markidis, Stefano
2014-01-01
Using a full kinetic, implicit particle-in-cell code, iPiC3D, we studied the properties of plasma kinetic turbulence, such as would be found at the interface between the solar wind and the Earth magnetosphere at low latitude during northwards periods. In this case, in the presence of a magnetic field B oriented mostly perpendicular to the velocity shear, turbulence is fed by the disruption of a Kelvin-Helmholtz vortex chain via secondary instabilities, vortex pairing and non-linear interactions. We found that the magnetic energy spectral cascade between ion and electron inertial scales, $d_i$ and $d_e$, is in agreement with satellite observations and other previous numerical simulations; however, in our case the spectrum ends with a peak beyond $d_e$ due to the occurrence of the lower hybrid drift instability. The electric energy spectrum is influenced by effects of secondary instabilities: anomalous resistivity, fed by the development of the lower hybrid drift instability, steepens the spectral decay and, de...
Energy Technology Data Exchange (ETDEWEB)
Gill, Tarsem Singh [Dept. of Physics, Guru Nanak Dev Univ., Amritsar (India); Bala, Parveen [Dept. of Math. Stat. and Physics, Punjab Agricultural Univ., Ludhiana (India); Kaur, Harvinder [Dept. of Physics, Khalsa Coll., Amritsar (India)
2010-04-15
In the present investigation, we have studied ion-acoustic solitary waves in a plasma consisting of warm positive and negative ions and nonisothermal electron distribution. We have used reductive perturbation theory (RPT) and derived a dispersion relation which supports only two ion-acoustic modes, viz. slow and fast. The expression for phase velocities of these modes is observed to be a function of parameters like nonisothermality, charge and mass ratio, and relative temperature of ions. A modified Korteweg-de Vries (KdV) equation with a (1+1/2) nonlinearity, also known as Schamel-mKdV model, is derived. RPT is further extended to include the contribution of higher-order terms. The results of numerical computation for such contributions are shown in the form of graphs in different parameter regimes for both, slow and fast ion-acoustic solitary waves having several interesting features. For the departure from the isothermally distributed electrons, a generalized KdV equation is derived and solved. It is observed that both rarefactive and compressive solitons exist for the isothermal case. However, nonisothermality supports only the compressive type of solitons in the given parameter regime. (orig.)