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  • 1.
    Asenjo, Felipe A.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zamanian, Jens
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johansson, Petter
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Semi-relativistic effects in spin-1/2 quantum plasmas2012In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 14, 073042- p.Article in journal (Refereed)
    Abstract [en]

    Emerging possibilities for creating and studying novel plasma regimes, e. g. relativistic plasmas and dense systems, in a controlled laboratory environment also require new modeling tools for such systems. This motivates theoretical studies of the kinetic theory governing the dynamics of plasmas for which both relativistic and quantum effects occur simultaneously. Here, we investigate relativistic corrections to the Pauli Hamiltonian in the context of a scalar kinetic theory for spin-1/2 quantum plasmas. In particular, we formulate a quantum kinetic theory for the collective motion of electrons that takes into account effects such as spin-orbit coupling and Zitterbewegung. We discuss the implications and possible applications of our findings.

  • 2.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Physics.
    A coupled system for nonlinear wave progation combining wake field generation with a Kerr-nonlinearity2004In: Physica Scripta topical issue T113, 2004, 20-23 p.Conference paper (Refereed)
  • 3.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Virtual issue to honour Lennart Stenflo on his 75th birthday: foreword2015In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, no 6, 1-2 p., 060303Article in journal (Other academic)
  • 4.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Eriksson, Daniel
    Umeå University, Faculty of Science and Technology, Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Physics.
    Graviton mediated photon-photon scattering in general relativity2006In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 74, no 12, 124028-124032 p.Article in journal (Refereed)
    Abstract [en]

    In this paper we consider photon-photon scattering due to self-induced gravitational perturbations on a Minkowski background. We focus on four-wave interaction between plane waves with weakly space and time dependent amplitudes, since interaction involving a fewer number of waves is excluded by energy-momentum conservation. The Einstein-Maxwell system is solved perturbatively to third order in the field amplitudes and the coupling coefficients are found for arbitrary polarizations in the center of mass system. Comparisons with calculations based on quantum field theoretical methods are made, and the small discrepancies are explained.

  • 5.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Eriksson, Daniel
    Umeå University, Faculty of Science and Technology, Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Physics.
    Nonlinear resonant wave interaction in vacuum2004In: Physica Scripta - Topical Issue T107: INTERNATIONAL TOPICAL CONFERENCE ON PLASMA PHYSICS: COMPLEX PLASMAS IN THE NEW MILLENNIUM, 2004, 209-212 p.Conference paper (Refereed)
  • 6.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Forsberg, Mats
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Eriksson, Daniel
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Interaction between gravitational waves and plasma waves in the Vlasov description2010In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, no 76, 345-353 p.Article in journal (Refereed)
    Abstract [en]

    The nonlinear interaction between electromagnetic, electrostatic and gravitational waves in a Vlasov plasma is reconsidered. By using a orthonormal tetrad description the three-wave coupling coefficients are computed. Comparing with previous results, it is found that the present theory leads to algebraic expression that are much reduced, as compared to those computed using a coordinate frame formalism. Furthermore, here we calculate the back reaction on the gravitational waves, and a simple energy conservation law is deduced in the limit of a cold plasma.

  • 7.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Holkundkar, Amol
    Umeå University, Faculty of Science and Technology, Department of Physics. Department of Physics, Birla Institute of Technology and Science, Rajasthan, India.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics. Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden.
    Particle-in-cell simulations of electron spin effects in plasmas2013In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 79, no 4, 377-382 p.Article in journal (Refereed)
    Abstract [en]

    We present a particle-in-cell code accounting for the magnetic dipole force and for the magnetization currents associated with the electron spin. The electrons are divided into spin-up and spin-down populations relative to the magnetic field, where the magnetic dipole force acts in opposite directions for the two species. To validate the code, we study wakefield generation by an electromagnetic pulse propagating parallel to an external magnetic field. The properties of the generated wakefield are shown to be in good agreement with previous theoretical results. Generalizations of the code to account for other quantum effects are discussed. © Cambridge University Press 2013.

  • 8.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Lundin, Joakim
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nonlinear quantum electrodynamics in vacuum and plasmas2010In: New frontiers in advanced plasma physics, American Institute of Physics (AIP), 2010, 24-34 p.Conference paper (Refereed)
    Abstract [en]

    We consider high field physics due to quantum electrodynamics, in particular those that can be studied in the next generation of laser facilities. Effective field theories based on the Euler-Heisenberg Lagrangian are briefly reviewed, and examples involving plasma- and vacuum physics are given.

  • 9.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Lundin, Joakim
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zamanian, Jens
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stefan, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nonlinear wave interaction and spin models in the magnetohydrodynamic regime2011In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 13, no August, 083017-08331 p.Article in journal (Refereed)
    Abstract [en]

    Here we consider the influence on the electron spin in the magnetohydrodynamic (MHD) regime. Recently developed models that include spin-velocity correlations are taken as the starting point. A theoretical argument is presented, suggesting that in the MHD regime a single-fluid electron model with spin correlations is equivalent to a model with spin-up and spin-down electrons constituting different fluids, but where the spin-velocity correlations are omitted. Three-wave interaction of two shear Alfven waves and a compressional Alfven wave is then taken as a model problem to evaluate the asserted equivalence. The theoretical argument turns out to be supported, because the predictions of the two models agree completely. Furthermore, the three-wave coupling coefficients obey the Manley-Rowe relations, which further support the soundness of the models and the validity of the assumptions made in the derivation. Finally, we point out that the proposed two-fluid model can be incorporated in standard particle-in-cell schemes with only minor modifications.

  • 10.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Ferromagnetic behavior in magnetized plasmas2007In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, ISSN 1063-651X, E-ISSN 1095-3787, Vol. 76, no 055403(R), 4- p.Article in journal (Refereed)
    Abstract [en]

    We consider a low-temperature plasma within a newly developed magnetohydrodynamic fluid model. Inaddition to the standard terms, the electron spin, quantum particle dispersion, and degeneracy effects areincluded. It turns out that the electron spin properties can give rise to ferromagnetic behavior in certainregimes. If additional conditions are satisfied, a homogeneous magnetized plasma can even be unstable. Thishappens in the low-temperature high-density regime, when the magnetic properties associated with the spin canovercome the stabilizing effects of the thermal and Fermi pressure, to cause a Jeans-like instability.

  • 11.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    On the possibility of metamaterial properties in spin plasmas2008In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 10, no 11, 115031- p.Article in journal (Refereed)
    Abstract [en]

    The fluid theory of plasmas is extended to include the properties of electron spin. The linear theory of waves in a magnetized plasma is presented, and it is shown that the spin effects cause a change of the magnetic permeability. Furthermore, by changing the direction of the external magnetic field, the magnetic permeability may become negative. This leads to instabilities in the long wavelength regimes. If these can be controlled, however, the spin plasma becomes a metamaterial for a broad range of frequencies, i.e. above the ion cyclotron frequency but below the electron cyclotron frequency. The consequences of our results are discussed.

  • 12.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Spin magnetohydrodynamics2007In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 9, 277- p.Article in journal (Refereed)
    Abstract [en]

    Starting from the non-relativistic Pauli description of spin-½ particles, a set of fluid equations, governing the dynamics of such particles interacting with external fields and other particles, is derived. The equations describe electrons, positrons, holes and similar conglomerates. In the case of electrons, the magnetohydrodynamic limit of an electron–ion plasma is investigated. The results should be of interest and relevance both to laboratory and astrophysical plasmas.

  • 13.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Spin solitons in magnetized pair plasmas2007In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 14, no 11, 2107-4 sidor p.Article in journal (Refereed)
    Abstract [en]

    A set of fluid equations, taking into account the spin properties of the electrons and positrons in a magnetoplasma, are derived. The magnetohydrodynamic limit of the pair plasma is investigated. It is shown that the microscopic spin properties of the electrons and positrons can lead to interesting macroscopic and collective effects in strongly magnetized plasmas. In particular, it is found that new Alfvénic solitary structures, governed by a modified Korteweg–de Vries equation, are allowed in such plasmas. These solitary structures vanish if the quantum spin effects are neglected. Our results should be of relevance for astrophysical plasmas, e.g., in pulsar magnetospheres, as well as for low-temperature laboratory plasmas.

  • 14.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Bingham, Robert
    Rutherford Appleton Laboratory.
    Collier, John
    Rutherford Appleton Laboratory.
    Evans, Roger
    Rutherford Appleton Laboratory.
    Laboratory soft x-ray emission due to the Hawking-Unruh effect?2008In: Classical and quantum gravity, ISSN 0264-9381, E-ISSN 1361-6382, Vol. 25, no 14, 145005- p.Article in journal (Refereed)
    Abstract [en]

    The structure of spacetime, quantum field theory, and thermodynamics are all connected through the concepts of the Hawking and Unruh temperatures. The possible detection of the related radiation constitutes a fundamental test of such subtle connections. Here a scheme is presented for the detection of Unruh radiation based on currently available laser systems. By separating the classical radiation from the Unruh response in frequency space, it is found that the detection of Unruh radiation is possible in terms of soft x-ray photons using current laser-electron beam technology. The experimental constraints are discussed and a proposal for an experimental design is given.

  • 15.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Eliasson, Bengt
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shukla, Padma Kant
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Quantum-electrodynamical photon splitting in magnetized Nonlinear pair plasmas2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 12, 5001-4 sidor p.Article in journal (Refereed)
    Abstract [en]

    We present for the first time the nonlinear dynamics of quantum electrodynamic (QED) photon splitting in a strongly magnetized electron-positron (pair) plasma. By using a QED corrected Maxwell equation, we derive a set of equations that exhibit nonlinear couplings between electromagnetic (EM) waves due to nonlinear plasma currents and QED polarization and magnetization effects. Numerical analyses of our coupled nonlinear EM wave equations reveal the possibility of a more efficient decay channel, as well as new features of energy exchange among the three EM modes that are nonlinearly interacting in magnetized pair plasmas. Possible applications of our investigation to astrophysical settings, such as magnetars, are pointed out.

  • 16.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Manfredi, Giovanni
    Quantum plasma effects in the classical regime2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 17, 5001-4 sidor p.Article in journal (Refereed)
    Abstract [en]

    For quantum effects to be significant in plasmas it is often assumed that the temperature over density ratio must be small. In this paper we challenge this assumption by considering the contribution to the dynamics from the electron spin properties. As a starting point we consider a multicomponent plasma model, where electrons with spin-up and spin-down are regarded as different fluids. By studying the propagation of Alfvén wave solitons we demonstrate that quantum effects can survive in a relatively high-temperature plasma. The consequences of our results are discussed.

  • 17.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shukla, Padma K.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Generation of gravitational radiation in dusty plasmas and supernovae2005In: JETP Letters: Journal of Experimental And Theoretical Physics Letters, ISSN 0021-3640, E-ISSN 1090-6487, Vol. 81, no 4, 135-139 p.Article in journal (Refereed)
    Abstract [en]

    We present a novel nonlinear mechanism for exciting a gravitational radiation pulse (or a gravitational wave) by dust magnetohydrodynamic (DMHD) waves in dusty astrophysical plasmas. We derive the relevant equations governing the dynamics of nonlinearly coupled DMHD waves and a gravitational wave (GW). The system of equations is used to investigate the generation of a GW by compressional Alfvén waves in a type II supernova. The growth rate of our nonlinear process is estimated, and the results are discussed in the context of the gravitational radiation accompanying supernova explosions.

  • 18.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shukla, Padma
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Anomalous reflection and excitation of surface waves in metamaterials2007In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 367, no 3, 233-236 p.Article in journal (Refereed)
    Abstract [en]

    We consider reflection of electromagnetic waves from layered structures with various dielectric and magnetic properties, including metamaterials. Assuming periodic variations in the permittivity, we find that the reflection is in general anomalous. In particular, we note that the specular reflection vanishes and that the incident energy is totally reflected in the backward direction, when the conditions for resonant excitation of leaking surface waves are fulfilled.

  • 19.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shukla, Padma K.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Dispersion relation for electromagnetic wave propagation in a strongly magnetized plasma2006In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 8, no January, 16- p.Article in journal (Refereed)
    Abstract [en]

    A dispersion relation for electromagnetic wave propagation in a strongly magnetized cold plasma is deduced, taking photon–photon scattering into account. It is shown that the combined plasma and quantum electrodynamic effect is important for understanding the mode-structures in magnetar and pulsar atmospheres. The implications of our results are discussed.

  • 20.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zamanian, Jens
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Dusty spin plasmas2008In: Multifacets of dusty plasmas: Fifth international conference on the physics of dusty plasmas / [ed] Maya Flikop, New York: American Institute of Physics , 2008, , 5 p.97-100 p.Conference paper (Other academic)
    Abstract [en]

    A fluid model is derived, taking into account the effect of spin magnetization of electrons as well as of magnetized dust grains. The model is analyzed, and it is found that both the acoustic velocity and the Alfven velocity is decreased due to the magnetization effects. Furthermore, for low-temperature high density plasmas, it is found that the linear wave modes can be unstable, due to the magnetic attraction of individual fluid elements. The significance of our results are discussed.

  • 21.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zamanian, Jens
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Spin kinetic models of plasmas: semiclassical and quantum mechanical theory2009In: New developments in nonlinear plasma physics, American Institute of Physics (AIP), 2009, 280-289 p.Conference paper (Refereed)
    Abstract [en]

    In this work a recently published semiclassical spin kinetic model, generalizing those of previous authors are discussed. Some previously described properties are reviewed, and a new example illustrating the theory is presented. The generalization to a fully quantum mechanical description is discussed, and the main features of such a theory is outlined. Finally, the main conclusions are presented.

  • 22.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zamanian, Jens
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Ericsson, Åsa
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Mana, Piero L
    Effects of the g factor in semiclassical kinetic plasma theory2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 24, 245002-245006 p.Article in journal (Refereed)
    Abstract [en]

    A kinetic theory for spin plasmas is put forward, generalizing those of previous authors. In the model, the ordinary phase space is extended to include the spin degrees of freedom. Together with Maxwell's equations, the system is shown to be energy conserving. Analyzing the linear properties, it is found that new types of wave-particle resonances are possible that depend directly on the anomalous magnetic moment of the electron. As a result, new wave modes, not present in the absence of spin, appear. The implications of our results are discussed.

  • 23.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zamanian, Jens
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stefan, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Spin and magnetization effects in plasmas2011In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 53, no 7, 074013- p.Article in journal (Refereed)
    Abstract [en]

    Quantum effects in plasmas are of interest for a diverse set of systems, and have thus as a field been revived and attracted a lot of attention from a wide community over the past decade. In models of quantum plasmas, the effects studied mostly are due to the quantum particle dispersion and tunnelling. Such effects can be of importance in dense systems and on short length scales. There are also a number of effects related to spin and statistics. However, up to recently the magnetization effect in plasmas due to the intrinsic electron spin has been largely ignored. The magnetization dynamics of e.g. solids has many important applications, such as components for memory storage, but has also been discussed in more 'proper' plasma environments, such as fusion plasmas. Furthermore, also from a basic science point-of-view the effects of intrinsic spin and gyromagnetic effects are of considerable interest. Here we give a short review of a number of different models for treating magnetization effects in plasmas, with a focus on recent results. In particular, the transition between kinetic models and fluid models is discussed. We also give a number of examples of applications of such theories, as well as an outlook for possible future work.

  • 24.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Misra, Amar P
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Spin contribution to the ponderomotive force in a plasma2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 105, no 10, 105004- p.Article in journal (Refereed)
    Abstract [en]

    The concept of a ponderomotive force due to the intrinsic spin of electrons is developed. An expression containing both the classical as well as the spin-induced ponderomotive force is derived. The results are used to demonstrate that an electromagnetic pulse can induce a spin-polarized plasma. Furthermore, it is shown that, for certain parameters, the nonlinear backreaction on the electromagnetic pulse from the spin magnetization current can be larger than that from the classical free current. Suitable parameter values for a direct test of this effect are presented.

  • 25.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shukla, Padma
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Department of Physics.
    A new decay channel for compressional Alfven waves in plasmas2008In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 74, no 1, 99-105 p.Article in journal (Refereed)
    Abstract [en]

    We present a new efficient wave decay channel involving nonlinear interactions between a compressional Alfv´en wave, a kinetic Alfv´en wave, and a modified ion sound wave in a magnetized plasma. It is found that the wave coupling strength of the ideal magnetohydrodynamic (MHD) theory is much increased when the effects due to the Hall current are included in a Hall–MHD description of wave–wave interactions. In particular, with a compressional Alfv´en pump wave well described by the ideal MHD theory, we find that the growth rate is very high when the decay products have wavelengths of the order of the ion thermal gyroradius or shorter, in which case they must be described by the Hall–MHD equations. The significance of our results to the heating of space and laboratory plasmas as well as for the Solar corona and interstellar media are highlighted.

  • 26.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stefan, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Kinetic theory of fully degenerate electrons in the long scale limit2013In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 88, no 2, 023107- p.Article in journal (Refereed)
    Abstract [en]

    The kinetic theory of fully degenerate electrons in a weakly coupled plasma is considered. We derive an evolution equation for a generalized Fermi surface that also depends on the electron spin state. The equation allows for the study of weakly nonlinear modifications of the Fermi surface within perturbation theory. We apply the theory to Landau damping of ion-acoustic waves. The transition to the nonlinear stage and the nonlinear modification of the Fermi surface are investigated.

  • 27.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, L.
    Large amplitude electron plasma oscillations2014In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 378, no 22-23, 1632-1635 p.Article in journal (Refereed)
    Abstract [en]

    We consider a cold plasma in order to find new large-amplitude wave solutions in the long-wavelength limit. Accordingly we derive two generic coupled equations which describe the energy exchange between the electrostatic and electromagnetic waves. A new kind of quasi-periodic behavior is found. Our derivations may be considered as a prerequisite to extended studies of stimulated Raman scattering for cases where the wave amplitudes are so large that standard perturbation techniques are not applicable.

  • 28.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, L.
    Nonlinear dynamics of large amplitude modes in a magnetized plasma2014In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 21, no 12, 122301Article in journal (Refereed)
    Abstract [en]

    We derive two equations describing the coupling between electromagnetic and electrostatic oscillations in one-dimensional geometry in a magnetized cold and non-relativistic plasma. The nonlinear interaction between the wave modes is studied numerically. The effects of the external magnetic field strength and the initial electromagnetic polarization are of particular interest here. New results can, thus, be identified. 

  • 29.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, L.
    Nonlinear wave interactions of kinetic sound waves2015In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 33, no 8, 1007-1010 p.Article in journal (Refereed)
    Abstract [en]

    We reconsider the nonlinear resonant interaction between three electrostatic waves in a magnetized plasma. The general coupling coefficients derived from kinetic theory are reduced here to the low-frequency limit. The main contribution to the coupling coefficient we find in this way agrees with the coefficient recently presented in Annales Geophysicae. But we also deduce another contribution which sometimes can be important, and which qualitatively agrees with that of an even more recent paper. We have thus demonstrated how results derived from fluid theory can be improved and generalized by means of kinetic theory. Possible extensions of our results are outlined.

  • 30.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, L.
    Three-wave coupling coefficients for perpendicular wave propagation in a magnetized plasma2015In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 22, no 10, 104503Article in journal (Refereed)
    Abstract [en]

    The resonant interaction between three waves in a uniform magnetized plasma is reconsidered. Starting from previous kinetic expressions, we limit our investigation to waves propagating perpendicularly to the external magnetic field. It is shown that reliable results can only be obtained in the two-dimensional case, i.e., when the wave vectors have both x and y components. 

  • 31.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, Lennart
    Alfven wave interactions within the Hall-MHD description2013In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 79, no 5, 909-911 p.Article in journal (Refereed)
    Abstract [en]

    We show that comparatively simple expressions for the Alfven wave coupling coefficients can be deduced from the well-known Hall-magnetohydrodynamics (MHD) model equations.

  • 32.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Physics.
    Kinetic and quantum electrodynamical theory for circularly polarized waves in a plasma2007In: Physics Letters A, Vol. 371, 462- p.Article in journal (Refereed)
    Abstract [en]

    The theory for large amplitude circularly polarized waves propagating along an external magnetic field is further developed. Relativistic effects, quantum electrodynamical effects due to vacuum polarization and magnetization, as well as kinetic effects are included in our formalism. A general dispersion relation, which unites previous results, is derived. As a specific example, a low-frequency kinetic mode with a detailed dependence on the electron distribution function is studied.

  • 33.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Department of Physics.
    On the parametric decay of waves in magnetized plasmas2009In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 75, 9-13 p.Article in journal (Refereed)
    Abstract [en]

    We reconsider the theory for three-wave interactions in cold plasmas. In particular, we demonstrate that previously overlooked formulations of the general theory are highly useful when deriving concrete expressions for specific cases. We also point out that many previous results deduced directly from the basic plasma equations contain inappropriate approximations leading to unphysical results. Finally, generalizations to more elaborate plasma models containing, for example, kinetic effects are given.

  • 34.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, Lennart
    Department of Physics, Linköping University, SE-581 83 Linköping, Sweden .
    Stimulated Brillouin scattering in magnetized plasmas2013In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 79, no Special Issue 06, 983-986 p.Article in journal (Refereed)
    Abstract [en]

    Previous theory for stimulated Brillouin scattering is reconsidered and generalized. We introduce an effective ion sound velocity that turns out to be useful in describing scattering instabilities.

  • 35.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology.
    Three-wave coupling coefficients for a magnetized plasma2012Conference paper (Refereed)
  • 36.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, Lennart
    Three-wave coupling coefficients for a magnetized plasma2012In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 85, no 3, 035504- p.Article in journal (Refereed)
    Abstract [en]

    The resonant interaction between three waves in a uniform magnetized plasma is reconsidered. Starting from previous kinetic expressions, which contain a general but too little used result, we are able to improve the formulae. This leads to an explicit expression for the three-wave coupling coefficient which applies for arbitrary wave propagation in a magnetized Vlasov plasma.

  • 37.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Physics.
    Three-wave coupling coefficients for a warm magnetized multicomponent plasma2007In: Physica Scripta, Vol. 75, 216- p.Article in journal (Refereed)
  • 38.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wave Generation in a Warm Magnetized Multi-Component Plasma2014In: Contributions to Plasma Physics, ISSN 0863-1042, E-ISSN 1521-3986, Vol. 54, no 7, 623-625 p.Article in journal (Refereed)
    Abstract [en]

    The resonant interaction between three waves propagating perpendicularly to an external magnetic field in a plasma is considered. We present the explicit expressions for the three wave coupling coefficients of a warm multi-component plasma. The results of previous work on the generation of THz radiation by laser plasma interaction are significantly improved. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  • 39.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Physics.
    Shukla, Padma K.
    Umeå University, Faculty of Science and Technology, Physics.
    Nonlinear interactions between kinetic Alfven and ion-sound waves2006In: Solar Physics, Vol. 236, 285- p.Article in journal (Refereed)
  • 40.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shukla, Padma K.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nonlinear interactions between three inertial Alfvén waves2007In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 73, no 1, 9-13 p.Article in journal (Refereed)
    Abstract [en]

    The resonant coupling between Alfvén waves is reconsidered. New results are found for cold agnetoplasmas where temperature effects are negligible.

  • 41.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Physics.
    Shukla, Padma K.
    Umeå University, Faculty of Science and Technology, Physics.
    Parametric couplings between kinetic Alfvén and dispersive ion-acoustic waves in the solar corona2006In: Proceedings of the 13th International Congress on Plasma Physics, Kiev, Ukraine, May 2006, 2006, C112- p.Conference paper (Refereed)
  • 42.
    Brodin, Gert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zamanian, Jens
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Mendonca, J. T.
    The transition from the classical to the quantum regime in nonlinear Landau damping2015In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, no 6, 068020Article in journal (Other academic)
    Abstract [en]

    Starting from the Wigner–Moyal equation coupled to Poisson’s equation, a simplified set of equations describing nonlinear Landau damping of Langmuir waves is derived. This system is studied numerically, with a particular focus on the transition from the classical to the quantum regime. In the quantum regime several new features are found. This includes a quantum modified bounce frequency, and the discovery that bounce-like amplitude oscillations can take place even in the absence of trapped particles. The implications of our results are discussed.

  • 43.
    Bychkov, Vitaly
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Matyba, Piotr
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Akkerman, Vyacheslav
    Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544-5263, USA.
    Modestov, Mikhail
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Valiev, Damir
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Law, Chung K.
    Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544-5263, USA.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edman, Ludvig
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Speedup of doping fronts in organic semiconductors through plasma instability2011In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, no 1, 016103-016107 p.Article in journal (Refereed)
    Abstract [en]

    The dynamics of doping transformation fronts in organic semiconductor plasma is studied for application in light-emitting electrochemical cells. We show that new fundamental effects of the plasma dynamics can significantly improve the device performance. We obtain an electrodynamic instability, which distorts the doping fronts and increases the transformation rate considerably. We explain the physical mechanism of the instability, develop theory, provide experimental evidence, perform numerical simulations, and demonstrate how the instability strength may be amplified technologically. The electrodynamic plasma instability obtained also shows interesting similarity to the hydrodynamic Darrieus-Landau instability in combustion, laser ablation, and astrophysics.

  • 44.
    Ekman, Robin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zamanian, Jens
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Exchange corrections in a low-temperature plasma2015In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 92, no 1, 013104Article in journal (Refereed)
    Abstract [en]

    We have studied the exchange corrections to linear electrostatic wave propagation in a plasma using a quantum kinetic formalism. Specifically, we have considered the zero-temperature limit. In order to simplify the calculations we have focused on the long-wavelength limit, i.e., wavelengths much longer than the de Broglie wavelength. For the case of ion-acoustic waves we have calculated the exchange correction both to the damping rate and the real part of the frequency. For Langmuir waves the frequency shift due to exchange effects is found. Our results are compared with the frequency shifts deduced from commonly used exchange potentials which are computed from density-functional theory.

  • 45.
    Eriksson, Daniel
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Physics.
    Stenflo, Lennart
    Umeå University, Faculty of Science and Technology, Physics.
    Possibility to measure elastic photon-photon scattering in vacuum2004In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 70, no 1, 013808- p.Article in journal (Refereed)
    Abstract [en]

    Photon-photon scattering in vacuum due to the interaction with virtual electron-positron pairs is a consequence of quantum electrodynamics. A way for detecting this phenomenon has been devised based on interacting modes generated in microwave wave guides or cavities [G. Brodin, M. Marklund, and L. Stenflo, Phys. Rev. Lett. 87, 171801 (2001)]. Here we materialize these ideas, suggest a concrete cavity geometry, make quantitative estimates and propose experimental details. It is found that detection of photon-photon scattering can be within the reach of present day technology.

  • 46.
    Forsberg, Mats
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Harmonic generation of gravitational wave induced Alfven waves2008In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 77, no 2, 024050-024050-6 p.Article in journal (Refereed)
    Abstract [en]

    Here we consider the nonlinear evolution of Alfvén waves that have been excited by gravitational waves from merging binary pulsars. We derive a wave equation for strongly nonlinear and dispersive Alfvén waves. Because of the weak dispersion of the Alfvén waves, significant wave steepening can occur, which in turn implies strong harmonic generation. We find that the harmonic generation is saturated due to dispersive effects, and use this to estimate the resulting spectrum. Finally we discuss the possibility of observing the above process.

  • 47.
    Forsberg, Mats
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Linear theory of gravitational wave propagation in a magnetized, relativistic Vlasov plasma2010In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 82, no 12, 124029Article in journal (Refereed)
    Abstract [en]

    We consider propagation of gravitational waves in a magnetized plasma, using the linearized Maxwell-Vlasov equations coupled to Einstein's equations. A set of coupled electromagnetic-gravitational wave equations are derived that can be straightforwardly reduced to a single dispersion relation. We demonstrate that there is a number of different resonance effects that can enhance the influence of the plasma on the gravitational waves.

  • 48.
    Forsberg, Mats
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shukla, Padma K.
    Institut für Theoretische Physik IV and Centre for Plasma Science and Astrophysics, Fakultät für Physik und Astronomie, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
    Moortgat, J.
    Department of Physics and Astronomy, University of Rochester, Bausch & Lomb Hall, P.O. Box 270171, 600 Wilson Boulevard, Rochester, New York 14627-0171, USA .
    Nonlinear interactions between gravitational radiation and modified Alfvén modes in astrophysical dusty plasmas2006In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 74, 064014-064014-5 p.Article in journal (Refereed)
    Abstract [en]

    We present an investigation of nonlinear interactions between gravitational radiation and modified Alfvén modes in astrophysical dusty plasmas. Assuming that stationary charged dust grains form neutralizing background in an electron-ion-dust plasma, we obtain the three-wave coupling coefficients and calculate the growth rates for parametrically coupled gravitational radiation and modified Alfvén-Rao modes. The threshold value of the gravitational wave amplitude associated with convective stabilization is particularly small if the gravitational frequency is close to twice the modified Alfvén wave frequency. The implication of our results to astrophysical dusty plasmas is discussed.

  • 49.
    Forsberg, Mats
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Papadopoulos, Demetrios
    Department of Physics, Section of Astrophysics, Astronomy and Mechanics, Thessaloniki, Greece.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Influence of strong field vacuum polarization on gravitational-electromagnetic wave interaction2010In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 82, no 2, 024001-024001-7 p.Article in journal (Refereed)
    Abstract [en]

    The interaction between gravitational and electromagnetic waves in the presence of a static magnetic field is studied. The field strength of the static field is allowed to surpass the Schwinger critical field, such that the QED effects of vacuum polarization and magnetization are significant. Equations governing the interaction are derived and analyzed. It turns out that the energy conversion from gravitational to electromagnetic waves can be significantly altered due to the QED effects. The consequences of our results are discussed.

  • 50.
    Haas, F
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Marklund, Mattias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Brodin, Gert
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zamanian, Jens
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Fluid moment hierarchy equations derived from quantum kinetic theory2010In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 374, no 3, 481-484 p.Article in journal (Refereed)
    Abstract [en]

    A set of quantum hydrodynamic equations are derived from the moments of the electrostatic mean-field Wigner kinetic equation. No assumptions are made on the particular local equilibrium or on the statistical ensemble wave functions. Quantum diffraction effects appear explicitly only in the transport equation for the heat flux triad, which is the third-order moment of the Wigner pseudo-distribution. The general linear dispersion relation is derived, from which a quantum modified Bohm–Gross relation is recovered in the long wave-length limit. Nonlinear, traveling wave solutions are numerically found in the one-dimensional case. The results shed light on the relation between quantum kinetic theory, the Bohm–de Broglie–Madelung eikonal approach, and quantum fluid transport around given equilibrium distribution functions.

123 1 - 50 of 113
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