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  • 1.
    Asenjo, Felipe A.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Zamanian, Jens
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Brodin, Gert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Johansson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Semi-relativistic effects in spin-1/2 quantum plasmas2012Ingår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 14, s. 073042-Artikel i tidskrift (Refereegranskat)
    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. Bashinov, A. V.
    et al.
    Gonoskov, A. A.
    Kim, A. V.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Mourou, G.
    Sergeev, A. M.
    Electron acceleration and emission in a field of a plane and converging dipole wave of relativistic amplitudes with the radiation reaction force taken into account2013Ingår i: Quantum electronics (Woodbury, N.Y.), ISSN 1063-7818, E-ISSN 1468-4799, Vol. 43, nr 4, s. 291-299Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A comparative analysis is performed of the electron emission characteristics as the electrons move in laser fields with ultra-relativistic intensity and different configurations corresponding to a plane or tightly focused wave. For a plane travelling wave, analytical expressions are derived for the emission characteristics, and it is shown that the angular distribution of the radiation intensity changes qualitatively even when the wave intensity is much less than that in the case of the radiation-dominated regime. An important conclusion is drawn that the electrons in a travelling wave tend to synchronised motion under the radiation reaction force. The characteristic features of the motion of electrons are found in a converging dipole wave, associated with the curvature of the phase front and nonuniformity of the field distribution. The values of the maximum achievable longitudinal momenta of electrons accelerated to the centre, as well as their distribution function are determined. The existence of quasi-periodic trajectories near the focal region of the dipole wave is shown, and the characteristics of the emission of both accelerated and oscillating electrons are analysed.

  • 3. Betschart, G.
    et al.
    Dunsby, P.K.S.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Cosmic magnetic fields from velocity perturbations in the early Universe2004Ingår i: Classical and Quantum Gravity, Vol. 21, s. 2115-2125Artikel i tidskrift (Refereegranskat)
  • 4. Betschart, G.
    et al.
    Zunckel, C.
    Dunsby, P.K.S.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Primordial magnetic seed field amplification by gravitational waves2005Ingår i: Physical Review D, Vol. 72, nr 12, s. 123514-Artikel i tidskrift (Refereegranskat)
  • 5.
    Betschart, Gerold
    et al.
    University of Cape Town.
    Zunckel, Caroline
    University of Cape Town.
    Dunsby, Peter K S
    University of Cape Town.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Reply to "Comment on 'Primordial magnetic seed field amplification by gravitational waves'"2007Ingår i: Physical review D, ISSN 1550-7998, Vol. 75, nr 8, s. 7902-4 sidorArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    Here we respond to the comment by Tsagas on our earlier paper. We show that the results in that comment are flawed and cannot be used for drawing conclusions about the nature of magnetic field amplification by gravitational waves and give further support that the results of our earlier paper are correct.

  • 6.
    Bezett, Alice
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Bychkov, Vitaly
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Lundh, Emil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Kobyakov, Dmitry
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Magnetic Richtmyer-Meshkov instability in a two-component Bose-Einstein condensate2010Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 82, nr 4, s. 043608-Artikel, forskningsöversikt (Refereegranskat)
  • 7.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Eriksson, Daniel
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Graviton mediated photon-photon scattering in general relativity2006Ingår i: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 74, nr 12, s. 124028-124032Artikel i tidskrift (Refereegranskat)
    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.

  • 8.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Eriksson, Daniel
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Nonlinear resonant wave interaction in vacuum2004Ingår i: Physica Scripta - Topical Issue T107: INTERNATIONAL TOPICAL CONFERENCE ON PLASMA PHYSICS: COMPLEX PLASMAS IN THE NEW MILLENNIUM, 2004, s. 209-212Konferensbidrag (Refereegranskat)
  • 9.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Forsberg, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Eriksson, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Interaction between gravitational waves and plasma waves in the Vlasov description2010Ingår i: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, nr 76, s. 345-353Artikel i tidskrift (Refereegranskat)
    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.

  • 10.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Holkundkar, Amol
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Department of Physics, Birla Institute of Technology and Science, Rajasthan, India.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden.
    Particle-in-cell simulations of electron spin effects in plasmas2013Ingår i: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 79, nr 4, s. 377-382Artikel i tidskrift (Refereegranskat)
    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.

  • 11.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ferromagnetic behavior in magnetized plasmas2007Ingår i: 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, nr 055403(R), s. 4-Artikel i tidskrift (Refereegranskat)
    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.

  • 12.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    On the possibility of metamaterial properties in spin plasmas2008Ingår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 10, nr 11, s. 115031-Artikel i tidskrift (Refereegranskat)
    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.

  • 13.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Spin magnetohydrodynamics2007Ingår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 9, s. 277-Artikel i tidskrift (Refereegranskat)
    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.

  • 14.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Spin solitons in magnetized pair plasmas2007Ingår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 14, nr 11, s. 2107-4 sidorArtikel i tidskrift (Refereegranskat)
    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.

  • 15.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    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?2008Ingår i: Classical and quantum gravity, ISSN 0264-9381, E-ISSN 1361-6382, Vol. 25, nr 14, s. 145005-Artikel i tidskrift (Refereegranskat)
    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.

  • 16.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Eliasson, Bengt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Shukla, Padma Kant
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Quantum-electrodynamical photon splitting in magnetized Nonlinear pair plasmas2007Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, nr 12, s. 5001-4 sidorArtikel i tidskrift (Refereegranskat)
    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.

  • 17.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Manfredi, Giovanni
    Quantum plasma effects in the classical regime2008Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, nr 17, s. 5001-4 sidorArtikel i tidskrift (Refereegranskat)
    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.

  • 18.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Shukla, Padma K.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Generation of gravitational radiation in dusty plasmas and supernovae2005Ingår i: JETP Letters: Journal of Experimental And Theoretical Physics Letters, ISSN 0021-3640, E-ISSN 1090-6487, Vol. 81, nr 4, s. 135-139Artikel i tidskrift (Refereegranskat)
    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.

  • 19.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Stenflo, Lennart
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Shukla, Padma
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Anomalous reflection and excitation of surface waves in metamaterials2007Ingår i: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 367, nr 3, s. 233-236Artikel i tidskrift (Refereegranskat)
    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.

  • 20.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Stenflo, Lennart
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Shukla, Padma K.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Dispersion relation for electromagnetic wave propagation in a strongly magnetized plasma2006Ingår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 8, nr January, s. 16-Artikel i tidskrift (Refereegranskat)
    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.

  • 21.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Zamanian, Jens
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Dusty spin plasmas2008Ingår i: Multifacets of dusty plasmas: Fifth international conference on the physics of dusty plasmas / [ed] Maya Flikop, New York: American Institute of Physics , 2008, , s. 5s. 97-100Konferensbidrag (Övrigt vetenskapligt)
    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.

  • 22.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Zamanian, Jens
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Spin kinetic models of plasmas: semiclassical and quantum mechanical theory2009Ingår i: New developments in nonlinear plasma physics, American Institute of Physics (AIP), 2009, s. 280-289Konferensbidrag (Refereegranskat)
    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.

  • 23.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Zamanian, Jens
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ericsson, Åsa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Mana, Piero L
    Effects of the g factor in semiclassical kinetic plasma theory2008Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 24, s. 245002-245006Artikel i tidskrift (Refereegranskat)
    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.

  • 24.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Zamanian, Jens
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Stefan, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Spin and magnetization effects in plasmas2011Ingår i: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 53, nr 7, s. 074013-Artikel i tidskrift (Refereegranskat)
    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.

  • 25.
    Brodin, Gert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Misra, Amar P
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Spin contribution to the ponderomotive force in a plasma2010Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 105, nr 10, s. 105004-Artikel i tidskrift (Refereegranskat)
    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.

  • 26.
    Burza, M.
    et al.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Gonoskov, Arkady
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Genoud, G.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Persson, A.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Svensson, K.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Quinn, M.
    Univ Strathclyde, SUPA Dept Phys, Glasgow G4 0NG, Lanark, Scotland.
    McKenna, P.
    Univ Strathclyde, SUPA Dept Phys, Glasgow G4 0NG, Lanark, Scotland.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wahlström, C.-G.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Hollow microspheres as targets for staged laser-driven proton acceleration2011Ingår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 13, s. 013030-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A coated hollow core microsphere is introduced as a novel targetin ultra-intense laser–matter interaction experiments. In particular, it facilitates staged laser-driven proton acceleration by combining conventional target normal sheath acceleration (TNSA), power recycling of hot laterally spreading electrons and staging in a very simple and cheap target geometry. During TNSA of protons from one area of the sphere surface, laterally spreading hot electrons form a charge wave. Due to the spherical geometry, this wave refocuses on the opposite side of the sphere, where an opening has been laser micromachined.This leads to a strong transient charge separation field being set up there, which can post-accelerate those TNSA protons passing through the hole at the right time. Experimentally, the feasibility of using such targets is demonstrated. A redistribution is encountered in the experimental proton energy spectra, as predicted by particle-in-cell simulations and attributed to transient fields set up by oscillating currents on the sphere surface.

  • 27.
    Burza, M.
    et al.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Gonoskov, Arkady
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Svensson, K.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Wojda, F.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Persson, A.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Hansson, M.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Genoud, G.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wahlström, C-G.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Lundh, O.
    Lund Univ, Dept Phys, SE-22100 Lund, Sweden.
    Laser wakefield acceleration using wire produced double density ramps2013Ingår i: Physical Review Special Topics. Accelerators and Beams, ISSN 1098-4402, E-ISSN 1098-4402, Vol. 16, nr 1, s. 011301-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel approach to implement and control electron injection into the accelerating phase of a laser wakefield accelerator is presented. It utilizes a wire, which is introduced into the flow of a supersonic gas jet creating shock waves and three regions of differing plasma electron density. If tailored appropriately, the laser plasma interaction takes place in three stages: Laser self-compression, electron injection, and acceleration in the second plasma wave period. Compared to self-injection by wave breaking of a nonlinear plasma wave in a constant density plasma, this scheme increases beam charge by up to 1 order of magnitude in the quasimonoenergetic regime. Electron acceleration in the second plasma wave period reduces electron beam divergence by ≈25%, and the localized injection at the density downramps results in spectra with less than a few percent relative spread.

  • 28.
    Bychkov, Vitaly
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Jukimenko, Olexy
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Modestov, Mikhail
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Nonliner dynamics of corrugated doping fronts in organic optoelectronic devices2012Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, nr 24, s. 245212-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, it was demonstrated that electrochemical doping fronts in organic semiconductors exhibit a new fundamental instability growing from multidimensional perturbations [ Bychkov et al.  Phys. Rev. Lett. 107 016103 (2011)]. In the instability development, linear growth of tiny perturbations goes over into a nonlinear stage of strongly distorted doping fronts. Here we develop the nonlinear theory of the doping front instability and predict the key parameters of a corrugated doping front, such as its velocity, in close agreement with the experimental data. We show that the instability makes the electrochemical doping process considerably faster. We obtain the self-similar properties of the front shape corresponding to the maximal propagation velocity, which allows for a wide range of controlling the doping process in the experiments. The developed theory provides the guide for optimizing the performance of organic optoelectronic devices such as light-emitting electrochemical cells.

  • 29.
    Bychkov, Vitaly
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Modestov, Mikhail
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    The Rayleigh-Taylor instability and internal waves in quantum plasmas2008Ingår i: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 372, nr 17, s. 3042-3045Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Influence of quantum effects on the internal waves and the Rayleigh-Taylor instability in plasma is investigated. It is shown that quantum pressure always stabilizes the RT instability. The problem is solved both in the limit of short-wavelength perturbations and exactly for density profiles with layers of exponential stratification. In the case of stable stratification, quantum pressure modifies the dispersion relation of the inertial waves. Because of the quantum effects, the internal waves may propagate in the transverse direction, which was impossible in the classical case. A specific form of pure quantum internal waves is obtained, which do not require any external gravitational field.

  • 30.
    Bychkov, Vitaly
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Matyba, Piotr
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Akkerman, Vyacheslav
    Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544-5263, USA.
    Modestov, Mikhail
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Valiev, Damir
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Brodin, Gert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Law, Chung K.
    Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544-5263, USA.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Speedup of doping fronts in organic semiconductors through plasma instability2011Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, nr 1, s. 016103-016107Artikel i tidskrift (Refereegranskat)
    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.

  • 31.
    Bychkov, Vitaly
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Modestov, Mikhail
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Magnetohydrodynamic instability in plasmas with intrinsic magnetization2010Ingår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 17, nr 11, s. 112107-112112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    From a magnetofluid description with intrinsic magnetization, a new plasma instability is obtained. The plasma magnetization is produced by the collective electron spin. The instability develops in a nonuniform plasma when the electron concentration and temperature vary along an externally applied magnetic field. Alfvén waves play an important role in the instability. The instability properties are numerically investigated for a particular example of an ultrarelativistic degenerate plasma in exploding white dwarfs.

  • 32.
    Bychkov, Vitaly
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Modestov, Mikhail
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    The Darrieus-Landau instability in fast deflagration and laser ablation2008Ingår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 15, nr 3, s. 032702-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The problem of the Darrieus-Landau instability at a discontinuous deflagration front in a compressible flow is solved. Numerous previous attempts to solve this problem suffered from the deficit of boundary conditions. Here, the required additional boundary condition is derived rigorously taking into account the internal structure of the front. The derived condition implies a constant mass flux at the front; it reduces to the classical Darrieus-Landau condition in the limit of an incompressible flow. It is demonstrated that in general the solution to the problem depends on the type of energy source in the flow. In the common case of a strongly localized source, compression effects make the Darrieus-Landau instability considerably weaker. Particularly, the instability growth rate is reduced for laser ablation in comparison to the classical incompressible case. The instability disappears completely in the Chapman-Jouguet regime of ultimately fast deflagration.

  • 33.
    Bychkov, Vitaly
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Modestov, Mikhail
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    The structure of weak shocks in quantum plasmas2008Ingår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 15, nr 3, s. 032309-032322Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure of a weak shock in a quantum plasma is studied, taking into account both dissipation terms due to thermal conduction and dispersive quantum terms due to the Bohm potential. Unlike quantum systems without dissipations, even a small thermal conduction may lead to a stationary shock structure. In the limit of zero quantum effects, the monotonic Burgers solution for the weak shock is recovered. Still, even small quantum terms make the structure nonmonotonic with the shock driving a train of oscillations into the initial plasma. The oscillations propagate together with the shock. The oscillations become stronger as the role of Bohm potential increases in comparison with thermal conduction. The results could be of importance for laser-plasma interactions, such as inertial confinement fusion plasmas, and in astrophysical environments, as well as in condensed matter systems.

  • 34. Clarkson, C.
    et al.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Betschart, G.
    Dunsby, P.K.S.
    The electromagnetic signature of black hole ringdown2004Ingår i: The Astrophysical Journal, Vol. 613, s. 492-505Artikel i tidskrift (Refereegranskat)
  • 35. Clarkson, Chris
    et al.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Photon gas dynamics in the early universe2008Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 659, nr 1-2, s. 54-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quantum electrodynamics predicts that photons undergo one-loop scattering. The combined effect of this on the behaviour of a photon gas for temperatures above similar to 10(10) K results in a softening of the equation of state. We calculate the effect this has on the effective equation of state in the early universe, taking into account all the species of the Standard Model. The change to the dynamics of the early universe is discussed.

  • 36.
    Dion, Claude
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Jukimenko, Olexy
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Modestov, M
    Nordita.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Bychkov, Vitaly
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Anisotropic properties of spin avalanches in crystals of nanomagnets2013Ingår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 87, nr 1, artikel-id 014409Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anisotropy effects for spin avalanches in crystals of nanomagnets are studied theoretically with the external magnetic field applied at an arbitrary angle to the easy axis. Starting with the Hamiltonian for a single nanomagnet in the crystal, two essential quantities characterizing spin avalanches are calculated: the activation and Zeeman energies. The calculation is performed numerically for a wide range of angles and analytical formulas are derived within the limit of small angles. The anisotropic properties of a single nanomagnet lead to anisotropic behavior of the magnetic deflagration speed. Modifications of the magnetic deflagration speed are investigated for different angles between the external magnetic field and the easy axis of the crystals. Anisotropic properties of magnetic detonation are also studied, which concern, first of all, the temperature behind the leading shock and the characteristic time of spin switching in the detonation.

  • 37.
    Eriksson, Daniel
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Brodin, Gert
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Stenflo, Lennart
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Possibility to measure elastic photon-photon scattering in vacuum2004Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 70, nr 1, s. 013808-Artikel i tidskrift (Refereegranskat)
    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.

  • 38.
    Forsberg, Mats
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Brodin, Gert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    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 plasmas2006Ingår i: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 74, s. 064014-064014-5Artikel i tidskrift (Refereegranskat)
    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.

  • 39.
    Gonoskov, Arkady A.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Korzhimanov, Artem V.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Kim, A. V.
    Russian Acad Sci, Inst Appl Phys, Nizhnii Novgorod 603950, Russia.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sergeev, A. M.
    Russian Acad Sci, Inst Appl Phys, Nizhnii Novgorod 603950, Russia.
    Ultrarelativistic nanoplasmonics as a route towards extreme-intensity attosecond pulses2011Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 84, nr 4, s. 046403-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The generation of ultrastrong attosecond pulses through laser-plasma interactions offers the opportunity to surpass the intensity of any known laboratory radiation source, giving rise to new experimental possibilities, such as quantum electrodynamical tests and matter probing at extremely short scales. Here we demonstrate that a laser irradiated plasma surface can act as an efficient converter from the femto- to the attosecond range, giving a dramatic rise in pulse intensity. Although seemingly similar schemes have been described in the literature, the present setup differs significantly from the previous attempts. We present a model describing the nonlinear process of relativistic laser-plasma interaction. This model, which is applicable to a multitude of phenomena, is shown to be in excellent agreement with particle-in-cell simulations. The model makes it possible to determine a parameter region where the energy conversion from the femto- to the attosecond regime is maximal. Based on the study we propose a concept of laser pulse interaction with a target having a groove-shaped surface, which opens up the potential to exceed an intensity level of 10(26) W/cm(2) and observe effects due to nonlinear quantum electrodynamics with upcoming laser sources.

  • 40. Gonoskov, Arkady
    et al.
    Bashinov, A
    Gonoskov, Ivan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Harvey, C
    Ilderton, A
    Kim, A
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Mourou, G
    Sergeev, M
    Anomalous radiative trapping in laser fields of extreme intensity2014Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 113, s. 014801-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate that charged particles in a suciently intense standing wave are compressed toward, and oscillate synchronously at, the antinodes of the electric eld. We call this unusualbehaviour `anomalous radiative trapping' (ART). We show using dipole pulses, which oer a pathto increased laser intensity, that ART opens up new possibilities for the generation of radiationand particle beams, both of which are high-energy, directed and collimated. ART also provides a mechanism for particle control in high-intensity quantum-electrodynamics experiments.

  • 41.
    Gonoskov, Arkady
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Gonoskov, Ivan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Harvey, Christopher
    Ilderton, Antony
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Kim, Arkady
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Mourou, Gérard
    Sergeev, Alexander
    Probing nonperturbative QED with optimally focused laser pulses2013Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 111, nr 6, s. 060404-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study nonperturbative pair production in intense, focused laser fields called e-dipole pulses. We address the conditions required, such as the quality of the vacuum, for reaching high intensities without initiating beam-depleting cascades, the number of pairs which can be created, and experimental detection of the created pairs. We find that e-dipole pulses offer an optimal method of investigating nonperturbative QED.

  • 42.
    Gonoskov, Ivan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Department of Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
    Single-step propagators for calculation of time evolution in quantum systems with arbitrary interactions2016Ingår i: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 202, s. 211-215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose and develop a general method of numerical calculation of the wave function time evolution in a quantum system which is described by Hamiltonian of an arbitrary dimensionality and with arbitrary interactions. For this, we obtain a general n-order single-step propagator in closed-form, which could be used for the numerical solving of the problem with any prescribed accuracy. We demonstrate the applicability of the proposed approach by considering a quantum problem with non-separable time-dependent Hamiltonian: the propagation of an electron in focused electromagnetic field with vortex electric field component. 

  • 43.
    Grönlund, Andreas
    et al.
    Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences - SE-901 83 Umeå, Sweden.
    Eliasson, Bengt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Evolution of rogue waves in interacting wave systems2009Ingår i: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 86, nr 2, s. 24001-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Large-amplitude water waves on deep water have long been known in the seafaring community, and are the cause of great concern for, e.g., oil platform constructions. The concept of such freak waves is nowadays, thanks to satellite and radar measurements, well established within the scientific community. There are a number of important models and approaches for the theoretical description of such waves. By analyzing the scaling behavior of freak wave formation in a model of two interacting waves, described by two coupled non-linear Schrödinger equations, we show that there are two different dynamical scaling behaviors above and below a critical angle θc of the direction of the interacting waves, below which all wave systems evolve and display statistics similar to a wave system of non-interacting waves. The results equally apply to other systems described by the non-linear Schrödinger equations, and should be of interest when designing optical wave guides.

  • 44.
    Haas, F
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Brodin, Gert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Zamanian, Jens
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Fluid moment hierarchy equations derived from quantum kinetic theory2010Ingår i: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 374, nr 3, s. 481-484Artikel i tidskrift (Refereegranskat)
    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.

  • 45.
    Haas, Fernando
    et al.
    Universidade do Vale do Rio dos Sinos, Brazil.
    Zamanian, Jens
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Brodin, Gert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Fluid moment hierarchy equations derived from gauge invariant quantum kinetic theory2010Ingår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 12, s. 073027-073039Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The gauge invariant electromagnetic Wigner equation is taken as the basis of a fluid-like system describing quantum plasmas, derived from the moments of the gauge invariant Wigner function. The use of the standard, gauge-dependent Wigner function is shown to produce inconsistencies if a direct correspondence principle is applied. The propagation of linear transverse waves is considered and it is shown to be in agreement with the kinetic theory in the long-wavelength approximation, provided that an adequate closure is chosen for the macroscopic equations. A general recipe to solve the closure problem is suggested.

  • 46.
    Hansson, Tobias
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wallin, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Brodin, Gert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Scalar Wigner theory for polarized light in nonlinear Kerr media2013Ingår i: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 30, nr 6, s. 1765-1769Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A scalar Wigner distribution function for describing polarized light is proposed in analogy with the treatment of spin variables in quantum kinetic theory. The formalism is applied to the propagation of circularly polarized light in nonlinear Kerr media, and an extended phase-space evolution equation is derived along with invariant quantities. The formalism is additionally used to analyze the modulational instability. (C) 2013 Optical Society of America

  • 47.
    Harvey, Chris
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Heinzl, Thomas
    Ilderton, Anton
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Intensity-dependent electron mass shift in a laser field: existence, universality, and detection2012Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 109, nr 10, s. 100402-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electron mass shift in a laser field has long remained an elusive concept. We show that the mass shift can exist in pulses but that it is neither unique nor universal: it can be reduced by pulse shaping. We show also that the detection of mass shift effects in laser-particle scattering experiments is feasible with current technology, even allowing for the transverse structure of realistic beams.

  • 48.
    Harvey, Christopher
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Heinzl, Thomas
    University of Plymouth.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Symmetry Breaking from Radiation Reaction in Ultra-Intense Laser Fields2011Ingår i: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 84, nr 11, s. 116005-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We discuss radiation reaction effects on charges propagating in ultraintense laser fields. Our analysis is based on an analytic solution of the Landau-Lifshitz equation. We suggest quantifying radiation reaction in terms of a symmetry breaking parameter associated with the violation of null translation invariance in the direction opposite to the laser beam. As the Landau-Lifshitz equation is nonlinear, the energy transfer within the pulse is rather sensitive to initial conditions. This is elucidated by comparing colliding and fixed target modes in electron laser collisions.

  • 49.
    Harvey, Christopher
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Effects of radiation damping on the dynamics of electrons in ELI intensity Laser fields2012Ingår i: Light at extreme intensities 2011, American Institute of Physics (AIP), 2012, s. 13-16Konferensbidrag (Refereegranskat)
    Abstract [en]

    An electron in the presence of a high intensity laser field, such as that anticipated at ELI, will be accelerated so strongly that its own radiation emission may significantly affect its motion. This opens up the possibility of testing experimentally the classical theory of radiation reaction in such a context. We therefore explore the effects of radiation damping on the dynamics of electrons in optical laser pulses. In the case of high intensities and high initial electron energies, the trajectories and net energy changes of the electrons are found to be significantly altered. These effects are found to become increasingly significant the closer one gets to a directly head on collision between the laser and electrons.

  • 50.
    Harvey, Christopher
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Marklund, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Radiation damping in pulsed Gaussian beams2012Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 85, nr 1, s. 013412-013424Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider the effects of radiation damping on the electron dynamics in a Gaussian-beam model of a laser field. For high intensities, i.e., with dimensionless intensity a0≫1, it is found that the dynamics divides into three regimes. For low-energy electrons (low initial γ factor, γ0) the radiation damping effects are negligible. At higher energies, but still at 2γ0<a0, the damping alters the final displacement and the net energy change of the electron. For 2γ0>a0 one is in a regime of radiation-reaction-induced electron capture. This capture is found to be stable with respect to the spatial properties of the electron beam and results in a significant energy loss of the electrons. In this regime the plane-wave model of the laser field provides a good description of the dynamics, whereas for lower energies the Gaussian-beam and plane-wave models differ significantly. Finally the dynamics is considered for the case of an x-ray free-electron laser field. It is found that the significantly lower intensities of such fields inhibit the damping effects.

1234 1 - 50 av 162
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