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On Models of Quantum Plasmas and their Nonlinear Implications
Umeå University, Faculty of Science and Technology, Department of Physics.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The theory of quantum plasmas dates back to the first attempts of Wigner, Moyal and others to find a suitable formalism to describe many body quantum systems, and from this foundation a rich field has emerged. A plasma is a system consisting of many charged particles, and in a quantum plasma these particles have quantum mechanical properties, such as for example spin. Quantum properties of individual particles are often negligible on macroscopic scales, but due to collective interaction in the plasma certain phenomena arise that can only be explained by considering the fundamental quantum properties of the particles.

In this thesis kinetic descriptions, derived following the work of Wigner et al. and extended to also include particle spin, are employed to study various nonlinear phenomena related to the magnetic field generation and the ponderomotive force in quantum plasmas consisting of spin 1/2 particles. A specific model to study the special case of low temperature degenerate quantum plasmas by only considering dynamics on the surface of the velocity distribution sphere is also derived, and is applied to the problem of nonlinear Landau damping. Furthermore, by taking moments of the full kinetic theory a more nimble spin plasma fluid model is derived. This formalism is then applied to a variety of nonlinear problems involving the ponderomotive force and wave-wave interaction. Where possible the fluid model is shown to be in agreement with results derived from the considerably more complex full kinetic theory.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2014. , 23 p.
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:umu:diva-86733ISBN: 978-91-7601-008-2 (print)OAI: oai:DiVA.org:umu-86733DiVA: diva2:703306
Public defence
2014-05-08, Naturvetarhuset, N430 kl 10:00 den 8:e maj, Umeå universitet, Umeå, 10:00
Opponent
Supervisors
Available from: 2014-03-19 Created: 2014-03-06 Last updated: 2014-03-18Bibliographically approved
List of papers
1. Nonlinear wave interaction and spin models in the magnetohydrodynamic regime
Open this publication in new window or tab >>Nonlinear wave interaction and spin models in the magnetohydrodynamic regime
2011 (English)In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 13, no August, 083017-08331 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Bristol, UK: Institute of Physics Pub., 2011
National Category
Physical Sciences
Identifiers
urn:nbn:se:umu:diva-47668 (URN)10.1088/1367-2630/13/8/083017 (DOI)000294672100008 ()
Available from: 2011-10-03 Created: 2011-09-27 Last updated: 2017-12-08Bibliographically approved
2. Kinetic theory of fully degenerate electrons in the long scale limit
Open this publication in new window or tab >>Kinetic theory of fully degenerate electrons in the long scale limit
2013 (English)In: 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) Published
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.

Place, publisher, year, edition, pages
USA: American Physical Society, 2013
National Category
Physical Sciences
Identifiers
urn:nbn:se:umu:diva-80752 (URN)10.1103/PhysRevE.88.023107 (DOI)000323576400016 ()
Available from: 2013-09-25 Created: 2013-09-25 Last updated: 2017-12-06Bibliographically approved
3. Linear and nonlinear wave propagation in weakly relativistic quantum plasmas
Open this publication in new window or tab >>Linear and nonlinear wave propagation in weakly relativistic quantum plasmas
2013 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 20, no 1, 012114- p.Article in journal (Refereed) Published
Abstract [en]

We consider a recently derived kinetic model for weakly relativistic quantum plasmas. We find that that the effects of spin-orbit interaction and Thomas precession may alter the linear dispersion relation for a magnetized plasma in case of high plasma densities and/or strong magnetic fields. Furthermore, the ponderomotive force induced by an electromagnetic pulse is studied for an unmagnetized plasma. It turns out that for this case the spin-orbit interaction always gives a significant contribution to the quantum part of the ponderomotive force.

National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:umu:diva-67312 (URN)10.1063/1.4773897 (DOI)
Available from: 2013-03-18 Created: 2013-03-15 Last updated: 2017-12-06Bibliographically approved
4. Effects of the electron spin on the nonlinear generation of quasi-static magnetic fields in a plasma
Open this publication in new window or tab >>Effects of the electron spin on the nonlinear generation of quasi-static magnetic fields in a plasma
2010 (English)In: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 76, no 6, 865-873 p.Article in journal (Refereed) Published
Abstract [en]

Through an extended kinetic model, we study the nonlinear generation of quasi-static magnetic fields by high-frequency fields in a plasma, taking into account the effects of the electron spin. It is found that although the largest part of the nonlinear current in a moderate density, moderate temperature plasma is due to the classical terms, the spin may still give a significant contribution to the magnetic field generation mechanism. Applications of our results are discussed.

Place, publisher, year, edition, pages
Cambridge University Press, 2010
Identifiers
urn:nbn:se:umu:diva-38736 (URN)10.1017/S0022377810000516 (DOI)000284043700008 ()
Funder
Swedish Research Council
Available from: 2010-12-27 Created: 2010-12-27 Last updated: 2017-12-11Bibliographically approved
5. Ponderomotive force due to the intrinsic spin in extended fluid and kinetic models
Open this publication in new window or tab >>Ponderomotive force due to the intrinsic spin in extended fluid and kinetic models
Show others...
2011 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 83, no 3, 036410-036416 p.Article in journal (Refereed) Published
Abstract [en]

In this paper we calculate the contribution to the ponderomotive force in a plasma from the electron spin using a recently developed model. The spin-fluid model used in the present paper contains spin-velocity correlations, in contrast to previous models used for the same purpose. Is its then found that previous terms for the spin-ponderomotive force are recovered, but also that additional terms appear. Furthermore, the results due to the spin-velocity correlations are confirmed using the spin-kinetic theory. The significance of our results is discussed.

Place, publisher, year, edition, pages
American Physical Society, 2011
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:umu:diva-50783 (URN)10.1103/PhysRevE.83.036410 (DOI)
Available from: 2011-12-21 Created: 2011-12-21 Last updated: 2017-12-08Bibliographically approved
6. From extended phase space dynamics to fluid theory
Open this publication in new window or tab >>From extended phase space dynamics to fluid theory
2010 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 17, no 10, 102109-102112 p.Article in journal (Refereed) Published
Abstract [en]

We derive a fluid theory for spin-1/2 particles starting from an extended kinetic model based on a spin-projected density matrix formalism. The evolution equation for the spin density is found to contain a pressurelike term. We give an example where this term is important by looking at a linear mode previously found in a spin kinetic model.

Place, publisher, year, edition, pages
American Institute of Physics, 2010
Keyword
basic plasma phenomena, waves, instabilities
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:umu:diva-37382 (URN)10.1063/1.3496053 (DOI)000283772200010 ()
Available from: 2010-11-01 Created: 2010-11-01 Last updated: 2017-12-12Bibliographically approved

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