| 1. |
- Lundin, Joakim, 1978-, et al.
(författare)
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Linearized kinetic theory of spin-1/2 particles in magnetized plasmas
- 2010
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : APS physics. - 1063-651X .- 1095-3787. ; 82:5, s. 054607-10 pages
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Tidskriftsartikel (refereegranskat)abstract
- We have considered linear kinetic theory, including the electron-spin properties in a magnetized plasma. The starting point is a mean-field Vlasov-like equation, derived from a fully quantum-mechanical treatment, where effects from the electron-spin precession and the magnetic dipole force are taken into account. The general conductivity tensor is derived, including both the free current contribution and the magnetization current associated with the spin contribution. We conclude the paper with an extensive discussion of the quantummechanical boundary where we list parameter conditions that must be satisfied for various quantum effects to be influential.
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| 2. |
- Lundin, Joakim, 1978-
(författare)
-
QED and collective effects in vacuum and plasmas
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The theory of quantum electrodynamics (QED) was born out of an attempt to merge Einsteins theory of special relativity and quantum mechanics. Einsteins energy/mass equivalence together with Heisenberg's uncertainty principle allows for particle pairs to be spontaneously created and annihilated in vacuum. These spontaneous fluctuations gives the quantum vacuum properties analogous to that of a nonlinear medium. Although these fluctuations in general does not give note of themselves, effects due to their presence can be stimulated or enhanced through external means, such as boundary conditions or electromagnetic fields. Whereas QED has been very well tested in the high-energy, low-intensity regime using particle accelerators, the opposite regime where the photon energy is low but instead the intensity is high is still to a large degree not investigated. This is expected to change with the rapid progress of modern high-power laser-systems. In this thesis we begin by studying the QED effect of photon-photon scattering. This process has so far not been successfully verified experimentally, but we show that this may change already with present day laser powers. We also study QED effects due to strong magnetic fields. In particular, we obtain an analytical description for vacuum birefringence valid at arbitrary field strengths. Astrophysics already offer environments where QED processes may be influential, e.g. in neutron star and magnetar environments. For astrophysical purposes we investigate how effects of QED can be implemented in plasma models. In particular, we study QED dispersive effects due to weak rapidly oscillating fields, nonlinear effects due to slowly varying strong fields, as well as QED effects in strongly magnetized plasmas. Effects of quantum dispersion and the electron spin has also been included in an extended plasma description, of particular interest for dense and/or strongly magnetized systems.
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