Kinetic theory of linear fluctuations in magnetized and unmagnetized collisionfree plasmas
Astrophysics and Astronomy
Final Report Abstract
Fluctuations are a generic feature of all plasmas due to the finite random velocities of the plasma particles. The two major scientific objectives of this project were (i) the extension of the kinetic plasma fluctuation theory in unmagnetized plasmas calculating in particular the associated density and velocity fluctuation spectra of weakly propagating and weakly amplified/damped modes (collective and non-collective modes), and (ii) the development of the general kinetic fluctuation theory for magnetized plasmas using the existing fluctuation theory of unmagnetized plasmas. In both cases the classical linear fluctuation theory, based on the coupled Klimontovich-Maxwell equations, is developed with two important generalizations: no restrictions on the generally complex frequency ω = ωR + ıΓ of the fluctuations are made, and the calculations use the correct relativistic relation p = mγp v between plasma particle momentum p and velocity v with the Lorentz factor γp = √ 1 + (p/mc)2. The intergalactic medium (IGM) at high redshifts is the most prominent unmagnetized fully-ionized cosmic plasma, i.e. it is not permeated by an ordered magnetic (and/or electric) field. However, the IGM contains electric and magnetic field fluctuations, which play an important role in the understanding of the origin of cosmic magnetic fields. Especially seed magnetic fields are needed for later amplification by possible kinetic instabilities from anisotropic plasma particle distribution functions, MHD instabilities and/or the MHD dynamo process. For two phases of the early universe IGM, the reionization era at redshift z≈20 and the pamyprepanne era at redshifts 1.4 · 10^12 ≥ z ≥ 6 · 10^9 , the properties of the fluctuations are quantatively calculated. During the pamyprepanne random electric and magnetic fields in the form of aperiodic fluctuations with very high tera-Gauss strengths |δB| and |δE| were generated by the relativistic electron-positron pairs on spatial scales greater than L ≈ 10^−10 cm with 100 percent volume filling factor. These aperiodic fluctuations have a substantial energy density though about three orders of magnitude smaller than the superluminal photon energy density, so that the aperiodic fluctuations have a negligible influence on the radiation-driven cosmological evolution during the pamyprepanne. For magnetized plasmas the rigorous relativistic kinetic theory to calculate linear electromagnetic fluctuations in magnetized plasmas was developed. This theory allows us to calculate the resulting spontaneous emission coefficients and damping or growth rates for any orientation angle of the wave vector with respect to the ordered magnetic field, although the details are involved.
Publications
- Electromagnetic fluctuations in magnetized plasmas I: The rigorous relativistic kinetic theory, Phys. of Plasmas 22 (2015) 072108
Schlickeiser, R. and Yoon, P. H.
(See online at https://doi.org/10.1063/1.4926828) - Electromagnetic fluctuations in magnetized plasmas II: Extension of the theory for parallel wave vectors, Phys. of Plasmas 22 (2015) 102111
Schlickeiser, R., Ganz, A.. Kolberg, U. and Yoon, P. H.
(See online at https://doi.org/10.1063/1.4933210) - Amplification of collective magnetic fluctuations in magnetized bi-Maxwellian plasmas for parallel wave vectors. I. Electron-proton plasma Astrophys. J. 829 (2016) 41
Vafin, S., Schlickeiser, R. and Yoon, P. H.
(See online at https://doi.org/10.3847/0004-637X/829/1/41) - Weak turbulence theory for collisional plasmas, Phys. Rev. E 93 (2016) 033203
Yoon, P. H., Ziebell, L. F., Kontar, E. P. and Schlickeiser, R.
(See online at https://doi.org/10.1103/PhysRevE.93.033203) - Spontaneous emission of Alfvenic fluctuations, Plasma Phys. Contr. Fusion 59 (2017) 095002
Yoon, P. H., Lopez, R. A., Vafin, S., Kim, S. and Schlickeiser, R.
(See online at https://doi.org/10.1088/1361-6587/aa77c3) - Spontaneous emission of electromagnetic fluctuations in kappa magnetized plasmas, Plasma Phys. Contr. Fusion 59 (2017) 125003
Kim, S., Schlickeiser, R., Yoon, P. H., Lopez, R. A. and Lazar, M.
(See online at https://doi.org/10.1088/1361-6587/aa8898) - Velocity fluctuations driven by the damped aperiodic mode in the intergalactic medium, Astrophys. J. 844 (2017) 124
Kolberg, U., Schlickeiser, R. and Yoon, P. H.
(See online at https://doi.org/10.3847/1538-4357/aa7d05) - Kinetic theory of small-amplitude fluctuations in astrophysical plasmas, Phys. Rep. 783 (2018) 1
Kolberg, U. and Schlickeiser, R.
(See online at https://doi.org/10.1016/j.physrep.2018.10.003) - Primordial plasma fluctuations I. Magnetization of the early universe by dark aperiodic fluctuations in the past myon and prior electron annihilation epoch, Astrophys. J. 857 (2018) 29
Schlickeiser, R., Kolberg, U.,and Yoon, P. H.
(See online at https://doi.org/10.3847/1538-4357/aab3dd) - On the equilibrium between proton distribution and compressible kinetic Alfvenic fluctuations, Mon. Not. R. Astr. Soc. 482 (2019) 4279
Yoon, P. H. and Schlickeiser, R.
(See online at https://doi.org/10.1093/mnras/sty2925)
