Speaker: George Livadiotis from Southwest Research Institute
Title: Kappa Distributions: Theory and Applications in Space Plasmas
Abstract: Classical collisional particle systems residing in thermal equilibrium have their particle velocity/energy distribution function stabilized into a Maxwell-Boltzmann distribution. On the contrary, space and astrophysical plasmas are exotic collisionless particle systems residing in stationary states characterized by the so-called kappa distribution function. Kappa distributions have become increasingly widespread across the physics of astrophysical plasma processes, describing particles in the heliosphere, from the solar wind and planetary magnetospheres to the heliosheath and beyond, the interstellar and intergalactic plasmas. A breakthrough in the field came with the connection of kappa distributions with statistical mechanics and thermodynamics: kappa distributions maximize the entropy of nonextensive statistical mechanics under the constraints of canonical ensemble, while particle systems exchanging heat with each other are eventually stabilized into a kappa distribution. The seminar will review the physical foundations and recent developments of kappa distributions in space and astrophysical plasmas.