Proc Natl Acad Sci U S A. 2025 Apr 29;122(17):e2417813122. doi: 10.1073/pnas.2417813122. Epub 2025 Apr 22.
ABSTRACT
Generic equilibria are derived for turbulent relaxing plasmas via an entropy-maximization procedure that accounts for the short-time conservation of certain collisionless invariants. The conservation of these collisionless invariants endows the system with a partial “memory” of its prior conditions but is imperfect on long time scales due to the development of a turbulent cascade to small scales, which breaks the precise conservation of phase volume, making this memory imprecise. The equilibria are still determined by the short-time collisionless invariants, but the invariants themselves are driven to a universal form by the nature of the turbulence. This is numerically confirmed for the case of beam instabilities in one-dimensional electrostatic plasmas, where sufficiently strong turbulence appears to cause the distribution function of particle energies to develop a universal power-law tail, with exponent -2.
PMID:40261929 | DOI:10.1073/pnas.2417813122
