The existence of several characteristic times during the collisional relaxation of fine velocity structures is investigated by means of Eulerian numerical simulations of a spatially homogeneous force-free weakly collisional plasma. The effect of smoothing out velocity gradients on the evolution of global quantities, such as temperature and entropy, is discussed, suggesting that plasma collisionality can locally increase due to velocity space deformations of the particle velocity distribution function. These results support the idea that high-resolution measurements of the particle velocity distribution function are crucial for an accurate description of weakly collisional systems, such as the solar wind, in order to answer relevant scientific questions, related, for example, to particle heating and energization.

Collisional relaxation of fine velocity structures in plasmas

Pezzi O;VALENTINI, Francesco;VELTRI, Pierluigi
2016-01-01

Abstract

The existence of several characteristic times during the collisional relaxation of fine velocity structures is investigated by means of Eulerian numerical simulations of a spatially homogeneous force-free weakly collisional plasma. The effect of smoothing out velocity gradients on the evolution of global quantities, such as temperature and entropy, is discussed, suggesting that plasma collisionality can locally increase due to velocity space deformations of the particle velocity distribution function. These results support the idea that high-resolution measurements of the particle velocity distribution function are crucial for an accurate description of weakly collisional systems, such as the solar wind, in order to answer relevant scientific questions, related, for example, to particle heating and energization.
2016
Solar wind turbulence; Coulomb collisions; Electron acoustic waves
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Descrizione: Oreste Pezzi, Francesco Valentini, and Pierluigi Veltri, Collisional Relaxation of Fine Velocity Structures in Plasmas, Phys. Rev. Lett. 116, 145001, 2016. The publisher version is available at https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.145001; DOI: 10.1103/PhysRevLett.116.145001.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/143547
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