KU Leuven CmPA Seminar: Spectral properties and energy cascade at kinetic scales in collisionless plasma turbulence

KU Leuven Centre for mathematical Plasma-Astrophysics Seminar

Title:     Spectral properties and energy cascade at kinetic scales in collisionless plasma turbulence

Speaker: Giuseppe Arro from CmPA


Thanks to accurate in situ solar wind (SW) observations, it is now clearly estabilished that the turbulent magnetic field spectrum follows a Kolmogorov-like scaling at MHD scales and steepens below ion scales, where a different power law develops. Recent satellite measurements reveled the presence of a second spectral break at electron scales, where the magnetic field spectrum seems to decrease exponentially. The formation of this exponential falloff is still under debate and its relation with dissipation is unclear. We investigate the spectral properties of the turbulent cascade at sub-ion scales by means of a fully kinetic, energy conserving particle-in-cell simulation of plasma turbulence. Consistently with satellite observations, we find that the magnetic field spectrum behaves like a power law at kinetic scales, with an exponential decay at electron scales. The same exponential falloff is observed for the electron velocity spectrum but not for the ion velocity spectrum, that drops like a steep power law before reaching electron scales. The development of these spectral features is analyzed in terms of the high-pass filtered electromagnetic work and pressure-strain interaction of both electrons and ions. We find that the electrons are the main responsible for the formation of the exponential range and for the dissipation of magnetic energy that is first converted into electron fluid flow energy and finally into internal energy via the pressure-strain interaction.


The seminars are in hybrid mode, you can follow in person in room 200B 00.07 or online  at the (permanent) link:



Thursday, April 21, 2022 - 14:00 to 15:00

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