Electron acceleration by an Alfvénic pulse propagating in an auroral plasma cavityReport as inadecuate

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1 LUTH - Laboratoire Univers et Théories 2 IRAP - Institut de recherche en astrophysique et planétologie

Abstract : With the help of a 2.5-D particle-in-cell simulation code, we investigate the physics of the acceleration of auroral electrons, through the interaction of an isolated Alfvén wave packet with a plasma density cavity. The cavity is edged by density gradients perpendicular to the magnetic field. We show that a single passing of an isolated wave packet over a infinite cavity creates an electron beam. It triggers local current and beam-plasma instabilities and small-scale coherent electric structures. The energy flux of downgoing electrons is significantly increased, whereas upgoing electrons are also accelerated, even if no beam is formed. Accelerated electrons remain after the passage of the Alfvénic pulse, allowing the observation of energetic particles without any significant electromagnetic perturbation. The dependence of this process on the electron to ion mass ratio is consistent with its control by inertial effects.

Keywords : Magnetospheric Physics: Auroral phenomena 2407 Magnetospheric Physics: Electric fields 2411 Magnetospheric Physics: Energetic particles: precipitating Magnetospheric Physics: Numerical modeling Magnetospheric Physics: Plasma waves and instabilities 2471

Author: F. Mottez - Vincent Génot -

Source: https://hal.archives-ouvertes.fr/


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