Two-stage acceleration of interstellar ions driven by high-energy lepton plasma flows

Cui, YunQian and Sheng, Zheng-Ming and Lu, QuanMing and Li, YuTong and Zhang, Jie (2015) Two-stage acceleration of interstellar ions driven by high-energy lepton plasma flows. Science China: Physics, Mechanics and Astronomy, 58 (10). 105201. ISSN 1869-1927 (https://doi.org/10.1007/s11433-015-5715-2)

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Abstract

We present the particle-in-cell (PIC) simulation results of the interaction of a high-energy lepton plasma flow with background electron-proton plasma and focus on the acceleration processes of the protons. It is found that the acceleration follows a two-stage process. In the first stage, protons are significantly accelerated transversely (perpendicular to the lepton flow) by the turbulent magnetic field "islands" generated via the strong Weibel-type instabilities. The accelerated protons shows a perfect inverse-power energy spectrum. As the interaction continues, a shockwave structure forms and the protons in front of the shockwave are reflected at twice of the shock speed, resulting in a quasi-monoenergetic peak located near 200 MeV under the simulation parameters. The presented scenario of ion acceleration may be relevant to cosmic-ray generation in some astrophysical environments.