Energetic electron tail production from binary encounters of discrete electrons and ions in a sub-Dreicer electric field

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RESEARCH ARTICLE| OCTOBER 20 2023

Energetic electron tail production from binary encounters of discrete electrons and ions in a sub-Dreicer electric field

Paul M. Bellan

Phys. Plasmas 30, 103901 (2023)

https://doi.org/10.1063/5.0167004

Abstract:

During transient instabilities in a 2 eV, highly collisional MHD-driven plasma jet experiment, evidence of a 6 keV electron tail was observed via x-ray measurements. The cause for this unexpected high energy tail is explored using numerical simulations of the Rutherford scattering of a large number of electrons and ions in the presence of a uniform electric field that is abruptly turned on as in the experiment. When the only active processes are Rutherford scattering and acceleration by the electric field, contrary to the classical Fokker–Planck theory of plasma resistivity, it is found that no steady state develops, and instead, the particle kinetic energy increases continuously. However, when a power loss mechanism is introduced mimicking atomic line radiation, a near steady state can develop and, in this case, an energetic electron tail similar to that observed in the experiment can develop. The reasons underlying this behavior are analyzed, and it is shown that an important consideration is that Rutherford scattering is dominated by the cumulative effect of grazing collisions, whereas atomic line radiation requires an approximately direct rather than a grazing collision.

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The data provided here in the  zip file is the raw data used to make the figures and animations in the paper. The zip file also contains the figures used to make the animations. The configurations are as described in the paper. The file titled data organization explains the format of the data files. The code was written in IDL.

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