Characterizing filamentary magnetic structures in counter-streaming plasmas by Fourier analysis of proton images
arXiv:1910.04070 · doi:10.1063/1.5100728
Abstract
Proton imaging is a powerful tool for probing electromagnetic fields in a plasma, providing a path-integrated map of the field topology. However, in cases where the field structure is highly inhomogeneous, inferring spatial properties of the underlying field from proton images can be difficult. This problem is exemplified by recent experiments which used proton imaging to probe the filamentary magnetic field structures produced by the Weibel instability in collisionless counter-streaming plasmas. In this paper, we perform analytical and numerical analysis of proton images of systems containing many magnetic filaments. We find that, in general, the features observed on proton images do not directly correspond to the spacing between magnetic filaments (the magnetic wavelength) as has previously been assumed, and that they instead correspond to the filament size. We demonstrate this result by Fourier analysis of synthetic proton images for many randomized configurations of magnetic filaments. Our results help guide the interpretation of experimental proton images of filamentary magnetic structures in plasmas.
arXiv commentThis article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Physics of Plasmas 26, 102303 (2019) and may be found at https://doi.org/10.1063/1.5100728 . 8 pages, 7 figures
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