Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mixing the solar wind proton and electron scales. Theory and 2D-PIC
  simulations of firehose instability   Firehose-like instabilities (FIs) are cited in multiple astrophysical
applications. Of particular interest are the kinetic manifestations in
weakly-collisional or even collisionless plasmas, where these instabilities are
expected to contribute to the evolution of macroscopic parameters. Relatively
recent studies have initiated a realistic description of FIs, as induced by the
interplay of both species, electrons and protons, dominant in the solar wind
plasma. This work complements the current knowledge with new insights from
linear theory and the first disclosures from 2D PIC simulations, identifying
the fastest growing modes near the instability thresholds and their long-run
consequences on the anisotropic distributions. Thus, unlike previous setups,
these conditions are favorable to those aperiodic branches that propagate
obliquely to the uniform magnetic field, with (maximum) growth rates higher
than periodic, quasi-parallel modes. Theoretical predictions are, in general,
confirmed by the simulations. The aperiodic electron FI (a-EFI) remains
unaffected by the proton anisotropy, and saturates rapidly at low-level
fluctuations. Regarding the firehose instability at proton scales, we see a
stronger competition between the periodic and aperiodic branches. For the
parameters chosen in our analysis, the a-PFI is excited before than the p-PFI,
with the latter reaching a significantly higher fluctuation power. However,
both branches are significantly enhanced by the presence of anisotropic
electrons. The interplay between EFIs and PFIs also produces a more pronounced
proton isotropization.

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The categories of this paper are: math
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con