Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kinetic instability of ion acoustic mode in permeating plasmas   In plasmas with electron drift (current) relative to static ions, the ion
acoustic wave is subject to the kinetic instability which takes place if the
directed electron speed exceeds the ion acoustic speed. The instability
threshold becomes different in the case of one quasi-neutral electron-ion
plasma propagating through another static quasi-neutral (target) plasma. The
threshold velocity of the propagating plasma may be well below the ion acoustic
speed of the static plasma. Such a current-less instability may frequently be
expected in space and astrophysical plasmas.

34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess