Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A study of stability of the "plasma - beam" system for the Lorentz
  plasma   The stability of the system comprising the cold immobile Lorentz plasma of
density $N_e$ and the directed nonrelativistic (velocity $\vec{V}$) electronic
beam of a small density $N'_e << N_e$ is investigated. The instability
increment of the system is found via analysis of the electric permittivity
$\epsilon(\omega)$ in the limiting case of $\omega$ being much greater than the
effective frequency of collisions. A conclusion is made that the system in
question is stable with respect to oscillations with relatively small values of
$\vec{k} \vec{V}$.

34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an