Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Wake field generation and nonlinear evolution in a magnetized
  electron-positron-ion plasma   The nonlinear propagation of a circularly polarized electromagnetic (CPEM)
wave in a strongly magnetized electron-positron-ion plasma is investigated. Two
coupled equations describing the interaction between a high-frequency CPEM wave
and the low-frequency electrostatic wake field are derived. It is found that
the generation of the wake fields depends on the presence of the ion species.
The wake field generation in turn leads to de-acceleration and frequency down
conversion of the electromagnetic pulse.

9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn