Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Trapping, Compression and Acceleration of an Electron Bunch in the
  Nonlinear Laser Wakefield   A scheme of laser wakefield acceleration, when a relatively rare and long
bunch of non-relativistic or weakly-relativistic electrons is initially in
front of the laser pulse, is suggested and considered. The motion of test
electrons is studied both in the one-dimensional case (1D wakefield) and in the
three-dimensional laser wakefield excited in a plasma channel. It is shown that
the bunch is trapped, effectively compressed both in longitudinal and
transverse directions and accelerated to ultra-relativistic energies in the
region of first accelerating maximum of the wakefield. The accelerated bunch
has sizes much less than the plasma wavelength and relatively small energy
spread.

22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ