Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A New Injection and Acceleration Scheme of Positrons in the Laser-Plasma
  Bubble Regime   A novel approach for positron injection and acceleration in laser driven
plasma wakefield is proposed. A theoretical model is developed and confirmed
through PIC simulation. One ring-shaped beam and one co-axially propagating
Gaussian beam drive wakefields in a preformed plasma volume filled with both
electrons and positrons. The laser's ponderomotive force as well as the charge
separation force in the front bucket of the first bubble are utilized to
provide the transverse momenta of injected positrons and those positrons can be
trapped by the focusing field and then accelerated by the wakefield. The
simulation shows that a relatively high-charge, quasi-monoenergetic positron
beams can be obtained.

19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex