Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Enhanced laser-driven electron beam acceleration due to
  ionization-induced injection   We report an overall enhancement of a laser wakefield acceleration (LWFA)
using the ionization injection in a mixture of 0.3 % nitrogen gas in 99.7 %
helium gas. Upon the interaction of 30 TW, 30 fs laser pulses with a gas jet of
the above gas mixture, > 300 MeV electron beams were generated at a helium
plasma densities of 3.3-8.5*10^18 cm^{-3}. Compared with the electron
self-injection in pure helium gas jet, the ionization injection has led to the
generation of electron beams with higher energies, higher charge, lower density
threshold for trapping, and a narrower energy spread without dark current (low
energy electrons) or multiple bunches. It is foreseen that further optimization
of such a scheme is expected to bring the electron beam energy-spread down to 1
%, making them suitable for driving ultra-compact free-electron lasers

6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg