Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Space-frequency model of amplified spontaneous emission and
  super-radiance in free electron laser operating in the linear and non-linear
  regimes   A three-dimensional, space-frequency model for the excitation of
electromagnetic radiation in a free-electron laser is presented. The approach
is applied in a numerical particle code WB3D, simulating the interaction of a
free-electron laser operating in the linear and non-linear regimes. Solution of
the electromagnetic excitation equations in the frequency domain inherently
takes into account dispersive effects arising from the cavity and the gain
medium. Moreover, it facilitates the consideration of statistical features of
the electron beam and the excited radiation, necessary for the study of
spontaneous emission, synchrotron amplified spontaneous emission (SASE),
super-radiance and noise. We employ the code to study the statistical and
spectral characteristics of the radiation generated in a pulsed beam
free-electron laser operating in the millimeter wavelengths. The evolution of
radiation spectrum, excited when a Gaussian shaped bunch with a random
distribution of electrons is passing through the wiggler, was investigated.

33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an