Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Free electron lasers assisted by pseudo energy bands   We propose a new scheme for high gain harmonic generation free electron
lasers (HGHG FELs), which is seeded by a pair of intersecting laser beams to
interact with an electron beam in a modulator undulator located in a dispersive
section. The interference of the laser beams gives rise to a two-dimensional
modulation in the energy-time phase space because of a strong correlation
between the electron energy and the position in the direction of dispersion.
This eventually forms pseudo energy bands in the electron beam, which results
in efficient harmonic generation in HGHG FELs in a similar manner to the
well-known scheme using the echo effects, with the requirement on the energy
modulation being much more relaxed.

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The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
16
The categories of this paper are: stat
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph