Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Atomic inner-shell radiation seeded free-electron lasers   In order to effectively improve the output quality of X-ray free electron
laser (XFEL), we theoretically propose an XFEL scheme seeded by atomic
inner-shell laser. As well known, an atomic inner-shell laser based on neutral
atoms and pumped by an XFEL has been experimentally demonstrated, which
produced sub-femtosecond X-ray pulses with increased temporal coherence. It
shows that, by using the inner-shell laser as a seed to modulate the electron
bunch, very stable and almost fully-coherent short-wavelength XFEL pulses can
be generated. The proposed scheme holds promising prospects in X-ray
wavelengths, and even shorter.

23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat