Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The potential for extending the spectral range accessible to the
  European XFEL down to 0.05 nm   Specifications of the European XFEL cover a range of wavelengths down to 0.1
nm. The baseline design of the European XFEL assumes standard (SASE) FEL mode
for production of radiation i.e. only one photon beam at one fixed wavelength
from each baseline undulator with tunable gap. Recent developments in the field
of FEL physics and technology form a reliable basis for an extensions of the
mode of operation of XFEL facilities. This paper explores how the wavelength of
the output radiation can be decreased well beyond the European XFEL design,
down to 0.05 nm. In the proposed scheme, which is based on the use "fresh
bunch" technique, simultaneous operation at two different wavelengths possible.
It is shown that one can generate simultaneously, in the same baseline
undulator with tunable gap, high intensity radiation at 0.05 nm at saturation,
and high intensity radiation around 0.15 nm according to design specifications.
We present a feasibility study and we make exemplifications with the parameters
of SASE2 line of the European XFEL.

26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci