Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Polarization control of an X-ray free electron laser oscillator   High-intensity, fully coherent X-ray radiation with a tunable polarization
over a wide spectral range is of great importance to many experiments. In this
paper, we propose a tapered crossed-polarized undulator configuration for X-ray
free electron laser oscillator (XFELO) to produce arbitrarily polarized X-ray
pulses in hard X-ray region. A numerical example utilizing the parameters of
the Shanghai High-Repetition-Rate XFEL and Extreme Light Facility (SHINE) is
presented to demonstrate the generation of polarization controllable, fully
coherent Hard X-ray pulses with 99.9% polarization degree and 20 KHz
polarization switching rate. This scheme also holds the possibility to be used
in cavity tunable XFELO.

18
The categories of this paper are: econ
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess