Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Self-Seeded FEL Wavelength Extension with High-Gain Harmonic Generation   We study a self-seeded high-gain harmonic generation (HGHG) free-electron
laser (FEL) scheme to extend the wavelength of a soft X-ray FEL. This scheme
uses a regular self-seeding monochromator to generate a seed laser at the
wavelength of 1.52 nm, followed by a HGHG configuration to produce coherent,
narrow-bandwidth harmonic radiations at the GW level. The 2nd and 3rd harmonic
radiation are investigated with start-to-end simulations. Detailed studies on
the FEL performance and shot-to-shot fluctuations are presented.

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The categories of this paper are: supr-con
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The categories of this paper are: math
25
The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
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The categories of this paper are: cmp-lg
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th