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Abstract: In this paper, a fully coherent radiation option with controllable polarization is proposed for the Shanghai deep ultraviolet free electron laser (FEL) test facility. Intensive start-to-end simulation suggests that the two crossed planar undulators which generate the horizontal and vertical linear polarized FEL, should be placed as close as possible for avoiding the polarization performance degradation of the final combined FEL radiation. With the existence of the phase-shifter between the two crossed radiators, Fourier-Transform-Limited output radiation with 100nJ order pulse energy, 5ps full pulse length and circular polarization degree above 90% could be achieved. [Copyright &y& Elsevier]

Observational black carbon (BC) data are needed at high resolution in vast areas to better study the climatic and environmental effect of BC aerosols. The BC concentration from Shanghai to Arctic Ocean was measured with an aethalometer (AE31) by the 7th Chinese National Arctic Research Expedition (CHINARE) during July to September 2016. A generally decreasing distribution of BC was shown from mid to high latitudes. The average BC concentration of the 7th CHINARE was higher than previous expeditions, at 22.77 ng m −3 in the Arctic Ocean. Moreover, we found heavy BC aerosols appearing occasionally during the CHINARE navigation. Therefore the impact of terrestrial transport was discussed based on the Arctic Transport Potential model. It was found that air pollution sources such as fires in the Arctic Circle of Eurasia could lead to BC transport to the high Arctic, inducing a high BC concentration of 95.62 ng m −3 . [ABSTRACT FROM AUTHOR]