Optical Nanoantennas for Multiband Surface-Enhanced Infrared and Raman Spectroscopy

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Optical properties and oxidation resistance of different transition metals for soft X-ray and EUV applications

The results of a comparative study of Ru-, Mo-, Nb- and Pd- coatings designed for grazing angle applications in the soft X-ray and extreme ultraviolet (EUV) spectrum are presented. Optical properties and temporal stability of coatings were investigated using EUV reflectometry at 13.5 nm and grazing incidence X-ray reflectometry (GIXR) with Cu-Kα radiation. Nb- and Mo-coatings showed a strong inclination to surface oxidation at ambient atmosphere leading to reflectivity losses. The Pd coating as a noble transition metal showed the highest oxidation resistance over a period of one year. The best reflective properties at 13.5 nm were achieved by Ru coatings. GIXR simulation results of the time dependent surface oxidation were used to predict the reflective properties of the studied coatings following four months of storage in an ambient atmosphere for a wide spectral range (5.0 nm–40.0 nm)

Interface characterization in B-based multilayer mirrors for next generation lithography

The interfaces in La/B4C and LaN/B4C multilayer mirrors designed for near normal incidence reflection of 6.x nm EUV light were investigated by grazing incidence X-ray reflectometry, high-resolution transmission electron microscopy and EUV reflectometry. The thickness and roughness asymmetries of the different interfaces in both studied systems have been identified. A development of interface roughness with an increasing number of bilayers was found by different investigation methods. For near normal incidence, R = 51.1% @ λ = 6.65 nm could be reached with our La/B4C multilayer mirrors, whereas R = 58.1% was achieved with LaN/B4C multilayers at the same wavelength

Assessment of erosion/deposition on the W7-X first-wall after completion of the first phase of divertor operation

Assessment of erosion/deposition on the W7-X first-wallafter completion of the first phase of divertor operationC. P. Dhard, M. Baldena, S. Brezinsekb, T. Dittmarb, P. Hireta, M. Mayera, S. Masuzakic, G. Motojimac,D. Naujoks, M. Rasinskib, N. Sandigd, J. H. Schmidt-Denckera, R. Yib, D. Zhaobandthe W7-X TeamMax-Planck-Institut für Plasmaphysik, Wendelsteinstrasse 1, 17491 Greifswald, GermanyaMax-Planck-Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, GermanybForschungszentrum Jülich GmbH, Institut für Energie-und Klimaforschung-Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), 52425 Jülich, Germanyc National Institute for Fusion Science, 322-6 Oroshi, Toki 509-5292, JapandFreie Universität Berlin, Kaiserswertherstrasse 16-18, 14195 Berlin, [email protected] first operationalphase of the stellarator Wendelstein 7-X (W7-X) was completed towards the end of 2018. This phase consisted of three plasma campaigns, the first withlimiterplasmas and the remaining two with tenTest Divertor Units(TDUs)and protectivetiles surrounding the plasma. All these were made of fine grain graphite.During these campaigns, the stored plasma energy was increased gradually up to 200 MJ.With ca.62 % area of the plasma-facing components covered with carbon and the rest with stainless steel, carbon-based impurities are expected to play a significant role for the plasma-wall interactions. In order to study these, a number of samples were installed in regions of the TDU with high particle-and power fluxes as well as onfirst wall components with comparatively lower heat loads. Since a large number of plasma-facing components were removed forinstallingthe actively cooled high heat flux divertorsmade of carbon-fiber compositesfor the next operation campaigns, this provided a good opportunity to study thesecomponents. This paper covers the erosion/deposition studies onselected samples exposed during whole campaigns.About2200 Ti-Zr-Mo screws,distributed uniformly along the toroidal and poloidal directions over the whole torus, were chosen for the measurements. Altogether ca.30 000 screws have been used to fix the graphite tiles on the cooling structures, the plasma-facingscrew heads were coated with carbonmarker layers to study erosion/depositionover every campaign. After the last campaign,the chosenscrews were removed and the marker layer thicknesses were measured using a betascope which contains a 147Pm beta-source and a Geiger-Müller counter and measures the thickness of thin layers by measuring the back-scattered beta particles. On the outboard side stainless steel wall panels,44 Si-wafer and other long-term probes were installed and the measurements wereperformed for the erosion/depositions in these lowly loaded areas. The results of thesemeasurements analyzed together with additionalmeasurements on the graphite tiles will be presented in the paper