307 research outputs found
Extreme-ultraviolet multilayer coatings with high spectral purity for solar imaging
No full textFuture solar experiments designed to perform solar plasma diagnostics will also be based on extreme-ultravilet observations. Multilayer (ML) optics are essential in this spectral region since these coatings have high reflectivity at normal incidence. Typically, the reflectivity curve of a ML coating has a small but finite bandwidth, and this can be a serious drawback when several spectral lines fall within the bandwidth. In fact, spectral lines emitted by different ion species can correspond to different plasma conditions. We present the design, realization, and characterization of an innovative ML structure with high reflectivity coupled with a strong rejection ratio for two adjacent spectral features. The key element is an optimized capping layer structure deposited on top of the ML that preserves the performance reflectance at the target wavelength and at the same time suppresses the reflectance at specific adjacent wavelengths. Application to the Fe xv3×106 K coronal emission line at 28.4 nm with rejection of the He ii Lyman-α line at 30.4 nm is presented
Aperiodic multilayers with enhanced reflectivity for extreme ultraviolet lithography
No full textWe have developed novel aperiodic multilayers, covered by capping layers resistant to environmental attack, that offer superior performance for extreme ultraviolet lithography. We have designed these coatings using an optimization procedure based on an algorithm able to acquire domain knowledge inside the space of possible solutions. An integrated intensity increase of up to 2.18 times that obtained using standard periodic multilayers has been estimated. The aperiodic structures have minimal absorption in the topmost layers, which makes them especially insensitive to both the choice of capping layer material and any subsequent capping layer degradation due to oxidation or contamination. This property allows for the use of the most resilient capping layer materials available, thereby leading to a significantly improved lifetime. We have produced prototype capped aperiodic coatings and have measured their performance
SiC/Mg multilayer coatings for SCORE coronagraph: long term stability analysis
No full textSiC/Mg multilayers have been used as coatings of the Sounding-rocket CORonagraphic Experiment (SCORE) telescope mirrors launched during the NASA HERSCHEL program. This materials couple has been largely studied by researchers since it provides higher performances than a standard Mo/Si multilayer; the SCORE mirrors show in fact a peak reflectance of around 40% at HeII 30.4 nm. Nevertheless, long term stability of this coating is an open problem. A study on the aging and stability of this multilayer has been carried on. SiC/Mg multilayer samples characterized by different structural parameters have been deposited. They have been measured just after deposition and four years later to verify degradation based on natural aging. Experimental results and analysis are presented
Realization and characterization of XUV multilayer coating for attosecond pulses
No full textMultilayer techniques are used to obtain high reflectivity in the XUV
spectral region. This work presents the realization of aperiodic
multilayer mirrors for attosecond pulse compression and their
characterization through reflectivity and photoemission spectroscopy
measurements
High performance EUV multilayer structures insensitive to capping layer optical parameters
No full textWe have designed and tested a-periodic multilayer structures containing protective capping layers in order to obtain improved stability with respect to any possible changes of the capping layer optical properties (due to oxidation and contamination, for example)-while simultaneously maximizing the EUV reflection efficiency for specific applications, and in particular for EUV lithography. Such coatings may be particularly useful in EUV lithographic apparatus, because they provide both high integrated photon flux and higher stability to the harsh operating environment, which can affect seriously the performance of the multilayer-coated projector system optics. In this work, an evolutive algorithm has been developed in order to design these a-periodic structures, which have been proven to have also the property of stable performance with respect to random layer thickness errors that might occur during coating deposition. Prototypes have been fabricated, and tested with EUV and X-ray reflectometry, and secondary electron spectroscopy. The experimental results clearly show improved performance of our new a-periodic coatings design compared with standard periodic multilayer structures
INNOVATIVE DESIGN OF EUV MULTILAYER REFLECTIVE COATING FOR IMPROVED SPECTRAL FILTERING IN SOLAR IMAGING
No full textSpace optic instrumentation for the sun observation
in the Extreme Ultraviolet (EUV) spectral region is
often based on multilayer coating technology. Such
coatings have not negligible bandwidth, and therefore,
often the detected signal is due to the contribution of
different very close spectral lines. In this work we
present a study of innovative capping layer structures
covering the multilayer coating able to improve the
rejection of the unwanted lines and at the same time
preserving the reflectivity peak at the working
wavelength
Innovative methods for optimization and characterization of multilayer coatings
No full textA numerical method to design multilayer coating (ML) is presented. The mathematical tool is based on an "evolutive strategy" algorithm which provides aperiodic solutions by maximizing input merit functions. It allows the optimization of any kind of structures, comprising interlayers and capping layers, and modelling also inter-diffusion and interface roughness. It has been applied to the design of MLs for different applications, as photolithography, space instrumentation and short pulse preservation/compression. The optimization allows the control of the standing wave distribution inside the ML. When the EUV radiation interacts with the structure, the superposition of the incident and reflected electromagnetic wave generates a standing wave field distribution in the ML. An aperiodic design allows the regulation of the distribution of this field, attributing specific properties to the ML. An experimental technique to recover standing wave intensity on top of the ML is also cited. The technique is based on electron photoemission measurements, which allow to determine both reflectivity as well as phase on top of ML. Thanks to this technique, both tests of the ML performances compliance with expected theoretical ones and of degradation through time can be carried on
The Effect of Oil Price Shocks on the Czech Economy
No full textIn the course of 2002 up to the end of 2007, very steep growth of oil prices, but no remarkable slowdown of either the world economy or the Czech economy, was observed. This phenomenon raises a question about the impact of oil prices on modern economies. Analyzing the available data we can conclude that notwithstanding the full dependence of the Czech economy on oil imports, its overall dependence on imported energy sources is relatively low. Compared to the EU15 level the energy intensity of the Czech economy is quite high. Nevertheless, further improvements in this area are expected. Furthermore, the appreciation of CZK and the set-up of the tax system significantly reduced the volatility of the consumer oil price between 2002 and 2007. Using a structural CGE model we quantify the impact of oil price changes on the Czech economy and demonstrate that it is not dramatic despite the oil price turmoil in the years 2000 to the end of 2007. We find that a 20% increase in the CZK oil price tends to decrease the GDP level by 1:5% and 0:8% in the short and long run, respectively. Short-run annual GDP growth decreases by 0:3 p.p. Concerning prices, inflation would accelerate by around 0:4 p.p. per annum in the short run.CGE, Czech Republic, oil price.
Long-term stability of Mg/SiC multilayers
No full textMg/SiC multilayers have been selected to coat the primary and secondary mirrors of the SCORE (Sounding-rocket CORonagraphic Experiment) telescope, a part of the NASA HERSCHEL program. Their experimental reflectance at the He II 30.4 nm wavelength is twice as much that of standard Mo/Si multilayer coatings, with a large improvement of the instrument effective area. Nevertheless, their long-term stability still needs to be evaluated in order to consider them as a valuable candidate for instrumentation of a long term space mission. A study is carried out on different Mg/SiC samples designed and fabricated varying the structural parameters and/or the capping layer material and thickness, which have been monitored for four years after deposition
Handleiding voor onderwijzers, ten gebruike van Weilands Nederduitsche spraakkunst ten dienste der scholen.
No full textHerkomst: "De Windt [?] te St. Nikolaas"1e uitg.: [1809].Europeana-GoogleBooksKoninklijke Academie voor Nederlandse Taal- en Letterkund
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