The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, and by modelling codes that simulate edge-plasma conditions and the plasma-material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel)
This study demonstrates that Raman microscopy is a suitable technique for future post mortem analyses of JET and ITER plasma facing components. We focus here on laboratory deposited and bombarded samples of beryllium and beryllium carbides and start to build a reference spectral databases for fusion relevant beryllium-based materials. We identified the beryllium phonon density of states, its second harmonic and E 2G and B 2G second harmonic and combination modes for defective beryllium in the spectral range 300-700 and 700-1300 cm -1 , lying close to Be-D modes of beryllium hydrides. We also identified beryllium carbide signature, Be 2 C, combining Raman microscopy and DFT calculation. We have shown that, depending on the optical constants of the material probed, in depth sensitivity at the nanometer scale can be performed using different wavelengths. This way, we demonstrate that multi-wavelength Raman microscopy is sensitive to in-depth stress caused by ion implantation (down to ≈30 nm under the surface for Be) and Be/C concentration (down to 400 nm or more under the surface for Be+C), which is a main contribution of this work. The depth resolution reached can then be adapted for studying the supersaturated surface layer found on tokamak deposits.2
Die Chemie der Tetrathiooxalate, die erst in den letzten Jahren zuganglich geworden sind, wird in einer Ubersicht dargestellt. Tetrathiooxalate lassen sich durch Reduktion von Schwefelkohlenstoff entweder direkt als Salze darstellen oder ausgehend vom Reduktionsprodukt 2-Thioxo-l,3-dithiol-4,5-dithiolat iiber das 4,5-Bis(methylthio)-1,3-dithiol-2-on als Dimethylester erhalten. Fur die Bildung der verschiedenen Schwefelkohlenstoffreduktionsprodukte wird ein allgemeiner Reduktionsmechanismus vorgestellt. Die Salze der Tetrathiooxalsaure sind farbige kristalline Verbindungen mit geringer thermischer Stabilitat. Sie ergeben mit Elektrophilen meist komplexe Produktgemische. Durch Reduktion des Tetrathiooxalatanions sind Derivate des Ethentetrathiolats leicht zuganglich. Mit Schwennetallionen bildet das Tetrathiooxalatanion als vierzahniger Briickenligand Mehrkernkomplexe, die sich zum Teil durch eine hohe elektrische Leitfahigkeit auszeichnen. Der Tetrathiooxalsauredimethylester ist ein interessanter Synthesebaustein, der als 27r-und 4wKomponente in Cycloadditionsreaktionen eine Vielzahl von Produkten bildet.The chemistry of tetrathiooxalates which have been accessible since a few years is presented in a review. Tetrathiooxalates can be prepared by electrochemical reduction of carbon disulfide in dipolar aprotic solvents (acetonitrile, DMF) as slightly soluble tetraalkylammonium salts. Starting from 2-thioxo-l,3-dithiole-4,5-dithiolate, a reduction product of carbon disulfide, dimethyl tetrathiooxalate is obtained by photochemical decarbonylation of 4,5-bis(methylthio)-1,3-dithiol-2-one as intermediate. A general mechanism is proposed for the reduction of carbon disulfide. Depending on the reaction conditions either the dimerization of carbon disulfide radical anions to tetrathiooxalate or the reaction of the radical anion with carbon disulfide can be considered as the key steps in the mechanism. Salts of tetrathiooxalic acid are colored crystalline compounds with low thermal stability. With electrophiles they mostly react to form complex mixtures of products. Under suitable conditions dimethyl tetrathiooxalate can be prepared as the main product by direct methylation. Reduction of the tetrathiooxalate anion gives ethenetetrathiolate which can be alkylated to tetrakis(alky1thio)ethenes. The reduction of dimethyl tetrathiooxalate with subsequent alkylation also yields such products. With heavy-metal ions the tetrathiooxalate anion reacts as a tetradentate ligand to give dinuclear and trinuclear as well as polynuclear complexes partly possessing high electrical conductivity. Dimethyl tetrathiooxalate is an attractive building block in the synthesis of heterocyclic compounds. With alkenes and alkynes dimethyl tetrathiooxalate reacts in cycloadditions as 27r-and 4?r-component, respectively. 1,3-Dithioles are obtained by reaction with diazo compounds. With isocyanides 2-imino-l,3-dithioles are produced. Disubstituted alkylidenetriphenylphosphoranes also form 1,3-dithioles. The aminolysis of dimethyl tetrathiooxalate gives ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.