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Several experiments were conducted in ASDEX Upgrade to prove the suitability of tungsten as a divertor target material under the conditions of a high density and low temperature divertor. The observed fluxes from a tungsten tile into the plasma are low, in keeping with the extremely low sputtering yields. In addition, the very favourable effect of `prompt redeposition' (redeposition during the first gyration) could be confirmed by the experiments. Cooling of the edge region by neon injection seems permissible, i.e. neon impurity sputtering did not increase the eroded fluxes of tungsten. The transport and accumulation behaviour were investigated by means of the laser blow-off technique. No accumulation effects could be observed in ohmic discharges. In discharges with NBI heating but without ICRH, strong accumulation can occur. High heat flux tests were performed on graphite tiles coated with plasma sprayed tungsten, which withstood a thermal load of 15 MW/m2 lasting 2 s as well as 1000 cycles of 10 MW/m2 for 2 s without disabling damage. Owing to the encouraging results, an experiment using a tungsten divertor is planned in ASDEX Upgrade

In this work EBIT measurements in the spectral range of 4–7 nm with electron energies from 0.7 keV to 4 keV are compared in detail with tokamak spectra from ASDEX Upgrade. The energy and temperature dependence of spectral lines and features are investigated and an identification of the charge states W39+–W45+ for spectral lines between 4.5 nm and 6.5 nm is possible by taking cross sections from atomic data produced by plane-wave Born calculations via the Cowan code. In the range 12–14 nm the identification of spectral lines emitted by tungsten is improved even though no EBIT measurements are available, as special tokamak discharges have provided ideal possibilities for analysis. These discharges show spectra which are dominated by the emissions from a small region with a narrow electron temperature range. Therefore, only very few ion states contribute to the emission in contrast to the usual case where in the tokamak spectra the emissions of a larger number of ion states are superimposed. Tokamak spectra for varying electron temperature are also used to investigate the correlation to EBIT spectra for the quasicontinuum feature at 5 nm which is emitted by ion states W27+–W35+. We conclude that the narrower features in the EBIT spectra at a certain electron beam energy result from the smaller number of coexisting ion states.

Abstract. The Berlin EBIT has been established by the Max-Planck-Institut für Plasmaphysik to generate atomic physics data in support of research in the field of controlled nuclear fusion by measuring the radiation from highly charged ions, particularly tungsten ions, in the x-ray, extreme ultraviolet and visible spectral ranges. With EBIT a selected ensemble of ions in specific charge states can be produced, stored and excited for spectroscopic investigations. Employing this technique, we have investigated the soft x-ray lines at 0.56 nm from Cu-like W 45+ to V-like W 50+ ions originating from 3d-4f transitions, which are also observed in the high-temperature core plasma of the ASDEX Upgrade tokamak. A further study focuses on Silike W 60+ to Ne-like W 64+ tungsten ions predicted to dominate the core plasma of ITER and radiate strongly at 0.13 nm from n=3-2 transitions.

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Os constituintes voláteis das secreções cefálicas de 11 espécies brasileiras de abelhas sem ferrão da linha Tetragonisca -Tetragona foram analisados. Foram identificados 145 compostos, por cromatografia gasosa e espectrometria de massas, dentre os quais 72 ésteres, 22 álcoois, 16 ácidos carboxílicos, 13 terpenos, 8 aldeídos, 4 compostos aromáticos, 2 lactonas e 1 diidropirano. As relações estruturais, origem e a distribuição detes compostos são discutidas. Com respeito à composição qualitativa e quantitativa, cada espécie mostra um buquê de odores, os quais são obtidos a partir de componentes poucos específicos. Em algumas espécies proximamente relacionadas foram observadas similaridades no buquê de odores. As fragmentações no espectro de massas de ésteres graxos e dos ésteres insaturados derivatizados com DMDS são discutidas em detalhes.The volatile constituents of cephalic secrections of 11 Brazilian social stingless bee species of the Tetragonisca -Tetragona line have been analysed. By gas chromatography/mass spectrometry 145 compounds could be identified which include 72 esters, 22 alcohols, 16 carboxylic acids, 13 terpenoids, 8 aldehydes, 7 ketones, 4 aromatic compounds, 2 lactones and 1 dihydropyran. Structural relations, origin, and distribution of these compounds are discussed. With respect to qualitative and quantitative composition, each species shows a specific odour pattern which is made up by less specific components. To a certain extent, closely related species show some similarities in the odour bouquets.The mass spectrometric fragmentation patterns of typical wax type esters and DMDS derivatives of unsaturated esters are discussed in detail.

The nest of the stingless bee,Trigona (Tetragonisca) angustula, is guarded by bees positioned in the nest entrance and others hovering in front of it. Hovering guard bees track returning foragers sideways along the last 10 cm in front of the nest, but intercept and incapacitate nest intruders by clinging with mandibles to wings and legs. When attacked by the cleptobiotic stingless beeLestrimelitta limao, the colony strengthens its aerial defense with hundreds of additional hoverers. To test our hypothesis that this reaction is due to interspecific chemical communication based on kairomone effects, we presented synthetic cephalic volatiles of both species at the nest entrance and counted the number of bees leaving the nest and taking up hovering positions. We conclude that guard bees recognizeL. limao by the major terpenoids of their volatile cephalic secretions, geranial, neral (=citral) and 6-methyl-5-hepten-2-one; other components may fine-tune this recognition. The effect of chemical stimuli is not significantly enhanced by combination with a dummy ofL. limao. Guard bees, we hypothesize, respond to this kairomone by secreting a species specific alarm pheromone; a major component of this pheromone, benzaldehyde, recruits additional bees to defend the nest.

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