Search

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

Establishing a model for classification of the clinical disease manifestations in primary Sjögren’s syndrome is a challenge with important implications for handling individual patients and for describing and analyzing patient materials. Based on the pathobiology of primary SS we define three (1–3) “exocrine” and four (4–7) “nonexocrine” subgroubs of disease manifestations. Accordingly, 1) “surface exocrine disease” includes the diagnostic features from eyes (keratoconjunctivitis sicca) and mouth (xerostomia), and the manifestations from upper airways (rhinitis sicca, xerotracheitis) and skin (xeroderma). Involvement of the excretory parenchyma of the lungs, hepatobiliary system, pancreas, intestinal tract and kidneys is designated 2) “internal organ exocrine disease”. Thes manifestations are potentially severe, do not lead to subjective dryness, and none of them are diagnostic for the disease. We suggest 3) “monoclonal B-lymphocyte disease” (lymphoma) to be an exocrine disease manifestation because it originates mostly from the immunoinflammatory foci of the autoimmune exocrinopathy. The nonexocrine manifestations are subgrouped into: 4) “inflammatory vascular disease” (vasculitis and perivasculitis), 5) “noninflammatory vascular disease” (Raynaud), 6) “mediator-induced disease” (hematologic cytopenia, fever and fatigue) and 7) “autoimmune endocrine disease”. Subdividing the seven subgroups leads to a third order of classification in which single and separate manifestations are placed. The descriptive and analytic power of the proposed model for classification of disease manifestations in primary Sjögren’s syndrome should be evaluated in clinical studies.

Quantitative and qualitative assessment of the clinical disease manifestations in 41 primary Sjogren's syndrome (pSS) patients was performed according to a new classification model. Frequencies of subgrouped disease manifestations were as follows: 1) surface exocrine disease: 100%, 2) internal organ exocrine disease: 63%, 3) monoclonal B lymphocyte disease: 5%, 4) inflammatory vascular disease: 71%, 5) non-inflammatory vascular disease: 59%, 6) mediator induced disease: 98%. Summary scores for severity of surface exocrine disease correlated to the summary scores of all other disease manifestations (p = 0.02), to the summary scores of internal organ exocrine disease (p = 0.003), and to the summary scores of mediator induced disease (p = 0.03). Blood leucocyte counts showed significant negative correlations to levels of plasma IgG, serum IgA-RF, IgM-RF, anti-SSA/SSB antibodies, IL-6, and IL-lRa. We conclude that the model made detailed analysis of the clinical presentation of pSS possible, and thus may assist in elucidating important pathobiological aspect of the disease.

Tungsten migration in ASDEX Upgrade was investigated by analysis of deposition on long term sample probes and by erosion and deposition studies using two probe manipulator systems in the midplane and the outer divertor plate respectively. Divertor retention was determined by measuring the total tungsten production in the divertor and comparison with the spectroscopically measured tungsten content in the confined plasma. The fraction of tungsten deposited on limiters in the main chamber compared to deposition in the divertor was determined by injecting tungsten into the main plasma using laser ablation and determining the deposition of these atoms on collector probes. The ratio of inner divertor to outer divertor tungsten deposition was obtained from surface analysis of long term sample probes.

Tungsten coated tiles, manufactured by plasma spray on graphite, were mounted in the divertor of the ASDEX Upgrade tokamak and cover almost 90% of the surface facing the plasma in the strike zone. Over 500 plasma discharges, among which around 300 were heated with heating powers up to 10 MW, were performed up to now. The tungsten flux in the divertor was monitored by a WI line at 400.8 nm. In the plasma centre an array of spectral lines at 5 nm emitted by ionisation states around W XXX was monitored. Under normal discharge conditions W-concentrations of around 10 or even lower were found. The influence on the main plasma parameters was negligible. In a few low power discharges accumulation of tungsten occurred and the temperature profile was flattened. The concentrations of the intrinsic impurities carbon and oxygen are comparable to the discharges with graphite divertor. Furthermore, the density-limits and the β-limits remained unchanged and no negative influence on the energy confinement as well as on the H-mode threshold was found.