Nine organophosphate esters, which are commercially used as plasticizers and/or flame retardants, were identified and quantified in air samples from some common indoor work environments, i.e., an office building, a day care center, and three school buildings. One of the compounds was identified as tri(2-chloroethyl) phosphate, a substance that has been shown to be a neurotoxic and genotoxic agent. The concentration levels of this substance were found to be as high as 250 ng/m 3 . In order to examine whether the organophosphates were transferred from the outdoor air, the occurrence of organophosphates in outdoor ambient air was investigated. The levels of the individual compounds in the outdoor air samples were found to be less than 1 ng/m 3 , which indicates that the main sources of organophosphates in indoor air were located indoors. A comparison between the studied indoor environments showed large differences in the concentration profiles of the nine identified compounds. This was most probably due to the large variation in indoor materials, furniture, and equipment between the different indoor work environments. A method for sampling and analysis is described and evaluated. Samples were collected by pumping air through filter and polyurethane foam plugs. At a low sampling rate, 3 L/min, the organophosphates were strongly associated with the filter, by polar interactions either directly to the filter or to the particulate phase adsorbed on the filter. Ultrasonication was shown to be a fast and efficient extraction method for all of the organophosphates studied.
Recent experiments at ASDEX Upgrade have achieved advanced scenarios with high β N (>3) and confinement enhancement over ITER98(y, 2) scaling, H H98y2 = 1.1-1.5, in steady state. These discharges have been obtained in a modified divertor configuration for ASDEX Upgrade, allowing operation at higher triangularity, and with a changed neutral beam injection (NBI) system, for a more tangential, off-axis beam deposition. The figure of merit, β N H ITER89-P , reaches up to 7.5 for several seconds in plasmas approaching stationary conditions. These advanced tokamak discharges have low magnetic shear in the centre, with q on-axis near 1, and edge safety factor, q 95 in the range 3.3-4.5. This q-profile is sustained by the bootstrap current, NBI-driven current and fishbone activity in the core. The off-axis heating leads to a strong peaking of the density profile and impurity accumulation in the core. This can be avoided by adding some central heating from ion cyclotron resonance heating or electron cyclotron resonance heating, since the temperature profiles are stiff in this advanced scenario (no internal transport barrier). Using a combination of NBI and gas fuelling line, average densities up to 80-90% of the Greenwald density are achieved, maintaining good confinement. The best integrated results in terms of confinement, stability and ability to operate at high density are obtained in highly shaped configurations, near double null, with δ = 0.43. At the highest densities, a strong reduction of the edge localized mode activity similar to type II activity is observed, providing a steady power load on the divertor, in the range of 6 MW m −2 , despite the high input power used (>10 MW).
The MHD stability of a tiigh-j3 p tokamak equilibrium with a pressure pedestal is examined with and without line-tying stabilization. The FLR stabilization is separately estimated. With a pedestal increase, the instability mode spectrum changes from predominantly n = 1 to a broader one (possibly centred around n = 2), and the perturbation shows increasingly localized structure near the plasma edge. This might resemble the edge relaxation phenomenon. When the pedestal is large enough, most instabilities, ideal and resistive, tend to be stabilized. The present calculations consider a pedestal only in a pressure profile (not in a current density profile) and do not treat an actual separatrix geometry. Calculations with pedestals in both profiles in a separatrix geometry will be presented in a future publication.
Cross-field particle and energy transport in diverted ASDEX discharges with up to 2.2 MW neutral-beam heating is studied by testing transport code predictions against experimental data. With neutral injection, enhanced coefficients of electron heat diffusivity and diffusion are found which are independent of density, temperatures and pbloidal beta over a large parameter range (x e = 2.9 X10 4 cm 2 s" 1 and D = 0.2 x e )-The ion heat diffusivity continues to be one to three times the neoclassical value. The period with degraded confinement can be considerably delayed in relation to the beams and is found to be correlated with a characteristic change in the shape of the electron temperature profile due to neutral injection and with the time behaviour of the sawtooth period. Energy and particle confinement do not deteriorate with increasing beam power. It is found that the sawtooth activity does not significantly impair the confinement outside the q = 1 surface. A possible connection between degradation of confinement and non-thermal electron or ion velocity distributions, plasma rotation and drift-wave turbulence is discussed.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.