Showing papers by "William D. Langer published in 1989"
TL;DR: In this article, Graedel et al. used time-dependent models of the ion-molecule chemistry of dense interstellar clouds (Graedel, Langer, and Frerking, 1982) to calculate the abundances of key observational species used to interpret cloud properties.
Abstract: Revised time-dependent models of the ion-molecule chemistry of dense interstellar clouds (Graedel, Langer, and Frerking, 1982) are used to calculate the abundances of key observational species used to interpret cloud properties and study interstellar chemistry. Consideration is given to nitrogen-, oxygen-, and carbon-bearing molecules and isotopic ratios over a hydrogen density range of 1,000-50,000/cu cm and a temperature range of 10-40 K. The results for over 15 species, including C-13 variants, are presented in tables and graphs. The results are compared to abundance observations in TMC-1 and other interstellar clouds, showing that most observed abundances can be predicted by the models. 72 references.
107 citations
TL;DR: In this paper, the effect of releasing carbon and methane into TFTR was modeled using the DEGAS code and the carbon neutral transport at the boundary of the plasma boundary layer.
8 citations
TL;DR: The theory of carbon transport in a plasma boundary layers is important for understanding the impurity penetration, and carbon and hydrogen recycling, in tokamaks using carbon compounds as limiters and as wall coatings.
Abstract: The theory of carbon transport in a plasma boundary layers is important for understanding the impurity penetration, and carbon and hydrogen recycling, in tokamaks using carbon compounds as limiters and as wall coatings. Neutral carbon kinetics and transport at the edge of plasma devices where chemical release is a source of carbon are modeled. Plasma reactions with carbon and hydrocarbons are important for such modeling, and these collisional processes are summarized. Combining the reaction schemes and kinetics in the DEGAS code makes it possible to treat the neutral transport at the plasma boundary layer. Results of such modeling of the atomic carbon and methane distribution at the edge are presented for comparison with recent carbon probe experiments performed on the Divertor and Injection Tokamak Experiment (DITE).
3 citations
01 Jan 1989
TL;DR: In this paper, a column density map of the Orion A molecular cloud is presented, which reveals several peaks in the main filament with column densities greater than 4·1016 cm−2.
Abstract: Moderate resolution (2,5) observations of the 13CO J=1→0 and J=2→1 lines in the Orion A molecular cloud reveal that 13CO is optically thick over all the main filament. We present a 13CO column density map of this region, as deduced from both lines using an LVG code. This map reveals several peaks in the main filament with column densities greater than 4·1016 cm−2.
01 Jan 1989