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Velocity distribution functions of dust particles of various sizes are simulated in different regions of a tokamak using the DUSTT code. It is shown that dust particles accelerated by plasma flows can reach very high speed >1 km/s at the terminal stages of vaporization. Collisions of beryllium and tungsten dust particles with beryllium wall are modeled with the LS-DYNA material structural analysis code. It is demonstrated that the collisions at high speed ∼1 km/s can cause significant damage to the wall or complete dust destruction depending on dust and wall material parameters.

If R is a ring of coefficients and G a finite group, then a flat RG-module which is projective as an R-module is necessarily projective as an RG-module. More generally, if H is a subgroup of finite index in an arbitrary group Γ, then a flat RΓmodule which is projective as an RH-module is necessarily projective as an RΓ-module. This follows from a generalization of the first theorem to modules over strongly G-graded rings. These results are proved using the following theorem about flat modules over an arbitrary ring S: If a flat S-module M sits in a short exact sequence 0 → M → P → M → 0 with P projective, then M is projective. Some other properties of flat and projective modules over group rings of finite groups, involving reduction modulo primes, are also proved.

Let G be a finite group and k a field of characteristic p dividing |G|. In this paper, we examine the action of the Steenrod operations on the Tate cohomology Ĥ∗(G,k). In particular, we prove that all Steenrod operations from negative to positive degree Tate cohomology vanish if and only if all products in negative degree Tate cohomology vanish.

It has been known for a long time that microscopic dust appears in plasmas in fusion devices. Recently it was shown that dust can be responsible for the termination of long- discharges. Also, in ITER-scale experiments dust can pose safety problems related to its chemical activity, tritium retention and radioactive content. In particular, the presence of dust in the vacuum chamber of ITER is one of the main concerns of the ITER licensing process. Here we review recent progress in the understanding of different experimental and theoretical aspects of the physics of dust dynamics and transport in fusion plasmas and discuss the remaining issues.

Geothermal and geopressure as well as geologic and geophysical data were studied to evaluate the potential for future development of geothermal resources underlying the Alabama Coastal Plain. Wire-line log data compiled and interpreted from more than 1300 oil and gas test wells included maximum recorded temperatures, mud weights, rock resistivities as related to geopressure, formation tops, fault locations, and depths to basement rock. The Alabama Coastal Plain area is underlain by a conduction dominated, deep sedimentary basin where geothermal gradients are low to moderate (1.0 to 1.8/sup 0/F/100 feet). In some areas of southwest Alabama, abnormally high temperatures are found in association with geopressured zones within the Haynesville Formation of Jurassic age; however, rocks of poor reservoir quality dominate this formation, with the exception of a 200-square-mile area centered in southernmost Clarke County where a porous and permeable sand unit is encased within massive salt deposits of the lower Haynesville. The results of a petrograhic study of the Smackover Formation, which underlies the Haynesville, indicate that this carbonate rock unit has sufficient porosity in some areas to be considered a potential geothermal reservoir. Future development of geothermal resources in south Alabama will be restricted to low or moderate temperature, non-electricmore » applications, which constitute a significant potential energy source for applications in space heating and cooling and certain agricultural and industrial processes.« less

In the Alabama valley and ridge, Middle Ordovician carbonates are exposed in two northeast-southwest-trending outcrop belts separated by the Helena fault. Northwest to southeast transits across these outcrop belts illustrate a well-defined shallow to deep water transition. West of the Helena fault, the Middle Ordovician is represented by a transgressive-regressive sequence of peritidal and shallow subtidal carbonates of the Chickamauga Limestone, deposited in tidal-flat, low-energy open-shelf, and high-energy shoal environments. Tidal-flat deposits consist of peloidal and intraclastic wackestones and packstones containing abundant exposure indicators. These grade into light-colored, skeletal wackestones and packstones containing a diverse faunal assemblage rich in algae, indicating deposition in a shallow, low-energy, open-shelf setting. High energy shoal deposition is represented by a 20-80 ft thick sequence of cross-bedded skeletal grainstone. Included within the grainstone are pods of bryozoan-sponge-algal bafflestone and bindstone that represent small mud-rich bioherms. East of the Helena fault, the Middle Ordovician series consists of deeper water carbonates of the Lenoir and Little Oak Limestones and graptolitic shales of the Athens Formation. The Lenoir and Little Oak are composed of dark-colored, even-bedded, skeletal wackestones which, with the exception of scattered Nuia, lack algae, indicating deposition in the deeper part of the photic zone. Thesemore » wackestones grade southeastward into very finely laminated, argillaceous mudstones and calcareous shales of the Athens Formation. The Athens is dark colored, organic-rich, lacking in bottom-dwelling fauna, and contains common synsedimentary slump structures suggesting deposition in an anoxic, lower slop environment.« less