[en] The decay rate of an excited stat atom into a ground state atom and a photon of momentum k depends on the photon mode structure and also the number of photons present in those modes. This paper considers the extent to which the rate o spontaneous emission may be altered by the mode structure of the atom (caused, e.g., by a trap) and in particular by the presence of other ground state atoms in the modes. The authors predict that this rate is enhanced in the presence of occupied atom modes for boson atoms and strongly suppressed for Fermi atoms

[en] The Fast Induction Heating technique was developed for the single fuel channel replacement program. This technique was successfully used at Pickering A and Bruce A stations to undo the rolled joints between calandria tubes and calandria tube inserts. The technique has been improved, making it simpler and faster. The improved equipment uses solid state technology instead of an oscillator tube. The improved technique is more attractive for both single and large scale fuel channel replacement. 5 refs., 5 figs

[en] The observation of electronic energy transfer to XeO(¹Σ⁺) from xenon atoms excited by two-photon absorption is reported. Electronically excited xenon atoms in the 5p⁵6p configuration are produced through two-photon excitation at 248.4 nm (KrF*). Subsequent energy transfer from excited rare-gas atoms to N₂O leads to the appearance of XeO(¹Σ⁺), which is identified by the detection of its characteristic green emission band. These measurements are in accord with estimates of the relevant two-photon amplitudes for Xe and N₂O. Kinetic studies utilizing these techniques provide a flexible method for the study of selective excitation and energy transfer in a wide class of atomic and molecular materials

No abstract available

[en] In toroidal plasma confinement devices, the highly energetic fusion products will have trajectories defining drift surfaces that deviate considerably from the magnetic surfaces. An understanding of these drift surfaces is important for efficient operation of a fusion reactor. By appropriate choice of electron energy on the Compact Auburn Torsatron [Fusion Technol. 18, 281 (1990)], normalized drift surface shifts similar to those for fusion products in a reactor can be studied. As a benchmark, a set of experiments have been conducted to study the axis position and central rotational transform associated with varying vertical fields. Corresponding experiments have been conducted which measure the axis position and central transform associated with the drift surfaces of highly energetic electrons. These experiments were compared and a theoretical model incorporating the spatial nonuniformity of the applied vertical magnetic field was developed. The experimental results agreed well with this theory

[en] We have observed phase singularities due to vortex excitation in Bose-Einstein condensates. Vortices were created by moving a laser beam through a condensate. They were observed as dislocations in the interference fringes formed by the stirred condensate and a second unperturbed condensate. The velocity dependence for vortex excitation and the time scale for re-establishing a uniform phase across the condensate were determined

[en] Magnetic islands in toroidal plasma confinement devices are generated by resonant magnetic error fields. Energetic particle drift surfaces can differ substantially from magnetic flux surfaces. In this Letter the first direct measurement of islands in energetic particle drift surfaces are presented. The understanding of these drift islands is important for the optimization of plasma confinement. These drift islands are demonstrated to form in energetic electron drift surfaces as a result of resonant magnetic field perturbations and resonant, applied electric field perturbations. The results, once corrected for inherent magnetic error fields, agree well with theoretical predictions. copyright 1995 American Institute of Physics

[en] The primary heat transport system pressurizer vessels at Darlington NGS have required substantial maintenance of the gasketed joints. Two of these joints are the upper inspection port and the lower manway. In at least one instance there has been erosion damage to the carbon steel sealing faces from leakage of the high energy primary fluid. In the work described in the paper, each of the two closures was re-engineered to incorporate a seal welded diaphragm in place of the gasket. This approach for which patent protection is sought, required machining and weld build up of the nozzle gasket area to facilitate seal welding of a custom diaphragm plate. The closure covers were modified to support the diaphragm and were reinstalled using the original bolting arrangement. The paper describes the re-engineering of these closures as well as the retrofit of the seal welded diaphragms in the field. (author)

[en] Twenty-two patients with vertebral primaries were registered in the Intergroup Ewing's Sarcoma Study between 1973 and 1977. The radiation doses to the primary tumors ranged between 3800 and 6200 rad. All patients received intensive combination chemotherapy. After a followup ranging between 14 and 62 months, 14 patients remained disease-free. All patients with primary tumor of the cervical and dorsal spine remained disease-free. Of eight patients with lesions in the distal spine, (sacrococcygeal region) six developed recurrence, in three a local recurrence was observed despite doses of 6000 rad or higher. Doses of 5000 rad or less (in addition to combination chemotherapy as used in the Intergroup Ewing's Study) appear adequate in controlling the primary tumors of the proximal segments of the spinal column

[en] Poloidal plasma rotation has been driven in the Compact Auburn Torsatron (CAT) [R. F. Gandy et al., Fusion Technol. 18, 281 (1990)]. In these studies, a biased electrode is used to establish the rotation. Currents of up to 1 A are injected into hydrogen, helium, and argon plasmas from a biased electrode placed inside of the last closed magnetic flux surface of the CAT device. The response of the plasma to the injected current is measured with Langmuir, Mach, and emissive probes. Poloidal plasma velocities of up to 10 km/s in hydrogen plasmas are measured by the Mach probe. The plasma density and electron temperature increased during the driven rotation, and there are indications of improved particle confinement. The experimental measurements show generally good agreement with a model of plasma rotation by Coronado and Talmadge. Experiments also show that the sign of the injected current (i.e., the direction of the radial electric field) has a significant impact on the effect of the driven rotation. A reduction in the particle transport is observed only for radially inward electric fields. copyright 1998 American Institute of Physics