Structural requirements for the magnet system include unique spatial constraints and materials restrictions to meet the operational needs of the unusual configuration. All of the magnets are liquid helium cooled which represents about 1500 tonnes of 4.5 K structure in the vacuum environment of the large vessel. Magnet support structures must satisfy complex load conditions, including electromagnetic (both normal-operating and fault conditions) and seismically induced. Improved plasma confinement, characterized by long particle lifetimes, requires attention to coil alignment and field errors. Continued monitoring of field accuracy and possible adjustment during operation are contemplated. Operating conditions for the magnet system include rapid cooldown and warm-up to minimize down time for maintenance.

Extensive tidal studies in island wells and the lagoon at Enewetak Atoll have shown that island ground water dynamics are controlled by a layered aquifer system. The surface aquifer of unconsolidated Holocene material extends to a depth of approximately 15 m, and has a hydraulic conductivity K = 60 m/day. From 15 to 60 m (approximate lagoon depth) the reef structure consists of successive layers of altered Pleistocene materials, with bulk permeability substantially higher than that of the surface aquifer. Because of wave set-up over the windward reef and the limited pass area for outflow at the south end of the atoll, lagoon tides rise in phase with the ocean tides but fall later than the ocean water level. This results in a net lagoon-to-ocean head which can act as the driving force for outflow through the permeable Pleistocene aquifer. This model suggests that fresh water, nutrients or radioactive contaminants found in island ground water or reef interstitial water may be discharged primarily into the ocean rather than the lagoon. Atoll island fresh water resources are controlled by recharge, seawater dilution due to vertical tidal mixing between the surface and deeper aquifers, and by loss due to entrainment by the …

Copper targets used in RTNS II, which is the world's most intense 14-MeV neutron source, contain water cooling channels for temperature control. There are two methods for fabricating these targets: (1) diffusion bonding a copper panel containing photoetched channels to another copper panel, and (2) an electroforming technique which involves filling the photoetched channels with wax, plating thick copper to seal over the channels and then removing the wax. Development of this latter process and results obtained with it are described.

Controlled test atmospheres can be produced using a variety of techniques. Gases are usually generated by using flow dilution methods while vapors are produced by using solvent injection and vaporization, saturation, permeation and diffusion techniques. The resulting gas mixtures can be monitored and measured using flame ionization, photoionization, electrochemical and infrared analytical systems. An ideal system for the production of controlled test atmospheres would not only be able to generate controlled test atmospheres, but also monitor all pertinent environmental parameters, such as temperature, humidity, and air flow.

The methods to be employed to form and control plasma potentials in the TMX Upgrade tandem mirror with thermal barriers are described. ECRH-generated mirror -confined electron plasmas are used to establish a negative potential region to isolate the end-plug and central-cell celectrons. This thermal isolation will allow a higher end-plug electron temperature and an increased central-cell confining potential. Improved axial central-cell ion confinement results since higher temperature central-cell ions can be confined. This paper describes: (1) calculations of the sensitivity of barrier formation to vacuum conditions and to the presence of impurities in the neutral beams, (2) calculations of microwave penetration and absorption used to design the ECRH system, and (3) techniques to limit electron runaway to high energies by localized microwave beams and by relativistic detuning.

The Kirkpatrick-Baez microscopes are described along with their role as the workhorse of the x-ray imaging devices. This role is being extended with the development of a 22X magnification Kirkpatrick-Baez x-ray microscope with multilayer x-ray mirrors. These mirrors can operate at large angles, high x-ray energies, and have a narrow, well defined x-ray energy bandpass. This will make them useful for numerous experiments. However, where a large solid angle is needed, the Woelter microscope will still be necessary and the technology needed to build them will be useful for many other types of x-ray optics.

This review article surveys recent work on computer representation of molecular surfaces. Several different algorithms are discussed for producing vector or raster drawings of space-filling models formed as the union of spheres. Other smoother surfaces are also considered.

In a development effort to extract mechanical property information from miniature specimens, standard diamond pyramid microhardness (DPH) tests have been conducted at Hanford Engineering Development Laboratory (HEDL) on specimens irradiated in RTNS-II; and techniques to extend the information available from microhardness tests have been developed at the University of California, Santa Barbara (UCSB). In tests at HEDL, radiation hardening has only been observed in relatively pure materials irradiated to neutron fluences less than 4 x 10/sup 17/ n/cm/sup 2/. In copper, specifically, a proportional increase in the DPH with neutron fluence has been observed, and this microhardness increase has been correlated with an increase in the 0.2 percent offset yield strength. At UCSB it has been found that hardness and microhardness data obtained with spherical indenters can be used to determine the true stress-true plastic strain relationship of the test material; moreover, it has been found that features of the indentation lip geometry can be used to characterize localized flow phenomena like Lueders strain in steel. Consequently, microhardness test techniques appear attractive for small specimen test applications.

X-ray emission spectra are important diagnostics for studying laser-coupling and energy transport. We have begun exploring the sensitivity of such measurements to the plasma density and temperature profiles. The one-dimensional radiation transport equation is solved for various temperature and density profiles. Spectra are calculated in both the LTE and CRE approximations, bracketing the relevant ionization regimes. Their applicability to real plasmas is discussed. The calculated spectra are compared with measurements from different Z targets. This comparison explores the possible temperature and density parameters. Such comparisons can be used to interpret present experimental results as well as guide the design of future experiments.

This System consists of the Master Timing Transmitter and the Local Timing Receivers. The Master Timing Transmitter located in the control room initiates timing messages, abort messages and precise delay messages. A sync message is sent when one of the other three is not being sent. The Local Timing Receiver, located in the equipment area, decodes the incoming messages and generates 6 MHz, 3MHz and 1 MHz continuous clocks. A 250 KHz sync clock is derived from the sync messages, to which all pulse outputs are synchronized. The Local Timing Receiver also provides two ON-OFF delay counters of 64 bits each, and one OFF delay counter of 32 bits. Detection of abort messages and an out-of-sync signal will automatically disable all outputs.

The Workshop on Core and Sample Curation was held to discuss the best means of handling, distributing, and advertising samples and data collected during a Continental Scientific Drilling Program (CSDP) and to establish better communication between sample curators regarding common problems. It was geneerally agreed that CSDP samples should be handled, on a regional basis, by existing data systems and sample repositories judged to have adequate staff and support. Repository design, sample handling procedures, and sample accounting systems were discussed. Across North America, support for curation of geological samples was varied, but it was strongest within states or regions with well-established energy and mineral industries. A well-supported repository pays for itself through the circulation and preservation of samples and stratigraphic information. A national CSDP must have a well-established curatorial policy and system of regional repositories to circulate information and samples throughout the scientific community. Well-curated samples and data are a national resource with considerable benefits for industry and academia. Attendees agreed to form a Society of Geoscience Curators to maintain communication between curators from private, government, and university repositories and core research laboratories.