The use of ion-focusing and a conditioned beam greatly enhances FEL gain in the VUV and Soft X-Ray range. The equations governing FEL amplification are derived and results of a linear analysis are noted. Numerical results, including 3D effects and having an order of magnitude improvement in gain, are presented for a 30 {Angstrom} example. 3 refs., 2 figs., 1 tab.

A new ground state source of negative hydrogen ions with polarized nuclei ({rvec H}{sup {minus}}) is being developed at BNL. Extensive developmental research has been aimed at improving each element of ({rvec H}{sup {minus}}) production: cold H{degrees} beam, spin selection and focusing magnets, and ionizer. These elements have recently been integrated into a source. A first test with the accommodator nozzle cooled only to liquid nitrogen temperatures resulted in 5 {mu}A of H{sup {minus}}. Tests at liquid helium temperatures are now beginning. 7 refs., 1 fig.

A continuous wave doppler radar system has been designed which is portable, easily deployable and can be remotely controlled. The system is immune to ground clutter and is used for wind speed detection and direction determination. Nearly real time digital signal processing is performed by an Analog Devices ADSP-21020, a 40-bit floating point Digital Signal Processing (DSP) microprocessor. This paper provides an overview of the design of the system including the radio frequency (RF) to digital interface. The various DSP detection algorithms are discussed and compared to system performance and sensitivity. Finally, DSP performance is compared to the performance of an earlier system using Analog Device's ADSP-2100. 6 refs.

When 001 plates of KD{sub 2}PO{sub 4} (KD*P) are used in Pockels cells, strain induced refractive index variations result in beam depolarization and transmitted wavefront distortion. The depolarization is determined by the induced birefringence while the wavefront distortion is controlled by the average index shift. Here we show that the birefringence is determined by the shear stress in the xy-plane of the crystal while the average index shift depends only on the normal stresses. Furthermore, for depolarization losses of 0.1 to 1.0% and wavefront distortion of 0.1 to 1.0{lambda}, the critical range of stress is 10{sup 5} to 10{sup 6} Pa. We also present measured depolarization loss and wavefront distortion profiles for 5, 16 and 27cm, 95% deuterated, KD*P crystals. Using the analysis described above we show that the maximum internal stresses in the crystals are within the critical range, but that the area averaged stresses are substantially lower. We find that crystals from different locations along the length of a boule have similar strain birefringence and wavefront distortion profiles indicating that the growth conditions which generate the internal strain persist throughout much of the growth history of the boule. Finally, we discuss potential sources of strain in KD*P. 8 …

In this paper, we present a broad comparison of studies for a selected set of parameters for different nuclear reactor types including the next generation. This serves as an overview of key parameters which provide a semi-quantitative decision basis for selecting nuclear strategies. Out of a number of advanced reactor designs of the LWR type, gas cooled type, and FBR type, currently on the drawing board, the Advanced Light Water Reactors (ALWR) seem to have some edge over other types of the next generation of reactors for the near-term application. This is based on a number of attributes related to the benefit of the vast operating experience with LWRs coupled with an estimated low risk profile, economics of scale, degree of utilization of passive systems, simplification in the plant design and layout, modular fabrication and manufacturing. 32 refs., 1 fig., 3 tabs.

This paper provides a brief and mostly non-technical description of the militarily important features of nuclear weapons, of the physical phenomena associated with individual explosions, and of the expected or possible results of the use of many weapons in a nuclear war. Most emphasis is on the effects of so-called ``strategic exchanges.``

This article describes the synthesis and characterization of C₆₀, by means of electron microscopy, electron states, cyclic voltammetry and other techniques.

In the HYLIFE-2 Inertial Confinement Fusion reactor, an array of Flibe (Li{sub 2}BeFe{sub 4}) jets is designed to protect the chamber from the fusion radiation. During the fusion pulse the Flibe jets sustain an instantaneous neutron and X-ray heating. The high energy neutrons from fusion can penetrate deep into the Flibe jets and the sudden increase in internal energy can induce a great pressure rise inside the jets. The subsequent relaxation of the jets is important for the reactor design, because the configuration of the jets will control the subsequent impact forces of vapor and liquid on the reactor chamber wall. The calculations for the lithium jets in the HYLIFE-1 reactor were done previously by using a compressible flow model with a soft sphere equation of state for lithium. A similar equation of state model for Flibe was recently developed. This model allows us to use the same compressible analysis code to calculate the pressure field in the Flibe jets and to estimate the upper bound of the Flibe tension limit. With these results we can analyze the mechanisms of jet relaxation and breakup. 4 refs., 1 fig.

Flibe (Li{sub 2}BeF{sub 4}) is a candidate material for the liquid blanket in the HYLIFE-2 fusion reactor. The thermodynamic properties of the material are important for the study of thermohydraulic behavior of the concept design, including the compressible analysis of the blanket isochoric heating problem and resulting jet breakup. The equation of state provides the relationship between all the thermodynamic properties. Previously, a soft sphere model of liquid equation of state was used for describing a number of liquid metals. In this paper we have fitted the available experimental data for liquid Flibe with a modified soft sphere model. 5 refs.

Several buildings at Y-12 Plant rely on unreinforced hollow clay tile walls (HCTW) infilled between unbraced, non-moment resisting steel frames to resist natural phenomena forces, seismic and wind. One critical building relies on moment resisting steel frames in one direction while relying on unreinforced HCTWs infilled between the columns in the orthogonal direction to resist these forces. The HCTWs must act as shear walls while maintaining out-of-plane lateral stability. In assessing the safety of these buildings to seismic forces, several models to study the in- and out-of-plane effects were made and analyzed. The study of the moment resisting steel framed building indicated that bending stresses in the walls were induced by building drift and not by inertial forces per se. The discovery of this phenomenon was some what of a surprise in that the analysis performed is not typically used in design of these structures. The study indicated that the walls began to crack at their interface with the foundation at a low ``g`` level and that horizontal cracking at different elevations continued until the walls exhibited little bending resistance. This paper presents results of the study for out-of-plane behavior of unreinforced HCTWs infilled between adjacent moment resisting steel frames …

Like most large networked sites our users depend heavily on the electronic mail system for both internal and off-site communications. Unfortunately the sendmail.cf file, which is used to control the behavior of the sendmail program, is somewhat cryptic and difficult to decipher for the neophyte. So, on one hand you have a highly visible, frequently used utility, and on the other hand a not-so-easily acquired system administration forte. Here is the sendmail topology of our site, what premises we based it on, and the parts of the sendmail.cf files which support the topology.

Adaptive Mesh Refinement (AMR) in conjunction with high order upwind finite difference methods has been used effectively on a variety of problems. In this paper we discuss an implementation of an AMR finite difference method that solves the equations of gas dynamics with two material species in three dimensions. An equation for the evolution of volume fractions augments the gas dynamics system. The material interface is preserved and tracked from the volume fractions using a piecewise linear reconstruction technique. 14 refs., 4 figs.

Our general objective is to further the development of efficient continuous mild coal gasification processes. Our efforts this year have been in four main areas. A new thrust has been to identify and develop efficient processes to separate the vapor product stream into particulate-free liquid and mist-free gas. We continued work aimed at predicting heat transfer rates (hence throughput) in externally-heated twin-screw pyrolyzers. We sought to provide technical support for the design, installation, startup, and operation of the DOE-sponsored 500 kg/hr twin-screw mild gasification unit at Coal Technology Corporation (CTC). A smaller laboratory effort had the objective of identifying and testing the reaction mechanisms of sulfur species during coal pyrolysis. Detailed subproject objectives are given in their respective sections. 20 refs., 4 figs., 1 tab.

Recent data on low-mass X-ray binaries (LMXBs) and millisecond pulsars (MSPs) pose a challenge to evolutionary theories which neglect the effects of disk and comparison irradiation. Here we discuss the main features of a radiation-driven (RD) evolutionary model that may be applicable to several LMXBs. According to this model, radiation from the accreting compact star in LMXBs vaporizes'' the accretion disk and the companion star by driving a self-sustained mass loss until a sudden accretion-turn off occurs. The main characteristics of the RD-evolution are: (1) lifetime of RD-LMXB's is of order 10{sup 7} years or less; (2) both the orbital period gap and the X-ray luminosity may be consequences of RD-evolution of LMXB's containing lower main sequence and degeneration companion stars; (3) the companion star may transfer mass to the primary even if it underfills its Roche lobe; (4) a class of recycled MSPs can continue to vaporize the low-mass companions by a strong pulsar wind even after the accretion turn-off; (5) the RD-evolutionary model resolves the apparent statistical descrepancy between the number of MSPs and their LMXB progenitors in the Galaxy. We discuss the implications of the discovery of single MSPs in low-density globular clusters and the recent measurements …

Recent data on low-mass X-ray binaries (LMXBs) and msec pulsars (MSPs) pose a challenge to evolutionary which neglect the effects of disk and companion irradiation. Here we discuss the main features of a radiation-driven (RD) evolutionary model that may be applicable to several LMXBs. According to this model, irradiation from the accreting compact star LMXBs vaporizes'' the accretion disk and the companion star by driving a self-sustained mass loss until a sudden accretion-turn of occurs. The main characteristics of the RD-evolution are: (1) the lifetime of RD-LMXB's is of order 10{sup 7} years or less: (2) both the orbital period gap and the X-ray luminosity may be consequences of RD-evolution of LMXB's containing lower main sequence and degenerate companion stars; (3) the companion star may transfer mass to the primary even if it underfills its Roche lobe; (4) the recycled msec pulsar can continue to vaporize the low-mass companion star even after the accretion turn-off produced by a strong pulsar wind; (5) the RD-evolutionary model resolves the apparent statistical discrepancy between the number of MSP's and their LMXB progenitors. 14 refs., 1 fig., 1 tab.

We present a first principles method for calculating positron lifetimes in solids, based on self-consistent calculations using the Linear Muffin-Tin Orbital method. Local density approximations are used for both electron-electron and electron-positron interactions. Results are presented for a variety of elemental metals and vacancies to demonstrate the reliability of this approach. Theoretical calculations of positron lifetimes can be used to interpret experimental data. As an examples of this, we interpret our experimental lifetime data for the oxide superconductor Ba{sub 1-x}K{sub x}BiO{sub 3} using calculations based on this method. 12 refs., 3 figs.

The Kohn variational method is one of simplest, and oldest, techniques for performing scattering calculations. Nevertheless, a number of formal problems, as well as practical difficulties associated with the computation of certain required matrix elements, delayed its application to electron--molecule scattering problems for many years. This paper will describe the recent theoretical and computational developments that have made the complex'' Kohn variational method a practical tool for carrying out calculations of low energy electron--molecule scattering. Recent calculations on a number of target molecules will also be summarized. 41 refs., 7 figs.

Acoustic emission is being investigated as a way to continuously monitor the space station Freedom for damage caused by space debris impact and seal failure. Experiments run to date focused on detecting and locating simulated and real impacts and leakage. These were performed both in the laboratory on a section of material similar to a space station shell panel and also on the full-scale common module prototype at Boeing's Huntsville facility. A neural network approach supplemented standard acoustic emission detection and analysis techniques. 4 refs., 5 figs., 1 tab.

Beam based alignment is being routinely applied in the SLC Final Focus and has proved to be a very useful tool for determining the quality of the zeroth order orbit as defined by various beam line elements. Given the stringent requirement on the beam quality at the interaction point, a well aligned beam line is essential in that it minimizes the confusion which would otherwise arise in the higher order optics, the demand called on the correctors which also serve as optical knobs, and the problem associated with the background radiation. In the SLC final focus we have been relying on an interplay between the field survey and the orbit analysis to achieve this purpose. Mechanical alignment generally provides coordinate information of various beam line elements and offset values inferred from these data and the model of the beam line. Beam based alignment is done mainly by recording the beam orbit under controlled experiment where optical elements or orbit conditions are varied. Due to the complexity of the beamline layout and special power supply configuration in the SLC Final Focus, the latter method is useful only when coupled with off-line analysis which disentangles the data taken at each measurement. In …

This report discusses the following topics on momentum analysis in tokamaks and stellarators: the momentum balance equation; deposition of torque by neutral beams; effects of toroidal rotation; and experimental observations. (LSP)

In the study of geographic disease clusters, an alternative to traditional methods based on rates is to analyze case locations on a transformed map in which population density is everywhere equal. Although the analyst's task is thereby simplified, the specification of the density equalizing map projection (DEMP) itself is not simple and continues to be the subject of considerable research. Here a new DEMP algorithm is described, which avoids some of the difficulties of earlier approaches. The new algorithm (a) avoids illegal overlapping of transformed polygons; (b) finds the unique solution that minimizes map distortion; (c) provides constant magnification over each map polygon; (d) defines a continuous transformation over the entire map domain; (e) defines an inverse transformation; (f) can accept optional constraints such as fixed boundaries; and (g) can use commercially supported minimization software. Work is continuing to improve computing efficiency and improve the algorithm. 21 refs., 15 figs., 2 tabs.

A new atomic force microscope incorporating microfabricated cantilevers and employing laser beam deflection for force detection has been constructed and is being applied to studied of biological material. In this study, T4 bacteriophage virus particles were deposited from solution onto electronic grade flat silicon wafers and imaged in air with the microscope. Microliter droplets of the solution were deposited and either allowed to dry or removed with blotting paper. The images show both isolated viruses and aggregates of various sizes. The external structure as well as strands believed to be DNA streaming out of the virus could be observed. The construction of the microscope and its performance are also described. 19 refs., 4 figs.

A new atomic force microscope incorporating microfabricated cantilevers and employing laser beam deflection for force detection has been constructed and is being applied to studied of biological material. In this study, T4 bacteriophage virus particles were deposited from solution onto electronic grade flat silicon wafers and imaged in air with the microscope. Microliter droplets of the solution were deposited and either allowed to dry or removed with blotting paper. The images show both isolated viruses and aggregates of various sizes. The external structure as well as strands believed to be DNA streaming out of the virus could be observed. The construction of the microscope and its performance are also described. 19 refs., 4 figs.

Experiments at the p{bar p} colliders at CERN and FNAL have an active program of heavy flavor physics. Recently, CDF at FNAL and UA1 at CERN have measured rare decays of the {Beta}{sup 0} {minus} {bar {Beta}}{sup 0} mixing. CDF has signals for {Beta}{sup {plus minus}} {yields} J/{psi}K{sup {plus minus}} and {Beta}{sup 0} {yields} J/{psi}K{sup *0}. Both CDF and UA1 have set limits on the branching ratio of {Beta}{sup 0} {yields} {mu}{sup +}{mu}{sup {minus}} and have measured {Beta}{sup 0} {minus} {bar {Beta}}{sup 0} mixing. CDF, UA1 and UA2 at CERN have searched for the top quark and set limits on its mass. Prospects for t and b physics at FNAL in the near future are presented. 21 refs., 14 figs.