The Solid-State, Heat-Capacity Laser (SSHCL), under development at Lawrence Livermore National Laboratory (LLNL) is a large aperture (100 cm{sup 2}), confocal, unstable resonator requiring near-diffraction-limited beam quality. There are two primary sources of the aberrations in the system: residual, static aberrations from the fabrication of the optical components and predictable, time-dependent, thermally-induced index gradients within the gain medium. A deformable mirror placed within the cavity is used to correct the aberrations that are sensed externally with a Shack-Hartmann wavefront sensor. Although the complexity of intracavity adaptive correction is greater than that of external correction, it enables control of the mode growth within the resonator, resulting in the ability to correct a more aberrated system longer. The overall system design, measurement techniques and correction algorithms are discussed. Experimental results from initial correction of the static aberrations and dynamic correction of the time-dependent aberrations are presented.

Alloy 22 (UNS N60622) is a nickel-based alloy, which is extensively used in aggressive industrial applications, especially due to its resistance to localized corrosion and stress corrosion cracking in high chloride environments. The purpose of this work was to characterize the anodic behavior of Alloy 22 in concentrated calcium chloride (CaCl{sub 2}) brines and to evaluate the inhibitive effect of nitrate, especially to localized corrosion. Standard electrochemical tests such as polarization resistance and cyclic polarization were used. Results show that the corrosion potential of Alloy 22 was approximately -360 mV in the silver-silver chloride (SSC) scale and independent of the tested temperature. Cyclic polarization tests showed that Alloy 22 was mainly susceptible to localized attack in 5 M CaCl{sub 2} at 75 C and higher temperatures. The addition of nitrate in a molar ratio of chloride to nitrate equal to 10 increased the onset of localized corrosion to approximately 105 C. The addition of nitrate to the solution also decreased the uniform corrosion rate and the passive current of the alloy.

One approach for heating a target to ''Warm Dense Matter'' conditions (similar, for example, to the interiors of giant planets or certain stages in Inertial Confinement Fusion targets), is to use intense ion beams as the heating source (see refs.[6] and [7] and references therein for motivation and accelerator concepts). By consideration of ion beam phase space constraints, both at the injector, and at the final focus, and consideration of simple equations of state and relations for ion stopping, approximate conditions at a target foil may be calculated. Thus target temperature and pressure may be calculated as a function of ion mass, ion energy, pulse duration, velocity tilt, and other accelerator parameters. We connect some of these basic parameters to help search the extensive parameter space (including ion mass, ion energy, total charge in beam pulse, beam emittance, target thickness and density).

Heavy ion and radiation transport calculations are in progress for conceptual beam dump designs for the fragmentation line of the proposed Rare Isotope Accelerator (RIA). Using the computer code PHITS, a preliminary design of a motor-driven rotating wheel beam dump and adjacent downstream multipole has been modeled. Selected results of these calculations are given, including neutron and proton flux in the wheel, absorbed dose and displacements per atom in the hub materials, and heating from prompt radiation and from decay heat in the multipole.

Electron clouds and gas pressure rise limit the performance of many major accelerator rings. We are studying these issues experimentally with {approx}1 MeV heavy-ion beams, coordinated with significant efforts in self-consistent simulation and theory. The experiments use multiple diagnostics, within and between quadrupole magnets, to measure the sources and accumulation of electrons and gas. In support of these studies, we have measured gas desorption and electron emission coefficients for potassium ions impinging on stainless steel targets at angles near grazing incidence. Our goal is to measure the electron particle balance for each source--ionization of gas, emission from beam tubes, and emission from an end wall--determine the electron effects on the ion beam and apply the increased understanding to mitigation. We describe progress towards that goal.

An attractive blanket concept for the fusion reactor is the dual coolant Pb-17Li liquid (DCLL) breeder design. Reduced activation ferritic steel (RAFS) is used as the structural material. Helium is used to cool the first wall and blanket structure, and the self-cooled breeder Pb-17Li is circulated for power conversion and for tritium breeding. A SiCf/SiC composite insert is used as the magnetohydrodynamic (MHD) insulation to reduce the impact from the MHD pressure drop of the circulating Pb-17Li and as the thermal insulator to separate the high temperature Pb-17Li from the helium cooled RAFS structure. For the reference tokamak power reactor design, this blanket concept has the potential of satisfying the design limits of RAFS while allowing the feasibility of having a high Pb-17Li outlet temperature of 700 C. We have identified critical issues for the concept, some of which include the first wall design, the assessment of MHD effects with the SiC-composite flow coolant insert, and the extraction and control of the bred tritium from the Pb-17Li breeder. R&D programs have been proposed to address these issues. At the same time we have proposed a test plan for the DCLL ITER-Test Blanket Module program.

We are testing a high-current-density high-brightness Argon-Ion Source for Heavy Ion Fusion applications. The 100-kV 20-{micro}s source has produced up to 5 mA of Ar{sup +} in a single beamlet. The extraction current density is 100 mA/cm2. We have measured the emittance of the beamlet, and the fraction of Ar{sup ++} ions under several operating conditions. We present measurements of the extracted current density as a function of RF power and gas pressure ({approx} 2 mT), current density uniformity, and energy dispersion (due to charge exchange). We are testing a 80-kV 61-hole multi-beamlet array that will produce a total current > 200 mA. In the current experiments the beamlets are not merged into a single beam. A 500-kV experiment where the beamlets will be merged to a produce 0.5-A beam is being planned.

None

Human DNA can be damaged by natural metabolism through free radical production. It has been suggested that the equilibrium between innate damage and cellular DNA repair results in an oxidative DNA damage background that potentially contributes to disease and aging. Efforts to quantitatively characterize the human oxidative DNA damage background level based on measuring 8-oxoguanine lesions as a biomarker have led to estimates varying over 3-4 orders of magnitude, depending on the method of measurement. We applied a previously developed and validated quantitative pathway model of human DNA base excision repair, integrating experimentally determined endogenous damage rates and model parameters from multiple sources. Our estimates of at most 100 8-oxoguanine lesions per cell are consistent with the low end of data from biochemical and cell biology experiments, a result robust to model limitations and parameter variation. Our results show the power of quantitative system modeling to interpret composite experimental data and make biologically and physiologically relevant predictions for complex human DNA repair pathway mechanisms and capacity.

Poroelasticity is the theoretical framework used to describe the coupled processes which occur when a fluid bearing porous material is deformed by a stress field. The theoretical basis for the treatment of problems in poroelasticity has been derived in an extensive body of work over the last fifty years, most notably by Biot. Many of Biot`s successors have attempted to find relationships between the physical properties of the material to be analyzed and the Biot coefficients. Our approach to this problem has both theoretical and experimental components. The general theoretical objective is to produce estimates of the Biot coefficients which are more realistic e.g.. are not limited by assumptions which preclude their use for real earth materials. Experiments are designed to measure the coefficients (or parameters which are directly related to them) which have not been measured as yet to provide new insight for improving the theory of poroelasticity. The experimental program is designed to determine the mechanical and transport properties of a well characterized set of synthetic and natural sandstones from static to ultrasonic frequencies.

Pulses of 140 GHz microwaves have been produced at a 2 kHz rate using the ETA-III induction linac and IMP wiggler. The accelerator was run in bursts of up to 50 pulses at 6 MeV and greater than 2 kA peak current. A feedback timing control system was used to synchronize acceleration voltage pulses with the electron beam, resulting in sufficient reduction of the corkscrew and energy sweep for efficient FEL operation. Peak microwave power for short bursts was in the range 0.5--1.1 GW, which is comparable to the single-pulse peak power of 0.75--2 GW. FEL bursts of more than 25 pulses were obtained.

Triangulations without large angles have a number of applications in numerical analysis and computer graphics. In particular, the convergence of a finite element calculation depends on the largest angle of the triangulation. Also, the running time of a finite element calculation is dependent on the triangulation size, so having a triangulation with few Steiner points is also important. Bern, Dobkin and Eppstein pose as an open problem the existence of an algorithm to triangulate a planar straight-line graph (PSLG) without large angles using a polynomial number of Steiner points. We solve this problem by showing that any PSLG with {upsilon} vertices can be triangulated with no angle larger than 7{pi}/8 by adding O({upsilon}{sup 2}log {upsilon}) Steiner points in O({upsilon}{sup 2} log{sup 2} {upsilon}) time. We first triangulate the PSLG with an arbitrary constrained triangulation and then refine that triangulation by adding additional vertices and edges. Some PSLGs require {Omega}({upsilon}{sup 2}) Steiner points in any triangulation achieving any largest angle bound less than {pi}. Hence the number of Steiner points added by our algorithm is within a log {upsilon} factor of worst case optimal. We note that our refinement algorithm works on arbitrary triangulations: Given any triangulation, we show how to …

A well-stirred reactor experiment and chemical kinetic modeling effort were performed in order to study the effect of ethylene oxidation on the conversion of nitric oxide (NO) to nitrogen dioxide (NO{sub 2}). Parameters examined in this study were temperature (1003--1260K) and input hydrocarbon concentration (220--3270 ppmv wet). The stirred reactor residence time was maintained at {approximately}2 milliseconds. Kinetic calculations indicated the NO to NO{sub 2} conversion proceeded through the ``HO{sub 2} mechanism``, NO + HO{sub 2} {yields} NO{sub 2} + OH, and the majority of the conversion occurred within the well-stirred reactor. The chemical kinetic mechanism used to model the percent conversion of the NO to NO{sub 2}, C{sub 2}H{sub 4}, CH{sub 4}, CO and CO{sub 2} concentrations showed excellent agreement with the experimental data, thereby validating the ethylene oxidation mechanism. Reaction pathway analysis and logarithmic sensitivity analysis were combined to analyze the ethylene oxidation structure and HO{sub 2} production process. The analysis revealed the primary ethylene oxidation pathway has the potential to form two HO{sub 2} radicals per ethylene consumed, thus making the ethylene a significant agent in promoting conversion of NO to NO{sub 2}. The secondary ethylene oxidation pathway is a potent chain branching process which furthers ethylene …

This paper describes ORNL's management of its fusion energy program. Guidelines for effective management are given. (JDH)

Electroweak unification suggests that there should be WW and ZZ physics analogous to {gamma}{gamma} physics. Indeed, WW and ZZ collisions will provide an opportunity to search for the Higgs boson at future high energy colliders. Cross sections in the picobarn range are predicted for Higgs boson production at the proposed 40-TeV SSC. While other states may be produced by WW and ZZ collisions, it is the Higgs boson that looms as the most attractive objective. 31 refs., 5 figs.

We are developing an advanced process for treatment of mixed wastes in molten salt media at temperatures of 700--1000{degrees}C. Waste destruction has been demonstrated in a single stage oxidation process, with destruction efficiencies above 99.9999% for many waste categories. The molten salt provides a heat transfer medium, prevents thermal surges, and functions as an in situ scrubber to transform the acid-gas forming components of the waste into neutral salts and immobilizes potentially fugitive materials by a combination of particle wetting, encapsulation and chemical dissolution and solvation. Because the offgas is collected and assayed before release, and wastes containing toxic and radioactive materials are treated while immobilized in a condensed phase, the process avoids the problems sometimes associated with incineration processes. We are studying a potentially improved modification of this process, which treats oxidizable wastes in two stages: pyrolysis followed by catalyzed molten salt oxidation of the pyrolysis gases at ca. 700{degrees}C. 15 refs., 5 figs., 1 tab.

This paper reviews the data on multiplicities in high energy interactions. Results from e/sup +/e/sup -/ annihilation, from neutrino interactions, and from hadronic collisions, both diffractive and nondiffractive, are compared and contrasted. The energy dependence of the mean charged multiplicity, <n/sub ch/>, as well as the rapidity density at Y = 0 are presented. For hadronic collisions, the data on neutral pion production shows a strong correlation with <n/sub ch/>. The heavy particle fractions increase with ..sqrt..s up to the highest energies. The charged particle multiplicity distributions for each type of reaction show a scaling behavior when expressed in terms of the mean. Attempts to understand this behavior, which was first predicted by Koba, Nielsen, and Olesen, are discussed. The multiplicity correlations and the energy variation of the shape of the KNO scaling distribution provide important constraints on models. Some extrapolations to the energies of the Superconducting Super Collider are made. 51 refs., 27 figs.

A recent concept for collective acceleration and focusing of a high energy electron bunch is discussed, in the context of its possible applicability to large linear colliders in the TeV range. The scheme can be considered to be a member of the general class of two-beam accelerators, where a high current, low voltage beam produces the acceleration fields for a trailing high energy bunch.

As a long range goal for the production of high intensity neutrons, Argonne National Laboratory has proposed the construction of a 1.5 GeV FFAG Spiral Sector Accelerator called ASPUN. The 500-MeV injector for this proposed accelerator is a smaller FFAG Spiral Sector Accelerator named Mini-ASPUN. Until such a time as the larger machine could be built, it was planned that Mini-ASPUN would replace the present RCS now being used for the IPNS program at Argonne. In order to obtain an accurate estimation of the orbits and betatron oscillations in such a machine, it is necessary that realistic field values be used in the equations of motion. Obtaining these fields from 3-dimensional relaxation calculations is both time consuming and costly. However, because of the required scaling of the machine, the field-generating potential of three variables can be separated into a known function of the radius and a function of two variables. The second order differential equation satisfied by this function can be solved by ordinary relaxation methods. The fields generated from a mesh of values for this function will be accurate except for the extreme inside and outside orbits, which will be affected by the necessary termination of the inside and …

It is concluded that the dynamic range of a streak tube does not depend on whether it uses a fine-mesh or an open structure to provide the extraction field. An RCA C-73435 streak tube body was fitted with two extraction grid structures by replacing the conventional open grid with a steel plate containing two apertures. One aperture simulated the open grid structure; the other was a 2 x 20 mm slit covered with a fine mesh (40 wires per mm, 38% transmissive). The apertures were equal distances above and below the tube axis. Using 35-ps pulses, dynamic range curves were taken at 1.06 ..mu..m on one aperture at a time, while blocking the other aperture. As we anticipated, the tube saturated at nearly the same point for the open and mesh apertures. The noise levels for both apertures were almost equal and very close to the film fog level. Noise level was lower than for earlier measurements on other makes of tubes with a fine-mesh grid. The dynamic range for both apertures was in the order of 6000, which indicates that the lower dynamic range of other tubes must be due to something other than the use of a fine-mesh …

A new system of detectors (MPS II) which has been installed and operated in the Brookhaven National Laboratory Multiparticle Spectrometer (MPS), consisting of short drift distance drift chambers is briefly described. (WHK)

This paper reports the measurements of beam breakup (BBU) instability performed on the Advanced Test Accelerator (ATA) up to the end of February, 1984. The main objective was to produce a high current usable electron beam at the ATA output. A well-known instability is BBU which arises from the accelerator cavity modes interacting with the electron beam. The dominant mode is TM/sub 130/ at a frequency of approximately 785 MHz. It couples most strongly to the beam motion and has been observed to grow in the Experimental Test Accelerator (ETA) which has only eight accelerator cavities. ATA has one hundred and seventy cavities and, therefore, the growth of BBU is expected to be more severe. In this paper, BBU measurements are reported for ATA with beam currents of 4 to 7 kA. Analysis showed that the growth of the instability with propagation distance was as expected for the lower currents. However, the high-current data showed an apparent higher growth rate than expected. An explanation for this anomaly is given in terms of a ''corkscrew'' excitation. The injector BBU noise level for a field emission brush cathode was found to be an order of magnitude lower than for a cold plasma …

Attempts to further improve the beam brightness from field emission cathodes are currently centered on the issue of how beam optics and phase mixing within the injector transport tend to ''average down'' the beam brightness. Particle simulation work indicates that beam brightness can be significantly improved by simply reducing the injector transport magnetic field and losing peak transport current, i.e., only transporting that high brightness portion of the total current. The simulation results shown in Figure 8 suggest that beam brightness can be increased perhaps a factor of 5 or more simply by ''tuning for brightness'' rather than tuning for peak transported current. If this can indeed be experimentally realized and the resulting beam matched onto accelerator transport (magnetic and/or laser guided) without emittance degradation then simple field emission cathodes would, at least in the immediately near term, saisfy the needs for 10 micron FEL experiments. 8 refs., 8 figs.

None