[en] A review of computational methods simulating the non-plasma transport of electrons and their attendant cascades is presented. Remarks are mainly restricted to linearized formalisms at electron energies above 1 keV. The effectiveness of various metods is discussed including moments, point-kernel, invariant imbedding, discrete-ordinates, and Monte Carlo. Future research directions and the potential impact on various aspects of science and engineering are indicated

[en] Absolute emission coefficient measurements on arc-generated uranium plasmas in local thermodynamic equilibrium are described for a wavelength bandwidth of 1050 to 6000 A. Low- and high-pressure arcs were investigated for their emission properties, characteristic temperatures and uranium partial pressures. Temperatures from 550 to 8000 K and uranium partial pressures from 0.001 to 0.01 atm were found at the arc centerline. The new emission data are compared with other similar experimental results and to existing theoretical calculations. The effects of cold-layer UF₆ photoabsorption on uranium plasma emission characteristics are established for UF₆ molecular densities ranging from 1.0 x 10¹⁶ to 1.0 x 10¹⁷ cm^-3 and layer thickness from 1.0 to 5.0 cm. Ab Initio atomic structure calculations were made using relativistic Hartree exchange wave functions, from which oscillator strength distributions were computed for transition arrays of interest. These calculations give supporting evidence as to the credibility of the measured emission at various wavelengths, particularly in the vacuum ultraviolet. It is suggested that a consistent picture as to the nature of uranimum plasma emission, at these plasma conditions, emerges and the capability now exists to successfully compute major emission features of uranium and other complex atomic systems

[en] Absolute emission coefficient measurements on arc-generated uranium plasmas in local thermodynamic equilibrium are described for a wavelength bandwidth of 1050 to 6000A. Low- and high-pressure arcs were investigated for their emission properties, characteristic temperatures and uranium partial pressures. Temperatures from 5500 to 8000 K and uranium partial pressures from 0.001 to 0.01 atm were found at the arc centerline. The new emission data are compared with other similar experimental results and to existing theoretical calculations. The effects of cold-layer UF₆ photoabsorption on uranium plasma emission characteristics are established for UF₆ molecular densities ranging from 1.0 x 10¹⁶ to 1.0 x 10¹⁷ cm^-3 and layer thickness from 1.0 to 5.0 cm

[en] Absolute emission coefficient measurements on arc-generated singly ionized uranium (UII) in local thermodynamic equilibrium are described for a wavelength bandwidth of 1050 to 6000 A. Plasma temperature and uranium partial pressure at the arc centerline were approximately 8000⁰K and 0.01 atm, respectively. The arc emission data compare favorably with experimental results obtained from UF₆ discharges, once allowance is made for the effects of cold-layer UF₆ photoabsorption on uranium plasma emission. Observed variation in the emission coefficient is well correlated with a composite of calculated oscillator-strength distribution for selected UII and UIII transition arrays. The theoretical treatment is based on a modified Hartree--Fock method for calculating the appropriate radial wave functions. Slater--Condon theory provides a detailed calculation of energy-level structures for both the upper and lower configuration of each transition array computed. However, the number of terms were truncated, when necessary, to accommodate size limitations of the matrices involved. With this theoretical approach, predictions are also offered as to the location of strong emission features for a hypothetical plasma dominated by doubly and triply ionized uranium. It is suggested that the capability now exists to predict successfully the location of major emission features of uranium and other complex systems for a substantial range of ionization stages

[en] The limb-darkening technique, a method for measuring monochromatic opacity information, which has had successful astrophysical applications, is reviewed. The application of the technique to laser-produced plasmas in materials and regimes of temperature and density of interest to weapons designers is discussed, and the magnitude of the limb-darkening effect in such situations is estimated. Finally, an experimental study, now in progress, to evaluate the feasibility of this approach is described. 10 figures

No abstract available

[en] Theoretical study of selected gamma-ray and electron diagnostic necessitates coupling Cerenkov radiation to electron/photon cascades. A Cerenkov production model and its incorporation into a general geometry Monte Carlo coupled electron/photon transport code is discussed. A special optical photon ray-trace is implemented using bulk optical properties assigned to each Monte Carlo zone. Good agreement exists between experimental and calculated Cerenkov data in the case of a carbon-dioxide gas Cerenkov detector experiment. Cerenkov production and threshold data are presented for a typical carbon-dioxide gas detector that converts a 16.7 MeV photon source to Cerenkov light, which is collected by optics and detected by a photomultiplier

No abstract available

[en] The National Ignition Facility (NIF) will have a large suite of sophisticated target diagnostics. This will allow thoroughly diagnosed experiments to be performed both at the ignition and pre-ignition levels. As part of the national effort Los Alamos National Laboratory will design, construct and implement a number of diagnostics for the NIF. This paper describes Los Alamos contributions to the ''phase I diagnostics.'' Phase I represents the most fundamental and basic measurement systems that will form the core for most work on the NIF. The Los Alamos effort falls into four categories: moderate to hard X-ray (time resolved imaging neutron spectroscopy- primarily with neutron time of flight devices; burn diagnostics utilizing gamma ray measurements; testing measurement concepts on the TRIDENT laser system at Los Alamos. Because of the high blast, debris and radiation environment, the design of high resolution X-ray imaging systems present significant challenges. Systems with close target proximity require special protection and methods for such protection is described. The system design specifications based on expected target performance parameters is also described. Diagnosis of nuclear yield and burn will be crucial to the NIF operation. Nuclear reaction diagnosis utilizing both neutron and gamma ray detection is discussed. The Los Alamos TRIDENT laser system will be used extensively for the development of new measurement concepts and diagnostic instrumentation. Some its potential roles in the development of diagnostics for NIF are given

[en] A review of nonplasma coupled electron/photon transport using Monte Carlo method is presented. Remarks are mainly restricted to linerarized formalisms at electron energies from 1 keV to 1000 MeV. Applications involving pulse-height estimation, transport in external magnetic fields, and optical Cerenkov production are discussed to underscore the importance of this branch of computational physics. Advances in electron multigroup cross-section generation is reported, and its impact on future code development assessed. Progress toward the transformation of MCNP into a generalized neutral/charged-particle Monte Carlo code is described. 48 refs