Multi-fluid code simulations including anomalous non-diffusive transport of plasma and impurities in the tokamak SOL (open access)

Multi-fluid code simulations including anomalous non-diffusive transport of plasma and impurities in the tokamak SOL

Fast intermittent transport has been observed in the scrape-off layer (SOL) of major tokamaks including Alcator C-Mod, DIII-D, and NSTX. This kind of transport is not diffusive but rather convective. It strongly increases plasma flux to the chamber walls and enhances the recycling of neutral particles in the main chamber. We discuss anomalous cross-field convection (ACFC) model for impurity and main plasma ions and its relation to intermittent transport events, i.e. plasma density blobs and holes in the SOL. Along with plasma diffusivity coefficients, our transport model introduces time-independent anomalous cross-field convective velocity. In the discharge modelling, diffusivity coefficients and ACFC velocity profiles are adjusted to match a set of representative experimental data. We use this model in the edge plasma physics code UEDGE to simulate the multi-fluid two-dimensional transport for these three tokamaks. We present simulation results suggesting the dominance of anomalous convection in the far SOL transport. These results are consistent with the hypothesis that the chamber wall is an important source of impurities and that different impurity charge states have different directions of anomalous convective velocity.
Date: November 25, 2003
Creator: Pigarov, A. Yu; West, W. P.; Soukhanovskii, V.; Rognlien, T. D.; Maingi, R.; Lipschultz, B. et al.
Object Type: Article
System: The UNT Digital Library
Monitoring Plan for RCRA Groundwater Assessment at the 216-U-12 Crib, Interim Change Notice 1 (open access)

Monitoring Plan for RCRA Groundwater Assessment at the 216-U-12 Crib, Interim Change Notice 1

This ICN corrects a typing error that was identified for one of the wells listed in Tables 4.1 and 4.2 on page 4.3 of the original document.
Date: November 25, 2003
Creator: Williams, Bruce A.
Object Type: Report
System: The UNT Digital Library
Coherence Measurements of a Transient 14.7 nm X-ray Laser (open access)

Coherence Measurements of a Transient 14.7 nm X-ray Laser

We present the longitudinal coherence measurement of the transient inversion collisional x-ray laser for the first time. The Ni-like Pd x-ray laser at 14.68 nm is generated by the LLNL COMET laser facility and is operating in the gain-saturated regime. Interference fringes are produced using a Michelson interferometer setup in which a thin multilayer-coated membrane is used as a beam splitter. The longitudinal coherence length for the picosecond duration 4d{sup 1}S{sub 0} {yields} 4p{sup 1}P{sub 1} lasing transition is determined to be {approx}400 {micro}m (1/e HW) by adjusting the length of one interferometer arm and measuring the resultant variation in fringe visibility. This is four times improved coherence than previous measurements on quasi-steady state schemes largely as a result of the narrower line profile in the lower temperature plasma. The inferred gain-narrowed linewidth of {approx}0.29 pm is also substantially narrower than previous measurements on quasi-steady state x-ray laser schemes. This study shows that the coherence of the x-ray laser beam can be improved by changing the laser pumping conditions. The x-ray laser is operating at 4 - 5 times the transform-limited pulse.
Date: November 25, 2003
Creator: Remond, C; Dunn, J; Delmotte, F; Nilsen, J; Hubert, S; Ravet, M et al.
Object Type: Article
System: The UNT Digital Library
Possible Incorporation of Neptunium in Uranyl (VI) Alteration Phases (open access)

Possible Incorporation of Neptunium in Uranyl (VI) Alteration Phases

This study examines existing data on Np behavior from both spent fuel and borosilicate glass tests in effort to resolve issues concerning the selection of possible solubility limiting phases for neptunium and the methods for detecting neptunium at low levels in spent fuel. These issues were raised in a recent report by Finch and Fortner (2002) that argues that the Np analysis with Electron Energy-Loss Spectroscopy (EELS) reported by Buck et al., (1998) is incorrect and that based on a series of experiments with Np-doped U3O8, NpO2 should be adopted as the solubility controlling phase for Np, in the Yucca Mountain performance assessment model. In this report, we will refute the claim that EELS is unable to detect Np and will suggest that the use of NpO2 as the Np solubility controlling phase is not supported by available scientific data from both spent fuel and borosilicate glass.
Date: November 25, 2003
Creator: Buck, Edgar C.; McNamara, Bruce K.; Douglas, Matthew & Hanson, Brady D.
Object Type: Report
System: The UNT Digital Library
Full-Scale Cookoff Model Validation Experiments (open access)

Full-Scale Cookoff Model Validation Experiments

This paper presents the experimental results of the third and final phase of a cookoff model validation effort. In this phase of the work, two generic Heavy Wall Penetrators (HWP) were tested in two heating orientations. Temperature and strain gage data were collected over the entire test period. Predictions for time and temperature of reaction were made prior to release of the live data. Predictions were comparable to the measured values and were highly dependent on the established boundary conditions. Both HWP tests failed at a weld located near the aft closure of the device. More than 90 percent of unreacted explosive was recovered in the end heated experiment and less than 30 percent recovered in the side heated test.
Date: November 25, 2003
Creator: McClelland, M. A.; Rattanapote, M. K.; Heimdahl, E. R.; Erikson, W. E.; Curran, P. O. & Atwood, A. I.
Object Type: Article
System: The UNT Digital Library
Groundwater Monitoring Plan for the 216-S-10 Pond and Ditch, Interim Change Notice 1 (open access)

Groundwater Monitoring Plan for the 216-S-10 Pond and Ditch, Interim Change Notice 1

During 2003, the upgradient well 299-W26-7 went dry and one new groundwater monitoring well was installed downgradient (well 299-W26-14) of the 216-S-10 pond and ditch. This ICN updates the groundwater monitoring wells for the 216-S-10 pond and ditch and adds a revised well location map to the plan.
Date: November 25, 2003
Creator: Williams, Bruce A.
Object Type: Report
System: The UNT Digital Library
Dislocation Image Stresses at Free Surfaces by the Finite Element Method (open access)

Dislocation Image Stresses at Free Surfaces by the Finite Element Method

The finite element method has been routinely used to calculate the image stresses of dislocation segments. When these segments intersect with surfaces, the image stresses at the surfaces diverges singularly. At the presence of these singularities, both convergence and accuracy of using the finite element method need to be examined critically. This article addresses these issues with the aim toward the application of dislocation dynamics simulations in thin films.
Date: November 25, 2003
Creator: Cai, W; Bulatov, V; Tang, M & Xu, G
Object Type: Article
System: The UNT Digital Library
Measurement of the absolute hohlraum wall albedo under ignition foot drive conditions (open access)

Measurement of the absolute hohlraum wall albedo under ignition foot drive conditions

We present the first measurements of the absolute albedos of hohlraums made from gold or from high-Z mixtures. The measurements are performed over the range of radiation temperatures (70-100 eV) expected during the foot of an indirect-drive temporally-shaped ignition laser pulse, where accurate knowledge of the wall albedo (i.e. soft x-ray wall re-emission) is most critical for determining capsule radiation symmetry. We find that the gold albedo agrees well with calculations using the super transition array opacity model, potentially providing additional margin for ICF ignition.
Date: November 25, 2003
Creator: Suter, L. J.; Wallace, R. J.; Hammel, B. A.; Weber, F. A.; Landen, O. L.; Campbell, K. M. et al.
Object Type: Article
System: The UNT Digital Library
Nanostructured Energetic Materials with Sol-Gel Methods (open access)

Nanostructured Energetic Materials with Sol-Gel Methods

The utilization of sol-gel chemical methodology to prepare nanostructured energetic materials as well as the concepts of nanoenergetics is described. The preparation and characterization of two totally different compositions is detailed. In one example, nanostructured aerogel and xerogel composites of sol-gel iron (III) oxide and ultra fine grained aluminum (UFG Al) are prepared, characterized, and compared to a conventional micron-sized Fe{sub 2}O{sub 3}/Al thermite. The exquisite degree of mixing and intimate nanostructuring of this material is illustrated using transmission and scanning electron microscopies (TEM and SEM). The nanocomposite material has markedly different energy release (burn rate) and thermal properties compared to the conventional composite, results of which will be discussed. Small-scale safety characterization was performed aerogels and xerogels of the nanostructured thermite. The second nanostructured energetic material consists of a nanostructured hydrocarbon resin fuel network with fine ammonium perchlorate (NH{sub 4}ClO{sub 4}) oxidizer present.
Date: November 25, 2003
Creator: Gash, A.; Satcher, J.; Simpson, R. & Clapsaddle, B.
Object Type: Article
System: The UNT Digital Library
Temporal Characterization of a Picosecond Laser-Pumped X-ray Laser (for Applications) (open access)

Temporal Characterization of a Picosecond Laser-Pumped X-ray Laser (for Applications)

Compact soft x-ray laser sources are now used routinely for various applications primarily because of their high repetition rate, high photon fluence and short pulse duration characteristics. For some of these applications, for example interferometry of high density laser-produced plasmas, longer optical drive pulses, 6-13 ps (FWHM), have been implemented to maximize the x-ray output and coherence. It is therefore important to know the x-ray laser pulse length, shape and repeatability for these specific experiments as a baseline measurement but also to better understand the temporal behavior as a function of the pumping conditions in general. We report a detailed temporal characterization of the picosecond-driven 14.7 nm Ni-like Pd ion x-ray laser on the Compact Multipulse Terawatt (COMET) laser at LLNL using an ultrafast x-ray streak camera measurement of a horizontal slice of the near-field x-ray laser pattern. This is measured as a function of the chirped pulse amplification pumping laser conditions, including varying the pump pulse from 0.5-27 ps (FWHM), varying the plasma column length as well as investigating traveling wave (TW) and non-TW irradiation conditions.
Date: November 25, 2003
Creator: Dunn, J; Nilsen, J; Shepherd, R; Shlyaptsev, V; Booth, R; Smith, R et al.
Object Type: Article
System: The UNT Digital Library
Spray nozzle pattern test for the DWPF HEME Task QA Plan. [Defense Waste Processing Facility (DWPF), High Efficiency Mist Eliminator (HEME)] (open access)

Spray nozzle pattern test for the DWPF HEME Task QA Plan. [Defense Waste Processing Facility (DWPF), High Efficiency Mist Eliminator (HEME)]

The DWPF melter off-gas systems have two High Efficiency Mist Eliminators (HEME) upstream of the High-Efficiency Particulates Air filters (HEPA) to remove fine mists and particulates from the off-gas. To have an acceptable filter life and an efficient operation, an air atomized water is spray on the HEME. The water spray keeps the HEME wet and dissolves the soluble particulates and enhances and HEME efficiency. DWPF Technical asked SRL to determine the conditions which will give satisfactory atomization and distribution of water so that the HEME will operate efficiently. The purpose of this document is to identify, QA controls to be applied in the pursuit of this task (WSRC-RP-91-1151).
Date: November 25, 1991
Creator: Lee, L.
Object Type: Report
System: The UNT Digital Library