1,391 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Transport Theory"  
Results: 1 - 24 next
open access

Delta f Monte Carlo Calculation Of Neoclassical Transport In Perturbed Tokamaks

Description: Non-axisymmetric magnetic perturbations can fundamentally change neoclassical transport in tokamaks by distorting particle orbits on deformed or broken flux surfaces. This so-called non-ambipolar transport is highly complex, and eventually a numerical simulation is required to achieve its precise description and understanding. A new delta#14;f particle code (POCA) has been developed for this purpose using a modi ed pitch angle collision operator preserving momentum conservation. POCA was succes… more
Date: April 11, 2012
Creator: Kimin Kim, Jong-Kyu Park, Gerrit Kramer and Allen H. Boozer
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

An Expression for the Temperature Gradient in Chaotic Fields

Description: A coordinate system adapted to the invariant structures of chaotic magnetic fields is constructed. The coordinates are based on a set of ghost-surfaces, defined via an action-gradient flow between the minimax and minimizing periodic orbits. The construction of the chaotic coordinates allows an expression describing the temperature gradient across a chaotic magnetic field to be derived. The results are in close agreement with a numerical calculation.
Date: December 22, 2008
Creator: Hudson, S.R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Neutron Diffusion Theory Programs and Their Application to Simple Critical Systems

Description: Introduction. The Lawrence Radiation Laboratory of the University of California has developed a series of reactor neutronic programs for an IBM 709 Data Processing System.. This paper presents a brief outline of these codes and includes the results of one- and two-dimensional diffusion calculations used to interpret data from a series of enriched-uranium beryllium-oxide moderated critical measurements. These were performed for the specific purpose of evaluating the computer programs. The time-i… more
Date: March 1960
Creator: Stone, Stuart P. & Lingenfelter, Richard E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Omniclassical Diffusion in Low Aspect Ratio Tokamaks

Description: Recently reported numerical results for axisymmetric devices with low aspect ratio A found radial transport enhanced over the expected neoclassical value by a factor of 2 to 3. In this paper, we provide an explanation for this enhancement. Transport theory in toroidal devices usually assumes large A, and that the ratio B{sub p}/B{sub t} of the poloidal to the toroidal magnetic field is small. These assumptions result in transport which, in the low collision limit, is dominated by banana orbits,… more
Date: March 19, 2004
Creator: Mynick, H. E.; White, R. B. & Gates, D. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Definition of two band parameters for use in photon transport calculations

Description: The multigroup photon diffusion equations are derived from the Boltzmann equation. Limitations and assumptions imposed by the diffusion equation are thus apparent. In addition, this approach serves to define all of the required diffusion parameters in terms of cross sections; the relationship to the multi-band parameters used in neutron transport calculations can thus be clearly established. All required two-band parameters are defined in terms of Planckian and Rosseland mean values. (RWR)
Date: April 1, 1978
Creator: Cullen, D. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Radiation transport phenomena and modeling - part A: Codes

Description: The need to understand how particle radiation (high-energy photons and electrons) from a variety of sources affects materials and electronics has motivated the development of sophisticated computer codes that describe how radiation with energies from 1.0 keV to 100.0 GeV propagates through matter. Predicting radiation transport is the necessary first step in predicting radiation effects. The radiation transport codes that are described here are general-purpose codes capable of analyzing a varie… more
Date: June 1, 1997
Creator: Lorence, L.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

On Carrier Facilitated Transport Through Membranes

Description: Facilitated transport is a process, whereby the diffusion of a solute across a membrane is chemically enhanced. In this report an analysis is given of a facilitated transport system involving a volatile species A which reacts with a nonvolatile carrier species B to form the nonvolatile product AB.
Date: June 1980
Creator: Kaper, H. G.; Leaf, G. K. & Matkowsky, Bernard J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

9-Zoom : A One-Dimensional, Multigroup, Neutron Diffusion Theory Reactor Code for the IBM 709

Description: The following document describes the usage and purpose of the neutron diffusion theory reactor program 9-Zoom, a memory-contained program that takes advantage of 709 features such as, for example, preferential order of multiply by zero, and for small problems approaches input-output limitations with excellent convergence properties.
Date: August 25, 1959
Creator: Stone, S. P.; Collins, E. T. & Lenihan, S. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

9-Zoom : A One-Dimensional, Multigroup, Neutron Diffusion Theory Reactor Code for the IBM 709 [Supplement]

Description: The following document describes the usage of the LRL 9-ZOOM code, a neutron diffusion theory reactor code for the IBM 709. The code has been modified to solve configuration of a series of stacked cylindrical disks, designating a new geometry case.
Date: July 12, 1960
Creator: Stone, S. P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The 4K ANGIE Code

Description: The ANGIE, one of a series of reactor neutronic programs for an IBM 709 or 7090 data processing system, solves the time-dependent, multi-group, neutron diffusion equation for 1 to 26 energy groups applied to a rectangular mesh superimposed on either an x-y or an r-z plane.
Date: March 5, 1962
Creator: Stone, Stuart P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Multigroup Methods for Neutron Diffusion Problems

Description: Abstract: "The age-diffusion is adequate to describe the neutron behavior of a very large class of nonthermal reactors (all except those whose dimensions are comparable to the neutron mean free path). Thus, a convenient means of obtaining an accurate solution to this equation is very useful for general reactor calculations. Methods for reducing the age-diffusion equation to a finite set of coupled ordinary differential equations, called multigroup equations, are described. The relative merits o… more
Date: August 20, 1953
Creator: Hurwitz, H., Jr. & Ehrlich, R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Theoretical Study of a Source of Intermediate Energy Neutrons

Description: Abstract. An analysis is made of a proposal to obtain neutrons of 15-25 Kev energy by moderating fast neutrons in aluminum and then reflecting off titanium. The fluxes calculated do not significantly exceed those obtainable from a standard antimony-beryllium photoneutron source. Two appendices treat aspects of the transport of neutrons through a slab of finite thickness.
Date: January 7, 1954
Creator: Bludman, Sidney A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

9-ANGIE : a Two-Dimensional, Multigroup, Neutron-Diffusion-Theory Reactor Code for the IBM 709 or 7090

Description: The 9-ANGIE, one of a series of reactor neutronic programs for an IBM 709 or 7090 data processing system, solves the time-dependent, multi-group, neutron diffusion equation for one to eighteen energy groups applied to a rectangular mesh superimposed on either an x-y or an r-z plane. It is characterized by its generalities in region description, boundary conditions, etc., without sacrificing simplicity of input preparation and ease of machine operation. The notation, the style, and the format ha… more
Date: October 28, 1960
Creator: Stone, Stuart P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

New slab geometry radiation transport differencing scheme

Description: Considerable effort has been directed toward seeking an optimal spatial differencing scheme for the neutron transport equation. This search led to a best scheme (using specific criteria to define ''best''): the linear characteristic method. However, we have recently considered radiative transfer problems in which the same problem may have both optically thick and optically thin regions, with the maximum optical thicknesses being much greater than those generally encountered in neutron transport… more
Date: January 1, 1985
Creator: Larsen, E.W.; Morel, J.E. & Miller, W.F. Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Transport of Parallel Momentum by Toroidal Ion Temperature Gradient Instability near Marginality

Description: The turbulent angular momentum flux carried by ions resonant with toroidal ion temperature gradient(ITG) instability is calculated via quasilinear calculation using the phase-space conserving gyrokinetic equation in the laboratory frame. The results near ITG marginality indicate that the inward turbulent equipartition (TEP) momentum pinch [Hahm T.S. et al 2007 Phys. Plasmas 14 072302] remains as the most robust part of pinch. In addition, ion temperature gradient driven momentum flux is inward … more
Date: October 20, 2009
Creator: Yoon, E. S. & Hahm, T. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

NUMERICAL SOLUTION OF TRANSIENT AND STEADY-STATE NEUTRON TRANSPORT PROBLEMS

Description: A general numerical procedure, called the discrete S/sub n/ method, for solving the neutron transport equation is described. The main topics relate to the derivation of suitable difference equations, and to the problem of solving these, while maintaining generality, accuracy, and reasonable computing speed. A few comparisons with other methods are made. (auth)
Date: May 16, 1959
Creator: Carlson, B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
Back to Top of Screen