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Finite Element Analysis of EC Insert Plug

Description: The proposed EC calorimeter insert plug was modeled with ANSYS to verify that the shell thickness calculated with beam formulas are adequate. The finite element model and dimensions is shown in Fig. 1. The geometry and shell thicknesses used were the best numbers available as of 3/28/86. The model includes only the inner and outer shells and intermediate structural discs. The total weight of the plug is calculated to be 75000 lbs. The plug is supported against this weight at the four nodes indicated in Fig. 1. A vertical constraint was used. The calorimeter plates are not explicitly modeled. Their weight is placed on the inner shell by giving the shell material an appropriate density and applying a global acceleration. In addition to the weight loading, there will also be a pressure loading applied to both end plates as a result of preloading the calorimeter plates compressively. This pressure is estimated to be 20 pSi, and was represented in the model as a uniform pressure applied across each end plate. The large axial force produced by this pressure precludes the possibility of attaching the inner shell to both end plates. Such attachments would be under unreasonably high stress as the plates were preloaded, and the inner shell would be under a state of tension in trying to resist the axial force. In the real structure, the inner shell will be attached to at most one of the end plates. The axial force is then developed solely in the outer shell, which has a considerable area of attachment. To emulate this in the finite model, nodal coupling was used to couple the shell laterally to both end plates and all intermediate discs to ensure weight transfer, but axially the shell was only coupled to one of the end plates. The materials ...
Date: April 1, 1986
Creator: Wands, R.
Partner: UNT Libraries Government Documents Department

Reservoir Behaviour in a Stimulated Hot Dry Rock System

Description: Research into the stimulation of hot dry rock (HDR) systems in crystalline rock has been underway in Cornwall, England for several years. Two deviated wells were drilled to a depth of 2100 m in 1981 with an interwell separation of 300 m. These wells were connected by massive hydraulic injections using water, but the interconnection was insufficient to permit long term circulation without excessive water losses. In 1985 a third well was drilled to a depth of 2600 m in a direction chosen from the analysis of the reservoir behavior during the previous circulation. A massive stimulation (200 l/s, 75 bbl/min) of gel was used to connect the wells and circulation was re-established in August 1985. Reservoir models have been developed from hydraulic analyses, thermal behavior, microseismic mapping, tracer dispersion and chemical modeling. The system behaves like an interconnected network of flow paths with a few dominant routes acting as flow conduits. The storage is associated with pressure dependent joint compliance, but it is isolated from the dominant flow paths. No unique physical model has yet been derived but the various techniques have been used to establish constraints on the geometry and nature of the heat transfer regions. The experiments are still in progress.
Date: January 21, 1986
Creator: Batchelor, Anthony S.
Partner: UNT Libraries Government Documents Department

Reinjection Model Studies in Fractured and Homogeneous Geothermal Systems

Description: Reinjection of geothermal waste waters has become an important topic of interest for industry as well as for research. The environmental concerns due to chemical composition of geothermal waste waters had urged the industry to dispose it underground. In several field applications no interference due to thermal front breakthrough was observed on the other hand some cases are reported where reinjection had caused severe declines in energy production due to unexpected breakthrough of injected water. Several analytical and numerical studies are available where the effect of fractures on the movement of thermal front are discussed. It was shown that when the conduction heat transfer from matrix to fracture dominates, retardation of the thermal front movement will be observed. Bodvarsson and Pruess considered the above problem in a five-spot well pattern. They observed as the amount of fluid injected reaches the amount produced, the long-term energy output of the system increases. Pruess in his study compares the behavior of porous medium and fractured medium in terms of pressure decline due to production. Temperature and pressure profiles are presented between an injector and a producer where heating of the injected water in porous medium and in fractured medium with small fracture spacing was high compared to a larger fracture spacing. Such observations from the numerical studies were checked against some limited field examples. However understanding of the injection effects in fractured reservoirs is limited. This work presents the results of laboratory experiments where effects of reinjection on temperature and pressure behavior of a porous medium and a fractured medium were investigated. The porous medium was a crushed limestone pack, with 10 mm average particle size, packed in a 3-D box model where injection and production ports are located on the diagonal ends simulating a five-spot pattern. The fractured medium was made from ...
Date: January 21, 1986
Creator: Okandan, E. & Hosca, H.
Partner: UNT Libraries Government Documents Department

Evolution of variable stars

Description: Throughout the domain of the H R diagram lie groupings of stars whose luminosity varies with time. These variable stars can be classified based on their observed properties into distinct types such as ..beta.. Cephei stars, delta Cephei stars, and Miras, as well as many other categories. The underlying mechanism for the variability is generally felt to be due to four different causes: geometric effects, rotation, eruptive processes, and pulsation. In this review the focus will be on pulsation variables and how the theory of stellar evolution can be used to explain how the various regions of variability on the H R diagram are populated. To this end a generalized discussion of the evolutionary behavior of a massive star, an intermediate mass star, and a low mass star will be presented. 19 refs., 1 fig., 1 tab.
Date: August 1, 1986
Creator: Becker, S.A.
Partner: UNT Libraries Government Documents Department

Symmetry issues in a class of ion beam targets using sufficiently short direct drive pulses

Description: Controlling asymmetries in direct drive ion beam targets depends upon the ability to control the effects of residual target asymmetries after an appropriate illumination scheme has already been utilized. A class of modified ion beam targets where residual asymmetries are ameliorated is considered. The illumination scheme used is an axially symmetric one convenient for reactor designs. Residual asymmetries are controlled by limiting the radial motion of the radius R/sub dep/ of peak ion energy deposition. Limiting the motion of R/sub dep/ is achieved by lengthening the time scale t/sub s/ where changes in R/sub dep/ adversely affect asymmetries. In our example, t/sub s/ becomes longer than the duration ..delta..t/sub D/ of the entire direct drive pulse train (t/sub s/ > ..delta..t/sub D/).
Date: October 23, 1986
Creator: Mark, J.W.K. & Lindl, J.D.
Partner: UNT Libraries Government Documents Department

Particle flux measurements with pump limiters

Description: The pressure buildup in pump limiters is a function of the incident particle flux, the pump limiter geometry, particle-surface interactions, and, under certain conditions, nonlinear effects due to interactions of the neutral gas with the incoming plasma. At sufficiently low density and for short pump limiter throat, the pressure observed in the pump limiter chamber is a direct measure of the particle flux at the limiter slot. This paper discusses a simple model for the correlation between particle flux and pump limiter pressure. In addition, some estimates are presented on the thermalization of fast neutrals in the pump limiter duct and its implications for ''enhanced particle collection.''
Date: January 1, 1986
Creator: Mioduszewski, P.
Partner: UNT Libraries Government Documents Department

High beta plasmas in the PBX tokamak

Description: Bean-shaped configurations favorable for high ..beta.. discharges have been investigated in the Princeton Beta Experiment (PBX) tokamak. Strongly indented bean-shaped plasmas have been successfully formed, and beta values of over 5% have been obtained with 5 MW of injected neutral beam power. These high beta discharges still lie in the first stability regime for ballooning modes, and MHD stability analysis implicates the external kink as responsible for the present ..beta.. limit.
Date: April 1, 1986
Creator: Bol, K.; Buchenauer, D.; Chance, M.; Couture, P.; Fishman, H.; Fonck, R. et al.
Partner: UNT Libraries Government Documents Department

Enhancement of confinement in tokamaks

Description: A plausible interpretation of the experimental evidence is that energy confinement in tokamaks is governed by two separate considerations: (1) the need for resistive MHD kink-stability, which limits the permissible range of current profiles - and therefore normally also the range of temperature profiles; and (2) the presence of strongly anomalous microscopic energy transport near the plasma edge, which calibrates the amplitude of the global temperature profile, thus determining the energy confinement time tau/sub E/. Correspondingly, there are two main paths towards the enhancement of tokamak confinement: (1) Configurational optimization, to increase the MHD-stable energy content of the plasma core, can evidently be pursued by varying the cross-sectional shape of the plasma and/or finding stable radial profiles with central q-values substantially below unity - but crossing from ''first'' to ''second'' stability within the peak-pressure region would have the greatest ultimate potential. (2) Suppression of edge turbulence, so as to improve the heat insulation in the outer plasma shell, can be pursued by various local stabilizing techniques, such as use of a poloidal divertor. The present confinement model and initial TFTR pellet-injection results suggest that the introduction of a super-high-density region within the plasma core should be particularly valuable for enhancing ntau/subE/. In D-T operation, a centrally peaked plasma pressure profile could possibly lend itself to alpha-particle-driven entry into the second-stability regime.
Date: May 1, 1986
Creator: Furth, H.P.
Partner: UNT Libraries Government Documents Department

Geometrical properties of an internal local octonionic space in curved space time

Description: A geometrical treatment on a flat tangent space local to a generalized complex, quaternionic, and octonionic space-time is constructed. It is shown that it is possible to find an Einstein-Maxwell-Yang-Mills correspondence in this generalized (Minkowskian) tangent space. 9 refs.
Date: April 1, 1986
Creator: Marques, S. & Oliveira, C.G.
Partner: UNT Libraries Government Documents Department

Analysis of the FELIX experiments with cantilevered beams and hollow cylinders

Description: Experiments have been performed with the FELIX facility at Argonne National Laboratory to study the coupling between eddy currents and deflections and to provide data for validating eddy current computer programs. Experiments with cantilevered beams in crossed steady and decaying magnetic fields verify that coupling effects act to alleviate the large currents, deflections, and stresses predicted by uncoupled analyses. Measurements of magnetic fields induced in conducting hollow cylinders are analyzed by exponential fitting and by transfer functions. Spatial variation in the parameters of the exponential fit and in those of the one- and two-pole transfer functions suggests that several eddy current modes are acting in the cylinder test pieces.
Date: January 1, 1986
Creator: Turner, L.R.; Hua, T.Q. & Lee, S.Y.
Partner: UNT Libraries Government Documents Department

Thermomechanical analysis of solid breeders in sphere-pac, plate, and pellet configurations

Description: The first configuration studied is called sphere-pac. It features small breeder spheres of three different diameters, thus allowing efficient packing and minimal void fraction. The concept originated as an attempt to minimize thermal stresses in the breeder and improve the predictability of the breeder-structure interface heat conduction. In general the breeder is made as thin as possible, to maximize the breeding ratio, so the cladding's integrity will likely be the life-limiting issue of this concept. The third breeder configuration is in the form of pellets cladded by steel tubes. The major thermomechanical issue of the pin-type designs is cracking, which would impair the thermal performance of the blanket. Fortunately, the pins can be sized to prevent cracking under normal operation. In this report we have treated each blanket generically, dealing with basic issues rather than design specifics. Our basic philosophy is to avoid cracking of the breeder if at all possible. It can be argued that cracking could be allowed, but this would sacrifice predictability of the blanket thermal performance and tritium release characteristics. Proper design can and should minimize breeder cracking.
Date: February 1, 1986
Creator: Blanchard, J.P. & Ghoniem, N.M.
Partner: UNT Libraries Government Documents Department

Superstrings and geometry of superspace

Description: These lectures present some recent developments in the sigma-model approach to the Green-Schwarzsuperstring. Among the topics included are: (1) interpretation of the free superstring as a flat superspace sigma-model; (2) propagation of the superstring in curved superspace; and (3) in the presence of background super Yang-Mills fields. The role of the world-sheet fermionic gauge symmetry needed to ensure consistent coupling to background fields is emphasized. 24 refs.
Date: May 1, 1986
Creator: Dhar, A.
Partner: UNT Libraries Government Documents Department

Construction of relativistic quantum theory: a progress report

Description: We construct the particulate states of quantum physics using a recursive computer program that incorporates non-determinism by means of locally arbitrary choices. Quantum numbers and coupling constants arise from the construction via the unique 4-level combinatorial hierarchy. The construction defines indivisible quantum events with the requisite supraluminal correlations, yet does not allow supraluminal communication. Measurement criteria incorporate c, h-bar and m/sub p/ or (not ''and'') G, connected to laboratory events via finite particle number scattering theory and the counter paradigm. The resulting theory is discrete throughout, contains no infinities, and, as far as we have developed it, is in agreement with quantum mechanical and cosmological fact.
Date: June 1, 1986
Creator: Noyes, H.P.
Partner: UNT Libraries Government Documents Department

The effect of target thickness on x-ray production by FXR (Flash X-Ray Machine)

Description: The electron-photon transport code SANDYL has been used to calculate the x-ray flux for a simplified Flash X-Ray Machine (FXR) bullnose geometry. Four different thicknesses (24.5, 36.75, 49, and 61.25 mils) were used for the tantalum bremsstrahlung target in order to study the effect of target thickness on the FXR output. The calculations were performed for a parallel 17 MeV electron beam, and the resulting angular distributions were then used to compute the forward flux for the more realistic case of a converging beam. Over the range of thicknesses studied, the x-ray energy content per steradian on axis was essentially independent of target thickness. The main reason for this is that, while the total x-ray flux coming out of the target increases with increasing target thickness, the angular width of that flux also increases. The implications for target wheel design are discussed. 3 refs., 7 figs.
Date: October 22, 1986
Creator: Back, N.L.
Partner: UNT Libraries Government Documents Department

Anomalies in quantum field theory and differential geometry

Description: Anomalies in field theory appeared first in perturbative computations involving Feynman diagrams. It is only recently that differential geometric techniques have been used to obtain the form of gauge and gravitational anomalies in a direct and simple way. This is possible because of the topological nature of the anomaly. In the first chapter of this thesis the gauged Wess-Zumino action is constructed by differential geometry methods. After reviewing the relevant techniques, an expression for the action valid in any (even) number of space-time dimensions is obtained. This expression is compared with Witten's result in four dimensions. The link between topology and the anomaly is provided by the appropriate index theorem. The index density is a supersymmetric invariant polynomial from which the anomaly and other related objects can be obtained through the use of the ''descent equations.'' A new proof of the Atiyah-Singer index theorem for the Dirac operator is presented. This proof is based on the use of a WKB approximation to evaluate the supertrace of the kernel for a supersymmetric hamiltonian. The necessary WKB techniques are developed and mechanical systems with bosonic and fermionic degrees of freedom are discussed.
Date: April 1, 1986
Creator: Manes, J.L.
Partner: UNT Libraries Government Documents Department