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Status of fusion maintenance

Description: Effective maintenance will be an essential ingredient in determining fusion system productivity. This level of productivity will result only after close attention is paid to the entire system as an entity and appropriate integration of the elements is made. The status of fusion maintenance is reviewed in the context of the entire system. While there are many challenging developmental tasks ahead in fusion maintenance, the required technologies are available in several high-technology industries, including nuclear fission.
Date: January 1, 1984
Creator: Fuller, G.M.
Partner: UNT Libraries Government Documents Department

Design considerations for achieving high vacuum integrity in fusion devices

Description: Achieving high vacuum integrity in fusion devices requires close attention to both the overall system configuration and the design details of joints and seals. This paper describes the factors in selecting the system configuration, from a vacuum standpoint, for the Princeton Plasma Physics Laboratory (PPPL) DCT-8 Tokamak device. The DCT-8 (driven current tokamak) is the eighth design in a series of tokamak concepts defined to cover the magnetic confinement and development gap between the Tokamak Fusion Test Reactor (TFTR) and the Engineering Test Reactor (ETR). Leak detection concept development is considered a vital activity, as well as the definition of a configuration that minimizes the consequences of leaks. A major part of the vacuum boundaries of the magnet system and the plasma system is common. For the major penetrations, primary and secondary seals are provided with vacuum control over the region between seals. The intent is to instrument these cavities and provide automated recordings of these measurements for leak maintenance.
Date: January 1, 1983
Creator: Fuller, G.M. & Haines, J.R.
Partner: UNT Libraries Government Documents Department

FED pumped limiter configuration issues

Description: Impurity control in the Fusion Engineering Device (FED) is provided by a toroidal belt pumped limiter. Limiter design issues addressed in this paper are (1) poloidal location of the limiter belt, (2) shape of the limiter surface facing the plasma, and (3) whether the belt is pumped from one or both sides. The criteria used for evaluation of limiter configuration features were sensitivity to plasma-edge conditions and ease of maintenance and fabrication. The evaluation resulted in the selection of a baseline FED limiter that is located at the bottom of the device and has a flat surface with a single leading edge.
Date: January 1, 1983
Creator: Haines, J.R. & Fuller, G.M.
Partner: UNT Libraries Government Documents Department

Thermal shock considerations for the TFCX limiter and first wall

Description: Resistance to thermal shock fracture of limiter and first wall surface material candidates during plasma disruption heating conditions is evaluated. A simple, figure-of-merit type thermal shock parameter which provides a mechanism to rank material candidates is derived. Combining this figure-of-merit parameter with the parameters defining specific heating conditions yields a non-dimensional thermal shock parameter. For values of this parameter below a critical value, a given material is expected to undergo thermal shock damage. Prediction of thermal shock damage with this parameter is shown to exhibit good agreement with test data. Applying this critical parameter value approach, all materials examined in this study are expected to experience thermal shock damage for nominal TFCX plasma disruption conditions. Since the extent of this damage is not clear, tests which explore the range of expected conditions for TFCX are recommended.
Date: January 1, 1983
Creator: Haines, J.R. & Fuller, G.M.
Partner: UNT Libraries Government Documents Department

DCT-8 pumped limiter design considerations

Description: Disruption erosion drives the life of the DCT-8 pumped limiter. This result came from an evaluation of beryllium (Be), beryllium oxide (BeO), and silicon carbide (SiC) as candidate surface tile materials. Beryllium oxide was selected as the reference tile materials. Beryllium oxide was selected as the reference tile material because it has the longest life: 13 full power hours (2300 burns at 20 s/burn) or 2.3 years of DCT-8 operation. The fabricability of any of the candidate materials and the ability to survive thermal shock conditions and electromagnetic loads imposed by distuptions are serious concerns. The most desirable materials from an engineering standpoint (graphite and high-Z, e.g., tantalum) were eliminated due to physical considerations.
Date: January 1, 1983
Creator: Fuller, G.M.; Cramer, B.A. & Haines, J.R.
Partner: UNT Libraries Government Documents Department

Generation of fluctuations from the quark-hadron transition in the early universe

Description: We present a model for the generation of isothermal baryon density fluctuations in the early universe associated with the quark-hadron transition. The model is based on thermal nucleation theory for the creation of bubbles of the new phase and on entropy conservation during the phase transition. We find that the baryon number transport characteristics together with the rapid motion of the phase boundary can result in baryon density fluctuations with amplitudes considerably larger than the chemical equilibrium limit. All of these results depend on uncertain quantities associated with the underlying QCD physics. We discuss how uncertainties in these quantities translate into uncertainties in the fluctuation amplitude, shape, and mean separation.
Date: June 1, 1988
Creator: Fuller, G.M.; Mathews, G.J. & Alcock, C.R.
Partner: UNT Libraries Government Documents Department

The quark-hadron phase transition in the early universe

Description: A first order phase transition between the quark-gluon plasma and the hadron gas can have important consequences for cosmology. These consequences result from the generation of isothermal baryon number density fluctuations as the universe passes through the phase transition. Calculations based upon simple models for the statistical mechanics of the two phases indicate that these fluctuations have large amplitude. The fluctuations persist after completion of the phase transition, being slowly damped by diffusion of baryon number. Upon decoupling of neutrons and protons at temperature T /approximately/ 1 MeV, the neutrons begin to diffuse rapidly out of the dense regions and substantial segregation of the neutrons and protons results. Light element nucleosynthesis then occurs at T /approximately/ 0.1 MeV. It is possible to reconcile the observed abundances of the light elements with model universes in which all of the matter is composed of baryons, the cosmological constant is zero, and the geometry is flat. 12 refs., 2 figs.
Date: June 24, 1988
Creator: Alcock, C.R.; Fuller, G.M. & Mathews, G.J.
Partner: UNT Libraries Government Documents Department

Density fluctuations from the quark-hadron epoch and primordial nucleosynthesis

Description: We present a simple thermodynamic model of the quark-hadron transition in the early universe and use this model to estimate how the size of isothermal baryon number fluctuations which emerge from this epoch depend on the temperature of the transition and other uncertain quantities of the underlying QCD physics. We calculate primordial nucleosynthesis in the presence of these fluctuations and find that ..cap omega.. = 1 in baryons is possible only if the measured abundances of /sup 7/Li and /sup 2/H reflect substantial destruction during the evolution of the galaxy. 29 refs., 7 figs.
Date: December 1, 1987
Creator: Fuller, G.M.; Mathews, G.J. & Alcock, C.R.
Partner: UNT Libraries Government Documents Department

First wall-shield design considerations for ETF

Description: ETF reactor designs have been developed for both the bundle divertor (Design 1) and single-null poloidal divertor (Design 2) impurity control concepts. The first wall-shield designs presented for these two reactors are basically the same. Access for repair and replacement is provided by dividing the torus into ten sectors that can be radially removed between adjacent toroidal field (TF) coils. Stainless steel, cooled by borated water, forms the basic structure of these sectors. Water-cooled tube panels, radiation-cooled graphite disruption armor, and water-cooled grraphite runaway electron armor are attached to the inside walls of these sectors to form the plasma chamber. The torus sectors are mounted to and form a vacuum seal with a torus support spool.
Date: January 1, 1980
Creator: Sager, P.H.; Fuller, G.M. & Engholm, B.A.
Partner: UNT Libraries Government Documents Department

Bulk Viscosity, Decaying Dark Matter, and the Cosmic Acceleration

Description: The authors discuss a cosmology in which cold dark-matter particles decay into relativistic particles. They argue that such decays could lead naturally to a bulk viscosity in the cosmic fluid. for decay lifetimes comparable to the present hubble age, this bulk viscosity enters the cosmic energy equation as an effective negative pressure. They investigate whether this negative pressure is of sufficient magnitude to account for the observed cosmic acceleration. They show that a single decaying species in a {Lambda} = 0, flat, dark-matter dominated cosmology can not reproduce the observed magnitude-redshift relation from Type Ia supernovae. However, a delayed bulk viscosity, possibly due to a cascade of decaying particles may be able to account for a significant fraction of the apparent cosmic acceleration. Possible candidate nonrelativistic particles for this scenario include sterile neutrinos or gauge-mediated decaying supersymmetric particles.
Date: September 26, 2006
Creator: Wilson, J R; Mathews, G & Fuller, G M
Partner: UNT Libraries Government Documents Department

FED reactor engineering features

Description: The Fusion Engineering Device (FED) Baseline design incorporates a number of features which were selected to enhance its maintainability, as well as limit cost and achieve reliable operation. An installation of ten TF coils and ten torus sectors was selected on the basis of plasma chamber segmentation studies and TF coil cost tradeoff studies, permitting removal of a torus sector with a single radial motion. The design also features a shield sector support spool which provides a plasma chamber vacuum boundary and access to the shield sectors. The vacuum seals are made at the outboard face of the torus so that they can be readily cut and rewelded. A pumped limiter provides plasma edge definition and impurity control. Ten individual blades are inserted through the shield sector in an arrangement that permits replacement without sector removal. ICRH is used for plasma bulk heating. Two EF coils, which are located inside the TF coil bore, are segmented so that they can be removed if necessary. The removal of the superconducting lower outboard EF coil, which is trapped under the TF coil assembly, presents a problem; consideration is being given to increasing its diameter and relocating it so that it can be lifted up around the TF coils.
Date: January 1, 1982
Creator: Sager, P.H.; Brown, T.G.; Fuller, G.M. & Smith, G.E.
Partner: UNT Libraries Government Documents Department

Electronic Method to Detect Persons Hidden Within Cargo containers

Description: Physical security technologies have been unable to address most `Trojan Horse' scenarios at vehicle portals which provide access through the perimeter of a secure area. Thorough visual searches of vehicle cargo containers are time consuming, involve a number of security personnel and are cursory at best. Vehicles entering or exiting a protected site provide an adversary with an easy pathway across secure boundaries. A method to detect the presence of persons hiding within a vehicle's enclosed cargo container has been developed by LQckheed Martin Energy Systems. The system measures vibrations coupled to the container and generated by the human heart. Each time the human heart beats, it generates a small but measurable shock wave. This shock wave is propagated through the body and transmitted to anything with which the body has contact. This wave is referred to as a baflistocardiograrn and is the mechanical equivalent to an electrocardiogram. Systems have been installed in several State prisons and have been independently tested and evaluated. The effectiveness of the system has been determined by the Thunder Mountain Evaluation Center at Fort Huachuca. Arizona. Sympathetic vibrations of the cargo container's surface can be collected using any of several detection methods, i.e. infrared, Doppler microwave, Doppler ultrasonic wave and geophones. The analog signal delivered by the sensors is passed through an amplifier and a low pass filter and then fed to a microprocessor via an analog to digital converter. When initiated by the operator, anafog signals are recorded for a specific interval of time and rate. At the end of the recording intervaL the data are analysed using wavelet transform techniques and compared with a ballistocardiographic template. If the collected data are similar, the system informs the operator that there is a high degree of probability that a person is within the vehicle. The ...
Date: November 10, 1997
Creator: Fuller, G. M.
Partner: UNT Libraries Government Documents Department

Neutron-transparent first wall for module testing

Description: Major design goals for FED-R are the achievement of: (1) a high level of neutron exposure of the test modules and (2) a capability for rapid changeout of test modules. A major factor in rapid changeout is perceived to be the location of the vacuum boundary. In FED-R this boundary was set at the first wall so that module changeout did not require the plasma chamber to be brought up to atmosphere. Efforts to realize these goals in the design resulted in a neutronically thin outboard wall for the vacuum vessel constructed of 316 stainless steel (SS) with helium as a coolant. A normalized 14-MeV neutron transmission of 0.82 is expected, with an inlet pressure of 2 MPa and a pumping power requirement of 8.7 MW. Other options considered in the study were aluminum as a wall material and water and sodium potassium (NaK) as coolants.
Date: January 1, 1983
Creator: Fuller, G.M.; Cramer, B.A.; Haines, J.R.; Kirchner, J.; Engholm, B.A. & Seki, M.
Partner: UNT Libraries Government Documents Department

Large-basis shell-model technology in nucleosynthesis and cosmology

Description: We discuss various applications of the Lanczos method to describe properties of many-body microscopic systems in nucleosynthesis and cosmology. These calculations include: solar neutrino detectors; beta-decay of excited nuclear states; electron-capture rates during a core-bounce supernova; exotic quarked nuclei as a catalyst for hydrogen burning; and the quark-hadron phase transition during the early universe. 27 refs., 3 figs.
Date: May 1, 1985
Creator: Mathews, G.J.; Bloom, S.D.; Takahashi, K.; Fuller, G.M. & Hausman, R.F. Jr.
Partner: UNT Libraries Government Documents Department

Electrically conducting first wall for the Fusion Engineering Device-A (FED-A) tokamak

Description: The first wall of the FED-A tokamak device must satisy two conflicting requirements. These are long eddy-current-decay time (low electrical resistance) and high neutron transparency. The trade-off between these requirements results in a baseline copper alloy shell design that satisfies the requirements for FED-A: a minimum eddy-current-decay time of 0.55 and a tritium-breeding ratio of 1.2. Aluminum alloys come close to meeting the requirements and would probably work. Stainless steel will not work in this application because shells thin enough to satisfy temperature and stress limits are not thick enough to permit long eddy-current-decay time and avoid disruption-induced melting. The baseline first-wall design is a rib-stiffened, double-wall construction. The total wall thickness is 1.5 cm, including a water-coolant channel of 0.5 cm. The first wall is divided into twelve 30/sup 0/ sectors. Flange rings at the ends of each sector are bolted together to form the torus. Structural support is provided at the top center of each sector.
Date: January 1, 1983
Creator: Cramer, B.A.; Fuller, G.M.; Haines, J.R.; Lee, V.D.; Wiffen, F.W. & Gohar, Y.
Partner: UNT Libraries Government Documents Department

Sterile neutrinos in the early universe

Description: We discuss the role played by right-handed sterile neutrinos in the early universe. We show how well known {sup 4}He constraint on the number of relativistic degrees of freedom at early times limits the equilibration of the right handed neutrino sea with the background plasma. We discuss how this allows interesting constraints to be placed on neutrino properties. In particular, a new limit on the Dirac mass of the neutrino is presented. 12 refs.
Date: November 14, 1990
Creator: Malaney, R.A. (Lawrence Livermore National Lab., CA (USA)) & Fuller, G.M. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Physics)
Partner: UNT Libraries Government Documents Department