10 Matching Results

Search Results

Advanced search parameters have been applied.

Generation of high-power, subpicosecond, submillimeter radiation for applications in novel device development and materials research

Description: This research exploits the high-energy, ultrafast laser technology and high voltage expertise at Los Alamos National Laboratory (LANL) to scale submillimeter-pulse generation with photoconducting antennas to large aperture sizes and high output powers. An experimental and theoretical approach was undertaken with a view towards optimizing the radiated output and determining the technology`s ultimate scalability. This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at LANL.
Date: December 31, 1995
Creator: Taylor, A.J.; Roberts, J.P.; Kurnit, N.A.; Benicewicz, P.K.; Rodriquez, G.; Redondo, A. et al.
Partner: UNT Libraries Government Documents Department

The fabrication of a vanadium-stainless steel test section for MHD testing of insulator coatings in flowing lithium

Description: To test the magnetohydrodynamic (MHD) pressure drop reduction performance of candidate insulator coatings for the ITER Vanadium/Lithium Breeding Blanket, a test section comprised of a V- 4Cr-4Ti liner inside a stainless steel pipe was designed and fabricated. Theoretically, the MHD pressure drop reduction benefit resulting, from an electrically insulating coating on a vanadium- lined pipe is identical to the benefit derived from an insulated pipe fabricated of vanadium alone. A duplex test section design consisting of a V alloy liner encased in a SS pressure boundary provided protection for vanadium from atmospheric contamination during operation at high temperature and obviated any potential problems with vanadium welding while also minimizing the amount of V alloy material required. From the MHD and insulator coating- point of view, the test section outer SS wall and inner V alloy liner can be modeled simply as a wall having a sandwich construction. Two 52.3 mm OD x 2.9 m long V-alloy tubes were fabricated by Century Tubes from 64 mm x 200 mm x 1245 mm extrusions produced by Teledyne Wah Chang. The test section`s duplex structure was subsequently fabricated at Century Tubes by drawing down a SS pipe (2 inch schedule 10) over one of the 53.2 mm diameter V tubes.
Date: December 31, 1996
Creator: Reed, C.B.; Mattas, R.F.; Smith, D.L.; Chung, H.; Tsai, H.-C.; Morgan, G.D. et al.
Partner: UNT Libraries Government Documents Department

A compilation of information on the {sup 31}P(p,{gamma}){sup 32}S reaction and properties of excited levels in {sup 32}S

Description: This report documents a survey of the literature, and provides a compilation of data contained therein, for the {sup 31}P(p,{gamma}){sup 32}S reaction. Attention here is paid mainly to resonance states in the compound-nuclear system {sup 32}S formed by {sup 31}P + p, with emphasis on radiative capture, i.e., gamma-ray decay channels ({sup 32}Si + {gamma}) which populate specific levels in {sup 32}S. The energy region near the proton separation energy for {sup 32}S is especially important in this context for applications in nuclear astrophysics. Properties of the excited states in {sup 32}S are also considered. Summaries of all the located references with significant content are provided and numerical data contained in them are compiled in EXFOR format where applicable.
Date: May 31, 2000
Creator: Smith, D. L. & Daly, J. T.
Partner: UNT Libraries Government Documents Department

Helium behavior in vanadium-based alloys irradiated in the dynamic helium charging experiments

Description: Helium effect of neutron irradiated vanadium alloys, containing titanium, has been studied using Dynamic Helium Charging Experiment (DHCE) in FFTF. Cavity formation was observed only in pure vanadium irradiated at 430 to 600 C and in V-5Ti irradiated at 600 C. No apparent cavity formation was obtained in V-3Ti-1Si and V-4Cr-4Ti. The precipitation of titanium oxide in V-5Ti, V-3Ti-1Si and V-4Cr-4Ti occurred in all irradiation conditions in this study and the precipitates of Ti{sub 5}Si{sub 3} only appeared in V-3Ti-1Si irradiated at 600 C up to 15 dpa with helium generation rate of 4 appmHe/dpa. It is suggested that titanium oxide plays an important role for suppression of cavity formation and swelling from early stage of irradiation. Detail characterization of precipitates and He effect for neutron damages in vanadium alloys are discussed here.
Date: December 31, 1996
Creator: Fukumoto, K.; Matsui, H.; Chung, H.M.; Gazda, J. & Smith, D.L.
Partner: UNT Libraries Government Documents Department

The light ion pulsed power induction accelerator for ETF

Description: Our Engineering Test Facility (ETF) driver concept is based on HERMES III and RHEPP technologies. Actually, it is a scaled-down version of the LMF design incorporating repetition rate capabilities of up to 10 Hz CW. The preconceptual design presented here provides 200-TW peak power to the ETF target during 10 ns, equal to 2-MJ total ion beam energy. Linear inductive voltage addition driving a self-magnetically insulated transmission line (MITL) is utilized to generate the 36-MV peak voltage needed for lithium ion beams. The {approximately} 3-MA ion current is achieved by utilizing many accelerating modules in parallel. Since the current per module is relatively modest ({approximately}300 kA), two-stage or one-stage extraction diodes can be utilized for the generation of singly charged lithium ions. The accelerating modules are arranged symmetrically around the fusion chamber in order to provide uniform irradiation onto the ETF target. In addition, the modules are fired in a programmed sequence in order to generate the optimum power pulse shape onto the target. This design utilizes RHEPP accelerator modules as the principal power source.
Date: December 31, 1994
Creator: Mazarakis, M.G.; Olson, R.E.; Olson, C.L.; Smith, D.L. & Bennett, L.F.
Partner: UNT Libraries Government Documents Department

Measured fast-neutron activation cross sections of Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti at 10.3 and 14.8 MeV and for the continuum neutron spectrum produced by 7-MeV deuterons on a thick Be-metal target

Description: Four identical sample packets containing elemental Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti have been irradiated in three distinct accelerator neutron fields, at Argonne National Laboratory and Los Alamos National Laboratory, USA, and Japan Atomic Energy Research Institute, Tokai, Japan, under the auspices of an International Atomic Energy Agency Coordinated Research Program to investigate the production of long-lived radionuclides for fusion waste disposal applications. Final experimental results are presented here for 13 distinct reactions which ultimately lead to production of the following activities: Ag-106m,108m; Co-60g; Cr-51; Eu-150g, -152g; Hf-175,-179m2; Mn-54; Sc-46g,-47,-48; Tb-158g. The neutron fluence standard used was Ni-58(n,p)Co-58. The measured data include differential cross section values at 10.3 and 14.8 MeV, and integral cross sections for the continuum neutron spectrum produced by 7-MeV deuterons incident on a thick Be-metal target. The U-238(n,f) cross section was also measured at 10.3 MeV as a consistency check on the experimental technique. Some of the results of this study are compared with corresponding values from earlier work at Argonne and from ENDF/B-6. 134 refs., 1 fig., 9 tabs.
Date: December 31, 1991
Creator: Meadows, J. W.; Smith, D. L.; Greenwood, L. R.; Haight, R. C.; Ikeda, Y. & Konno, C.
Partner: UNT Libraries Government Documents Department

Thermal response of substrate structural materials during a plasma disruption

Description: Intense energy fluxes to in-vessel components like the first wall and the divertor plate of a fusion reactor are expected during plasma disruptions. This high energy deposition in short times may cause severe surface erosion of these components resulting from melting and vaporization. Coatings and tile materials are proposed to protect and maintain the integrity of the underneath structural materials from both erosion losses as well as from high thermal stresses encountered during a disruption. The coating thickness should be large enough to withstand both erosion losses and to reduce the temperature rise in the substrate structural material. Yet the coating thickness should be minimized to reduce potential problems from radioactivity, toxicity, and plasma contamination. Tile materials such as graphite and coating materials such as tungsten and beryllium on structural materials like copper and steel are analyzed as potential divertor and first wall design options. The disruption is assumed to be composed of two phases: a thermal quench phase followed by a current quench phase. The minimum coating thickness required to protect the structural material is discussed for range of disruption parameters. 7 refs., 8 figs.
Date: December 31, 1991
Creator: Hassanein, A. & Smith, D. L.
Partner: UNT Libraries Government Documents Department

Structural materials for high-heat flux applications

Description: The structural materials for the ITER, (International Thermonuclear Experimental Reactor) divertor must perform reliably under complex and diverse operating requirements. Only a limited number of materials offer a potential for meeting these requirements for the wide temperature range of interest. The candidate materials considered in the ITER design activity include copper, molybdenum, niobium alloys. Molybdenum alloys being considered include dilute alloys of the TZM type and the Mo-Re system. Niobium alloys under consideration include Nb-V-Zr and Nb-Zr systems. Copper alloys being considered include precipitation strengthened alloys of the Glidcop and MAGT type, alloys of Cu-Mo system and dispersion hardened bronzes. The projected operating conditions for the ITER divertor and the criteria for evaluating the candidate materials are reviewed. This paper summarizes the data base and presents recent experimental results on these candidate divertor structural alloys.
Date: December 31, 1991
Creator: Rybin, V. V. & Smith, D. L.
Partner: UNT Libraries Government Documents Department

The LMF triaxial MITL voltage adder system

Description: The light-ion microfusion driver design consists of multiple accelerating modules fired in coincidence and sequentially in order to provide the desired ion energy, power pulse shape and energy deposition uniformity on an Inertial Confinement Fusion (ICF) target. The basic energy source is a number of Marx generators which, through the appropriate pulse power conditioning, provide the necessary voltage pulse wave form to the accelerating gaps or feeds of each module. The cavity gaps are inductively isolated, and the voltage addition occurs in the center conductor of the voltage adder which is the positive electrode while the electrons of the sheath flow closer to the outer cylinder which is the magnetically insulated cathode electrode. Each module powers a separate two-stage extraction diode which provides a low divergence ion beam. In order to provide the two separate voltage pulses required by the diode, a triaxial adder system is designed for each module. The voltage addition occurs in two separate MITLs. The center hollow cylinder (anode) of the second MITL also serves as the outer cathode electrode for the extension of the first voltage adder MITL. The voltage of the second stage is about twice that of the first stage. The cavities are connected in series to form the outer cylinder of each module. The accelerating modules are positioned radially in a symmetrical way around the fusion chamber. A preliminary conceptual design of the LMF modules with emphasis on the voltage adders and extension MITLs will be presented and discussed.
Date: December 31, 1992
Creator: Mazarakis, M. G.; Smith, D. L.; Bennett, L. F.; Lockner, T. R.; Olson, R. E. & Poukey, J. W.
Partner: UNT Libraries Government Documents Department

Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

Description: Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the {sup 16}O(n,p) {sup 16}N reaction using 14-MeV neutrons produced at the neutron source via the {sup 3}H(d,n) {sup 4}He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second {sup 16}N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1--2 minutes.
Date: December 31, 1995
Creator: Smith, D.L.; Ikeda, Yujiro & Uno, Yoshitomo
Partner: UNT Libraries Government Documents Department