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Lithium Pellet Injector Development for NSTX

Description: A pellet injector suitable for the injection of lithium and other low-Z pellets of varying mass into plasmas at precise velocities from 5 to 500 m/s is being developed for use on NSTX (National Spherical Torus Experiment). The ability to inject low-Z impurities will significantly expand NSTX experimental capability for a broad range of diagnostic and operational applications. The architecture employs a pellet-carrying cartridge propelled through a guide tube by deuterium gas. Abrupt deceleration of the cartridge at the end of the guide tube results in the pellet continuing along its intended path, thereby giving controlled reproducible velocities for a variety of pellets materials and a reduced gas load to the torus. The planned injector assembly has four hundred guide tubes contained in a rotating magazine with eight tubes provided for injection into plasmas. A PC-based control system is being developed as well and will be described elsewhere in these Proceedings. The development path and mechanical performance of the injector will be described.
Date: December 4, 2003
Creator: Gettelfinger, G.; Dong, J.; Gernhardt, R.; Kugel, H.; Sichta, P. & Timberlake, J.
Partner: UNT Libraries Government Documents Department

IMPURITIES IN RECLAIMED LEAD CASTINGS

Description: The nature of impurities found in reclaimed Pb and the effects of their inclusion in castings were investigated. It was concluded that impurities are difficult to remove and may result in unwanted casting characteristics. Recommendations for Pb reclamation are listed. (J.R.D.)
Date: August 1, 1958
Creator: Shepherd, D.M.
Partner: UNT Libraries Government Documents Department

Final Report - Effects of Impurities on Fuel Cell Performance and Durability

Description: This program is focused on the experimental determination of the effects of key hydrogen side impurities on the performance of PEM fuel cells. Experimental data has been leveraged to create mathematical models that predict the performance of PEM fuel cells that are exposed to specific impurity streams. These models are validated through laboratory experimentation and utilized to develop novel technologies for mitigating the effects of contamination on fuel cell performance. Results are publicly disseminated through papers, conference presentations, and other means.
Date: August 18, 2012
Creator: Molter, Trent
Partner: UNT Libraries Government Documents Department

Impact of the Wall Conditioning Program on Plasma Performance in NSTX

Description: High performance operating regimes have been achieved on NSTX (National Spherical Torus Experiment) through impurity control and wall-conditioning techniques. These techniques include HeGDC-aided boronization using deuterated trimethylboron, inter-discharge HeGDC, 350 C PFC bake-out followed by D2 and HeGDC, and experiments to test fueling discharges with either a He-trimethylboron mixture or pure trimethylboron. The impact of this impurity and density control program on recent advances in NSTX plasma performance is discussed.
Date: July 12, 2002
Creator: Kuge, H. W.; Soukhanovskii, V.; Bell, M.; Blanchard, W.; Gates, D.; LeBlanc, B. et al.
Partner: UNT Libraries Government Documents Department

Novel materials for laser refrigeration

Description: The status of optical refrigeration of rare-earth-doped solids is reviewed, and the various factors that limit the performance of current laser-cooling materials are discussed. Efficient optical refrigeration is possible in materials for which {Dirac_h}{omega}{sub max} < E{sub p}/8, where {Dirac_h}{omega}{sub max} is the maximum phonon energy of the host material and E{sub p} is the pump energy of the rare-earth dopant. Transition-metal and OH{sup -}impurities at levels >100 ppb are believed to be the main factors for the limited laser-cooling performance in current materials. The many components of doped ZBLAN glass pose particular processing challenges. Binary fluoride glasses such as YF{sub 3}-LiF are considered as alternatives to ZBLAN. The crystalline system KPb{sub 2}CI{sub 5} :Dy{sup 3+} is identified as a prime candidate for high-efficiency laser cooling.
Date: January 1, 2009
Creator: Hehlen, Markus P
Partner: UNT Libraries Government Documents Department

PROGRESS RELATING TO CIVILIAN APPLICATIONS DURING MARCH 1958

Description: The thermal conductivity and electrical resistivity of U encapsulated in Zircaloy-2 with NaK as a heat transfer material were determined prior to irradiation. The short-time rupture strength of 15% cold-worked Zircaloy-2 at 290, 345, and 4OO C is reported. Tests to develop the right-angle method of extrusion cladding of U with Al were continued. Pressure bonding of Al to Niplated U by temperature and gas-pressure tecchniques has produced sound metallurgical bonds. A series of 17 alloy compositions was prepared for corrosion testing in an effort to develop a natural-uranium fuel alloy with improved corrosion resistance. A stsdy of the oxidation of U0/sub 2/ was continued. The corrosion of stainless steel by chloride-contaminated nitric acid solutions is reported. Studies are reported on the solidification of unalloyed U ingots. A study of the reactions that may occur during the induction melting of U is reported. Specimens of enriched UN or UC dispersed in stainless steel and clad with stainless steel were investigated to determine tensile properties at elevated temperatures and resistance to irradiation damage. Electrical resistivity and tensile strength measurements were made on U0/sub 2/ stainless steel cermets at room temperatures. Work has continued on the investigation of hydrides of U-Zr alloys as fueled moderators. Investigations of the radiation stability of U-Zr alloys is presented. Corrosion data are reported on gamma- phase uranium alloys. The preparation of U-Nb alloys is described. Oxidation data on Nb and Nb alloys tested in dry air at 1000 and 12OO C are reported and discussed. Degassing experiments at 450 to 650 C were successfully performed on Nb-H/sub 2/, permitting calculation of diffusion coefficients. Diffusion coefficients for hydrogen in delta zirconium hydride are given. The use of Ti as a construction material continues to appear promising for both dissolver and the feed adjustment tank for the Darex ...
Date: April 1, 1958
Creator: Dayton, R.W. & Tipton, C.R. Jr.
Partner: UNT Libraries Government Documents Department

Processing of Special Metal for Hanford

Description: The object of this project is to reduce the impurities and raise the density of rejected slugs and briquetted turnings from these slugs by recasting the material. Summary and conclusions are (1) slugs and briquettes made from turnings produced when these slugs were machined can be recast with great improvement in quality; (2) casting this material is quite hard on graphite crucibles, but a long-range program might point the way to better graphite usage; (3) this metal run alone gives fair yields (88.8% to 94.8%) if heated to 2500 F and then cooled to 2400 F before pouring. Mixing with virgin metal improves the final quality, but does not materially increase the yield; (4) briquettes should not be mixed with magnesium before recasting.
Date: March 10, 1947
Creator: Oppold, William A.
Partner: UNT Libraries Government Documents Department

Wetting of metals and glasses on Mo

Description: The wetting of low melting point metals and Si-Ca-Al-Ti-O glasses on molybdenum has been investigated. The selected metals (Au, Cu, Ag) form a simple eutectic with Mo. Metal spreading occurs under nonreactive conditions without interdiffusion or ridge formation. The metals exhibit low (non-zero) contact angles on Mo but this requires temperatures higher than 1100 C in reducing atmospheres in order to eliminate a layer of adsorbed impurities on the molybdenum surface. By controlling the oxygen activity in the furnace, glass spreading can take place under reactive or nonreactive conditions. We have found that in the glass/Mo system the contact angle does not decrease under reactive conditions. In all cases, adsorption from the liquid seems to accelerate the diffusivity on the free molybdenum surface.
Date: January 8, 2008
Creator: Saiz, Eduardo; Tomsia, Antoni P.; Saiz, Eduardo; Lopez-Esteban, Sonia; Benhassine, Mehdi; de Coninck, Joel et al.
Partner: UNT Libraries Government Documents Department

RADIATION LEVELS IN THE VICINITY OF THE PURIFICATION DEMINERALIZERS. CORE 1, SEED 1. Test Results T-641306

Description: BS>A test was performed to determine the activity build-up inside the 1AC and 1BD purification demineralizer concrete enclosure. A maximum radiation level of 1100 mr/hr was detected inside the 1AC demineralizer enclosure at a point 10.0 ft from the top. The maximum radiation level inside the 1BD enclosure was 700 mr/hr at a point 9.5 ft below the top. An analysis of data from five tests indicates that the extent of the activity build-up, as well as the level of activity, is definitely increasing. (W.L.H.)
Date: October 10, 1960
Partner: UNT Libraries Government Documents Department

Comparison of impurities and time-dependent behavior for the ITER divertor

Description: This a the second part-of an ongoing project to model the divertor plasma for ITER. The UEDGE 2-D edge transport code is used to study the effect of impurities and tilted divertor plates to make a radiative divertor that can prevent excessive heat loads and adequately pump helium produced by fusion reactions in the core. The impurities are modeled using individual charge states with the local concentrations being determined by transport or as a fixed fraction of the hydrogenic ion density. For the multi-species model, helium, beryllium, carbon, and neon impurities are considered separately, together with the majority hydrogenic species, and a comparison is made of impurity spatial distribution and the power radiated at low impurity levels. At moderate to high impurity levels, typically only time-dependent solutions are found which are studied here for neon using both impurity models.
Date: February 25, 1997
Creator: Rensink, M.E.; Rognlien, T.D. & Hua, D.D.
Partner: UNT Libraries Government Documents Department