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Simultaneous measurement of the average ion-induced electron emission yield and the mean charge for isotachic ions in carbon foils

Description: Article discussing the simultaneous measurement of the average ion-induced electron emission yield and the mean charge for isotachic ions in carbon foils.
Date: February 1997
Creator: Arrale, A. M.; Zhao, Z. Y.; Kirchhoff, J. F.; Weathers, Duncan L.; McDaniel, Floyd Del. (Floyd Delbert), 1942- & Matteson, Samuel E.
Partner: UNT College of Arts and Sciences

Measurement of RT amplitudes and wavelengths of laser driven plates

Description: A laser drive plate, that is a dense solid plate drive by a laser heated, lower density plasma, is inherently Raleigh-Taylor (R-T) unstable, We have previously indicated that observed surface perturbation on the plate are probably R-T instabilities, initiated by the mode structure of the driving laser beam. Using a semi- transparent impact target viewed with a polarized Epi-Illuminated Confocal Streak Microscope, has allowed us to measure the amplitude and growth of the instability.
Date: October 16, 1997
Creator: Frank, A.M. & Gillespie, C.H.
Partner: UNT Libraries Government Documents Department

Nova experiments to investigate hydrodynamic instabilities in the solid state

Description: Experiments were done to shock compress and accelerate copper foils at peak presssures of {approximately}3 Mbar above and below the melt temperature to study the effects of material strength on hydrodynamic instabilities. An x-ray drive generated in a hohlraum target was used to generate the shock wave profiles. The growth of a preimposed perturbation at an embedded interface is diagnosed by x-ray radiography. Results obtained using a high contrastshaped laser pulse show that the growth of the modulation is delayed compared to fluid simulations,which could be due to material strength stabilization. In contrast, when a copper foil is placed above the melt temperature at {gt}3 Mbar with a single shock, it melts upon compression and the modulation growth is consistent with fluid modeling. Experimental results from copper shocked to 3 Mbar both below and above the melt temperature are presented and compared with simulation.
Date: July 8, 1997
Creator: Kalantar, D.H.; Remington, B.A.; Chandler, E.A.; Colvin, J.D.; Griswold, D.L.; Turner, R.E. et al.
Partner: UNT Libraries Government Documents Department

OPTIMIZATION OF FISSION FRAGMENT CATCHER FOIL EXPOSURE TIME

Description: The exposure-time for fission fragment catcher foils, used in nuclear reactor power mapping, was arbitrarily set at 20 minutes. Work performed to evaluate this choice and to attempt an optimization of the exposure time is reported. A true optimum was not found. Forty minute runs are suggested, however, as a practical optimization and as an alternative to the 20 minute runs in current usage. (auth)
Date: January 1, 1958
Creator: Renaker, J.N. & Clark, R.G.
Partner: UNT Libraries Government Documents Department

Eutectic bonding of a Ti sputter coated, carbon aerogel wafer to a Ni foil

Description: The formation of high energy density, storage devices is achievable using composite material systems. Alternate layering of carbon aerogel wafers and Ni foils with rnicroporous separators is a prospective composite for capacitor applications. An inherent problem exists to form a physical bond between Ni and the porous carbon wafer. The bonding process must be limited to temperatures less than 1000{degrees}C, at which point the aerogel begins to degrade. The advantage of a low temperature eutectic in the Ni-Ti alloy system solves this problem. Ti, a carbide former, is readily adherent as a sputter deposited thin film onto the carbon wafer. A vacuum bonding process is then used to join the Ni foil and Ti coating through eutectic phase formation. The parameters required for successfld bonding are described along with a structural characterization of the Ni foil-carbon aerogel wafer interface.
Date: June 1, 1994
Creator: Jankowski, A.F.; Hayes, J.P. & Kanna, R.L.
Partner: UNT Libraries Government Documents Department

Calculation of electron emission from a tantalum foil irradiated by 100-kV and 50-kV x-rays

Description: Two Monte Carlo programs, XITRAN and XMTRAN, were developed for calculating the emission of electrons from high-Z foils irradiated with x rays. XITRAN follows all individual elastic collisions of electrons with atoms, whereas XMTRAN uses the condensed-random-walk model. Both codes take into account photo-electrons, fluorescence radiation, and Auger electrons. Comparisons are made with an experiment by Dolan at Sandia Laboratories involving the backward and forward emission of electrons from a tantalum foil irradiated by 100-kV and 50-kV x-ray beams. There is good agreement between results from the XITRAN and XMTRAN codes. There emitted per incident x-ray photon, and in regard to the angular distribution of the emerging electrons. In regard to the electron energy spectra, there is fair agreement down to a spectral energy of 20 keV, whereas below 20 keV the calculated spectra lie considerably below the measurements.
Date: March 1, 1998
Creator: Berger, M.J.
Partner: UNT Libraries Government Documents Department

Stainless Steel Foil with Improved Creep-Resistance for Use in Primary Surface Recuperators for Gas Turbine Engines

Description: Primary surface recuperators (PSRs) are compact heat-exchangers made from thin-foil type 347 austenitic stainless steel, which boost the efficiency of land-based gas turbine engines. Solar Turbines uses foil folded into a unique corrugated pattern to maximize the primary surface area for efficient heat transfer between hot exhaust gas on one side, and the compressor discharge air on the other side of the foil. Allegheny-Ludlum produces 0.003 - 0.0035 in. thick foil for a range of current turbine engines using PSRs that operate at up to 660 degrees C. Laboratory-scale processing modification experiments recently have demonstrated that dramatic improvements can be achieved in the creep resistance of such typical 347 stainless steel foils. The modified processing enables fine NbC carbide precipitates to develop during creep at 650-700 degrees C, which provides strength even with a fine grain size. Such improved creep-resistance is necessary for advanced turbine systems that will demand greater materials performance and reliability at higher operating conditions. The next challenges are to better understand the nature of the improved creep resistance in these 347 stainless steel foil, and to achieve similar improvements with scale-up to commercial foil production.
Date: October 12, 1998
Creator: Browning, P. F.; Fitzpatrick, M.; Grubb, J. F.; Klug, R. C.; Maziasz, P. J.; Montague, J. P. et al.
Partner: UNT Libraries Government Documents Department

LIFE TIME OF CARBON STRIPPING FOILS FOR THE SPALLATION NEUTRON SOURCE.

Description: SNS requires thick carbon stripping foils (200 to 400 {micro}g/cm{sup 2} thick) to minimize the injection loss due to H{sup 0} emerging from the foil and the circulating beam loss due to Coulomb and nuclear scattering on the foil. Lifetimes of different types thick carbon foils had been measured in BNL Linac, using a 750 keV 6.7 Hz H{sup {minus}} beam. Beam current ({approximately}2 mA over a beam pulse) was selected such that the energy deposition on the foil would be equivalent to that by the SNS injected beam, which will be a 1 GeV 60 Hz H{sup {minus}} beam with a maximum average beam current of 2 mA (or 32 mA over a beam pulse). The tested foils included commercial carbon foils (made by Arizona Carbon Foil Co.), LANL carbon foils (by the mCADAD method), and diamond films prepared from a silicon wafer with a diamond film coating (made by Goodfellow Corp.). Foils were either single-layered or double-layered and were either with or without carbon fiber supports. The results showed that the diamond film had the longest lifetime. The relationship between the foil lifetime and the expected maximum temperature on the foil is also presented in the paper, using the 200{micro}g/cm{sup 2} thick Arizona carbon foils, which are supported by 5 {micro}m diameter carbon wires.
Date: June 18, 2001
Creator: LIAW,C.J.; LEE,Y.Y. & TUOZZOLO,J.
Partner: UNT Libraries Government Documents Department

Carbon stripper foils used in the Los Alamos PSR

Description: Carbon stripper foils produced by the modified controlled ACDC arc discharge method (mCADAD) at the Institute for Nuclear Study have been tested and used for high current 800-MeV beam production in the Proton Storage Ring (PSR) since 1993. Two foils approximately 110 {mu}g/cm{sup 2} each are sandwiched together to produce an equivalent 220 {mu}g/cm{sup 2} foil. The foil sandwitch is supported by 4-5 {mu}m diameter carbon filters attached to an aluminum frame. These foils have survived as long as five months during PSR normal beam production of near 70 {mu}A average current on target. Typical life-times of other foils vary from seven to fourteen days with lower on-target average current. Beam loss data also indicate that these foils have slower shrinkage rates than standard foils. Equipment has been assembled and used to produce foils by the mCADAD method at Los Alamos. These foils will be tested during 1997 operation.
Date: December 1, 1997
Creator: Borden, M.J.; Plum, M.A. & Sugai, I.
Partner: UNT Libraries Government Documents Department