489 Matching Results

Search Results

Advanced search parameters have been applied.

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


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

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


Description: A careful determination of /sub 2200/ from results of the Macklin- deSaussure manganese-bath experiment involves corrections for (1) the weak but nonzero transmission of subcadmium neutrons through the uranium or plutonium foils and (2) the small variation of with energy in the subcadmium region. The derivation of a single general expression for applying both these corrections is presented, and two lBM 704 codes (MTC and GTC) which were written especially to facilitate the numerical evaluation of this combined correction factor are described. (auth)
Date: August 17, 1959
Creator: Halbert, E.C.; Maskewitz, B.F. & Wynn, R.L.
Partner: UNT Libraries Government Documents Department

Influence of shockwave profile on ejection of micron-scale material from shocked Sn surfaces: an experimental study

Description: This effort experimentally investigates the relationship between shock-breakout pressure and the amount of micron-scale fragments ejected (ejecta) upon shock release at the metal/vacuum interface of Sn targets shocked with a supported shockwave. The results are compared with an analogous set derived from HE shocked Sn targets, Taylor shockwave loading. The supported shock-pulse was created by impacting a Sn target with a Ti64 (Ti-6Al-4V) impactor that was accelerated using a powder gun. Ejecta production at the free-surface or back-side of the Sn targets were characterized through use of piezoelectric pins and Asay foils, and heterodyne velocimetry verified the time of shock release and the breakout pressure.
Date: January 1, 2009
Creator: Zellner, Michael B; Byers, Mark E; Hammerberg, James E; Germann, Tim C; Dimonte, Guy; Rigg, Paulo A et al.
Partner: UNT Libraries Government Documents Department

Intense ion beams as a tool for opacity measurements in warm dense matter

Description: Opacity measurements in warm dense matter (WDM) provide a valuable benchmark for the diverging theoretical models in this regime. Heating of thin foils with intense heavy-ion beams allows one to create isolated samples of warm dense matter suitable for experimental determination of frequency-dependent opacities. A prerequisite for the measurements is the isothermal expansion of the heated foil. Hydrodynamic simulations predict that this condition is fulfilled. The analysis shows that existing ion-beam accelerators are capable to contribute to this field of research.
Date: January 1, 2009
Creator: Abdallah, Joseph; Tauschwiz, An; Jacoby, J; Maruhn, J A; Novikov, V G; Tauschwitz, A et al.
Partner: UNT Libraries Government Documents Department

The Use of Filamentary Targets to Produce Prolonged Secondary-Particle Beams in the Bevatron

Description: The foil technique for producing secondary-particle beams in a proton synchrotron is extended. Filamentary targets are described that are shown to produce secondaryparticle beams having almost arbitrary time duration and uniform intensity. The physical limitations imposed by available materials are discussed. (auth)
Date: March 1, 1960
Creator: Heard, H. G.
Partner: UNT Libraries Government Documents Department