Browsing by Subject "pressure"

Now showing 1 - 7 of 7

Characterization of deuterium clusters mixed with helium gas for an application in beam-target-fusion experiments
(2014-12) Bang, W.; Quevedo, H. J.; Bernstein, A. C.; Dyer, G.; Ihn, Y. S.; Cortez, J.; Aymond, F.; Gaul, E.; Donovan, M. E.; Barbui, M.; Bonasera, A.; Natowitz, J. B.; Albright, B. J.; Fernandez, J. C.; Ditmire, T.; Quevedo, H. J.; Bernstein, A. C.; Dyer, G.; Ihn, Y. S.; Cortez, J.; Aymond, F.; Gaul, E.; Donovan, M. E.; Ditmire, T.
We measured the average deuterium cluster size within a mixture of deuterium clusters and helium gas by detecting Rayleigh scattering signals. The average cluster size from the gas mixture was comparable to that from a pure deuterium gas when the total backing pressure and temperature of the gas mixture were the same as those of the pure deuterium gas. According to these measurements, the average size of deuterium clusters depends on the total pressure and not the partial pressure of deuterium in the gas mixture. To characterize the cluster source size further, a Faraday cup was used to measure the average kinetic energy of the ions resulting from Coulomb explosion of deuterium clusters upon irradiation by an intense ultrashort pulse. The deuterium ions indeed acquired a similar amount of energy from the mixture target, corroborating our measurements of the average cluster size. As the addition of helium atoms did not reduce the resulting ion kinetic energies, the reported results confirm the utility of using a known cluster source for beam-target-fusion experiments by introducing a secondary target gas.
Effect of Sparse-Build Internal Structure on Performance of Fused Deposition Modeling Tools Under Pressure
(University of Texas at Austin, 2016) Meng, S.; Mason, L.; Taylor, G.; Wang, X.; Leu, M.C.; Chandrashekhara, K.
Two different approaches to design a sparse-build tool for fabrication by the fused deposition modeling (FDM) process are compared. One approach uses a 2D lattice structure and the other approach is inspired by topology optimization. Ultem 9085 is used as the material, and the amount of material used to build the tool is kept constant to ensure a fair comparison. A solid tool is also included in the comparison. The performance of the tool under uniform pressure is simulated using finite element analysis (FEA) and the accuracy of the FEA results is verified by comparing them with experimentally measured data for a similar tool. The build material, support material, build time, maximum displacement, and maximum von Mises stress are compared for the three build approaches, with an emphasis on the pros and cons of each sparse-build tool with regards to performance under uniform pressure and fabrication by FDM.
Experimental Testing of Thick Wall Graphite Composite Rings
(0000-00-00) Headifen, R. N.;
Test results are presented from pressurizing thick walled graphite hoop wound composite rings to very high internal radial pressure. Hydraulic pressures exceeding 40,000 psi were obtained. The testing was performed on rings wound whh two different resins, a cyanate ester and a Bismaleimide (BMI) resin. To prevent axial delaminations at these high pressures, a thin bidirectional cloth G 11 lining was used inside the rings. The rings were monitored with strain gages and acoustic probes as the pressure was applied. Flaw-free cyanate ester rings survived the testing, indicating that the nominal transverse (radial) compressive strength of hoop-wound rings is higher than 40,000 psi.
High Viscosity Jetting System for 3D Reactive Inkjet Printing
(University of Texas at Austin, 2013) Yang, H.; He, Y.; Tuck, C.; Wildman, R.; Ashcroft, I.; Dickens, P.; Hague, R.
High viscosity ink is a potential solution for the improvement of current 3D ink jetting technology. In this study, experiments are carried out to study a series of inks with differing viscosities jetted with PicoDot™ jet valves under different process parameters of temperature and pressure. Results show that a wide range of ink materials from low viscosity (water like materials) to very high viscosity (thixotropic materials) can be jetted with the piezoelectric actuated jet valves without the need of solvents and surfactants. The jetting volume can be controlled under certain conditions between 2nl and 15nl. The jetting performances for low, medium and high viscosity inks have been recorded by high-speed video photography.
Letter to H.B. Stenzel from Chester Washburne on 1933-01-16
(1933-01-16) Washburne, Chester
Slow Light And Broadband Coherent Phonon Generation
(2012-02) Wang, Z.; Rakich, P.; Reinke, C.; Camacho, R.; Davids, P.; Wang, Zheng
Recent advance in controlling optical forces using nanostructures suggests that nanoscale optical waveguides are capable of generating coherent acoustic phonons efficiently through a combination of radiation pressure and electrostriction. We discuss the critical roles of group velocity in such processes. This photon-phonon coupling would allow an acoustic intermediary to perform on-chip optical delay with a capacity 10(5) greater than photonic delay lines of the same size.
The role of pressure in inverse design for assembly
(AIP Publishing, 2019-09-10) Lindquist, Beth A.; Jadrich, Ryan B.; Howard, Michael P.; Truskett, Thomas M.
Isotropic pairwise interactions that promote the self-assembly of complex particle morphologies have been discovered by inverse design strategies derived from the molecular coarse-graining literature. While such approaches provide an avenue to reproduce structural corre- lations, thermodynamic quantities such as the pressure have typically not been considered in self-assembly applications. In this work, we demonstrate that relative entropy optimization can be used to discover potentials that self-assemble into targeted cluster morphologies with a prescribed pressure when the iterative simulations are performed in the isothermal-isobaric ensemble. The benefits of this approach are twofold. First, the structure and the thermodynamics associated with the optimized interaction can be controlled simultaneously. Second, by varying the pressure in the optimization, a family of interparticle potentials that all self-assemble the same structure can be systemati- cally discovered, allowing for a deeper understanding of self-assembly of a given target structure and providing multiple assembly routes for its realization. Selecting an appropriate simulation ensemble to control the thermodynamic properties of interest is a general design strategy that could also be used to discover interaction potentials that self-assemble structures having, for example, a specified chemical potential.