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in creator/contributor: "MacPhee, A. G."  
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Developing the Physics Basis of Fast Ignition Experiments at Future Large Fusion-class lasers

Description: The Fast Ignition (FI) concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy (IFE) reactors. FI differs from conventional 'central hot spot' (CHS) target ignition by using one driver (laser, heavy ion beam or Z-pinch) to create a dense fuel and a separate ultra-short, ultra-intense laser beam to ignite the dense core. FI targets can burn with {approx} 3X lower density fuel than CHS targets, resu… more
Date: February 8, 2008
Creator: MacKinnon, A. J.; Key, M. H.; Hatchett, S.; MacPhee, A. G.; Foord, M.; Tabak, M. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

High resolution 17 keV to 75 keV backlighters for High Energy Density experiments

Description: We have developed 17 keV to 75 keV 1-dimensional and 2-dimensional high-resolution (< 10 {micro}m) radiography using high-intensity short pulse lasers. High energy K-{alpha} sources are created by fluorescence from hot electrons interacting in the target material after irradiation by lasers with intensity I{sub L} > 10{sup 17} W/cm{sup 2}. We have achieved high resolution point projection 1-dimensional and 2-dimensional radiography using micro-foil and micro-wire targets attached to low-Z… more
Date: February 25, 2008
Creator: Park, H.; Maddox, B. R.; Giraldez, E.; Hatchett, S. P.; Hudson, L.; Izumi, N. et al.
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Partner: UNT Libraries Government Documents Department
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Nail-like targets for laser plasma interaction experiments

Description: The interaction of ultra-high power picosecond laser pulses with solid targets is of interest both for benchmarking the results of hybrid particle in cell (PIC) codes and also for applications to re-entrant cone guided fast ignition. We describe the construction of novel targets in which copper/titanium wires are formed into 'nail-like' objects by a process of melting and micromachining, so that energy can be reliably coupled to a 24 {micro}m diameter wire. An extreme-ultraviolet image of the i… more
Date: December 18, 2007
Creator: Pasley, J.; Wei, M.; Shipton, E.; Chen, S.; Ma, T.; Beg, F. N. et al.
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Partner: UNT Libraries Government Documents Department
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Hot Electron Generation and Transport Using K(alpha) Emission

Description: We have conducted experiments on both the Vulcan and Titan laser facilities to study hot electron generation and transport in the context of fast ignition. Cu wires attached to Al cones were used to investigate the effect on coupling efficiency of plasma surround and the pre-formed plasma inside the cone. We found that with thin cones 15% of laser energy is coupled to the 40{micro}m diameter wire emulating a 40{micro}m fast ignition spot. Thick cone walls, simulating plasma in fast ignition, re… more
Date: October 15, 2009
Creator: Akli, K. U.; Stephens, R. B.; Key, M. H.; Bartal, T.; Beg, F. N.; Chawla, S. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A diamond detector for inertial confinement fusion X-ray bang-time measurements at the National Ignition Facility

Description: An instrument has been developed to measure X-ray bang-time for inertial confinement fusion capsules; the time interval between the start of the laser pulse and peak X-ray emission from the fuel core. The instrument comprises chemical vapor deposited polycrystalline diamond photoconductive X-ray detectors with highly ordered pyrolytic graphite X-ray monochromator crystals at the input. Capsule bang-time can be measured in the presence of relatively high thermal and hard X-ray background compone… more
Date: November 9, 2010
Creator: MacPhee, A. G.; Brown, C.; Burns, S.; Celeste, J.; Glenzer, S. H.; Hey, D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Limitation on Pre-pulse Level for Cone-Guided Fast-Ignition ICF

Description: The viability of fast-ignition (FI) inertial confinement fusion hinges on the efficient transfer of laser energy to the compressed fuel via multi-MeV electrons. Pre-formed plasma due to laser pre-pulse strongly influences ultra-intense laser plasma interactions and hot electron generation in the hollow cone of an FI target. We induced a prepulse and consequent preplasma in copper cone targets and measured the energy deposition zone of the main pulse by imaging the emitted K{sub {alpha}} radiati… more
Date: September 1, 2009
Creator: MacPhee, A. G.; Akli, K. U.; Beg, F. N.; Chen, C. D.; Chen, H.; Divol, L. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A Dual Channel X-ray Spectrometer for Fast Ignition Research

Description: A new Dual Channel Highly Ordered Pyrolytic Graphite (DC-HOPG) x-ray spectrometer was developed to study laser-generated electron beam transport. The instrument uses a pair of graphite crystals and has the advantage of simultaneously detecting self emission from low-Z materials in first diffraction order and high-Z materials in second order. The emissions from the target are detected using a pair of parallel imaging plates positioned in a such way that the noise from background is minimized and… more
Date: April 19, 2010
Creator: Akli, K. U.; Patel, P. K.; Van Maren, R.; Stephens, R. B.; Key, M. H.; Higginson, D. P. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

New approach to jitter reduction of an x-ray streak camera in accumulation mode.

Description: An x-ray streak camera operating in accumulation mode was developed for studying ultrafast dynamics at synchrotron facilities. A laser-triggered photoconductive switch was used as a sweeping unit to obtain low timing jitter. The fast rise time of the ramp pulse generated by the switch (90 ps) combined with the fast response of the traveling wave deflection plates (150 ps) significantly reduced the jitter caused by the shot-to-shot laser fluctuation. At {approx}1% rms (root mean square) laser en… more
Date: July 19, 2002
Creator: Liu, J.; MacPhee, A. G.; Liu, C.; Shan, B.; Wang, J. & Chang, Z.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Clocking Femtosecond X-Rays

Description: The Sub-Picosecond Pulse Source (SPPS) at the Stanford Linear Accelerator Center (SLAC) produces the brightest ultrafast x-ray pulses in the world, and is the first to employ compressed femtosecond electron bunches for the x-ray source. Both SPPS and future X-ray Free Electron Lasers (XFEL's) will use precise measurements of individual electron bunches to time the arrival of x-ray pulses for time-resolved experiments. At SPPS we use electro-optic sampling (EOS) to perform these measurements. He… more
Date: October 8, 2004
Creator: Cavalieri, A. L.; Fritz, D. M.; Lee, S. H.; Bucksbaum, P. H.; Reis, D. A.; Mills, D. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Observation of Structural Anisotropy and the Onset of Liquid-like Motion during the Non-thermal Melting of InSb

Description: The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquid-like dynamics. They also demonstrate that the root mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.
Date: September 30, 2005
Creator: Gaffney, K. J.; Lindenberg, A. M.; Larsson, J.; Sokolowski-Tinten, K.; Blome, C.; Synnergren, O. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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