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Electron-Heated Target Temperature Measurements in Petawatt Laser Experiments Based on Extreme Ultraviolet Imaging and Spectroscopy

Description: Three independent methods (XUV spectroscopy, imaging at 68 eV and 256 eV) have been used to measure planar target rear surface plasma temperature due to heating by hot electrons. The hot electrons are produced by ultra-intense laser plasma interactions using the 150 J, 0.5 ps Titan laser. Soft x-ray spectroscopy in the 50-400 eV region and imaging at the 68 eV and 256 eV photon energies were used to determine the rear surface temperature of planar CD targets. Temperatures were found to be in th… more
Date: May 2, 2008
Creator: Ma, T. A.; Beg, F. N.; Macphee, A. G.; Chung, H. K.; Key, M. H.; Mackinnon, A. J. et al.
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Partner: UNT Libraries Government Documents Department
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Temperature sensitivity of Cu K(alpha) imaging efficiency using a spherical Bragg reflecting crystal

Description: The Vulcan laser facility at the Rutherford Appleton Laboratory was used to study the interaction of a 75 J 10 ps, high intensity laser beam with low-mass solid, Cu targets. Two instruments were fielded as diagnostics of the Cu K-shell emission from the targets: A single photon counting CCD spectrometer provided the absolute K{sub {alpha}} yield and a spherically bent Bragg crystal recorded 2D monochromatic images with a spatial resolution of 10 {micro}m. Due to the shifting and broadening of t… more
Date: August 7, 2006
Creator: Akli, K. U.; Key, M. H.; Chung, H. K.; Hansen, S. B.; Freeman, R. R.; Chen, M. H. et al.
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Partner: UNT Libraries Government Documents Department
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Laser coupling to reduced-scale targets at NIF Early Light

Description: Deposition of maximum laser energy into a small, high-Z enclosure in a short laser pulse creates a hot environment. Such targets were recently included in an experimental campaign using the first four of the 192 beams of the National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technology 26, 755 (1994)], under construction at the University of California Lawrence Livermore National Laboratory. These targets demonstrate good laser coupling, reaching a radiation temp… more
Date: August 31, 2005
Creator: Hinkel, D. E.; Schneider, M. B.; Young, B. K.; Holder, J. P.; Langdon, A. B.; Baldis, H. A. et al.
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Partner: UNT Libraries Government Documents Department
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Benchmark Measurements of the Ionization Balance of Non-LTE Gold

Description: The authors present a series of benchmark measurements of the ionization balance of well characterized gold plasmas with and without external radiation fields at electron densities near 10{sup 21} cm{sup -3} and various electron temperatures spanning the range 0.8 to 2.4 keV. They have analyzed time- and space-resolved M-shell gold emission spectra using a sophisticated collisional-radiative model with hybrid level structure, finding average ion changes <Z> ranging from 42 to 50. At the l… more
Date: April 20, 2007
Creator: Heeter, R. F.; Hansen, S. B.; Fournier, K. B.; Foord, M. E.; Froula, D. H.; Mackinnon, A. J. 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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LDRD Final Report - 01-FS-004

Description: This report describes the results from an experimental program to investigate the feasibility of laser produced MeV protons as a diagnostic of electric fields or shock compressed materials. The experimental campaign was very successful, and has led to substantial advances in the characterization and optimization of proton sources from ultra-intense laser-solid interaction. This is a subject of the highest scientific interest [1] and is highly relevant to developing its use as a possible NIF imp… more
Date: January 23, 2002
Creator: Mackinnon, A. J.
Item Type: Refine your search to only Report
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.
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Partner: UNT Libraries Government Documents Department
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Development of Compton Radiography Diagnostics for Inertial Confinement Fusion Implosions

Description: An important diagnostic tool for inertial confinement fusion will be time-resolved radiographic imaging of the dense cold fuel surrounding the hot spot. The measurement technique is based on point-projection radiography at photon energies from 60-200 keV where the Compton effect is the dominant contributor to the opacity of the fuel or pusher. We have successfully applied this novel Compton Radiography technique to the study of the final compression of directly driven plastic capsules at the OM… more
Date: November 16, 2010
Creator: Tommasini, R.; Hatchett, S. P.; Hey, D. S.; Izumi, N.; Koch, J. A.; Landen, O. L. et al.
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Partner: UNT Libraries Government Documents Department
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Neutron spectrometry - An essential tool for diagnosing implosions at the National Ignition Facility

Description: DT neutron yield (Y{sub n}), ion temperature (T{sub i}) and down-scatter ratio (dsr) determined from measured neutron spectra are essential metrics for diagnosing the performance of Inertial Confinement Fusion (ICF) implosions at the National Ignition Facility (NIF). A suite of neutron-Time-Of-Flight (nTOF) spectrometers and a Magnetic Recoil Spectrometer (MRS) have been implemented in different locations around the NIF target chamber, providing good implosion coverage and the redundancy requir… more
Date: May 2, 2012
Creator: Mackinnon, A. J.; Johnson, M. G.; Frenje, J. A.; Casey, D. T.; Li, C. K.; Seguin, F. H. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Shock timing on the National Ignition Facility: the first precision tuning series

Description: Ignition implosions on the National Ignition Facility (NIF) [Lindl et al., Phys. Plasmas 11, 339 (2004)] are driven with a very carefully tailored sequence of four shock waves that must be timed to very high precision in order to keep the fuel on a low adiabat. The first series of precision tuning experiments on NIF have been performed. These experiments use optical diagnostics to directly measure the strength and timing of all four shocks inside the hohlraum-driven, cryogenic deuterium-filled … more
Date: October 27, 2011
Creator: Robey, H. F.; Celliers, P. M.; Kline, J. L. & Mackinnon, A. J.
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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South pole bang-time diagnostic on the National Ignition Facility

Description: The south pole bang-time (SPBT) diagnostic views National Ignition Facility (NIF) implosions through the lower hohlraum laser entrance hole to measure the time of peak x-ray emission (peak compression) in indirect drive implosions. Five chemical-vapor-deposition (CVD) diamond photoconductive detectors (PCD's) with different filtrations and sensitivities record the time-varying x rays emitted by the target. Wavelength-selecting highly oriented pyrolytic graphite (HOPG) crystal mirror monochromat… more
Date: May 1, 2012
Creator: MacPhee, A.; Edgell, D.; Bradley, D. K.; Bond, E. J.; Burns, S.; Callahan, D. A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Reaching Isochoric States of Matter by Ultrashort-Pulse Proton Heating

Description: The aim of this LDRD is to develop two completely new methods for creating and probing warm dense states of matter (plasmas at several eV at solid density), which will enable the direct measurement of fundamental material properties such as the opacity and equation of state (EOS). There is in this warm dense regime an almost complete lack of quantitative experimental data--primarily because of the difficulty in creating uniform, single temperature/density plasmas on which to make measurements. … more
Date: February 28, 2005
Creator: Patel, P. K.; Mackinnon, A. J.; Allen, M.; Foord, M. E.; Shepherd, R. & Price, D. F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Integrated Laser-Target Interaction Experiments on the RAL Petawatt Laser

Description: Since the construction of the first Petawatt laser on the Nova laser facility at Lawrence Livermore National Laboratory we are witnessing the emergence of similar Petawatt-class laser systems at laboratories all around the world. This new generation of lasers, able to deliver several hundred joules of energy in a sub-picosecond pulse, has enabled a host of new discoveries to be made and continues to provide a valuable tool to explore new regimes in relativistic laser-plasma physics--encompassin… more
Date: October 11, 2006
Creator: Patel, P. K.; Key, M. H.; Mackinnon, A. J.; Berry, R.; Borghesi, M.; Chambers, D. M. 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
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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
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Imaging of Plasmas using Proton Beams Generated by Ultra-Intense Laser Pulses

Description: Proton imaging is a diagnostic with enormous potential for the investigation of fundamental plasma physics problems which were impossible to explore up to now. By using this diagnostic, for the first time the measurement of transient electric fields in dense plasmas has been obtained, determining their evolution on a picosecond scale with micrometric spatial resolution. The data is of great relevance to Inertial Confinement Fusion both in the conventional and Fast Ignitor approach. Detailed ana… more
Date: January 15, 2002
Creator: Borghesi, M.; Campbell, D. H.; Clarke, R. J.; Galimberti, M.; Gizzi, L. A.; Haines, M. G. et al.
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Partner: UNT Libraries Government Documents Department
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Letter: Meyerhofer

Description: This letter confirms that the Laboratory for Laser Energetics (LLE) was an important part of the FY10 NIF Polar Drive Exploding Pusher experiments on the National Ignition Facility (NIF). These experiments were designed by LLE to produce requested neutron yields to calibrate and qualify nuclear diagnostics. LLE built a deuterium-tritium filling system for the glass shells and provided them to LLNL for mounting. In FY10, four exploding pusher implosions were performed with measured neutron yield… more
Date: January 6, 2011
Creator: Mackinnon, A. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Progress in Long Scale Length Laser-Plasma Interactions

Description: The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 mm and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3{omega}) with a total intensity of 2 x 10{sup 15} W cm{sup -2}. The targets were filled with 1 atm of CO{sub 2} producing of up to 7 mm long homogeneous… more
Date: November 11, 2003
Creator: Glenzer, S. H.; Arnold, P.; Bardsley, G.; Berger, R. L.; Bonanno, G.; Borger, T. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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