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Laser heating of solid matter by light pressure-driven shocks

Description: Heating by irradiation of a solid surface in vacuum with 5 x 10{sup 20} W cm{sup -2}, 0.8 ps, 1.05 {micro}m wavelength laser light is studied by x-ray spectroscopy of the K-shell emission from thin layers of Ni, Mo and V. A surface layer is heated to {approx} 5 keV with an axial temperature gradient of 0.6 {micro}m scale length. Images of Ni Ly{sub {alpha}} show the hot region has a {approx} 25 {micro}m diameter, much smaller than {approx} 70 {micro}m region of K{sub {alpha}} emission. 2D parti… more
Date: May 4, 2007
Creator: Akli, K.; Hansen, S. B.; Kemp, A. J.; Freeman, R. R.; Beg, F. N.; Clark, D. et al.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

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.
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.
Partner: UNT Libraries Government Documents Department
open access

Proton Fast Ignition

Description: No Description Available.
Date: January 27, 2005
Creator: Key, M. H.; Freeman, R. R.; Hatchett, S. P.; MacKinnon, A. J.; Patel, P. K.; Snavely, R. A. et al.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

Proton Beam Focusing and Heating in Petawatt Laser-Solid Interactions

Description: It has recently been demonstrated that femtosecond-laser generated proton beams may be focused. These protons, following expansion of the Debye sheath, emit off the inner concave surface of hemispherical shell targets irradiated at their outer convex pole. The sheath normal expansion produces a rapidly converging proton beam. Such focused proton beams provide a new and powerful means to achieve isochoric heating to high temperatures. They are potentially important for measuring the equation of … more
Date: August 13, 2003
Creator: Snavely, R. A.; Gu, P.; King, J.; Hey, D.; Akli, K.; Zhang, B. B. et al.
Partner: UNT Libraries Government Documents Department
open access

Fast Ignition: Physics Progress in the US Fusion Energy Program and Prospects for Achieving Ignition.

Description: Fast ignition (FI) has significant potential advantages for inertial fusion energy and it is therefore being studied as an exploratory concept in the US fusion energy program. FI is based on short pulse isochoric heating of pre-compressed DT by intense beams of laser accelerated MeV electrons or protons. Recent experimental progress in the study of these two heating processes is discussed. The goal is to benchmark new models in order to predict accurately the requirements for full-scale fast ig… more
Date: October 16, 2002
Creator: Key, M. H.; Andersen, C.; Cowan, T.; Fisch, N.; Freeman, R.; Hatchett, S. et al.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

High Energy K(alpha) Radiography Using High-intensity, Short-pulse Lasers

Description: We have performed experiments using Callisto, the Vulcan 100 TW and the Vulcan Petawatt high intensity lasers to understand the characteristics of high energy, K{alpha} x-ray sources and to implement workable radiography solutions at 20-100 keV. Our measurements show that the K{alpha} size from a simple foil target is larger than 60 {micro}m, far larger than the experiment resolution requirement. The total K{alpha} yield is independent of target thicknesses verifying that refluxing plays a majo… more
Date: November 16, 2005
Creator: Park, H.; Izumi, N.; Key, M. H.; King, J. A.; Koch, J. A.; Landen, O. L. et al.
Partner: UNT Libraries Government Documents Department
open access

LSP Calculations of Cone-Wire Experiments

Description: Recent experiments at the Institute of Laser Engineering (ILE) in Japan [1] and at Rutherford Appleton Laboratory (RAL) in the United Kingdom [2] have shown good coupling of short-pulse high-intensity laser light into high-energy electrons channeled down a narrow fiber. Such target configurations are being considered as backlighter targets on the National Ignition Facility (NIF). We will report on LSP calculations of these cone-wire experiments and other candidate target configurations. These c… more
Date: June 13, 2005
Creator: Town, R. J.; Cottrill, L. A.; Key, M. H.; Kruer, W. L.; Langdon, A. B.; Lasinski, B. F. et al.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

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.
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.
Partner: UNT Libraries Government Documents Department
open access

Gigagauss Magnetic Field Generation From High Intensity Laser Solid Interactions

Description: Intense laser (>10<sup>21</sup> W/cm2 ) sources using pulse compression techniques in the sub-picosecond time frame have been used to create dynamic electric field strenghs in excess of 100 Megavolts/micron with associated magnetic field strengths in the Gigagauss regime. We have begun a series of experiments using the Petawatt Laser system at LLNL to determine the potential of these sources for a variety of applications. Hot electron spectra from laser-target interactions in Au have been measu… more
Date: October 15, 1998
Creator: Cowan, T.; Moran, M.; Hammer, J.; Hatchett, S.; Hunt, A.; Key, M. H. et al.
Partner: UNT Libraries Government Documents Department
open access

The Potential of Fast Ignition and Related Experiments With a Petawatt Laser Facility

Description: A model of energy gain induced by fast ignition of thermonuclear burn in compressed deuterium-tritium fuel, is used to show the potential for 300x gain with a driver energy of 1 M J, if the National Ignition Facility (NIF) were to be adapted for fast ignition. The physics of fast ignition has been studied using a petawatt laser facility at the Lawrence Livermore National Laboratory. Laser plasma interaction in a preformed plasma on a solid target leads to relativistic self-focusing evidenced by… more
Date: April 6, 2000
Creator: Key, M. H.; Campbell, E. M.; Cowan, T. E.; Hatchett, S. P.; Henry, E. A.; Koch, J. A. et al.
Partner: UNT Libraries Government Documents Department
open access

Probing High Density Plasmas With Soft X-Ray Lasers

Description: No Description Available.
Date: August 1, 1997
Creator: Celliers, P.; Barbee, T. W., Jr.; Cauble, R.; Da Silva, L. B.; Decker, C. D.; Kalantar, D. H. et al.
Partner: UNT Libraries Government Documents Department
open access

Measurement by Xuv Laser Radiography of Hydrodynamic Perturbations in Laser Accelerated Thin Foil Targets

Description: A novel diagnostic application of XUV lasers has been developed for the study of the hydrodynamic imprinting of laser speckle pattern on directly driven laser fusion targets. A neon-like Yttrium laser operating at 15.5 nm is used to probe thin foils of Si irradiated with an SSD smoothed laser at 0.35 mm wavelength and 6 10{sup 12} Wcm{sup {minus}2} intensity, simulating the initial phase of irradiation a laser fusion capsule. Measurements of the perturbations in target opacity are made by XUV r… more
Date: July 11, 1995
Creator: Key, M. H.; Kalantar, D. H. & Barbee, T. W., Jr.
Partner: UNT Libraries Government Documents Department
open access

Progress in Fast Ignitor Research With the Nova Petawatt Laser Facility

Description: The physics of fast ignition is being studied using a petawatt laser facility at the Lawrence Livermore National Laboratory. Performance of the PW laser with deformable mirror wavefront control giving intensities up to 3x10{sup 20} Wcm{sup {minus}2} is described. Measurements of the efficiency of conversion of laser energy to relativistic electrons and of their energy spectrum and angular distribution including an observed narrow beam angle of {+-}15{degree}, are reported. Heating by the electr… more
Date: November 10, 1998
Creator: Cowan, T. E.; Hammel, B. A.; Hatchett, S. P.; Henry, E. A.; Key, M. H.; Kilkenny, J. D. et al.
Partner: UNT Libraries Government Documents Department
open access

Studies of Electron Transport and Isochoric Heating and Their Applicability to Fast Ignition

Description: Experimental measurements of electron transport and isochoric heating in 100 J, 1 ps laser irradiation of solid A1 targets are presented. Modeling with a hybrid PIC code is compared with the data and good agreement is obtained using a heuristic model for the electron injection. The relevance for fast ignition is discussed.
Date: October 30, 2003
Creator: Key, M. H.; Amiranoff, F.; Andersen, C.; Batani, D.; Baton, S. D.; Cowan, T. et al.
Partner: UNT Libraries Government Documents Department
open access

Magnetic Guiding for Electron Fast Ignition

Description: No Description Available.
Date: June 22, 2012
Creator: Strozzi, D. J.; Tabak, M.; Larson, D. J.; Shay, H. D.; Divol, L.; Kemp, A. J. et al.
Partner: UNT Libraries Government Documents Department
open access

Properties and Applications of Laser Generated X-Ray Sources

Description: The rapid development of laser technology and related progress in research using lasers is shifting the boundaries where laser based sources are preferred over other light sources particularly in the XUV and x-ray spectral region. Laser based sources have exceptional capability for short pulse and high brightness and with improvements in high repetition rate pulsed operation, such sources are also becoming more interesting for their average power capability. This study presents an evaluation of… more
Date: February 25, 2002
Creator: Smith, R F & Key, M H
Partner: UNT Libraries Government Documents Department
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