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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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A Bremsstrahlung Spectrometer using k-edge and Differential Filters with Image plate dosimeters

Description: A Bremsstrahlung spectrometer using k-edge and differential filtering has been used with Image Plate dosimeters to measure the x-ray fluence from short-pulse laser/target interactions. An electron spectrometer in front of the Bremsstrahlung spectrometer deflects electrons from the x-ray line of sight and simultaneously measures the electron spectrum. The response functions were modeled with the Monte Carlo code Integrated Tiger Series 3.0 and the dosimeters calibrated with radioactive sources. … more
Date: May 2, 2008
Creator: Chen, C.; Mackinnon, A.; Beg, F.; Chen, H.; Key, M.; King, J. A. et al.
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Partner: UNT Libraries Government Documents Department
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Fast Electron Generation in Cones with Ultra-Intense Laser Pulses

Description: Experimental results from copper cones irradiated with ultra-intense laser light are presented. Spatial images and total yields of Cu K{sub {alpha}} fluorescence were measured as a function of the laser focusing properties. The fluorescence emission extends into the cone approximately 300 {micro}m from the cone tip and cannot be explained by ray tracing including cone wall absorption. In addition the total fluorescence yield from cones is an order of magnitude higher than for equivalent mass fo… more
Date: December 7, 2007
Creator: Mackinnon, A.; VanWoerkom, L.; Akli, K.; Bartal, T.; Beg, F.; Chawla, S. et al.
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Partner: UNT Libraries Government Documents Department
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Extreme Ultraviolet Imaging of Electron Heated Targets in Petawatt Laser Experiments

Description: The study of the transport of electrons, and the flow of energy into a solid target or dense plasma, is instrumental in the development of fast ignition inertial confinement fusion. An extreme ultraviolet (XUV) imaging diagnostic at 256 eV and 68 eV provides information about heating and energy deposition within petawatt laser-irradiated targets. XUV images of several irradiated solid targets are presented.
Date: November 29, 2007
Creator: Ma, T.; MacPhee, A.; Key, M.; Akli, K.; Mackinnon, A.; Chen, C. et al.
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Partner: UNT Libraries Government Documents Department
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Diagnostics for Fast Ignition Science

Description: The concept for Electron Fast Ignition Inertial Confinement Fusion demands sufficient laser energy be transferred from the ignitor pulse to the assembled fuel core via {approx}MeV electrons. We have assembled a suite of diagnostics to characterize such transfer. Recent experiments have simultaneously fielded absolutely calibrated extreme ultraviolet multilayer imagers at 68 and 256eV; spherically bent crystal imagers at 4 and 8keV; multi-keV crystal spectrometers; MeV x-ray bremmstrahlung and e… more
Date: May 6, 2008
Creator: MacPhee, A.; Akli, K.; Beg, F.; Chen, C.; Chen, H.; Clarke, R. 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
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.
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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.
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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
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