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Dynamics of gas-filled hohlraums

Description: In order to prevent high-Z plasma from filling in the hohlraum in indirect drive experiments, a low-Z material, or tamper is introduced into the hohlraum. This material, when fully ionized is typically less than one-tenth of the critical density for the laser light used to illuminate the hohlraum. This tamper absorbs little of the laser light, thus allowing most of the laser energy to be absorbed in the high-Z material. However, the pressure associated with this tamper is sufficient to keep the… more
Date: April 24, 1995
Creator: Orzechowski, T.J.; Kauffman, R.L. & Kirkwood, R.K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Use of thin wall imaging in the diagnosis of laser heated hohlraums

Description: High-Z, laser heated hohlraums can be made thick enough to contain thermal radiation, yet thin enough to let out x-rays >{approximately}6keV produced by hot, relatively dense blow-off plasma. The authors use such ``thin wall hohlraums`` to observe the physical location of hot, dense, laser produced hohlraum plasmas. This technique has allowed them to come to some understanding of laser transport/deposition, plasma stagnation and bulk plasma filling.
Date: May 14, 1996
Creator: Suter, L.J.; Thiessen, A.R.; Ze, F.; Kauffman, R.; Price, R.H.; Rupert, V.C. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Accelerated screening methods for determining chemical and thermal stability of refreigerant-lubricant mixtures. Part II: Experimental comparison and verification of methods. Final report, volume I

Description: The research reported herein was performed to develop an accelerated screening method for determining the chemical and thermal stabilities of refrigerant/lubricant mixtures. The developed screening method was designed to be safe and to produce accelerated stability rankings that are in agreement with the rankings determined by the current test, Sealed Glass Tube Method to Test the Chemical Stability of Material for Use Within Refrigerant Systems, ANSI/ASHRAE Method 97-1989. The accelerated scre… more
Date: September 1, 1995
Creator: Kauffman, R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Accelerated screening methods for determining chemical and thermal stability of refrigerant-lubricant mixtures, Part II: Experimental comparison and verification of methods. Volume 2, In situ conductivity data

Description: Data are presented for the accelerated screening methods for determining chemical and thermal stability of refrigerant-lubricant mixtures.
Date: September 1, 1995
Creator: Kauffman, R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Radiation drive in laser heated hohlraums

Description: Nearly 10 years of Nova experiments and analysis have lead to a relatively detailed quantitative and qualitative understanding of radiation drive in laser heated hohlraums. Our most successful quantitative modelling tool is 2D Lasnex numerical simulations. Analysis of the simulations provides us with insight into the details of the hohlraum drive. In particular we find hohlraum radiation conversion efficiency becomes quite high with longer pulses as the accumulated, high Z blow-off plasma begin… more
Date: November 3, 1995
Creator: Suter, L.J.; Kauffman, R.L. & Darrow, C.B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Improved gas-filled hohlraum performance on Nova with beam smoothing

Description: Gas-filled hohlraums are presently the base line ignition target design for the National Ignition Facility. Initial Nova experiments on gas-filled hohlraums showed that radiation temperature was reduced due to SBS and SRS scattering losses and that implosion symmetry had shifted compared with vacuum hohlraums and calculations. Subsequent single beam experiments imaging thermal x-ray emission showed the shift is due to laser-plasma heating dynamics and filarnentation in a flowing plasma. Experim… more
Date: December 2, 1997
Creator: Kauffman, R. L.; Powers, L. V. & Dixit, S. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Utility of the National Ignition Facility for inertial fusion energy and radiation sciences experiments

Description: NIF is being configured so as to not preclude conduct of radiation experiments that will contribute to evaluating the readiness of military systems and components to withstand radiation environments. The range of possible experimental environments and the flexibility to introduce various types of experimental packages suggests synergism with experiments related to Inertial Fusion Energy development on NIF. Design status of NIF features to support radiation experiments is described, and a relati… more
Date: June 14, 1996
Creator: Tobin, M.; Karpenko, V.; Kauffman, R.; Anderson, A.; Simonson, G.; Kruger, H. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Efficient production of 2--10 keV x-rays by laser heated ``underdense radiators``

Description: The next generation of high power lasers offers the prospect of creating multi-kilovolt x-rays with {gt}10% efficiency. Such efficiencies are achieved with ``underdense radiators``, a non- traditional source of laser generated x-rays. Applications of these sources with the proposed National Ignition Facility (NIF) include volume preheating of experiments; bright, multi-keV backlighting; pumps for fluorescent imaging of capsule dopants and Doppler velocimetry; uniform irradiation of large test o… more
Date: May 22, 1996
Creator: Suter, L. J.; Kauffman, R. L.; Maxon, M. S. & Davis, J. F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Lawrence Livermore National Laboratory's activities to achieve ignition by x-ray drive on the National Ignition Facility

Description: The National Ignition Facility (NIF) is a MJ-class glass laser-based facility funded by the Department of Energy which has achieving thermonuclear ignition and moderate gain as one of its main objectives. In the summer of 1998, the project is about 40% complete, and design and construction is on schedule and on cost. The NIF will start firing onto targets in 2001, and will achieve full energy in 2004. The Lawrence Livermore National Laboratory (LLNL), together with the Los Alamos National Labor… more
Date: July 20, 1998
Creator: Bernat, T. P.; Hammel, B. A.; Kauffman, R. L.; Kilkenny, J. D.; Landen, O. L.; Lindl, J. D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Review of hohlraum coupling

Description: Extensive experiments have been done to characterize laser-heated hohlraum targets for indirect drive inertial fusion. Scattered light and fast electrons from laser-plasma instabilities have been found not to be significant for short wavelength light. Scaling of radiation temperature with laser power has been studied at several Laboratories and can be represented by a simple power balance scaling for experiments using short wavelength light. Measurements of x-ray production and energy loss in h… more
Date: January 30, 1995
Creator: Kauffman, R.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Progress Toward Ignition on the National Ignition Facility

Description: The principal approach to ignition on the National Ignition Facility (NIF) is indirect drive. A schematic of an ignition target is shown in Figure 1. The laser beams are focused through laser entrance holes at each end of a high-Z cylindrical case, or hohlraum. The lasers irradiate the hohlraum walls producing x-rays that ablate and compress the fuel capsule in the center of the hohlraum. The hohlraum is made of Au, U, or other high-Z material. For ignition targets, the hohlraum is {approx}0.5 … more
Date: October 17, 2011
Creator: Kauffman, R L
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The ICF Status and Plans in the United States

Description: The United States continues to maintain its leadership in ICF as it moves toward the goal of ignition. The flagship of the program is the National Ignition Facility (NIF) presently under construction at LLNL. Experiments had begun on the first four beams of the National Ignition Facility just at the time of the last IFSA Conference. Several new successful campaigns have been conducted since then in planar hydrodynamics and hohlraums as well as activating the VISAR diagnostic for equation of sta… more
Date: October 12, 2005
Creator: Moses, E.; Miller, G. & Kauffman, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Hard X-ray and Hot Electron Environment in Vacuum Hohlraums at NIF

Description: Time resolved hard x-ray images (hv > 9 keV) and time integrated hard x-ray spectra (hv = 18-150 keV) from vacuum hohlraums irradiated with four 351 nm wavelength NIF laser beams are presented as a function of hohlraum size and laser power and duration. The hard x-ray images and spectra provide insight into the time evolution of the hohlraum plasma filling and the production of hot electrons. The fraction of laser energy detected as hot electrons (f{sub hot}) and a comparison to a filling mo… more
Date: September 22, 2005
Creator: McDonald, J. W.; Suter, L. J.; Landen, O. L.; Foster, J. M.; Celeste, J. R.; Holder, J. P. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The National Ignition Facility: The World's Largest Laser

Description: The National Ignition Facility (NIF) is a 192-beam laser facility presently under construction at LLNL. When completed, NIF will be a 1.8-MJ, 500-TW ultraviolet laser system. Its missions are to obtain fusion ignition and to perform high energy density experiments in support of the U.S. nuclear weapons stockpile. Four of the NIF beams have been commissioned to demonstrate laser performance including target and beam alignment. During this time, NIF demonstrated on a single-beam basis that it wil… more
Date: September 29, 2005
Creator: Moses, E I; Bibeau, C; Bonanno, R E; Haynam, C A; MacGowan, B J; Kauffman, R L et al.
Item Type: Refine your search to only Article
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.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Superthermal Electron Distribution

Description: This memo discusses the analysis of the high-energy x-ray distribution from a laser-induced plasma to determine the superthermal electron distribution. The methods of deconvolution outlined in I are similar to formulae derived in the literature not including and including effects due to electron stopping. In II the methods are applied to an x-ray spectrum from an Au disc irradiated by ARGUS.
Date: December 20, 2007
Creator: Kauffman, R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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