TITLE

Convergent ablator performance measurements

AUTHOR(S)
Hicks, D. G.; Spears, B. K.; Braun, D. G.; Olson, R. E.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L.
PUB. DATE
October 2010
SOURCE
Physics of Plasmas;Oct2010, Vol. 17 Issue 10, p102703
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other convergent ablator performance parameters have been measured using a single streaked x-ray radiograph. Traditional Abel inversion of such a radiograph is ill-posed since backlighter intensity profiles and x-ray attenuation by the ablated plasma are unknown. To address this we have developed a regularization technique which allows the ablator density profile ρ(r) and effective backlighter profile I0(y) at each time step to be uniquely determined subject to the constraints that ρ(r) is localized in radius space and I0(y) is delocalized in object space. Moments of ρ(r) then provide the time-resolved areal density, mass, and average radius (and thus velocity) of the remaining ablator material. These results are combined in the spherical rocket model to determine the ablation pressure and mass ablation rate during the implosion. The technique has been validated on simulated radiographs of implosions at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)] and implemented on experiments at the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)].
ACCESSION #
54858498

 

Related Articles

  • Streaked radiography measurements of convergent ablator performance (invited). Hicks, D. G.; Spears, B. K.; Braun, D. G.; Olson, R. E.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L. // Review of Scientific Instruments;Oct2010, Vol. 81 Issue 10, p10E304 

    The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other ablator rocket parameters have been measured using a single streaked x-ray radiograph. A regularization...

  • Reconstruction of 2D x-ray radiographs at the National Ignition Facility using pinhole tomography (invited). Field, J. E.; Rygg, J. R.; Barrios, M. A.; Benedetti, L. R.; Döppner, T.; Izumi, N.; Jones, O.; Khan, S. F.; Ma, T.; Nagel, S. R.; Pak, A.; Tommasini, R.; Bradley, D. K.; Town, R. P. J. // Review of Scientific Instruments;2014, Vol. 85 Issue 11, p1 

    Two-dimensional radiographs of imploding fusion capsules are obtained at the National Ignition Facility by projection through a pinhole array onto a time-gated framing camera. Parallax among images in the image array makes it possible to distinguish contributions from the capsule and from the...

  • AXIS: An instrument for imaging Compton radiographs using the Advanced Radiography Capability on the NIF. Hall, G. N.; Izumi, N.; Tommasini, R.; Carpenter, A. C.; Palmer, N. E.; Zacharias, R.; Felker, B.; Holder, J. P.; Allen, F. V.; Bell, P. M.; Bradley, D.; Montesanti, R.; Landen, O. L. // Review of Scientific Instruments;2014, Vol. 85 Issue 11, p1 

    Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System)...

  • A wedged-peak-pulse design with medium fuel adiabat for indirect-drive fusion. Zhengfeng Fan; He, X. T.; Jie Liu; Guoii Ren; Bin Liu; Junfeng Wu; Wang, L. F.; Wenhua Ye // Physics of Plasmas;2014, Vol. 21 Issue 10, p1 

    In the present letter, we propose the design of a wedged-peak pulse at the late stage of indirect drive. Our simulations of one- and two-dimensional radiation hydrodynamics show that the wedged-peakpulse design can raise the drive pressure and capsule implosion velocity without significantly...

  • Effects of variable x-ray preheat shielding in indirectly driven implosions. Landen, O. L.; Keane, C. J.; Hammel, B. A.; Levedahl, W. K.; Armendt, P. A.; Colvin, J. D.; Cable, M. D.; Cook, R.; Haan, S. W.; Dittrich, T. R.; Hatchett, S. P.; Hay, R. G.; Lerche, R. A.; McEachern, R.; Murphy, T. J.; Nelson, M. B.; Suter, L.; Wallace, R. J. // Physics of Plasmas;May96, Vol. 3 Issue 5, p2094 

    The performance of indirectly driven fusion capsules has been improved by mid Z doping of the plastic capsule ablator. The doping increases x-ray preheat shielding leading to a more isentropic compression, higher convergence, and higher neutron yield. A 43 increase in neutron yield is both...

  • Freezing and melting of water in a single cylindrical pore: The pore-size dependence of freezing and... Morishige, Kunimitsu; Kawano, Keiji // Journal of Chemical Physics;3/8/1999, Vol. 110 Issue 10, p4867 

    Studies the freezing and melting behavior of water in a single cylindrical pore. X-ray diffraction measurements of water confined inside the cylindrical pores of seven kinds of siliceous MCM-41 mesoporous materials; Size-dependent supercooling of water confined to the mesopores.

  • Surface melting on small particles. Peters, Kevin F.; Yip-Wah Chung // Applied Physics Letters;10/20/1997, Vol. 71 Issue 16, p2391 

    Observes surface melting on small particles using x-ray diffraction from lead crystallites. Dependence of melting temperature on particle size; Distinctions between melting and surface melting; Attainment of a sharp crystallite size distribution by melting the smaller particles.

  • 4.8-keV x-ray backlight framing method for observing images of soft-x-ray-driven fusion capsules. Katayama, M.; Shiraga, H.; Nakai, M.; Kobayashi, T.; Kato, Y. // Review of Scientific Instruments;Mar93, Vol. 64 Issue 3, p706 

    We report on a diagnostic method for observing the implosion asymmetry of soft-x-ray-driven fusion capsules. The method consists of an x-ray backlight source using a 4.8-keV quasi-monochromatic titanium x-ray source and a fast multiframe x-ray imaging system. With the proper combination of...

  • Two-axis goniometer for reflectivity measurements of x-ray diffractors used in fusion research... Peacock, N.J.; Barnsley, R.; O'Mullane, A. Patel M.; Singleton, M.; Ashall, J. // Review of Scientific Instruments;Jan1995, Vol. 66 Issue 1, p529 

    Describes the application of two-axis goniometer for reflective measurements of x-ray diffractors in fusion research. Method of placing the emissivities on an absolute basis; Sensitivity of the spectrometer constructed in terms of the efficiencies of separate components.

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics