Igor E Golovkin

Publications (59) View all

• Source

  Available from: sandia.gov

  Article: Iron-plasma transmission measurements at temperatures above 150 eV.

  J E Bailey, G A Rochau, C A Iglesias, J Abdallah, J J Macfarlane, I Golovkin, P Wang, R C Mancini, P W Lake, T C Moore, M Bump, O Garcia, S Mazevet
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  ABSTRACT: Measurements of iron-plasma transmission at 156+/-6 eV electron temperature and 6.9+/-1.7 x 10(21) cm(-3) electron density are reported over the 800-1800 eV photon energy range. The temperature is more than twice that in prior experiments, permitting the first direct experimental tests of absorption features critical for understanding solar interior radiation transport. Detailed line-by-line opacity models are in excellent agreement with the data.
  Physical Review Letters 01/2008; 99(26):265002. · 7.37 Impact Factor
• Conference Proceeding: Hybrid simulation algorithms for plasma accelerators

  C. Thoma, T.P. Hughes, D. Welch, D. Rose, R. Clark, I. Golovkin, J. MacFarlane
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  ABSTRACT: We describe hybrid particle-in-cell (PIC) algorithms which are used to model plasma jet accelerators for use in fusion energy research and other HEDP applications [1]. An electron-magnetohydrodynamic (EMHD) model has been developed and ported to the EM-PIC code LSP [2] to allow for modeling of dense plasma jets. This model, which uses PIC particles for ions and assumes that the electrons form a fluid which maintains the quasineutrality of the plasma, circumvents the need for prohibitively small timesteps needed to resolve electron plasma frequencies at high densities. Hall physics, important to the description of plasma jets, but usually neglected in standard MHD, are retained in this formulation. Plasma jet simulation results using the EMHD algorithm are presented and are compared to implicit PIC simulations at intermediate plasma densities (∼1016 cm⁻³).
  Pulsed Power Conference, 2007 16th IEEE International; 07/2007
• Source

  Available from: Igor E Golovkin

  Article: Short-N characteristic radiative transfer method in 2D cylindrical RZ coordinates

  Nicolas A. Pereyra, Joseph J. MacFarlane, Pamela R. Woodruff, Igor E. Golovkin, Ping Wang
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  ABSTRACT: We present a new radiative transfer method Short-N Characteristics that is a hybrid between the standard long characteristic methods and the standard short characteristic methods. We have implemented the numerical method within the SPECT3D imaging and spectral analysis application. Numerical experiments have shown that the short-N method is capable of reproducing the accuracy of the long characteristic methods, while delivering the CPU time efficiency of the short characteristic methods. We apply the short-N method to 2.5D cylindrical coordinates, i.e., we assume a 3D problem under azimuthal symmetry leading to a 2D mathematical problem with r-z as the independent spatial coordinates (2DRZ). We are currently working to extend this new method to other geometries.
  04/2007;
• Source

  Available from: S.A. Slutz

  Article: Hot dense capsule-implosion cores produced by Z-pinch dynamic Hohlraum radiation.

  J E Bailey, G A Chandler, S A Slutz, I Golovkin, P W Lake, J J MacFarlane, R C Mancini, T J Burris-Mog, G Cooper, R J Leeper, T A Mehlhorn, T C Moore, T J Nash, D S Nielsen, C L Ruiz, D G Schroen, W A Varnum
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  ABSTRACT: Hot dense capsule implosions driven by Z-pinch x rays have been measured using a approximately 220 eV dynamic Hohlraum to implode 1.7-2.1 mm diameter gas-filled CH capsules. The capsules absorbed up to approximately 20 kJ of x rays. Argon tracer atom spectra were used to measure the T(e) approximately 1 keV electron temperature and the n(e) approximately 1-4 x 10(23) cm(-3) electron density. Spectra from multiple directions provide core symmetry estimates. Computer simulations agree well with the peak emission values of T(e), n(e), and symmetry, indicating reasonable understanding of the Hohlraum and implosion physics.
  Physical Review Letters 03/2004; 92(8):085002. · 7.37 Impact Factor
• Chapter: Core temperature and density gradients in ICF

  J A Koch, T W Barbee, S Dalhed, S Haan, N Izumi, R W Lee, L A Welser, R C Mancini, F J Marshall, D Meyerhofer, T C Sangster, V A Smalyuk, J M Soures, L Klein, I Golovkin
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  ABSTRACT: We have developed a multiple monochromatic x-ray imaging diagnostic that uses an array of pinholes coupled to a multilayer Bragg mirror, and we have used this diagnostic to obtain unique multispectral imaging data of inertial-confinement fusion implosion plasmas. Argon dopants in the fuel allow emission images to be obtained in the Ar He-beta and Ly-beta spectral bands, and these images provide information on core temperature and density profiles. We have analyzed these images to obtain quasi-three-dimensional maps of electron temperature and scaled electron density within the core for several cases of drive symmetry, and we find quantitative and qualitative disagreement with one-dimensional hydrodynamics simulations. We also observed a two-lobed structure evolving for increasingly prolatc-asymmetric drive.
  01/2004: pages 53-60;