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Title: Reproducibility of NIF Hohlraum Measurments

Authors:
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Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1239175
Report Number(s):
LLNL-CONF-679201
DOE Contract Number:
AC52-07NA27344
Resource Type:
Conference
Resource Relation:
Conference: Presented at: 57th APS Division of Plasma Physics, Savannah, GA, United States, Nov 16 - Nov 20, 2015
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 70 PLASMA PHYSICS AND FUSION

Citation Formats

Moody, J D, Ralph, J E, Turnbull, D P, Casey, D T, Albert, F, Bachmann, B L, Doeppner, T, Divol, L, Grim, G P, Hohenberger, M, Hoover, M, Kritcher, A, Landen, O L, MacGowan, B J, Michel, P A, Moore, A S, Pino, J E, Schneider, M B, Tipton, R E, Smalyuk, V A, Spears, B, Strozzi, D J, and Widmann, K. Reproducibility of NIF Hohlraum Measurments. United States: N. p., 2015. Web.
Moody, J D, Ralph, J E, Turnbull, D P, Casey, D T, Albert, F, Bachmann, B L, Doeppner, T, Divol, L, Grim, G P, Hohenberger, M, Hoover, M, Kritcher, A, Landen, O L, MacGowan, B J, Michel, P A, Moore, A S, Pino, J E, Schneider, M B, Tipton, R E, Smalyuk, V A, Spears, B, Strozzi, D J, & Widmann, K. Reproducibility of NIF Hohlraum Measurments. United States.
Moody, J D, Ralph, J E, Turnbull, D P, Casey, D T, Albert, F, Bachmann, B L, Doeppner, T, Divol, L, Grim, G P, Hohenberger, M, Hoover, M, Kritcher, A, Landen, O L, MacGowan, B J, Michel, P A, Moore, A S, Pino, J E, Schneider, M B, Tipton, R E, Smalyuk, V A, Spears, B, Strozzi, D J, and Widmann, K. Thu . "Reproducibility of NIF Hohlraum Measurments". United States. doi:. https://www.osti.gov/servlets/purl/1239175.
@article{osti_1239175,
title = {Reproducibility of NIF Hohlraum Measurments},
author = {Moody, J D and Ralph, J E and Turnbull, D P and Casey, D T and Albert, F and Bachmann, B L and Doeppner, T and Divol, L and Grim, G P and Hohenberger, M and Hoover, M and Kritcher, A and Landen, O L and MacGowan, B J and Michel, P A and Moore, A S and Pino, J E and Schneider, M B and Tipton, R E and Smalyuk, V A and Spears, B and Strozzi, D J and Widmann, K},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Nov 05 00:00:00 EST 2015},
month = {Thu Nov 05 00:00:00 EST 2015}
}

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  • Our current OMEGA experimental campaign is developing the thin shell diagnostic for use on NIF with the needed accuracy. The thin shell diagnostic has the advantage of linearity over alternative measurement techniques, so that low-order modes will not corrupt the measurement of high-order modes. Although our random measurement errors are adequate, we need to monitor beam balance and ensure that the thin shells have a uniform thickness.
  • Recently the first hohlraum experiments have been performed at the National Ignition Facility (NIF) in support of indirect drive Inertial Confinement Fusion (ICF) designs. The effects of laser beam smoothing by spectral dispersion (SSD) and polarization smoothing (PS) on the beam propagation in long scale gas-filled pipes has been studied at plasma scales as found in indirect drive gas filled ignition hohlraum designs. The long scale gas-filled target experiments have shown propagation over 7 mm of dense plasma without filamentation and beam break up when using full laser smoothing. Vacuum hohlraums have been irradiated with laser powers up to 6more » TW, 1-9 ns pulse lengths and energies up to 17 kJ to activate several diagnostics, to study the hohlraum radiation temperature scaling with the laser power and hohlraum size, and to make contact with hohlraum experiments performed at the NOVA and Omega laser facilities. Subsequently, novel long laser pulse hohlraum experiments have tested models of hohlraum plasma filling and long pulse hohlraum radiation production. The validity of the plasma filling assessment in analytical models and in LASNEX calculations has been proven for the first time. The comparison of these results with modeling will be discussed.« less
  • The first quad of the NIF provides four nearly collinear f/20 laser beams, which can be treated as a single f/8 beam of maximum energy 16 kJ. We are designing experiments on halfraums in which the composite beam is focused in the plane of the (single) halfraum laser entry hole (LEH) with its symmetry axis collinear with the halfiaum symmetry axis. For most of the calculations, the halfraum diameter is 1.6mm, the LEH is 1.2mm, and axial length is 3.0mm. The incident laser power consists of an early foot followed by a final peak. Peak radiation temperatures for this relativelymore » narrow hohlraum are greater than for wider hohlraums of the same length. Plasma conditions within the halfraum are calculated with Lasnex using azimuthally symmetric, (r,z) geometry, taking into account a polyimide membrane which contains the fill gas (CH{sub 2}) within the halfraum. Estimates for microstructure growth due to the volume crystalline structure within a beryllium slab mounted in the halfraum sidewall are obtained by a post-processor, which applies plasma conditions within the halfraum to an ablatively accelerated, two-dimensional beryllium slab. We present a detailed simulation of the hohlraum conditions resulting from a laser spot of diameter 500 {mu}m, with peak intensity at 3.5 x 10{sup 15} W/cm{sup 2}, a comparison with a simulation with the same power-time profile at an intensity about 1/4 as great, and a comparison with a simulation with more detailed attention to hydro coupling between the gold and gas-fill regions of the hohlraum. We are currently attempting to model the consequences of possible beam filamentation during the pulse.« less
  • No abstract prepared.