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Title: Prediction of Atomic Scale Instabilities.


Abstract not provided.

; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the 9th U.S. National Congress on Computational Mechanics held July 23-26, 2007 in San Francisco, CA.
Country of Publication:
United States

Citation Formats

Zimmerman, Jonathan A., Delph, Terry J., and Rickman, Jeffrey M. Prediction of Atomic Scale Instabilities.. United States: N. p., 2007. Web.
Zimmerman, Jonathan A., Delph, Terry J., & Rickman, Jeffrey M. Prediction of Atomic Scale Instabilities.. United States.
Zimmerman, Jonathan A., Delph, Terry J., and Rickman, Jeffrey M. Thu . "Prediction of Atomic Scale Instabilities.". United States. doi:.
title = {Prediction of Atomic Scale Instabilities.},
author = {Zimmerman, Jonathan A. and Delph, Terry J. and Rickman, Jeffrey M.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}

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  • Abstract not provided.
  • Experiments on vented gas deflagrations performed in a 35 m/sup 3/ prismatic steel module show that Taylor instabilities may be the dominating mechanism governing the pressure load from even freely vented explosions depending on the point of ignition and venting lay-out. The pressures obtained are higher than expected based on simple volume scaling of previous explosion tests on laboratory scale. The simple volume scaling of vented gas deflagration based on constant burning speed thus seems to be invalid for vessel volumes at least up to 35 m/sup 3/ and is furthermore non-conservative. 5 refs.
  • The stability properties of the magnetotail current sheet against large scale modes is reviewed in the framework of ideal MHD, resistive MHD, and collisionless Vlasov theory. It appears that the small deviations from a plane sheet pinch (in particular a magnetic field component normal to the sheet) are important to explain the transition of the tail from a quiet stable state to an unstable dynamic state. It is found that the tail is essentially stable in ideal MHD, but unstable in resistive MHD, while both stable and unstable configurations are found within collisionless theory. The results favor an interpretation wheremore » the onset of magnetotail dyanmics leading to a sudden thinning of the plasma sheet and the ejection of a plasmoid is caused by the onset of a collisionless instability that either directly leads to the growth of a collisionless tearing mode or via microscopic turbulence to the growth of a resistive mode. The actual onset conditions are not fully explored yet by rigorous methods. The onset may be triggered by local conditions as well as by boundary conditions at the ionosphere or at the magnetopause (resulting from solar wind conditions). 53 refs., 5 figs.« less
  • At the same time we experimentally reproduced the plasma conditions expected within the NIF using plasmas produced by the Nova laser. The plasmas were created by irradiating a thin walled gas balloon or a sealed hohlraum containing of order one atmosphere of a low-Z gas (e.g. C{sub 5}H{sub 12}, C{sub 5}D{sub 12} or CO{sub 2}). When the gas is ionized and heated the resultant plasmas are homogeneous, and of high density ({approximately}10{sup 21} electron/cm{sup 3}) and temperature ({approximately}3 keV) with large scale density scale lengths ({approximately}2 mm). Nine of the Nova beams were used to produce the plasma, the tenthmore » beam was configured as an interaction beam that was sent through the performed plasma after a delay of order 500 psec. The SRS and SBS scattered from the plasma, together with the effects of the plasma on the transmitted beam, were studied as a function of the interaction beam intensity, beam smoothing and plasma constituents. The interaction beam was smoothed by using radon phase plates (RPPs), and 4 different colors within the f/8 beam to mimic the NIF laser architecture. The 4-color set-up divided the f/8 beam in to 4 separate quadrants each of which had its wavelength shifted relative to the other quadrants. The wavelength separation of the colors was approximately 1.4{Angstrom} at 3{omega}. Since each beam quadrant could have its frequency conversion crystals individually tuned for its wavelength, the 4-color scheme approximated ``bandwidth`` on the interaction beam without losing 3{omega} conversion efficiency. We have also studied the use of a laser bandwidth of approximately 0.7{Angstrom} and smoothing by Spectral Dispersion (SSD) with all of the quadrants set at the same color, to further reduce the reflected SBS. These studies were performed with both f/4.3 and f/8 interaction beam focusing.« less