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Results Progress and Plans for Magnetized Liner Inertial Fusion (MagLIF) on Z

Peterson, Kyle J.; Slutz, Stephen A.; Sinars, Daniel S.; Sefkow, Adam B.; Gomez, Matthew R.; Awe, Thomas J.; Harvey-Thompson, Adam J.; Geissel, Matthias G.; Schmit, Paul S.; Smith, Ian C.; McBride, Ryan D.; Rovang, Dean C.; Knapp, Patrick K.; Hansen, Stephanie B.; Jennings, Christopher A.; Harding, Eric H.; Porter, John L.; Vesey, Roger A.; Blue, Brent B.; Schroen, Diana G.; Tomlinson, Kurt T.

Abstract not provided.

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TYPE Presentation YEAR 2014
OSTI

Signatures of hot electrons and fluorescence in Mo Kα emission on Z

Physics of Plasmas

Hansen, Stephanie B.; Ampleford, David A.; Cuneo, M.E.; Ouart, N.; Jones, Brent M.; Jennings, C.A.; Dasgupta, A.; Coverdale, Christine A.; Rochau, G.A.; Dunham, Gregory S.; Giuliani, J.L.; Apruzese, J.P.

Recent experiments on the Z accelerator have produced high-energy (17 keV) inner-shell K-alpha emission from molybdenum wire array z-pinches. Extensive absolute power and spectroscopic diagnostics along with collisional-radiative modeling enable detailed investigation into the roles of thermal, hot electron, and fluorescence processes in the production of high-energy x-rays. We show that changing the dimensions of the arrays can impact the proportion of thermal and non-thermal K-shell x-rays. © 2014 AIP Publishing LLC.

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TYPE Conference YEAR 2014
ScopusOSTI

Diagnostic constraints on the amount of cold mass in imploded argon pinches on Z

AIP Conference Proceedings

Apruzese, J.P.; Jones, Brent M.; Giuliani, J.L.; Ouart, N.D.; Thornhill, J.W.; Harvey-Thompson, Adam J.; Ampleford, David A.; Jennings, C.A.; Hansen, Stephanie B.; Moore, N.W.; Lamppa, Derek C.; Coverdale, C.A.; Cuneo, M.E.; Rochau, G.A.

The refurbished Z machine at Sandia National Laboratories has been successfully configured to drive gas-puff Z pinches. A series of experiments using Ar loads produced K-shell yields of 330 ± 9% kJ, with highly reproducible K-shell spectra and power pulses. Using spectroscopic and power data, we are able to constrain the properties of both the cold, non-K-shell radiating mass as well as the hot K-shell component of the pinch plasma. As in previous gas-puff shots on the original version of Z, only about 1/4 to 1/3 of the load mass was heated to temperatures sufficient to produce K-shell x-rays.

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TYPE Conference Poster YEAR 2014
ScopusOSTI

Modified helix-like instability structure on imploding z-pinch liners that are pre-imposed with a uniform axial magnetic field

Physics of Plasmas

Awe, Thomas J.; Owen, Albert C.; Gomez, Matthew R.; Hansen, Stephanie B.; Herrmann, Mark H.; Jones, Michael J.; Mckenney, John M.; Robertson, Grafton K.; Rochau, G.A.; Savage, Mark E.; Stygar, William A.; Jennings, Christopher A.; McBride, Ryan D.; Lamppa, Derek C.; Martin, Matthew; Rovang, Dean C.; Sinars, Daniel S.; Slutz, Stephen A.; Cuneo, M.E.

Abstract not provided.

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TYPE Journal Article YEAR 2014
OSTIDOI

Observations of Modified Three-Dimensional Instability Structure for Imploding z -Pinch Liners that are Premagnetized with an Axial Field

Physical Review Letters

McBride, Ryan D.; Gomez, Matthew R.; Hansen, Stephanie B.; Herrmann, Mark H.; Mckenney, John M.; Robertson, Grafton K.; Rochau, G.A.; Savage, Mark E.; Stygar, William A.; Jennings, Christopher A.; Lamppa, Derek C.; Martin, Matthew; Rovang, Dean C.; Slutz, Stephen A.; Cuneo, M.E.; Owen, Albert C.; Sinars, Daniel S.

Novel experimental data are reported that reveal helical instability formation on imploding z -pinch liners that are premagnetized with an axial field. Such instabilities differ dramatically from the mostly azimuthally symmetric instabilities that form on unmagnetized liners. The helical structure persists at nearly constant pitch as the liner implodes. This is surprising since, at the liner surface, the azimuthal drive field presumably dwarfs the axial field for all but the earliest stages of the experiment. These fundamentally 3D results provide a unique and challenging test for 3D-magnetohydrodynamics simulations.

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TYPE Journal Article YEAR 2013
OSTIDOI

K-α emission spectroscopic analysis from a Cu Z-pinch

High Energy Density Physics

Jones, Brent M.; Ampleford, David A.; Hansen, Stephanie B.

Advances in diagnostic techniques at the Sandia Z-facility have facilitated the production of very detailed spectral data. In particular, data from the copper nested wire-array shot Z1975 provides a wealth of information about the implosion dynamics and ionization history of the pinch. Besides the dominant valence K- and L-shell lines in Z1975 spectra, K-α lines from various ionization stages were also observed. K-shell vacancies can be created from inner-shell excitation and ionization by hot electrons and from photo-ionization by high-energy photons; these vacancies are subsequently filled by Auger decay or resonance fluorescence. The latter process produces the K-α emission. For plasmas in collisional equilibrium, K-α emission usually occurs from highly charged ions due to the high electron temperatures required for appreciable excitation of the K-α transitions. Our simulation of Z1975 was carried out with the NRL 1-D DZAPP non-LTE radiation-hydrodynamics model, and the resulting K- and L-shell synthetic spectra are compared with measured radiation data. Our investigation will focus on K-α generation by both impacting electrons and photons. Synthetic K-α spectra will be generated either by self-consistently calculating the K-shell vacancy production in a full Z-pinch simulation, or by post-processing data from a simulation. The analysis of these K-α lines as well as K- and L-shell emission from valence electrons should provide quantitative information about the dynamics of the pinch plasma.

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TYPE Journal Article YEAR 2013
OSTIDOI

Pulsed-power driven inertial confinement fusion development at Sandia National Laboratories

Proposed for publication in 5th Special Issue of the IEEE Transactions on Plasma Science Z-Pinch Plasmas.

Cuneo, M.E.; Mazarakis, Michael G.; Lamppa, Derek C.; Kaye, Ronald J.; Nakhleh, Charles N.; Bailey, James E.; Hansen, Stephanie B.; McBride, Ryan D.; Herrmann, Mark H.; Lopez, A.; Peterson, Kyle J.; Ampleford, David A.; Jones, Michael J.; Savage, Mark E.; Jennings, Christopher A.; Martin, Matthew; Slutz, Stephen A.; Lemke, Raymond W.; Christenson, Peggy J.; Sweeney, Mary A.; Jones, Brent M.; Yu, Edmund Y.; McPherson, Leroy A.; Harding, Eric H.; Knapp, Patrick K.; Gomez, Matthew R.; Awe, Thomas J.; Stygar, William A.; Leeper, Ramon J.; Ruiz, Carlos L.; Chandler, Gordon A.; Mckenney, John M.; Owen, Albert C.; McKee, George R.; Matzen, M.K.; Leifeste, Gordon T.; Atherton, B.W.; Vesey, Roger A.; Smith, Ian C.; Geissel, Matthias G.; Rambo, Patrick K.; Sinars, Daniel S.; Sefkow, Adam B.; Rovang, Dean C.; Rochau, G.A.

Abstract not provided.

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TYPE Journal Article YEAR 2012
OSTIDOI

Spectroscopic study of z-pinch stagnation on Z

Rochau, G.A.; Bailey, James E.; Coverdale, Christine A.; Ampleford, David A.; Cuneo, M.E.; Jones, Brent M.; Jennings, Christopher A.; Yu, Edmund Y.; Hansen, Stephanie B.

Fast z-pinches provide intense 1-10 keV photon energy radiation sources. Here, we analyze time-, space-, and spectrally-resolved {approx}2 keV K-shell emissions from Al (5% Mg) wire array implosions on Sandia's Z machine pulsed power driver. The stagnating plasma is modeled as three separate radial zones, and collisional-radiative modeling with radiation transport calculations are used to constrain the temperatures and densities in these regions, accounting for K-shell line opacity and Doppler effects. We discuss plasma conditions and dynamics at the onset of stagnation, and compare inferences from the atomic modeling to three-dimensional magneto-hydrodynamic simulations.

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TYPE Conference YEAR 2010
OSTI

Doppler effects on 3-D non-LTE radiation transport and emission spectra

Hansen, Stephanie B.; Jones, Brent M.; Ampleford, David A.; Bailey, James E.; Rochau, G.A.; Coverdale, Christine A.; Jennings, Christopher A.; Cuneo, M.E.

Spatially and temporally resolved X-ray emission lines contain information about temperatures, densities, velocities, and the gradients in a plasma. Extracting this information from optically thick lines emitted from complex ions in dynamic, three-dimensional, non-LTE plasmas requires self-consistent accounting for both non-LTE atomic physics and non-local radiative transfer. We present a brief description of a hybrid-structure spectroscopic atomic model coupled to an iterative tabular on-the-spot treatment of radiative transfer that can be applied to plasmas of arbitrary material composition, conditions, and geometries. The effects of Doppler line shifts on the self-consistent radiative transfer within the plasma and the emergent emission and absorption spectra are included in the model. Sample calculations for a two-level atom in a uniform cylindrical plasma are given, showing reasonable agreement with more sophisticated transport models and illustrating the potential complexity - or richness - of radially resolved emission lines from an imploding cylindrical plasma. Also presented is a comparison of modeled L- and K-shell spectra to temporally and radially resolved emission data from a Cu:Ni plasma. Finally, some shortcomings of the model and possible paths for improvement are discussed.

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TYPE Conference YEAR 2010
OSTI

Scaling of X pinches from 1 MA to 6 MA

Sinars, Daniel S.; McBride, Ryan D.; Wenger, D.F.; Cuneo, M.E.; Yu, Edmund Y.; Harding, Eric H.; Hansen, Stephanie B.; Ampleford, David A.; Jennings, Christopher A.

This final report for Project 117863 summarizes progress made toward understanding how X-pinch load designs scale to high currents. The X-pinch load geometry was conceived in 1982 as a method to study the formation and properties of bright x-ray spots in z-pinch plasmas. X-pinch plasmas driven by 0.2 MA currents were found to have source sizes of 1 micron, temperatures >1 keV, lifetimes of 10-100 ps, and densities >0.1 times solid density. These conditions are believed to result from the direct magnetic compression of matter. Physical models that capture the behavior of 0.2 MA X pinches predict more extreme parameters at currents >1 MA. This project developed load designs for up to 6 MA on the SATURN facility and attempted to measure the resulting plasma parameters. Source sizes of 5-8 microns were observed in some cases along with evidence for high temperatures (several keV) and short time durations (<500 ps).

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TYPE SAND Report YEAR 2010
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3-Dimensional modeling of large diameter wire array high intensity K-shell radiation sources

Jennings, Christopher A.; Ampleford, David A.; Hansen, Stephanie B.; Cuneo, M.E.; Coverdale, Christine A.; Jones, Brent M.

Large diameter nested wire array z-pinches imploded on the Z-generator at Sandia National Laboratories have been used extensively to generate high intensity K-shell radiation. Large initial radii are required to obtain the high implosion velocities needed to efficiently radiate in the K-shell. This necessitates low wire numbers and large inter-wire gaps which introduce large azimuthal non-uniformities. Furthermore, the development of magneto-Rayleigh-Taylor instabilities during the implosion are known to generate large axial non-uniformity These effects motivate the complete, full circumference 3-dimensional modeling of these systems. Such high velocity implosions also generate large voltages, which increase current losses in the power feed and limit the current delivery to these loads. Accurate representation of the generator coupling is therefore required to reliably represent the energy delivered to, and the power radiated from these sources. We present 3D-resistive MHD calculations of the implosion and stagnation of a variety of large diameter stainless steel wire arrays (hv {approx} 6.7 keV), imploded on the Z-generator both before and after its refurbishment. Use of a tabulated K-shell emission model allows us to compare total and K-shell radiated powers to available experimental measurements. Further comparison to electrical voltage and current measurements allows us to accurately assess the power delivered to these loads. These data allow us to begin to constrain and validate our 3D MHD calculations, providing insight into ways in which these sources may be further optimized.

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TYPE Conference YEAR 2010
OSTI

Wire array Z-pinch length variations for K-shell x-ray generation on Z

Jones, Brent M.; Hansen, Stephanie B.; Coverdale, Christine A.; Cuneo, M.E.; Ampleford, David A.; Jennings, Christopher A.

Large diameter (50-70 mm) wire array z pinches are fielded on the refurbished Z machine to generate 1-10 keV K-shell x-ray radiation. Imploding with velocities approaching 100 cm/{micro}s, these loads create large dL/dt which generates a high voltage, stresses the convolute, and leads to current loss. High velocities are required to reach the few-keV electron temperatures required to strip moderate-atomic-number plasmas to the K shell, thus there is an inherent trade-off between achieving high velocity and stressing the pulsed power driver via the large dL/dt.Here, we present experiments in which the length of stagnated Cu and stainless steel z pinches was varied from 12-24 mm. The motivation in reducing the pinch height is to lower the final inductance and improve coupling to the generator. Shortening a Cu pinch from 20 to 12 mm by angling the anode glide plane reduced the final L and dL/dt, enhancing the feed current by 1.4 MA, nearly doubling the K-shell power per unit length, and increasing the net K-shell yield by 20%. X-ray spectroscopy is employed to assess differences in plasma conditions between the loads. Lengthening the pinch could lead to yield enhancements by increasing the mass participating in the implosion, provided the increased inductance is not overly detrimental to the current coupling. In addition to the experimental results, these scenarios are studied via thin-shell 0D and also magneto-hydrodynamic modeling with a coupled driver circuit model.

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TYPE Conference YEAR 2010
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Results 201–303 of 303
Results 201–303 of 303