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Radiatively-Cooled Magnetic Reconnection Experiments at the Z Pulsed-Power Facility

Hare, Jack; Datta, Rishabh; Sergey, Lebedev; Chittenden, Jerry; Crilly, Aidan; Bland, Simon; Halliday, Jack; Russell, Danny; Fox, Will; Hantao, Ji; Kuranz, Carolyn; Myers, Clayton E.; Aragon, Carlos A.; Jennings, Christopher A.; Ampleford, David A.; Beckwith, Kristian B.; Harding, Eric H.; Hansen, Stephanie B.; Dunham, Gregory S.; Edens, Aaron E.; Gonzalez, Josue; Harmon, Roger L.; Kellogg, Jeffrey W.; Jones, Michael J.; Looker, Quinn M.; Molina, Leo M.; Montoya, Michael L.; Patel, Sonal P.; Loisel, Guillaume P.; Speas, Christopher S.; Webb, Timothy J.; Yager-Elorriaga, David A.; Shipley, Gabriel A.; Chandler, Katherine

Abstract not provided.

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TYPE Conference Presenation YEAR 2022
DOIOSTI

Domination of the K-Radiation at a Z-Pinch Stagnation on Z by Numerous Tiny Spots and the Properties of the Spots Inferred by Experimental Determination of the K-Line Opacities

IEEE International Conference on Plasma Science

Maron, Y.; Bernshtam, V.; Zarnitsky, Y.; Fisher, V.; Nedostup, O.; Ampleford, David A.; Jennings, Christopher A.; Jones, Brent M.; Cuneo, M.E.; Rochau, G.A.; Dunham, Gregory S.; Loisel, Guillaume P.

Detailed analysis of both the line-intensity ratios and line shapes of the K-lines of elements of different abundances (Fe, Cr, Ni, and Mn) emitted from the stagnation of a steel wire-array implosion on Z, were used to determine the line opacities. While the opacities at the early time of stagnation appear to be consistent with a nearly uniform hot-plasma cylinder on-axis surrounded by a colder annulus, the opacities during the peak K-emission strongly suggest that the main K-emission is due to small hot regions (spots) spread over the stagnating column. The spots are shown to be at least 4× denser than expected based on a uniform-cylinder emission (namely, ni > 3 ×1020 cm-3 ), are of diameters of about 200 μ or less (where the smaller the spots the higher are the densities), and are thousands in number. The total mass of the spots was determined to be 3-10 % of the load mass, and their total volume 3-15 % of the O 1.2-mm stagnation-column volume, both are less than the respective values for the earlier period of lower K power.

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TYPE Conference Presenation YEAR 2022
DOIOSTIScopus

Background measurement methods for opacity experiments conducted at the Z facility

Review of Scientific Instruments

Dunham, Gregory S.; Nagayama, Taisuke N.; Bailey, James E.; Loisel, Guillaume P.

Laboratory experiments typically test opacity models by measuring spectrally resolved transmission of a sample using bright backlight radiation. A potential problem is that any unaccounted background signal contaminating the spectrum will artificially reduce the inferred opacity. Methods developed to measure background signals in opacity experiments at the Sandia Z facility are discussed. Preliminary measurements indicate that backgrounds are 9%-11% of the backlight signal at wavelengths less than 10 Å. Background is thus a relatively modest correction for all Z opacity data published to date. Future work will determine how important background is at longer wavelengths.

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TYPE Journal Article YEAR 2021
DOIOSTIScopusDOIOSTIScopus

Ride-along Z data LOS 170 and LOS 330 for university collaborators. Opacity 18b shot z3308, ZAPP18a shot Z3309 [Slides]

Loisel, Guillaume P.

Each instrument recorded the x-ray emission from the Z-pinch dynamic hohlraum (ZPDH): LOS 330 TREX 6A & B: recorded time resolved and time integrated absorption spectra from a radiatively heated Ne gas; and, LOS 170 are LM monochromatic and high-pass imagers, imaging the Z-pinch before and near stagnation.

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TYPE Other Report YEAR 2019
DOIOSTI

A compact multi-plane broadband (0.5-17 keV) spectrometer using a single acid phthalate crystal

Review of Scientific Instruments

Loisel, Guillaume P.; Lake, Patrick W.; Nielsen-Weber, Linda B.; Wu, Ming W.; Dunham, Gregory S.; Bailey, James E.; Rochau, G.A.

Acid phthalate crystals such as KAP crystals are a method of choice to record x-ray spectra in the soft x-ray regime (E ∼ 1 keV) using the large (001) 2d = 26.63 Å spacing. Reflection from many other planes is possible, and knowledge of the 2d spacing, reflectivity, and resolution for these reflections is necessary to evaluate whether they hinder or help the measurements. Burkhalter et al. [J. Appl. Phys., 52, 4379 (1981)] showed that the (013) reflection has efficiency comparable to the 2nd order reflection (002), and it can overlap the main first order reflection when the crystal bending axis (b-axis) is contained in the dispersion plane, thus contaminating the main (001) measurement in a convex crystal geometry. We present a novel spectrograph concept that makes these asymmetric reflections helpful by setting the crystal b-axis perpendicular to the dispersion plane. In such a case, asymmetric reflections do not overlap with the main (001) reflection and each reflection can be used as an independent spectrograph. Here we demonstrate an achieved spectral range of 0.8-13 keV with a prototype setup. The detector measurements were reproduced with a 3D ray-tracing code.

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TYPE Journal Article YEAR 2018
DOIOSTIScopus

Ride-along data LOS 130, 170 & LO330 shots z3139, 3140 and 3141

Loisel, Guillaume P.

Each instrument records the x-ray emission from the Z-pinch dynamic hohlraum (ZPDH); LOS 130 TIXTLs instruments record the absorption of the pinch backlighter through an expanding NaF/Mg foil; LOS 170 MLM instruments record monochromatic images at 276 and 528 eV energies near and before ZPDH stagnation time; LOS 330 TREX 6A & B: recoded time resolved absorption spectra from a radiatively heated Ne gas.

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TYPE Other Report YEAR 2017
DOIOSTIDOIOSTI

A 7.2 keV spherical x-ray crystal backlighter for two-frame, two-color backlighting at Sandia's Z Pulsed Power Facility

Review of Scientific Instruments

Schollmeier, Marius; Knapp, Patrick K.; Ampleford, David A.; Harding, Eric H.; Jennings, Christopher A.; Lamppa, Derek C.; Loisel, Guillaume P.; Martin, Matthew; Robertson, Grafton K.; Shores, Jonathon S.; Smith, Ian C.; Speas, Christopher S.; Weis, Matthew R.; Porter, John L.; McBride, Ryan D.

Many experiments on Sandia National Laboratories' Z Pulsed Power Facility - a 30 MA, 100 ns rise-time, pulsed-power driver - use a monochromatic quartz crystal backlighter system at 1.865 keV (Si Heα) or 6.151 keV (Mn Heα) x-ray energy to radiograph an imploding liner (cylindrical tube) or wire array z-pinch. The x-ray source is generated by the Z-Beamlet laser, which provides two 527-nm, 1 kJ, 1-ns laser pulses. Radiographs of imploding, thick-walled beryllium liners at convergence ratios CR above 15 [CR=ri(0)/ri(t)] using the 6.151-keV backlighter system were too opaque to identify the inner radius ri of the liner with high confidence, demonstrating the need for a higher-energy x-ray radiography system. Here, we present a 7.242 keV backlighter system using a Ge(335) spherical crystal with the Co Heα resonance line. This system operates at a similar Bragg angle as the existing 1.865 keV and 6.151 keV backlighters, enhancing our capabilities for two-color, two-frame radiography without modifying the system integration at Z. The first data taken at Z include 6.2-keV and 7.2-keV two-color radiographs as well as radiographs of low-convergence (CR about 4-5), high-areal-density liner implosions.

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TYPE Journal Article YEAR 2017
DOIOSTIScopus
Results 1–50 of 120
Results 1–50 of 120