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Optical Imaging on Z LDRD: Design and Development of Self-Emission and Debris Imagers

Yager-Elorriaga, David A.; Montoya, Michael M.; Bliss, David E.; Ball, Christopher R.; Atencio, Phillip M.; Carpenter, Brian C.; Fuerschbach, Kyle H.; Fulford, Karin W.; Lamppa, Derek C.; Lowinske, Michael C.; Lucero, Larry M.; Patel, Sonal P.; Romero, Anthony R.; Tanbakuchi, Anthony; Breznik-Young, Bonnie B.

We present an overview of the design and development of optical self-emission and debris imaging diagnostics for the Z Machine at Sandia National Laboratories. These diagnostics were designed and implemented to address several gaps in our understanding of visibly emitting phenomenon on Z and the post-shot debris environment. Optical emission arises from plasmas that form on the transmission line that delivers energy to Z loads and on the Z targets themselves; however, the dynamics of these plasmas are difficult to assess without imaging data. Addressing this, we developed a new optical imager called SEGOI (Self-Emission Gated Optical Imager) that leverages the eight gated optical imagers and two streak cameras of the Z Line VISAR system. SEGOI is a low cost, side-on imager with a 1 cm field of view and 30-50 µm spatial resolution, sensitive to green light (540-600 nm). This report outlines the design considerations and development of this diagnostic and presents an overview of the first diagnostic data acquired from four experimental campaigns. SEGOI was fielded on power flow experiments to image plasmas forming on and between transmission lines, on an inertial confinement fusion experiment called the Dynamic Screw Pinch to image low density plasmas forming on return current posts, on an experiment designed to measure the magneto Rayleigh-Taylor instability to image the instability bubble trajectory and self-emission structures, and finally on a Magnetized Liner Inertial Fusion (MagLIF) experiment to image the emission from the target. The second diagnostic developed, called DINGOZ (Debris ImagiNG on Z), was designed to improve our understanding of the post-shot debris environment. DINGOZ is an airtight enclosure that houses electronics and batteries to operate a high-speed (10-400 kfps) camera in the Z Machine center section. We report on the design considerations of this new diagnostic and present the first high-speed imaging data of the post-shot debris environment on Z.

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IMPROVED PERFORMANCE OF MAGNETIZED LINER INERTIAL FUSION EXPERIMENTS WITH HIGH-ENERGY LOW-MIX LASER PREHEAT CONFIGURATIONS

Harvey-Thompson, Adam J.; Geissel, Matthias G.; Weis, Matthew R.; Jennings, Christopher A.; Gomez, Matthew R.; Fein, Jeffrey R.; Ampleford, David A.; Bliss, David E.; Chandler, Gordon A.; Glinsky, Michael E.; Hahn, Kelly D.; Hansen, Stephanie B.; Hanson, Joseph C.; Harding, Eric H.; Knapp, Patrick K.; Mangan, Michael M.; Perea, L.; Peterson, Kyle J.; Porter, John L.; Rambo, Patrick K.; Robertson, Grafton K.; Rochau, G.A.; Ruiz, Carlos L.; Schwarz, Jens S.; Shores, Jonathon S.; Sinars, Daniel S.; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Whittemore, K.; Paguio, Reny P.; Smith, Gary L.; York, Adam Y.

Abstract not provided.

Update on MagLIF preheat experiments

Harvey-Thompson, Adam J.; Geissel, Matthias G.; Weis, Matthew R.; Galloway, B.R.; Fein, Jeffrey R.; Awe, Thomas J.; Crabtree, Jerry A.; Ampleford, David A.; Bliss, David E.; Glinsky, Michael E.; Gomez, Matthew R.; Hanson, Joseph C.; Harding, Eric H.; Jennings, Christopher A.; Kimmel, Mark W.; Perea, L.; Peterson, Kyle J.; Porter, James D.; Rambo, Patrick K.; Robertson, Grafton K.; Ruiz, Daniel E.; Schwarz, Jens S.; Shores, Jonathon S.; Slutz, Stephen A.; Smith, Ian C.; York, Adam Y.; Paguio, R.R.; Smith, G.E.; Maudlin, M.M.; Pollock, B.P.

Abstract not provided.

The Impact on Mix of Different Preheat Protocols

Harvey-Thompson, Adam J.; Geissel, Matthias G.; Jennings, Christopher A.; Weis, Matthew R.; Ampleford, David A.; Bliss, David E.; Chandler, Gordon A.; Fein, Jeffrey R.; Galloway, B.R.; Glinsky, Michael E.; Gomez, Matthew R.; Hahn, K.D.; Hansen, Stephanie B.; Harding, Eric H.; Kimmel, Mark W.; Knapp, Patrick K.; Perea, L.; Peterson, Kara J.; Porter, John L.; Rambo, Patrick K.; Robertson, Grafton K.; Rochau, G.A.; Ruiz, Daniel E.; Schwarz, Jens S.; Shores, Jonathon S.; Sinars, Daniel S.; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Whittemore, K.; Woodbury, Daniel W.; Smith, G.E.

Abstract not provided.

Progress in Implementing High-Energy Low-Mix Laser Preheat for MagLIF

Harvey-Thompson, Adam J.; Harvey-Thompson, Adam J.; Geissel, Matthias G.; Geissel, Matthias G.; Jennings, Christopher A.; Jennings, Christopher A.; Weis, Matthew R.; Weis, Matthew R.; Ampleford, David A.; Ampleford, David A.; Bliss, David E.; Bliss, David E.; Chandler, Gordon A.; Chandler, Gordon A.; Fein, Jeffrey R.; Fein, Jeffrey R.; Galloway, B.R.; Galloway, B.R.; Glinsky, Michael E.; Glinsky, Michael E.; Gomez, Matthew R.; Gomez, Matthew R.; Hahn, K.D.; Hahn, K.D.; Hansen, Stephanie B.; Hansen, Stephanie B.; Harding, Eric H.; Harding, Eric H.; Kimmel, Mark W.; Kimmel, Mark W.; Knapp, Patrick K.; Knapp, Patrick K.; Perea, L.; Perea, L.; Peterson, Kara J.; Peterson, Kara J.; Porter, John L.; Porter, John L.; Rambo, Patrick K.; Rambo, Patrick K.; Robertson, Grafton K.; Robertson, Grafton K.; Rochau, G.A.; Rochau, G.A.; Ruiz, Daniel E.; Ruiz, Daniel E.; Schwarz, Jens S.; Schwarz, Jens S.; Shores, Jonathon S.; Shores, Jonathon S.; Sinars, Daniel S.; Sinars, Daniel S.; Slutz, Stephen A.; Slutz, Stephen A.; Smith, Ian C.; Smith, Ian C.; Speas, Christopher S.; Speas, Christopher S.; Whittemore, K.; Whittemore, K.; Woodbury, Daniel W.; Woodbury, Daniel W.; Smith, G.E.; Smith, G.E.

Abstract not provided.

Z Line-VISAR: A Spatially Resolved Load Current Diagnostic at the Z Pulsed Power Facility

Bliss, David E.; Myers, Clayton E.; Jones, Michael J.; Baker, J.L.; Austin, Kevin N.; Bettnecourt, R &.; Bliss, E.; Celeste, J.C.; Celliers, P.C.; Clancy, T.C.; Cohen, S.; Crosley, M.C.; Datte, P.D.; Erskine, D.E.; Fratanduono, D.E.; Frieders, G.F.; Galbraith, J.G.; Hammer, J.H.; Hess, Mark H.; Jackson, J.; Jennings, Christopher A.; Johnson, Drew J.; Koen, D.K.; Lusk, J.L.; Martinez, A.M.; Massey, W.M.; McCarville, T.J.; McDonald, R.; McLean, H.M.; Raman, K.S.; Rodriguez, S.R.; Spencer, Decker C.; Springer, P.S.; de Dios, G.V.; Wong, J.W.

Abstract not provided.

Designing And Testing New MagLIF Preheat Protocols

Harvey-Thompson, Adam J.; Geissel, Matthias G.; Weis, Matthew R.; Jennings, Christopher A.; Glinsky, Michael E.; Peterson, Kyle J.; Awe, Thomas J.; Bliss, David E.; Gomez, Matthew R.; Harding, Eric H.; Hansen, Stephanie B.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; Porter, John L.; Rambo, Patrick K.; Rochau, G.A.; Schollmeier, Marius; Schwarz, Jens S.; Shores, Jonathon S.; Slutz, Stephen A.; Sinars, Daniel S.; Smith, Ian C.; Speas, Christopher S.

Abstract not provided.

MagLIF laser preheat update

Harvey-Thompson, Adam J.; Geissel, Matthias G.; Weis, Matthew R.; Jennings, Christopher A.; Glinsky, Michael E.; Peterson, Kyle J.; Awe, Thomas J.; Bliss, David E.; Gomez, Matthew R.; Harding, Eric H.; Hansen, Stephanie B.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; Schollmeier, Marius; Schwarz, Jens S.; Sefkow, Adam B.; Shores, Jonathon S.; Slutz, Stephen A.; Sinars, Daniel S.; Smith, Ian C.; Speas, Christopher S.; Wei, M.S.; Vesey, Roger A.; Porter, John L.

Abstract not provided.

Designing and testing new preheat protocols for MagLIF

Harvey-Thompson, Adam J.; Geissel, Matthias G.; Weis, Matthew R.; Peterson, Kyle J.; Glinsky, Michael E.; Awe, Thomas J.; Bliss, David E.; Gomez, Matthew R.; Harding, Eric H.; Hansen, Stephanie B.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; Porter, John L.; Rochau, G.A.; Schollmeier, Marius; Schwarz, Jens S.; Shores, Jonathon S.; Slutz, Stephen A.; Sinars, Daniel S.; Smith, Ian C.; Speas, Christopher S.

Abstract not provided.

Enhancing performance of magnetized liner inertial fusion at the Z facility

Physics of Plasmas

Slutz, S.A.; Gomez, Matthew R.; Hansen, Stephanie B.; Harding, Eric H.; Hutsel, Brian T.; Knapp, P.F.; Lamppa, Derek C.; Awe, T.J.; Ampleford, David A.; Bliss, David E.; Chandler, Gordon A.; Cuneo, M.E.; Geissel, Matthias G.; Glinsky, Michael E.; Harvey-Thompson, Adam J.; Hess, Mark H.; Jennings, C.A.; Jones, Brent M.; Laity, G.R.; Martin, M.R.; Peterson, Kyle J.; Porter, John L.; Rambo, Patrick K.; Rochau, G.A.; Ruiz, Carlos L.; Savage, Mark E.; Schwarz, Jens S.; Schmit, Paul S.; Shipley, Gabriel A.; Sinars, Daniel S.; Smith, Ian C.; Vesey, Roger A.; Weis, M.R.

The Magnetized Liner Inertial Fusion concept (MagLIF) [Slutz et al., Phys. Plasmas 17, 056303 (2010)] is being studied on the Z facility at Sandia National Laboratories. Neutron yields greater than 1012 have been achieved with a drive current in the range of 17-18 MA and pure deuterium fuel [Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)]. We show that 2D simulated yields are about twice the best yields obtained on Z and that a likely cause of this difference is the mix of material into the fuel. Mitigation strategies are presented. Previous numerical studies indicate that much larger yields (10-1000 MJ) should be possible with pulsed power machines producing larger drive currents (45-60 MA) than can be produced by the Z machine [Slutz et al., Phys. Plasmas 23, 022702 (2016)]. To test the accuracy of these 2D simulations, we present modifications to MagLIF experiments using the existing Z facility, for which 2D simulations predict a 100-fold enhancement of MagLIF fusion yields and considerable increases in burn temperatures. Experimental verification of these predictions would increase the credibility of predictions at higher drive currents.

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Recent Diagnostic Platform Accomplishments for Studying Vacuum Power Flow Physics at the Sandia Z Accelerator

Laity, George R.; Aragon, Carlos A.; Bennett, Nichelle L.; Bliss, David E.; Dolan, Daniel H.; Fierro, Andrew S.; Gomez, Matthew R.; Hess, Mark H.; Hutsel, Brian T.; Jennings, Christopher A.; Johnston, Mark D.; Kossow, Michael R.; Lamppa, Derek C.; Martin, Matthew; Patel, Sonal P.; Porwitzky, Andrew J.; Robinson, Allen C.; Rose, David V.; VanDevender, Pace V.; Waisman, Eduardo M.; Webb, Timothy J.; Welch, Dale R.; Rochau, G.A.; Savage, Mark E.; Stygar, William S.; White, William M.; Sinars, Daniel S.; Cuneo, M.E.

Abstract not provided.

Pushing Laser Pre-Heat in MagLIF

Geissel, Matthias G.; Geissel, Matthias G.; Harvey-Thompson, Adam J.; Fein, Jeffrey R.; Woodbury, Daniel W.; Davis, Daniel R.; Bliss, David E.; Scoglietti, Daniel S.; Gomez, Matthew R.; Ampleford, David A.; Awe, Thomas J.; Colombo, Anthony P.; Weis, Matthew R.; Jennings, Christopher A.; Glinsky, Michael E.; Slutz, Stephen A.; Ruiz, Daniel E.; Peterson, Kyle J.; Smith, Ian C.; Shores, Jonathon S.; Kimmel, Mark W.; Rambo, Patrick K.; Schwarz, Jens S.; Galloway, B.R.; Speas, Christopher S.; Porter, John L.

Abstract not provided.

Minimizing scatter-losses during pre-heat for magneto-inertial fusion targets

Physics of Plasmas

Geissel, Matthias G.; Harvey-Thompson, Adam J.; Awe, Thomas J.; Bliss, David E.; Glinsky, Michael E.; Gomez, Matthew R.; Harding, Eric H.; Hansen, Stephanie B.; Jennings, Christopher A.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; Peterson, Kyle J.; Schollmeier, Marius; Schwarz, Jens S.; Shores, Jonathon S.; Slutz, Stephen A.; Sinars, Daniel S.; Smith, Ian C.; Speas, C.S.; Vesey, Roger A.; Weis, Matthew R.; Porter, John L.

The size, temporal and spatial shape, and energy content of a laser pulse for the pre-heat phase of magneto-inertial fusion affect the ability to penetrate the window of the laser-entrance-hole and to heat the fuel behind it. High laser intensities and dense targets are subject to laser-plasma-instabilities (LPI), which can lead to an effective loss of pre-heat energy or to pronounced heating of areas that should stay unexposed. While this problem has been the subject of many studies over the last decades, the investigated parameters were typically geared towards traditional laser driven Inertial Confinement Fusion (ICF) with densities either at 10% and above or at 1% and below the laser's critical density, electron temperatures of 3-5 keV, and laser powers near (or in excess of) 1 × 1015 W/cm2. In contrast, Magnetized Liner Inertial Fusion (MagLIF) [Slutz et al., Phys. Plasmas 17, 056303 (2010) and Slutz and Vesey, Phys. Rev. Lett. 108, 025003 (2012)] currently operates at 5% of the laser's critical density using much thicker windows (1.5-3.5 μm) than the sub-micron thick windows of traditional ICF hohlraum targets. This article describes the Pecos target area at Sandia National Laboratories using the Z-Beamlet Laser Facility [Rambo et al., Appl. Opt. 44(12), 2421 (2005)] as a platform to study laser induced pre-heat for magneto-inertial fusion targets, and the related progress for Sandia's MagLIF program. Forward and backward scattered light were measured and minimized at larger spatial scales with lower densities, temperatures, and powers compared to LPI studies available in literature.

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MagLIF Pre-Heat Optimization on the PECOS Surrogacy Platform

Geissel, Matthias G.; Harvey-Thompson, Adam J.; Awe, Thomas J.; Ampleford, David A.; Bliss, David E.; Glinsky, Michael E.; Gomez, Matthew R.; Harding, Eric H.; Hansen, Stephanie B.; Jennings, Christopher A.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; Peterson, Kyle J.; Rambo, Patrick K.; Rochau, G.A.; Schollmeier, Marius; Shores, Jonathon S.; Sinars, Daniel S.; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Vesey, Roger A.; Weis, Matthew R.; Porter, John L.

Abstract not provided.

Pre-Heat Optimization for Magnetized Liner Inertial Fusion at Sandia

Geissel, Matthias G.; Harvey-Thompson, Adam J.; Awe, Thomas J.; Bliss, David E.; Glinsky, Michael E.; Gomez, Matthew R.; Harding, Eric H.; Hansen, Stephanie B.; Jennings, Christopher A.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; Peterson, Kyle J.; Schollmeier, Marius; Shores, Jonathon S.; Sinars, Daniel S.; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Vesey, Roger A.; Weis, Matthew R.; Porter, John L.

Abstract not provided.

A Path to Increased Performance in Magnetized Liner Inertial Fusion

Gomez, Matthew R.; Slutz, Stephen A.; Jennings, Christopher A.; Harvey-Thompson, Adam J.; Weis, Matthew R.; Lamppa, Derek C.; Hutsel, Brian T.; Ampleford, David A.; Awe, Thomas J.; Bliss, David E.; Chandler, Gordon A.; Geissel, Matthias G.; Hahn, Kelly D.; Hansen, Stephanie B.; Harding, Eric H.; Hess, Mark H.; Knapp, Patrick K.; Laity, George R.; Martin, Matthew; Nagayama, Taisuke N.; Rovang, Dean C.; Ruiz, Carlos L.; Savage, Mark E.; Schmit, Paul S.; Schwarz, Jens S.; Smith, Ian C.; Vesey, Roger A.; Yu, Edmund Y.; Cuneo, M.E.; Jones, Brent M.; Peterson, Kyle J.; Porter, John L.; Rochau, G.A.; Sinars, Daniel S.; Stygar, William A.

Abstract not provided.

Pre-Heat Optimization for Magnetized Liner Inertial Fusion at Sandia

Geissel, Matthias G.; Harvey-Thompson, Adam J.; Awe, Thomas J.; Bliss, David E.; Glinsky, Michael E.; Gomez, Matthew R.; Harding, Eric H.; Hansen, Stephanie B.; Jennings, Christopher A.; Kimmel, Mark W.; Knapp, Patrick K.; Peterson, Kyle J.; Schollmeier, Marius; Schwarz, Jens S.; Shores, Jonathon S.; Slutz, Stephen A.; Sinars, Daniel S.; Smith, Ian C.; Speas, Christopher S.; Vesey, Roger A.; Weis, Matthew R.; Porter, John L.

Abstract not provided.

Progress in Preconditioning MagLIF fuel and its Impact on Performance

Peterson, Kyle J.; Harvey-Thompson, Adam J.; Awe, Thomas J.; Bliss, David E.; Geissel, Matthias G.; Glinsky, Michael E.; Gomez, Matthew R.; Harding, Eric H.; Hansen, Stephanie B.; Jennings, Christopher A.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; Schollmeier, Marius; Schwarz, Jens S.; Sefkow, Adam B.; Shores, Jonathon S.; Slutz, Stephen A.; Sinars, Daniel S.; Smith, Ian C.; Speas, Christopher S.; Vesey, Roger A.; Weis, Matthew R.; Porter, John L.

Abstract not provided.

Developing a Pre-Heat Platform for MagLIF with Z-Beamlet

Geissel, Matthias G.; Awe, Thomas J.; Bliss, David E.; Campbell, Edward M.; Gomez, Matthew R.; Glinsky, Michael E.; Harding, Eric H.; Harvey-Thompson, Adam J.; Hansen, Stephanie B.; Jennings, Christopher A.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; Peterson, Kyle J.; Schollmeier, Marius; Schwarz, Jens S.; Sefkow, Adam B.; Shores, Jonathon S.; Sinars, Daniel S.; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Vesey, Roger A.; Porter, John L.; Rochau, G.A.

Abstract not provided.

SBS Measurements for Sandia's MagLIF Program

Geissel, Matthias G.; Awe, Thomas J.; Bliss, David E.; Campbell, Edward M.; Glinsky, Michael E.; Gomez, Matthew R.; Harding, Eric H.; Harvey-Thompson, Adam J.; Kimmel, Mark W.; Knapp, Patrick K.; Peterson, Kyle J.; Jennings, Christopher A.; Sefkow, Adam B.; Shores, Jonathon S.; Sinars, Daniel S.; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Weis, Matthew R.; Porter, John L.

Abstract not provided.

Nonlinear laser-plasma interaction in magnetized liner inertial fusion

Proceedings of SPIE - The International Society for Optical Engineering

Geissel, Matthias G.; Awe, T.J.; Bliss, David E.; Campbell, Edward M.; Gomez, Matthew R.; Harding, Eric H.; Harvey-Thompson, Adam J.; Hansen, Stephanie B.; Jennings, C.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; McBride, Ryan D.; Peterson, Kyle J.; Schollmeier, Marius; Scoglietti, Daniel S.; Sefkow, Adam B.; Shores, J.E.; Sinars, Daniel S.; Slutz, S.A.; Smith, Ian C.; Speas, C.S.; Vesey, Roger A.; Porter, John L.

Sandia National Laboratories is pursuing a variation of Magneto-Inertial Fusion called Magnetized Liner Inertial Fusion, or MagLIF. The MagLIF approach requires magnetization of the deuterium fuel, which is accomplished by an initial external B-Field and laser-driven pre-heat. While magnetization is crucial to the concept, it is challenging to couple sufficient energy to the fuel, since laser-plasma instabilities exist, and a compromise between laser spot size, laser entrance window thickness, and fuel density must be found. Nonlinear processes in laser plasma interaction, or laser-plasma instabilities (LPI), complicate the deposition of laser energy by enhanced absorption, backscatter, filamentation and beam-spray. Key LPI processes are determined, and mitigation methods are discussed. Results with and without improvement measures are presented.

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Implementing and diagnosing magnetic flux compression on the Z pulsed power accelerator

McBride, Ryan D.; Bliss, David E.; Gomez, Matthew R.; Hansen, Stephanie B.; Martin, Matthew; Jennings, Christopher A.; Slutz, Stephen A.; Rovang, Dean C.; Knapp, Patrick K.; Schmit, Paul S.; Awe, Thomas J.; Hess, Mark H.; Lemke, Raymond W.; Dolan, Daniel H.; Lamppa, Derek C.; Jobe, Marc R.; Fang, Lu F.; Hahn, Kelly D.; Chandler, Gordon A.; Cooper, Gary W.; Ruiz, Carlos L.; Robertson, Grafton K.; Cuneo, M.E.; Sinars, Daniel S.; Tomlinson, Kurt T.; Smith, Gary S.; Paguio, Reny P.; Intrator, Tom P.; Weber, Thomas E.; Greenly, John B.

We report on the progress made to date for a Laboratory Directed Research and Development (LDRD) project aimed at diagnosing magnetic flux compression on the Z pulsed-power accelerator (0-20 MA in 100 ns). Each experiment consisted of an initially solid Be or Al liner (cylindrical tube), which was imploded using the Z accelerator's drive current (0-20 MA in 100 ns). The imploding liner compresses a 10-T axial seed field, B z ( 0 ) , supplied by an independently driven Helmholtz coil pair. Assuming perfect flux conservation, the axial field amplification should be well described by B z ( t ) = B z ( 0 ) x [ R ( 0 ) / R ( t )] 2 , where R is the liner's inner surface radius. With perfect flux conservation, B z ( t ) and dB z / dt values exceeding 10 4 T and 10 12 T/s, respectively, are expected. These large values, the diminishing liner volume, and the harsh environment on Z, make it particularly challenging to measure these fields. We report on our latest efforts to do so using three primary techniques: (1) micro B-dot probes to measure the fringe fields associated with flux compression, (2) streaked visible Zeeman absorption spectroscopy, and (3) fiber-based Faraday rotation. We also mention two new techniques that make use of the neutron diagnostics suite on Z. These techniques were not developed under this LDRD, but they could influence how we prioritize our efforts to diagnose magnetic flux compression on Z in the future. The first technique is based on the yield ratio of secondary DT to primary DD reactions. The second technique makes use of the secondary DT neutron time-of-flight energy spectra. Both of these techniques have been used successfully to infer the degree of magnetization at stagnation in fully integrated Magnetized Liner Inertial Fusion (MagLIF) experiments on Z [P. F. Schmit et al. , Phys. Rev. Lett. 113 , 155004 (2014); P. F. Knapp et al. , Phys. Plasmas, 22 , 056312 (2015)]. Finally, we present some recent developments for designing and fabricating novel micro B-dot probes to measure B z ( t ) inside of an imploding liner. In one approach, the micro B-dot loops were fabricated on a printed circuit board (PCB). The PCB was then soldered to off-the-shelf 0.020- inch-diameter semi-rigid coaxial cables, which were terminated with standard SMA connectors. These probes were recently tested using the COBRA pulsed power generator (0-1 MA in 100 ns) at Cornell University. In another approach, we are planning to use new multi-material 3D printing capabilities to fabricate novel micro B-dot packages. In the near future, we plan to 3D print these probes and then test them on the COBRA generator. With successful operation demonstrated at 1-MA, we will then make plans to use these probes on a 20-MA Z experiment.

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Direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium

Science

Knudson, Marcus D.; Desjarlais, Michael P.; Becker, A.; Lemke, Raymond W.; Cochrane, Kyle C.; Savage, Mark E.; Bliss, David E.; Mattsson, Thomas M.; Redmer, R.

Eighty years ago, it was proposed that solid hydrogen would become metallic at sufficiently high density. Despite numerous investigations, this transition has not yet been experimentally observed. More recently, there has been much interest in the analog of this predicted metallic transition in the dense liquid, due to its relevance to planetary science. Here, we show direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium. Experimental determination of the location of this transition provides a much-needed benchmark for theory and may constrain the region of hydrogen-helium immiscibility and the boundary-layer pressure in standard models of the internal structure of gas-giant planets.

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Streak camera meeting summary

Dolan, Daniel H.; Bliss, David E.

Streak cameras are important for high-speed data acquisition in single event experiments, where the total recorded information (I) is shared between the number of measurements (M) and the number of samples (S). Topics of this meeting included: streak camera use at the national laboratories; current streak camera production; new tube developments and alternative technologies; and future planning. Each topic is summarized in the following sections.

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Copy of An overview of pulse compression and power flow in the upgraded Z pulsed power driver

Savage, Mark E.; Maenchen, John E.; McDaniel, Dillon H.; Pasik, Michael F.; Pointon, Timothy D.; Owen, Albert C.; Seidel, David B.; Stoltzfus, Brian S.; Struve, Kenneth W.; Warne, Larry K.; Bennett, Lawrence F.; Woodworth, Joseph R.; Bliss, David E.; Clark, Waylon T.; Coats, Rebecca S.; Elizondo-Decanini, Juan M.; LeChien, Keith R.; Harjes, Henry C.; Lehr, J.M.

Abstract not provided.

Fundamental science investigations to develop a 6-MV laser triggered gas switch for ZR: first annual report

Maenchen, John E.; Savage, Mark E.; Struve, Kenneth W.; Woodworth, Joseph R.; Lehr, J.M.; Warne, Larry K.; Bliss, David E.; Jorgenson, Roy E.; LeChien, Keith R.; McKee, George R.; Pasik, Michael F.; Rosenthal, Stephen E.

In October 2005, an intensive three-year Laser Triggered Gas Switch (LTGS) development program was initiated to investigate and solve observed performance and reliability issues with the LTGS for ZR. The approach taken has been one of mission-focused research: to revisit and reassess the design, to establish a fundamental understanding of LTGS operation and failure modes, and to test evolving operational hypotheses. This effort is aimed toward deploying an initial switch for ZR in 2007, on supporting rolling upgrades to ZR as the technology can be developed, and to prepare with scientific understanding for the even higher voltage switches anticipated needed for future high-yield accelerators. The ZR LTGS was identified as a potential area of concern quite early, but since initial assessments performed on a simplified Switch Test Bed (STB) at 5 MV showed 300-shot lifetimes on multiple switch builds, this component was judged acceptable. When the Z{sub 20} engineering module was brought online in October 2003 frequent flashovers of the plastic switch envelope were observed at the increased stresses required to compensate for the programmatically increased ZR load inductance. As of October 2006, there have been 1423 Z{sub 20} shots assessing a variety of LTGS designs. Numerous incremental and fundamental switch design modifications have been investigated. As we continue to investigate the LTGS, the basic science of plastic surface tracking, laser triggering, cascade breakdown, and optics degradation remain high-priority mission-focused research topics. Significant progress has been made and, while the switch does not yet achieve design requirements, we are on the path to develop successively better switches for rolling upgrade improvements to ZR. This report summarizes the work performed in FY 2006 by the large team. A high-level summary is followed by detailed individual topical reports.

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Wire initiation critical for radiation symmetry in Z-pinch-driven dynamic hohlraums

Physical Review Letters

Sanford, T.W.L.; Jennings, C.A.; Rochau, G.A.; Rosenthal, Stephen E.; Sarkisov, G.S.; Sasorov, P.V.; Stygar, William A.; Bennett, Lawrence F.; Bliss, David E.; Chittenden, J.P.; Cuneo, M.E.; Haines, M.G.; Leeper, Ramon J.; Mock, R.C.; Nash, Thomas J.; Peterson, D.L.

Axial symmetry in x-ray radiation of wire-array z pinches is important for the creation of dynamic hohlraums used to compress inertial-confinement-fusion capsules. We present the first evidence that this symmetry is directly correlated with the magnitude of the negative radial electric field along the wire surface. This field (in turn) is inferred to control the initial energy deposition into the wire cores, as well as any current shorting to the return conductor. © 2007 The American Physical Society.

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Progress in symmetric ICF capsule implosions and wire-array z-pinch source physics for double z-pinch driven hohlraums

Proposed for publication in Plasma Physics and Controlled Fusion.

Cuneo, M.E.; Nash, Thomas J.; Yu, Edmund Y.; Mehlhorn, Thomas A.; Matzen, M.K.; Vesey, Roger A.; Bennett, Guy R.; Sinars, Daniel S.; Stygar, William A.; Rambo, Patrick K.; Smith, Ian C.; Bliss, David E.

Over the last several years, rapid progress has been made evaluating the double-z-pinch indirect-drive, inertial confinement fusion (ICF) high-yield target concept (Hammer et al 1999 Phys. Plasmas 6 2129). We have demonstrated efficient coupling of radiation from two wire-array-driven primary hohlraums to a secondary hohlraum that is large enough to drive a high yield ICF capsule. The secondary hohlraum is irradiated from two sides by z-pinches to produce low odd-mode radiation asymmetry. This double-pinch source is driven from a single electrical power feed (Cuneo et al 2002 Phys. Rev. Lett. 88 215004) on the 20 MA Z accelerator. The double z-pinch has imploded ICF capsules with even-mode radiation symmetry of 3.1 {+-} 1.4% and to high capsule radial convergence ratios of 14-21 (Bennett et al 2002 Phys. Rev. Lett. 89 245002; Bennett et al 2003 Phys. Plasmas 10 3717; Vesey et al 2003 Phys. Plasmas 10 1854). Advances in wire-array physics at 20 MA are improving our understanding of z-pinch power scaling with increasing drive current. Techniques for shaping the z-pinch radiation pulse necessary for low adiabat capsule compression have also been demonstrated.

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Shockless magnetic acceleration of al flyer plates to ultra-high velocity using multi-megabar drive pressures

Lemke, Raymond W.; Knudson, Marcus D.; Davis, Jean-Paul D.; Bliss, David E.; Slutz, Stephen A.; Giunta, Anthony A.; Harjes, Henry C.

The intense magnetic field generated in the 20 MA Z-machine is used to accelerate metallic flyer plates to high velocity for the purpose of generating strong shocks in equation of state experiments. We present results pertaining to experiments in which a 0.085 cm thick Al flyer plate is magnetically accelerated across a vacuum gap into a quartz target. Peak magnetic drive pressures up to 4.9 Mbar were produced, which yielded a record 34 km/s flyer velocity without destroying it by shock formation or Joule heating. Two-dimensional MHD simulation was used to optimize the magnetic drive pressure on the flyer surface, shape the current pulse to accelerate the flyer without shock formation (i.e., quasi-isentropically), and predict the flyer velocity. Shock pressures up to 11.5 Mbar were produced in quartz. Accurate measurements of the shock velocity indicate that a fraction of the flyer is at solid density when it arrives at the target. Comparison of measurements and simulation results yields a consistent picture of the flyer state at impact with the quartz target.

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Optimization of magnetically accelerated, ultra-high velocity aluminum flyer plates for use in plate impact, shock wave experiments

Proposed for publication in the Journal of Applied Physics.

Lemke, Raymond W.; Knudson, Marcus D.; Bliss, David E.; Harjes, Henry C.; Slutz, Stephen A.

The intense magnetic field produced by the 20 MA Z accelerator is used as an impulsive pressure source to accelerate metal flyer plates to high velocity for the purpose of performing plate impact, shock wave experiments. This capability has been significantly enhanced by the recently developed pulse shaping capability of Z, which enables tailoring the rise time to peak current for a specific material and drive pressure to avoid shock formation within the flyer plate during acceleration. Consequently, full advantage can be taken of the available current to achieve the maximum possible magnetic drive pressure. In this way, peak magnetic drive pressures up to 490 GPa have been produced, which shocklessly accelerated 850 {micro}m aluminum (6061-T6) flyer plates to peak velocities of 34 km/s. We discuss magnetohydrodynamic (MHD) simulations that are used to optimize the magnetic pressure for a given flyer load and to determine the shape of the current rise time that precludes shock formation within the flyer during acceleration to peak velocity. In addition, we present results pertaining to plate impact, shock wave experiments in which the aluminum flyer plates were magnetically accelerated across a vacuum gap and impacted z-cut, {alpha}-quartz targets. Accurate measurements of resulting quartz shock velocities are presented and analyzed through high-fidelity MHD simulations enhanced using optimization techniques. Results show that a fraction of the flyer remains at solid density at impact, that the fraction of material at solid density decreases with increasing magnetic pressure, and that the observed abrupt decrease in the quartz shock velocity is well correlated with the melt transition in the aluminum flyer.

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Mass profile and instability growth measurements for 300-wire z-pinch implosions driven by 14-18, MA

Proposed for publication in Physical Review Letters.

Sinars, Daniel S.; Cuneo, M.E.; Yu, Edmund Y.; Bliss, David E.; Nash, Thomas J.; Deeney, Christopher D.; Mazarakis, Michael G.; Wenger, D.F.

We present the first comprehensive study of high wire-number, wire-array Z-pinch dynamics at 14-18 MA using x-ray backlighting and optical shadowgraphy diagnostics. The cylindrical arrays retain slowly expanding, dense wire cores at the initial position up to 60% of the total implosion time. Azimuthally correlated instabilities at the array edge appear during this stage which continue to grow in amplitude and wavelength after the start of bulk motion, resulting in measurable trailing mass that does not arrive on axis before peak x-ray emission.

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Progress in Z-Pinch driven dynamic-hohlraums for high-temperature radiation-flow and ICF experiments at Sandia National Laboratories

Sanford, Thomas W.; Cuneo, M.E.; Leeper, Ramon J.; Matzen, M.K.; Mehlhorn, Thomas A.; Slutz, Stephen A.; Nash, Thomas J.; Stygar, William A.; Olson, Richard E.; Olson, Craig L.; Bliss, David E.; Lemke, Raymond W.; Ruiz, Carlos L.; Bailey, James E.; Chandler, Gordon A.

Progress in understanding the physics of dynamic-hohlraums is reviewed for a system capable of generating 13 TW of axial radiation for high temperature (>200 eV) radiation-flow experiments and ICF capsule implosions.

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[Copy of characteristics and scaling of tungsten-wire-array z-pinch implosion dynamics at 20 MA.]

Proposed for publication in Physics of Plasmas.

Vesey, Roger A.; Yu, Edmund Y.; Nash, Thomas J.; Bliss, David E.; Bennett, Guy R.; Sinars, Daniel S.; Simpson, Walter W.; Ruggles, Larry R.; Wenger, D.F.; Garasi, Christopher J.; Aragon, Rafael A.; Fowler, William E.; Johnson, Drew J.; Keller, Keith L.; McGurn, John S.; Mehlhorn, Thomas A.; Speas, Christopher S.; Struve, Kenneth W.; Stygar, William A.; Chandler, Gordon A.

Abstract not provided.

A new laser trigger system for current pulse shaping and jitter reduction on Z

Digest of Technical Papers-IEEE International Pulsed Power Conference

Bliss, David E.; Collins, R.T.; Dalton, D.G.; Dawson, E.J.; Doty, R.L.; Downey, T.L.; Harjes, Henry C.; Illescas, E.A.; Knudson, Marcus D.; Lewis, B.A.; Mills, Jerry A.; Ploor, S.D.; Podsednik, Jason P.; Rogowski, Sonrisa T.; Shams, M.S.; Struve, Kenneth W.

A new laser trigger system (LTS) has been installed on Z that benefits the experimenter with reduced temporal jitter on the x-ray output, the confidence to use command triggers for time sensitive diagnostics and the ability to shape the current pulse at the load. This paper presents work on the pulse shaping aspects of the new LTS. Pulse shaping is possible because the trigger system is based on 36 individual lasers, one per each pulsed power module, instead of a single laser for the entire machine. The firing time of each module can be individually controlled to create an overall waveform that is the linear superposition of all 36 modules. In addition, each module can be set to a long- or short-pulse mode for added flexibility. The current waveform has been stretched from ∼100 ns to ∼250 ns. A circuit model has been developed with BERTHA Code, which contains the independent timing feature of the new LTS to predict and design pulse shapes. The ability to pulse-shape directly benefits isentropic compression experiments (ICE) and equation of state measurements (EOS) for the shock physics programs at Sandia National Laboratories. With the new LTS, the maximum isentropic loading applied to Cu samples 750 um thick has been doubled to 3.2 Mb without generating a shockwave. Macroscopically thick sample of Al, 1.5 mm, have been isentropically compressed to 1.7 Mb. Also, shockless Ti flyer-plates have been launched to 21 km·s-1, remaining in the solid state until impact.

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Self-consistent, 2D magneto-hydrodynamic simulations of magnetically driven flyer plate experiments on the Z-machine

Lemke, Raymond W.; Lemke, Raymond W.; Knudson, Marcus D.; Davis, Jean-Paul D.; Bliss, David E.; Harjes, Henry C.

The intense magnetic field generated in the 20 MA Z-machine is used to accelerate metallic flyer plates to high velocity (peak velocity {approx}20-30 km/s) for the purpose of generating strong shocks (peak pressure {approx}5-10 Mb) in equation of state experiments. We have used the Sandia developed, 2D magneto-hydrodynamic (MHD) simulation code ALEGRA to investigate the physics of accelerating flyer plates using multi-megabar magnetic drive pressures. Through detailed analysis of experimental data using ALEGRA, we developed a 2D, predictive MHD model for simulating material science experiments on Z. The ALEGRA MHD model accurately produces measured time dependent flyer velocities. Details of the ALEGRA model are presented. Simulation and experimental results are compared and contrasted for shots using standard and shaped current pulses whose peak drive pressure is {approx}2 Mb. Isentropic compression of Al to 1.7 Mb is achieved by shaping the current pulse.

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Scaling of high-mass tungsten-wire-array z-pinch discrete-wire implosion dynamics at 20 MA

Proposed for publication in Physical Review Letters.

Cuneo, M.E.; Yu, Edmund Y.; Garasi, Christopher J.; Oliver, Bryan V.; Aragon, Rafael A.; Bliss, David E.; Lazier, Steven E.; Mehlhorn, Thomas A.; Nielsen, D.S.; Sarkisov, Gennady S.; Cuneo, M.E.; Vesey, Roger A.; Wagoner, Tim C.; Chandler, Gordon A.; Waisman, Eduardo M.; Stygar, William A.; Nash, Thomas J.; Yu, Edmund Y.

Abstract not provided.

Z-pinch current-scaling experiments at 10[7] amps

Proposed for publication in Physical Review E.

Stygar, William A.; Matzen, M.K.; Mazarakis, Michael G.; McDaniel, Dillon H.; McGurn, John S.; Mckenney, John M.; Mix, L.P.; Muron, David J.; Ramirez, Juan J.; Ruggles, Larry R.; Stygar, William A.; Seamen, Johann F.; Simpson, Walter W.; Speas, Christopher S.; Spielman, Rick B.; Struve, Kenneth W.; Vesey, Roger A.; Wagoner, Tim C.; Gilliland, Terrance L.; Bennett, Guy R.; Ives, Harry C.; Jobe, Daniel O.; Lazier, Steven E.; Mills, Jerry A.; Mulville, Thomas D.; Pyle, John H.; Romero, Tobias M.; Seamen, Johann F.; Serrano, Jason D.; Smelser, Ruth S.; Fehl, David L.; Cuneo, M.E.; Bailey, James E.; Bliss, David E.; Chandler, Gordon A.; Leeper, Ramon J.

Abstract not provided.

Range-gated LADAR coherent imaging using parametric up-conversion of IR and NIR light for imaging with a visible-range fast-shuttered intensified digital CCD camera

Proceedings of SPIE-The International Society for Optical Engineering

Yates, George J.; McDonald, Thomas E.; Bliss, David E.; Cameron, Stewart M.; Zutavern, Fred J.; Zagarino, Paul

Research is presented on infrared (IR) and near infrared (NIR) sensitive sensor technologies for use in a high speed shuttered/intensified digital video camera system for range-gated imaging at "eye-safe" wavelengths in the region of 1.5 microns. The study is based upon nonlinear crystals used for second harmonic generation (SHG) in optical parametric oscillators (OPOs) for conversion of NIR and IR laser light to visible range light for detection with generic S-20 photocathodes. The intensifiers are "stripline" geometry 18-mm diameter microchannel plate intensifiers (MCPIIs), designed by Los Alamos National Laboratory and manufactured by Philips Photonics. The MCPIIs are designed for fast optical shuttering with exposures in the 100-200 ps range, and are coupled to a fast readout CCD camera. Conversion efficiency and resolution for the wavelength conversion process are reported. Experimental set-ups for the wavelength shifting and the optical configurations for producing and transporting laser reflectance images are discussed.

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Near Infrared (NIR) Imaging Techniques Using Lasers and Nonlinear Crystal Optical Parametric Oscillator/Amplifier (OPO/OPA) Imaging and Transferred Electron (TE) Photocathode Image Intensifiers

Bliss, David E.; Cameron, Stewart M.; Greives, Kenneth G.; Zutavern, Fred J.; Bliss, David E.

Laboratory experiments utilizing different near-infrared (NIR) sensitive imaging techniques for LADAR range gated imaging at eye-safe wavelengths are presented. An OPO/OPA configuration incorporating a nonlinear crystal for wavelength conversion of 1.56 micron probe or broadcast laser light to 807 nm light by utilizing a second pump laser at 532 nm for gating and gain, was evaluated for sensitivity, resolution, and general image quality. These data are presented with similar test results obtained from an image intensifier based upon a transferred electron (TE) photocathode with high quantum efficiency (QE) in the 1-2 micron range, with a P-20 phosphor output screen. Data presented include range-gated imaging performance in a cloud chamber with varying optical attenuation of laser reflectance images.

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120 Results
120 Results