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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.

Development of a cryogenically cooled platform for the Magnetized Liner Inertial Fusion (MagLIF) Program

Review of Scientific Instruments

Awe, T.J.; Shelton, Keegan P.; Sefkow, Adam B.; Lamppa, Derek C.; Baker, J.L.; Rovang, Dean C.; Robertson, Grafton K.

A cryogenically cooled hardware platform has been developed and commissioned on the Z Facility at Sandia National Laboratories in support of the Magnetized Liner Inertial Fusion (MagLIF) Program. MagLIF is a magneto-inertial fusion concept that employs a magnetically imploded metallic tube (liner) to compress and inertially confine premagnetized and preheated fusion fuel. The fuel is preheated using a ∼2 kJ laser that must pass through a ∼1.5-3.5-μm-thick polyimide "window" at the target's laser entrance hole (LEH). As the terawatt-class laser interacts with the dense window, laser plasma instabilities (LPIs) can develop, which reduce the preheat energy delivered to the fuel, initiate fuel contamination, and degrade target performance. Cryogenically cooled targets increase the parameter space accessible to MagLIF target designs by allowing nearly 10 times thinner windows to be used for any accessible gas density. Thinner LEH windows reduce the deleterious effects of difficult to model LPIs. The Z Facility's cryogenic infrastructure has been significantly altered to enable compatibility with the premagnetization and fuel preheat stages of MagLIF. The MagLIF cryostat brings the liquid helium coolant directly to the target via an electrically resistive conduit. This design maximizes cooling power while allowing rapid diffusion of the axial magnetic field supplied by external Helmholtz-like coils. A variety of techniques have been developed to mitigate the accumulation of ice from vacuum chamber contaminants on the cooled LEH window, as even a few hundred nanometers of ice would impact laser energy coupling to the fuel region. The MagLIF cryostat has demonstrated compatibility with the premagnetization and preheat stages of MagLIF and the ability to cool targets to liquid deuterium temperatures in approximately 5 min.

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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.

Neutron Diagnostic Development fro the Z Accelerator

Hahn, Kelly D.; Hahn, Kelly D.; Chandler, Gordon A.; Ruiz, Carlos L.; Jones, Brent M.; Gomez, Matthew R.; Knapp, Patrick K.; Sefkow, Adam B.; Hansen, Stephanie B.; Schmit, Paul S.; Harding, Eric H.; Norris, Edward T.; Torres, Jose A.; Cooper, Gary W.; Styron, Jedediah D.; Glebov, V.Yu.; Frenje, J.A.; Lahmann, B.L.; Gatu-Johnson, M.G.; Seguin, F.H.; Petrasso, R.D.; Fittinghoff, D.F.; May, M.M.; Snyder, L.S.; Moy, K.M.; Buckles, R.B.

Abstract not provided.

Investigating Laser Preheat and Applied Magnetic Fields Relevant to the MagLIF Fusion Scheme

Harvey-Thompson, Adam J.; Geissel, Matthias G.; Sefkow, Adam B.; Nagayama, Taisuke N.

The MAGnetized Liner Inertial Fusion (MagLIF) scheme has achieved thermonuclear fusion yields on the Z Facility by imploding a cylindrical liner filled with D 2 fuel that is preheated with a multi-kJ laser and pre-magnetized with an axial Bz=10 T magnetic field. Preheating (T e = 100- 200 eV) and pre-magnetizing (10-30 T) the fuel serves to reduce the implosion velocity required to achieve multi-keV fusion-relevant temperatures at stagnation with a modest radial convergence. The challenge of fuel preheat in MagLIF is to deposit multiple-kJ of energy into the underdense (n e /n c %3C0.1) fuel over %7E10 mm target length efficiently and without introducing contaminants. Once the fuel is heated the applied axial magnetic field (o ce t e %7E 10) needs to suppress electron thermal conduction sufficiently to prevent unacceptable heat losses to the liner walls. In this LDRD we investigated laser energy deposition at two facilities: The OMEGA-EP laser at the Laboratory for Laser Energetics and the Z-beamlet laser at Sandia National Labs utilizing the PECOS chamber. Multiple experiments were carried out investigating laser transmission through LEH foils, laser heating of underdense gasses and the effects of magnetization on laser preheat. The studies find that magneto-hydrodynamic simulations are able to reproduce energy deposition at MagLIF-like conditions but that at the intensities currently used to preheat MagLIF significant laser plasma instabilities (LPI) occur which partly explain the inability of codes to reproduce previous MagLIF preheat studies. The experiments find that reducing the intensity and smoothing the beam dramatically reduces the amount of stimulated Brillouin backscatter and produces deposition profiles more similar to those produced in simulations. The experiments have provided a large and varied dataset that can be compared to simulations. As part of the LDRD new experimental capabilities have also been developed that will be used to design future MagLIF integrated experiments and investigate fuel magnetization.

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Overview of Neutron diagnostic measurements for MagLIF Experiments on the Z Accelerator

Hahn, Kelly D.; Chandler, Gordon A.; Ruiz, Carlos L.; Cooper, Gary W.; Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Sinars, Daniel S.; Hansen, Stephanie B.; Knapp, Patrick K.; Schmit, Paul S.; Harding, Eric H.; Jennings, Christopher A.; Awe, Thomas J.; Geissel, Matthias G.; Rovang, Dean C.; Torres, Jose A.; Bur, James A.; Cuneo, M.E.; Glebov, V.Yu.; Harvey-Thompson, Adam J.; Hess, Mark H.; Johns, Owen J.; Jones, Brent M.; Lamppa, Derek C.; Lash, Joel S.; Martin, Matthew; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Reneker, Joseph R.; Robertson, Grafton K.; Rochau, G.A.; Savage, Mark E.; Smith, Ian C.; Styron, Jedediah D.; Vesey, Roger A.

Abstract not provided.

DIAGNOSING MAGNETIZED LINER INERTIAL FUSION EXPERIMENTS USING NEUTRON DIAGNOSTICS ON THE Z ACCELERATOR

Hahn, Kelly D.; Chandler, Gordon A.; Ruiz, Carlos L.; Cooper, Gary W.; Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Sinars, Daniel S.; Hansen, Stephanie B.; Knapp, Patrick K.; Schmit, Paul S.; Harding, Eric H.; Jennings, Christopher A.; Awe, Thomas J.; Geissel, Matthias G.; Rovang, Dean C.; Torres, Jose A.; Bur, James A.; Cuneo, M.E.; Glebov, V.Yu.; Harvey-Thompson, Adam J.; Hess, Mark H.; Johns, Owen J.; Jones, Brent M.; Lamppa, Derek C.; Lash, Joel S.; Martin, Matthew; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Reneker, Joseph R.; Robertson, Grafton K.; Rochau, G.A.; Savage, Mark E.; Smith, Ian C.; Styron, Jedediah D.; Vesey, Roger A.

Abstract not provided.

Fusion-neutron measurements for magnetized liner inertial fusion experiments on the Z accelerator

Journal of Physics: Conference Series

Hahn, K.D.; Chandler, Gordon A.; Ruiz, Carlos L.; Cooper, Gary W.; Gomez, Matthew R.; Slutz, S.; Sefkow, Adam B.; Sinars, Daniel S.; Hansen, Stephanie B.; Knapp, P.F.; Schmit, Paul S.; Harding, Eric H.; Jennings, C.A.; Awe, T.J.; Geissel, Matthias G.; Rovang, Dean C.; Torres, Jose A.; Bur, J.A.; Cuneo, M.E.; Glebov, V.Y.; Harvey-Thompson, Adam J.; Herrman, M.C.; Hess, Mark H.; Johns, Owen J.; Jones, Brent M.; Lamppa, Derek C.; Lash, Joel S.; Martin, M.R.; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Reneker, Joseph R.; Robertson, Grafton K.; Rochau, G.A.; Savage, Mark E.; Smith, Ian C.; Styron, Jedediah D.; Vesey, Roger A.

Several magnetized liner inertial fusion (MagLIF) experiments have been conducted on the Z accelerator at Sandia National Laboratories since late 2013. Measurements of the primary DD (2.45 MeV) neutrons for these experiments suggest that the neutron production is thermonuclear. Primary DD yields up to 3e12 with ion temperatures ∼2-3 keV have been achieved. Measurements of the secondary DT (14 MeV) neutrons indicate that the fuel is significantly magnetized. Measurements of down-scattered neutrons from the beryllium liner suggest ρRliner∼1g/cm2. Neutron bang times, estimated from neutron time-of-flight (nTOF) measurements, coincide with peak x-ray production. Plans to improve and expand the Z neutron diagnostic suite include neutron burn-history diagnostics, increased sensitivity and higher precision nTOF detectors, and neutron recoil-based yield and spectral measurements.

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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.

SNL perspective on the nTOF workshop

Jones, Brent M.; Hahn, Kelly D.; Ruiz, Carlos L.; Chandler, Gordon A.; Fehl, David L.; Lash, Joel S.; Knapp, Patrick K.; Gomez, Matthew R.; Hansen, Stephanie B.; Harding, Eric H.; McPherson, Leroy A.; Nelson, Alan J.; Rochau, G.A.; Schmit, Paul S.; Sefkow, Adam B.; Sinars, Daniel S.; Torres, Jose A.; Bur, James A.; Cooper, Gary W.; Bonura, Michael A.; Long, Joel L.; Styron, Jedediah D.; Buckles, Rob B.; Garza, Irene G.; Moy, Kenneth J.; Davis, Brent D.; Tinsley, Jim T.; Tiangco, Rod T.; Miller, Kirk M.; Mckenna, Ian M.

Abstract not provided.

Experimental Demonstration of the Stabilizing Effect of Dielectric Coatings on Magnetically Accelerated Imploding Metallic Liners

Physical Review Letters

Awe, T.J.; Peterson, Kyle J.; Yu, E.P.; McBride, Ryan D.; Sinars, Daniel S.; Gomez, Matthew R.; Jennings, C.A.; Martin, M.R.; Rosenthal, Stephen E.; Schroen, D.G.; Sefkow, Adam B.; Slutz, S.A.; Tomlinson, K.; Vesey, Roger A.

Enhanced implosion stability has been experimentally demonstrated for magnetically accelerated liners that are coated with 70 μm of dielectric. The dielectric tamps liner-mass redistribution from electrothermal instabilities and also buffers coupling of the drive magnetic field to the magneto-Rayleigh-Taylor instability. A dielectric-coated and axially premagnetized beryllium liner was radiographed at a convergence ratio [CR=Rin,0/Rin(z,t)] of 20, which is the highest CR ever directly observed for a strengthless magnetically driven liner. The inner-wall radius Rin(z,t) displayed unprecedented uniformity, varying from 95 to 130 μm over the 4.0 mm axial height captured by the radiograph.

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Scaling magnetized liner inertial fusion on Z and future pulsed-power accelerators

Physics of Plasmas

Slutz, S.A.; Stygar, William A.; Gomez, Matthew R.; Peterson, Kyle J.; Sefkow, Adam B.; Sinars, Daniel S.; Vesey, Roger A.; Campbell, E.M.; Betti, R.

The MagLIF (Magnetized Liner Inertial Fusion) concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)] has demonstrated fusion-relevant plasma conditions [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] on the Z accelerator with a peak drive current of about 18 MA. We present 2D numerical simulations of the scaling of MagLIF on Z as a function of drive current, preheat energy, and applied magnetic field. The results indicate that deuterium-tritium (DT) fusion yields greater than 100 kJ could be possible on Z when all of these parameters are at the optimum values: I.e., peak current = 25 MA, deposited preheat energy = 5 kJ, and Bz = 30 T. Much higher yields have been predicted [S. A. Slutz and R. A. Vesey, Phys. Rev. Lett. 108, 025003 (2012)] for MagLIF driven with larger peak currents. Two high performance pulsed-power accelerators (Z300 and Z800) based on linear-transformer-driver technology have been designed [W. A. Stygar et al., Phys. Rev. ST Accel. Beams 18, 110401 (2015)]. The Z300 design would provide 48 MA to a MagLIF load, while Z800 would provide 65 MA. Parameterized Thevenin-equivalent circuits were used to drive a series of 1D and 2D numerical MagLIF simulations with currents ranging from what Z can deliver now to what could be achieved by these conceptual future pulsed-power accelerators. 2D simulations of simple MagLIF targets containing just gaseous DT have yields of 18 MJ for Z300 and 440 MJ for Z800. The 2D simulated yield for Z800 is increased to 7 GJ by adding a layer of frozen DT ice to the inside of the liner.

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Delivering Kilojoules of Pre-Heat to Fusion Targets in Sandia's Z-Machine

Geissel, Matthias G.; Awe, Thomas J.; Campbell, E.M.C.; Gomez, Matthew R.; Harding, Eric H.; Harvey-Thompson, Adam J.; Hansen, Stephanie B.; Jennings, Christopher A.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; McBride, Ryan D.; Peterson, Kyle J.; Schollmeier, Marius; Sefkow, Adam B.; Shores, Jonathon S.; Sinars, Daniel S.; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Vesey, Roger A.; 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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Diagnosing laser-preheated magnetized plasmas relevant to magnetized liner inertial fusion

Physics of Plasmas

Harvey-Thompson, Adam J.; Sefkow, Adam B.; Nagayama, Taisuke N.; Wei, M.S.; Campbell, Edward M.; Fiksel, G.; Chang, P.Y.; Davies, J.R.; Barnak, D.H.; Glebov, V.Y.; Fitzsimmons, P.; Fooks, J.; Blue, B.E.

We present a platform on the OMEGA EP Laser Facility that creates and diagnoses the conditions present during the preheat stage of the MAGnetized Liner Inertial Fusion (MagLIF) concept. Experiments were conducted using 9 kJ of 3ω (355 nm) light to heat an underdense deuterium gas (electron density: 2.5×1020 cm-3=0.025 of critical density) magnetized with a 10 T axial field. Results show that the deuterium plasma reached a peak electron temperature of 670 ± 140 eV, diagnosed using streaked spectroscopy of an argon dopant. The results demonstrate that plasmas relevant to the preheat stage of MagLIF can be produced at multiple laser facilities, thereby enabling more rapid progress in understanding magnetized preheat. Results are compared with magneto-radiation-hydrodynamics simulations, and plans for future experiments are described.

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Laser Pre-Heat Studies for magLIF with Z-Beamlet

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

Abstract not provided.

Exploring magnetized liner inertial fusion with a semi-analytic model

McBride, Ryan D.; Slutz, Stephen A.; Sinars, Daniel S.; Vesey, Roger A.; Gomez, Matthew R.; Sefkow, Adam B.; Hansen, Stephanie B.; Cochrane, Kyle C.; Schmit, Paul S.; Knapp, Patrick K.; Geissel, Matthias G.; Harvey-Thompson, Adam J.; Jennings, Christopher A.; Martin, Matthew; Awe, Thomas J.; Rovang, Dean C.; Lamppa, Derek C.; Peterson, Kyle J.; Rochau, G.A.; Porter, John L.; Stygar, William A.; Cuneo, M.E.

Abstract not provided.

Laser-Fuel Coupling Studies for MagLIF with Z-Beamlet

Geissel, Matthias G.; Harvey-Thompson, Adam J.; Awe, Thomas J.; Campbell, Michael E.; Gomez, Matthew R.; Harding, Eric H.; Jennings, Christopher A.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; McBride, Ryan D.; Peterson, Kyle J.; Schollmeier, Marius; Schmit, Paul 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.

Abstract not provided.

Fusion-Neutron Measurements for Magnetized Liner Inertial Fusion Experiments on the Z Accelerator

Hahn, Kelly D.; Chandler, Gordon A.; Ruiz, Carlos L.; Cooper, Gary W.; Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Sinars, Daniel S.; Hansen, Stephanie B.; Knapp, Patrick K.; Schmit, Paul S.; Harding, Eric H.; Jennings, Christopher A.; Awe, Thomas J.; Geissel, Matthias G.; Rovang, Dean C.; Torres, Jose A.; Bur, James A.; Cuneo, M.E.; Glebov, V.Yu.; Harvey-Thompson, Adam J.; Herrmann, M.C.H.; Hess, Mark H.; Johns, Owen J.; Jones, Brent M.; Lamppa, Derek C.; Martin, Matthew; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Reneker, Joseph R.; Robertson, Grafton K.; Rochau, G.A.; Savage, Mark E.; Smith, Ian C.; Styron, Jedediah D.; Vesey, Roger A.

Abstract not provided.

X-ray Imaging of MagLIF Experiments Using a Spherically Bent Crystal Optic

Harding, Eric H.; Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Geissel, Matthias G.; Harvey-Thompson, Adam J.; Schollmeier, Marius; Peterson, Kyle J.; Awe, Thomas J.; Hansen, Stephanie B.; Hahn, Kelly D.; Knapp, Patrick K.; Schmit, Paul S.; Ruiz, Carlos L.; Sinars, Daniel S.; Jennings, Christopher A.; Smith, Ian C.; Rovang, Dean C.; Chandler, Gordon A.; Martin, Matthew; McBride, Ryan D.; Porter, John L.; Rochau, G.A.; Harding, Eric H.

Abstract not provided.

Exploring magnetized liner inertial fusion with a semi-analytic model

McBride, Ryan D.; Slutz, Stephen A.; Sinars, Daniel S.; Vesey, Roger A.; Gomez, Matthew R.; Sefkow, Adam B.; Hansen, Stephanie B.; Cochrane, Kyle C.; Rovang, Dean C.; Lamppa, Derek C.; Geissel, Matthias G.; Harvey-Thompson, Adam J.; Schmit, Paul S.; Knapp, Patrick K.; Awe, Thomas J.; Jennings, Christopher A.; Martin, Matthew; Peterson, Kyle J.; Rochau, G.A.; Porter, John L.; Stygar, William A.; Cuneo, M.E.

Abstract not provided.

LEH Transmission and Early Fuel Heating for MagLIF with Z-Beamlet

Geissel, Matthias G.; Harvey-Thompson, Adam J.; Awe, Thomas J.; Campbell, Edward M.; Gomez, Matthew R.; Harding, Eric H.; Jennings, Christopher A.; Kimmel, Mark W.; Knapp, Patrick K.; Lewis, Sean M.; McBride, Ryan D.; Peterson, Kyle J.; Schollmeier, Marius; Schmit, Paul S.; Sefkow, Adam B.; Shores, Jonathon S.; Sinars, Daniel S.; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Stahoviak, J.W.S.; Vesey, Roger A.; Porter, John L.

Abstract not provided.

Experimental Progress in Magnetized Liner Inertial Fusion (MagLIF)

Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Geissel, Matthias G.; Harvey-Thompson, Adam J.; Peterson, Kyle J.; Hansen, Stephanie B.; Hahn, Kelly D.; Knapp, Patrick K.; Schmit, Paul S.; Ruiz, Carlos L.; Sinars, Daniel S.; Awe, Thomas J.; Harding, Eric H.; Jennings, Christopher A.; Smith, Ian C.; Rovang, Dean C.; Chandler, Gordon A.; Cuneo, M.E.; Lamppa, Derek C.; Martin, Matthew; McBride, Ryan D.; Porter, John L.; Rochau, G.A.

Abstract not provided.

Recent progress in Magnetized Liner Inertial Fusion (MagLIF) experiments

Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Geissel, Matthias G.; Harvey-Thompson, Adam J.; Peterson, Kyle J.; Awe, Thomas J.; Hansen, Stephanie B.; Harding, Eric H.; Hahn, Kelly D.; Knapp, Patrick K.; Schmit, Paul S.; Ruiz, Carlos L.; Sinars, Daniel S.; Jennings, Christopher A.; Smith, Ian C.; Rovang, Dean C.; Chandler, Gordon A.; Martin, Matthew; McBride, Ryan D.; Porter, John L.; Rochau, G.A.

Abstract not provided.

Magnetized Liner Inertial Fusion on the Z Pulsed-Power Accelerator

McBride, Ryan D.; Sinars, Daniel S.; Slutz, Stephen A.; Gomez, Matthew R.; Sefkow, Adam B.; Hansen, Stephanie B.; Awe, Thomas J.; Peterson, Kyle J.; Knapp, Patrick K.; Schmit, Paul S.; Rovang, Dean C.; Geissel, Matthias G.; Vesey, Roger A.; Harvey-Thompson, Adam J.; Jennings, Christopher A.; Martin, Matthew; Lemke, Raymond W.; Hahn, Kelly D.; Harding, Eric H.; Cuneo, M.E.; Porter, John L.; Rochau, G.A.; Stygar, William A.

Abstract not provided.

Effects of magnetization on fusion product trapping and secondary neutron spectra

Physics of Plasmas

Knapp, P.F.; Schmit, Paul S.; Hansen, Stephanie B.; Gomez, Matthew R.; Hahn, K.D.; Sinars, Daniel S.; Peterson, Kyle J.; Slutz, S.A.; Sefkow, Adam B.; Awe, T.J.; Harding, Eric H.; Jennings, C.A.; Desjarlais, M.P.; Chandler, Gordon A.; Cooper, Gary W.; Cuneo, M.E.; Geissel, Matthias G.; Harvey-Thompson, Adam J.; Porter, John L.; Rochau, G.A.; Rovang, Dean C.; Ruiz, Carlos L.; Savage, Mark E.; Smith, Ian C.; Stygar, William A.; Herrmann, M.C.

By magnetizing the fusion fuel in inertial confinement fusion (ICF) systems, the required stagnation pressure and density can be relaxed dramatically. This happens because the magnetic field insulates the hot fuel from the cold pusher and traps the charged fusion burn products. This trapping allows the burn products to deposit their energy in the fuel, facilitating plasma self-heating. Here, we report on a comprehensive theory of this trapping in a cylindrical DD plasma magnetized with a purely axial magnetic field. Using this theory, we are able to show that the secondary fusion reactions can be used to infer the magnetic field-radius product, BR, during fusion burn. This parameter, not ρR, is the primary confinement parameter in magnetized ICF. Using this method, we analyze data from recent Magnetized Liner Inertial Fusion experiments conducted on the Z machine at Sandia National Laboratories. We show that in these experiments BR ≈ 0.34(+0.14/-0.06) MG cm, a ∼ 14x increase in BR from the initial value, and confirming that the DD-fusion tritons are magnetized at stagnation. This is the first experimental verification of charged burn product magnetization facilitated by compression of an initial seed magnetic flux.

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Diagnosing magnetized liner inertial fusion experiments on Z

Physics of Plasmas

Hansen, Stephanie B.; Gomez, Matthew R.; Sefkow, Adam B.; Slutz, S.A.; Sinars, Daniel S.; Hahn, K.D.; Harding, Eric H.; Knapp, P.F.; Schmit, Paul S.; Awe, T.J.; McBride, Ryan D.; Jennings, C.A.; Geissel, Matthias G.; Harvey-Thompson, Adam J.; Peterson, K.J.; Rovang, Dean C.; Chandler, Gordon A.; Cooper, Gary W.; Cuneo, M.E.; Herrmann, M.C.; Hess, Mark H.; Johns, Owen J.; Lamppa, Derek C.; Martin, M.R.; Porter, J.L.; Robertson, G.K.; Rochau, G.A.; Ruiz, C.L.; Savage, M.E.; Smith, I.C.; Stygar, W.A.; Vesey, R.A.; Blue, B.E.; Ryutov, D.; Schroen, D.G.; Tomlinson, K.

Magnetized Liner Inertial Fusion experiments performed at Sandia's Z facility have demonstrated significant thermonuclear fusion neutron yields (∼1012 DD neutrons) from multi-keV deuterium plasmas inertially confined by slow (∼10 cm/μs), stable, cylindrical implosions. Effective magnetic confinement of charged fusion reactants and products is signaled by high secondary DT neutron yields above 1010. Analysis of extensive power, imaging, and spectroscopic x-ray measurements provides a detailed picture of ∼3 keV temperatures, 0.3 g/cm3 densities, gradients, and mix in the fuel and liner over the 1-2 ns stagnation duration.

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Demonstration of thermonuclear conditions in magnetized liner inertial fusion experiments

Physics of Plasmas

Gomez, Matthew R.; Slutz, S.A.; Sefkow, Adam B.; Hahn, K.D.; Hansen, Stephanie B.; Knapp, P.F.; Schmit, Paul S.; Ruiz, Carlos L.; Sinars, Daniel S.; Harding, Eric H.; Jennings, C.A.; Awe, T.J.; Geissel, Matthias G.; Rovang, Dean C.; Smith, Ian C.; Chandler, Gordon A.; Cooper, Gary W.; Cuneo, M.E.; Harvey-Thompson, Adam J.; Herrmann, M.C.; Hess, Mark H.; Lamppa, Derek C.; Martin, M.R.; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Rochau, G.A.; Savage, Mark E.; Schroen, D.G.; Stygar, William A.; Vesey, Roger A.

The magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)] utilizes a magnetic field and laser heating to relax the pressure requirements of inertial confinement fusion. The first experiments to test the concept [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] were conducted utilizing the 19 MA, 100-ns Z machine, the 2.5-kJ, 1 TW Z Beamlet laser, and the 10-T Applied B-field on Z system. Despite an estimated implosion velocity of only 70-km/s in these experiments, electron and ion temperatures at stagnation were as high as 3-keV, and thermonuclear deuterium-deuterium neutron yields up to 2-×-1012 have been produced. X-ray emission from the fuel at stagnation had widths ranging from 50 to 110 μm over a roughly 80% of the axial extent of the target (6-8-mm) and lasted approximately 2-ns. X-ray yields from these experiments are consistent with a stagnation density of the hot fuel equal to 0.2-0.4-g/cm3. In these experiments, up to 5-×-1010 secondary deuterium-tritium neutrons were produced. Given that the areal density of the plasma was approximately 1-2-mg/cm2, this indicates the stagnation plasma was significantly magnetized, which is consistent with the anisotropy observed in the deuterium-tritium neutron spectra. Control experiments where the laser and/or magnetic field were not utilized failed to produce stagnation temperatures greater than 1-keV and primary deuterium-deuterium yields greater than 1010. An additional control experiment where the fuel contained a sufficient dopant fraction to substantially increase radiative losses also failed to produce a relevant stagnation temperature. The results of these experiments are consistent with a thermonuclear neutron source.

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Laser-to-hot-electron conversion limitations in relativistic laser matter interactions due to multi-picosecond dynamics

Physics of Plasmas

Schollmeier, Marius; Sefkow, Adam B.; Geissel, Matthias G.; Arefiev, A.V.; Flippo, K.A.; Gaillard, S.A.; Johnson, R.P.; Kimmel, Mark W.; Offermann, D.T.; Rambo, Patrick K.; Schwarz, Jens S.; Shimada, T.

High-energy short-pulse lasers are pushing the limits of plasma-based particle acceleration, x-ray generation, and high-harmonic generation by creating strong electromagnetic fields at the laser focus where electrons are being accelerated to relativistic velocities. Understanding the relativistic electron dynamics is key for an accurate interpretation of measurements. We present a unified and self-consistent modeling approach in quantitative agreement with measurements and differing trends across multiple target types acquired from two separate laser systems, which differ only in their nanosecond to picosecond-scale rising edge. Insights from high-fidelity modeling of laser-plasma interaction demonstrate that the ps-scale, orders of magnitude weaker rising edge of the main pulse measurably alters target evolution and relativistic electron generation compared to idealized pulse shapes. This can lead for instance to the experimentally observed difference between 45-MeV and 75-MeV maximum energy protons for two nominally identical laser shots, due to ps-scale prepulse variations. Our results show that the realistic inclusion of temporal laser pulse profiles in modeling efforts is required if predictive capability and extrapolation are sought for future target and laser designs or for other relativistic laser ion acceleration schemes.

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Recent Progress and Future Potential of Magnetized Liner Inertial Fusion (MagLIF)

Sandia journal manuscript; Not yet accepted for publication

Slutz, Stephen A.; Gomez, Matthew R.; Sefkow, Adam B.; Sinars, Daniel S.; Hahn, Kelly D.; Hansen, Stephanie B.; Harding, Eric H.; Knapp, Patrick K.; Schmit, Paul S.; Jennings, Christopher A.; Awe, Thomas J.; Herrmann, M.C.H.; Hess, Mark H.; Johns, Owen J.; Lamppa, Derek C.; Martin, Matthew; McBride, Ryan D.; Geissel, Matthias G.; Rovang, Dean C.; Chandler, Gordon A.; Cooper, Gary W.; Cuneo, M.E.; Harvey-Thompson, Adam J.; Peterson, Kyle J.; Porter, John L.; Robertson, Grafton K.; Rochau, G.A.; Ruiz, Carlos L.; Savage, Mark E.; Smith, Ian C.; Stygar, William A.; Vesey, Roger A.

The standard approaches to inertial confinement fusion (ICF) rely on implosion velocities greater than 300 km/s and spherical convergence to achieve the high fuel temperatures (T > 4 keV) and areal densities (ρr > 0.3 g/cm2) required for ignition1. Such high velocities are achieved by heating the outside surface of a spherical capsuleeither directly with a large number of laser beams (Direct Drive) or with x-rays generated within a hohlraum (Indirect Drive). A much more energetically efficient approach is to use the magnetic pressure generated by a pulsed power machine to directly drive an implosion. In this approach 5-10% of the stored energy can be converted to the implosion of a metal tube generally referred to as a “liner”. However, the implosion velocity is not very high 70-100 km/s and the convergence is cylindrical (rather than spherical) making it more difficult to achieve the high temperatures and areal densities needed for ignition.

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Experimental verification of the Magnetized Liner Inertial Fusion (MagLIF) concept

ICOPS/BEAMS 2014 - 41st IEEE International Conference on Plasma Science and the 20th International Conference on High-Power Particle Beams

Gomez, Matthew R.; Slutz, S.A.; Sefkow, Adam B.; Awe, T.J.; Chandler, Gordon A.; Cuneo, M.E.; Geissel, Matthias G.; Hahn, K.D.; Hansen, Stephanie B.; Harding, Eric H.; Harvey-Thompson, Adam J.; Herrmann, Mark H.; Jennings, C.A.; Knapp, P.F.; Lamppa, Derek C.; Martin, M.R.; McBride, Ryan D.; Peterson, Kyle J.; Porter, J.L.; Rochau, G.A.; Rovang, Dean C.; Ruiz, Carlos L.; Schmit, Paul S.; Sinars, Daniel S.; Smith, Ian C.

Abstract not provided.

Pulsed-coil magnet systems for applying uniform 10-30 T fields to centimeter-scale targets on Sandia's Z facility

Review of Scientific Instruments

Rovang, Dean C.; Lamppa, Derek C.; Cuneo, M.E.; Owen, A.C.; Mckenney, John M.; Johnson, Drew J.; Radovich, S.; Kaye, Ronald J.; McBride, Ryan D.; Alexander, Charles S.; Awe, T.J.; Slutz, S.A.; Sefkow, Adam B.; Haill, Thomas A.; Jones, Peter A.; Argo, J.W.; Dalton, D.G.; Robertson, Grafton K.; Waisman, Eduardo M.; Sinars, Daniel S.; Meissner, J.; Milhous, M.; Nguyen, D.N.; Mielke, C.H.

Sandia has successfully integrated the capability to apply uniform, high magnetic fields (10-30 T) to high energy density experiments on the Z facility. This system uses an 8-mF, 15-kV capacitor bank to drive large-bore (5 cm diameter), high-inductance (1-3 mH) multi-turn, multi-layer electromagnets that slowly magnetize the conductive targets used on Z over several milliseconds (time to peak field of 2-7 ms). This system was commissioned in February 2013 and has been used successfully to magnetize more than 30 experiments up to 10 T that have produced exciting and surprising physics results. These experiments used split-magnet topologies to maintain diagnostic lines of sight to the target. We describe the design, integration, and operation of the pulsed coil system into the challenging and harsh environment of the Z Machine. We also describe our plans and designs for achieving fields up to 20 T with a reduced-gap split-magnet configuration, and up to 30 T with a solid magnet configuration in pursuit of the Magnetized Liner Inertial Fusion concept.

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Adaptive Beam Smoothing with Plasma-Pinholes for Laser-Entrance-Hole Transmission Studies

Geissel, Matthias G.; Awe, Thomas J.; Campbell, Edward M.; Gomez, Matthew R.; Harding, Eric H.; Harvey-Thompson, Adam J.; Jennings, Christopher A.; Kimmel, Mark W.; Lewis, Sean M.; McBride, Ryan D.; Peterson, Kyle J.; Schollmeier, Marius; Sefkow, Adam B.; Shores, Jonathon S.; Sinars, Daniel S.; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Stahoviak, John W.; Porter, John L.

Abstract not provided.

Experimental demonstration of fusion-relevant conditions in magnetized liner inertial fusion

Physical Review Letters

Gomez, Matthew R.; Jennings, Christopher A.; Awe, Thomas J.; Geissel, Matthias G.; Rovang, Dean C.; Chandler, Gordon A.; Cuneo, M.E.; Harvey-Thompson, Adam J.; Herrmann, Mark H.; Hess, Mark H.; Slutz, Stephen A.; Johns, Owen J.; Lamppa, Derek C.; Martin, Matthew; McBride, Ryan D.; Peterson, Kyle J.; Robertson, Grafton K.; Rochau, G.A.; Ruiz, Carlos L.; Savage, Mark E.; Sefkow, Adam B.; Smith, Ian C.; Stygar, William A.; Vesey, Roger A.; Sinars, Daniel S.; Hahn, Kelly D.; Hansen, Stephanie B.; Harding, Eric H.; Knapp, Patrick K.; Schmit, Paul S.

This Letter presents results from the first fully integrated experiments testing the magnetized liner inertial fusion concept [S.A. Slutz et al., Phys. Plasmas 17, 056303 (2010)], in which a cylinder of deuterium gas with a preimposed axial magnetic field of 10 T is heated by Z beamlet, a 2.5 kJ, 1 TW laser, and magnetically imploded by a 19 MA current with 100 ns rise time on the Z facility. Despite a predicted peak implosion velocity of only 70 km/s, the fuel reaches a stagnation temperature of approximately 3 keV, with Te ≈ Ti, and produces up to 2e12 thermonuclear DD neutrons. In this study, X-ray emission indicates a hot fuel region with full width at half maximum ranging from 60 to 120 μm over a 6 mm height and lasting approximately 2 ns. The number of secondary deuterium-tritium neutrons observed was greater than 1010, indicating significant fuel magnetization given that the estimated radial areal density of the plasma is only 2 mg/cm2.

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Neutron Diagnostics on the Z machine

Jones, Brent M.; Hahn, Kelly D.; Ruiz, Carlos L.; Chandler, Gordon A.; Fehl, David L.; Lash, Joel S.; Knapp, Patrick K.; McPherson, Leroy A.; Nelson, Alan J.; Rochau, G.A.; Schmit, Paul S.; Sefkow, Adam B.; Sinars, Daniel S.; Torres, Jose A.; Cooper, Gary W.; Bonura, Michael A.; Long, Joel L.; Styron, Jedediah D.; Davis, Brent D.; Buckles, Rob B.; Moy, Ken M.; Miller, Kirk M.; Mckenna, Ian M.

Abstract not provided.

Demonstration of fusion relevant conditions in Magnetized Liner Inertial Fusion experiments on the Z facility

Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Sinars, Daniel S.; Hahn, Kelly D.; Hansen, Stephanie B.; Harding, Eric H.; Knapp, Patrick K.; Schmit, Paul S.; Jennings, Christopher A.; Awe, Thomas J.; Geissel, Matthias G.; Rovang, Dean C.; Chandler, Gordon A.; Cuneo, M.E.; Harvey-Thompson, Adam J.; Herrmann, Mark H.; Lamppa, Derek C.; Martin, Matthew; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Rochau, G.A.; Ruiz, Carlos L.; Savage, Mark E.; Smith, Ian C.; Vesey, Roger A.

Abstract not provided.

Demonstration of fusion relevant conditions in Magnetized Liner Inertial Fusion Experiments on the Z Facility

Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Sinars, Daniel S.; Hahn, Kelly D.; Hansen, Stephanie B.; Harding, Eric H.; Knapp, Patrick K.; Schmit, Paul S.; Jennings, Christopher A.; Awe, Thomas J.; Geissel, Matthias G.; Rovang, Dean C.; Chandler, Gordon A.; Cuneo, M.E.; Harvey-Thompson, Adam J.; Herrmann, Mark H.; Lamppa, Derek C.; Martin, Matthew; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Rochau, G.A.; Ruiz, Carlos L.; Savage, Mark E.; Smith, Ian C.; Vesey, Roger A.

Abstract not provided.

Modified 3D-helix-like instability structure for imploding Z-pinch liners that are premagnetized with a uniform axial field

Awe, Thomas J.; Jennings, Christopher A.; McBride, Ryan D.; Cuneo, M.E.; Lamppa, Derek C.; Martin, Matthew; Rovang, Dean C.; Sinars, Daniel S.; Slutz, Stephen A.; Owen, Albert C.; Gomez, Matthew R.; Hansen, Stephanie B.; Harding, Eric H.; Herrmann, Mark H.; Jones, Michael J.; Knapp, Patrick K.; Mckenney, John M.; Peterson, Kyle J.; Robertson, Grafton K.; Rochau, G.A.; Savage, Mark E.; Schmit, Paul S.; Sefkow, Adam B.; Stygar, William A.; Vesey, Roger A.; Yu, Edmund Y.; Tomlinson, Kurt T.; Schroen, Diana G.

Abstract not provided.

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.

Z-petawatt driven ion beam radiography development

Schollmeier, Marius; Sefkow, Adam B.; Geissel, Matthias G.; Schwarz, Jens S.; Rambo, Patrick K.

Laser-driven proton radiography provides electromagnetic field mapping with high spatiotemporal resolution, and has been applied to many laser-driven High Energy Density Physics (HEDP) experiments. Our report addresses key questions about the feasibility of ion radiography at the Z-Accelerator (%E2%80%9CZ%E2%80%9D), concerning laser configuration, hardware, and radiation background. Charged particle tracking revealed that radiography at Z requires GeV scale protons, which is out of reach for existing and near-future laser systems. However, it might be possible to perform proton deflectometry to detect magnetic flux compression in the fringe field region of a magnetized liner inertial fusion experiment. Experiments with the Z-Petawatt laser to enhance proton yield and energy showed an unexpected scaling with target thickness. Full-scale, 3D radiation-hydrodynamics simulations, coupled to fully explicit and kinetic 2D particle-in-cell simulations running for over 10 ps, explain the scaling by a complex interplay of laser prepulse, preplasma, and ps-scale temporal rising edge of the laser.

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Conceptual designs of 300-TW and 800-TW pulsed-power accelerators

Stygar, William A.; Fowler, William E.; Gomez, Matthew R.; Harmon, Roger L.; Herrmann, Mark H.; Huber, Dale L.; Hutsel, Brian T.; Bailey, James E.; Jones, Michael J.; Jones, Peter A.; Leckbee, Joshua L.; Lee, James R.; Lewis, Scot A.; Long, Finis W.; Lopez, Mike R.; Lucero, Diego J.; Matzen, M.K.; Mazarakis, Michael G.; McBride, Ryan D.; McKee, George R.; Nakhleh, Charles N.; Owen, Albert C.; Rochau, G.A.; Savage, Mark E.; Schwarz, Jens S.; Sefkow, Adam B.; Sinars, Daniel S.; Stoltzfus, Brian S.; Vesey, Roger A.; Wakeland, P.; Cuneo, M.E.; Flicker, Dawn G.; Focia, Ronald J.

Abstract not provided.

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.

Penetrating radiography of imploding and stagnating beryllium liners on the Z accelerator

Physical Review Letters

McBride, Ryan D.; Peterson, Kyle J.; Sefkow, Adam B.; Nakhleh, Charles N.; Laspe, Amy R.; Lopez, Mike R.; Smith, Ian C.; Atherton, B.W.; Savage, Mark E.; Stygar, William A.; Slutz, Stephen A.; Rogers, Thomas J.; Jennings, Christopher A.; Sinars, Daniel S.; Cuneo, M.E.; Herrmann, Mark H.; Lemke, Raymond W.; Martin, Matthew; Vesey, Roger A.

Abstract not provided.

Plasma power station with quasi spherical direct drive capsule for fusion yield and inverse diode for driver-target coupling

Fusion Science and Technology

VanDevender, J.P.; Cuneo, M.E.; Slutz, S.A.; Herrmann, Mark H.; Vesey, Roger A.; Sinars, Daniel S.; Seidel, David B.; Schneider, Larry X.; Mikkelson, Kenneth A.; Harper-Slaboszewicz, V.H.; Peyton, B.P.; Sefkow, Adam B.; Matzen, M.K.

The Meier-Moir economic model for Pulsed Power Driven Inertial Fusion Energy shows at least two approaches for fusion energy at 7 to 8 cents/kw-hr: One with large yield at 0.1 Hz and presented by M. E. Cuneo at ICENES 2011 and one with smaller yield at 3 Hz presented in this paper. Both use very efficient and low cost Linear Transformer Drivers (LTDs) for the pulsed power. We report the system configuration and end-toend simulation for the latter option, which is called the Plasma Power Station (PPS), and report the first results on the two, least mature, enabling technologies: a magnetically driven Quasi Spherical Direct Drive (QSDD) capsule for the fusion yield and an Inverse Diode for coupling the driver to the target. In addition, we describe the issues and propose to address the issues with a prototype of the PPS on the Saturn accelerator and with experiments on a short pulse modification of the Z accelerator test the validity of simulations showing megajoule thermonuclear yield with DT on a modified Z.

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Plasma Power Station with Quasi Spherical Direct Drive Capsule for Fusion Yield and Inverse Diode for Driver-Target Coupling

Fusion Science and Technology

Cuneo, M.E.; Matzen, M.K.; Sinars, Daniel S.; Slutz, Stephen A.; Herrmann, Mark H.; Vesey, Roger A.; Seidel, David B.; Schneider, Larry X.; Mikkelson, Kenneth A.; Harper-Slaboszewicz, V.H.; Sefkow, Adam B.

The Meier-Moir economic model for Pulsed Power Driven Inertial Fusion Energy shows at least two approaches for fusion energy at 7 to 8 cents/kw-hr: One with large yield at 0.1 Hz and presented by M. E. Cuneo at ICENES 2011 and one with smaller yield at 3 Hz presented in this paper. Both use very efficient and low cost Linear Transformer Drivers (LTDs) for the pulsed power. Here, we report the system configuration and end-to-end simulation for the latter option, which is called the Plasma Power Station (PPS), and report the first results on the two, least mature, enabling technologies: a magnetically driven Quasi Spherical Direct Drive (QSDD) capsule for the fusion yield and an Inverse Diode for coupling the driver to the target. In addition, we describe the issues and propose to address the issues with a prototype of the PPS on the Saturn accelerator and with experiments on a short pulse modification of the Z accelerator test the validity of simulations showing megajoule thermonuclear yield with DT on a modified Z.

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Above-60-MeV proton acceleration with a 150 TW laser system

Schollmeier, Marius; Geissel, Matthias G.; Sefkow, Adam B.; Rambo, Patrick K.; Schwarz, Jens S.; Atherton, B.W.

Laser-accelerated proton beams can be used in a variety of applications, e.g. ultrafast radiography of dense objects or strong electromagnetic fields. Therefore high energies of tens of MeV are required. We report on proton-acceleration experiments with a 150 TW laser system using mm-sized thin foils and mass-reduced targets of various thicknesses. Thin- foil targets yielded maximum energies of 50 MeV. A further reduction of the target dimensions from mm-size to 250 x 250 x 25 microns increased the maximum proton energy to >65 MeV, which is comparable to proton energies measured only at higher-energy, Petawatt-class laser systems. The dependence of the maximum energy on target dimensions was investigated, and differences between mm-sized thin foils and mass-reduced targets will be reported.

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Ultrafast 25 keV backlighting for experiments on Z

Geissel, Matthias G.; Schollmeier, Marius; Kimmel, Mark W.; Pitts, Todd A.; Rambo, Patrick K.; Schwarz, Jens S.; Sefkow, Adam B.; Atherton, B.W.

To extend the backlighting capabilities for Sandia's Z-Accelerator, Z-Petawatt, a laser which can provide laser pulses of 500 fs length and up to 120 J (100TW target area) or up to 450 J (Z / Petawatt target area) has been built over the last years. The main mission of this facility focuses on the generation of high energy X-rays, such as tin Ka at 25 keV in ultra-short bursts. Achieving 25 keV radiographs with decent resolution and contrast required addressing multiple problems such as blocking of hot electrons, minimization of the source, development of suitable filters, and optimization of laser intensity. Due to the violent environment inside of Z, an additional very challenging task is finding massive debris and radiation protection measures without losing the functionality of the backlighting system. We will present the first experiments on 25 keV backlighting including an analysis of image quality and X-ray efficiency.

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Ultrafast 25 keV backlighting for experiments on Z

Geissel, Matthias G.; Atherton, B.W.; Pitts, Todd A.; Schollmeier, Marius; Headley, Daniel I.; Kimmel, Mark W.; Rambo, Patrick K.; Robertson, Grafton K.; Sefkow, Adam B.; Schwarz, Jens S.; Speas, Christopher S.

To extend the backlighting capabilities for Sandia's Z-Accelerator, Z-Petawatt, a laser which can provide laser pulses of 500 fs length and up to 120 J (100TW target area) or up to 450 J (Z/Petawatt target area) has been built over the last years. The main mission of this facility focuses on the generation of high energy X-rays, such as tin K{alpha} at 25 keV in ultra-short bursts. Achieving 25 keV radiographs with decent resolution and contrast required addressing multiple problems such as blocking of hot electrons, minimization of the source, development of suitable filters, and optimization of laser intensity. Due to the violent environment inside of Z, an additional very challenging task is finding massive debris and radiation protection measures without losing the functionality of the backlighting system. We will present the first experiments on 25 keV backlighting including an analysis of image quality and X-ray efficiency.

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High-efficiency high-energy Ka source for the critically-required maximum illumination of x-ray optics on Z using Z-petawatt-driven laser-breakout-afterburner accelerated ultrarelativistic electrons LDRD

Bennett, Guy R.; Sefkow, Adam B.

Under the auspices of the Science of Extreme Environments LDRD program, a <2 year theoretical- and computational-physics study was performed (LDRD Project 130805) by Guy R Bennett (formally in Center-01600) and Adam B. Sefkow (Center-01600): To investigate novel target designs by which a short-pulse, PW-class beam could create a brighter K{alpha} x-ray source than by simple, direct-laser-irradiation of a flat foil; Direct-Foil-Irradiation (DFI). The computational studies - which are still ongoing at this writing - were performed primarily on the RedStorm supercomputer at Sandia National Laboratories Albuquerque site. The motivation for a higher efficiency K{alpha} emitter was very clear: as the backlighter flux for any x-ray imaging technique on the Z accelerator increases, the signal-to-noise and signal-to-background ratios improve. This ultimately allows the imaging system to reach its full quantitative potential as a diagnostic. Depending on the particular application/experiment this would imply, for example, that the system would have reached its full design spatial resolution and thus the capability to see features that might otherwise be indiscernible with a traditional DFI-like x-ray source. This LDRD began FY09 and ended FY10.

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Proton acceleration experiments with Z-Petawatt

Schollmeier, Marius; Geissel, Matthias G.; Sefkow, Adam B.; Kimmel, Mark W.; Rambo, Patrick K.; Schwarz, Jens S.; Atherton, B.W.

The outline of this presentation: (1) Proton acceleration with high-power lasers - Target Normal Sheath Acceleration concept; (2) Proton acceleration with mass-reduced targets - Breaking the 60 MeV threshold; (3) Proton beam divergence control - Novel focusing target geometry; and (4) New experimental capability development - Proton radiography on Z.

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Pulsed power driven Magneto-Rayleigh-Taylor experiments

Slutz, Stephen A.; Herrmann, Mark H.; Vesey, Roger A.; Sefkow, Adam B.; Sinars, Daniel S.; Rovang, Dean C.; Peterson, Kyle J.; Cuneo, M.E.

Numerical simulations indicate that significant fusion yields (>100 kJ) may be obtained by pulsed-power-driven implosions of cylindrical metal liners onto magnetized and preheated deuterium-tritium fuel. The primary physics risk to this approach is the Magneto-Rayleigh-Taylor (MRT) instability, which operates during both the acceleration and deceleration phase of the liner implosion. We have designed and performed some experiments to study the MRT during the acceleration phase, where the light fluid is purely magnetic. Results from our first series of experiments and plans for future experiments will be presented. According to simulations, an initial axial magnetic field of 10 T is compressed to >100 MG within the liner during the implosion. The magnetic pressure becomes comparable to the plasma pressure during deceleration, which could significantly affect the growth of the MRT instability at the fuel/liner interface. The MRT instability is also important in some astronomical objects such as the Crab Nebula (NGC1962). In particular, the morphological structure of the observed filaments may be determined by the ratio of the magnetic to material pressure and alignment of the magnetic field with the direction of acceleration [Hester, ApJ, 456, 225 1996]. Potential experiments to study this MRT behavior using the Z facility will be presented.

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Simulations and experiments of intense ion beam compression in space and time

Proposed for publication in Physics of Plasmas.

Sefkow, Adam B.

The Heavy Ion Fusion Science Virtual National Laboratory has achieved 60-fold longitudinal pulse compression of ion beams on the Neutralized Drift Compression Experiment (NDCX) [P. K. Roy et al., Phys. Rev. Lett. 95, 234801 (2005)]. To focus a space-charge-dominated charge bunch to sufficiently high intensities for ion-beam-heated warm dense matter and inertial fusion energy studies, simultaneous transverse and longitudinal compression to a coincident focal plane is required. Optimizing the compression under the appropriate constraints can deliver higher intensity per unit length of accelerator to the target, thereby facilitating the creation of more compact and cost-effective ion beam drivers. The experiments utilized a drift region filled with high-density plasma in order to neutralize the space charge and current of an {approx}300 keV K{sup +} beam and have separately achieved transverse and longitudinal focusing to a radius <2 mm and pulse duration <5 ns, respectively. Simulation predictions and recent experiments demonstrate that a strong solenoid (B{sub Z} < 100 kG) placed near the end of the drift region can transversely focus the beam to the longitudinal focal plane. This paper reports on simulation predictions and experimental progress toward realizing simultaneous transverse and longitudinal charge bunch focusing. The proposed NDCX-II facility would capitalize on the insights gained from NDCX simulations and measurements in order to provide a higher-energy (>2 MeV) ion beam user-facility for warm dense matter and inertial fusion energy-relevant target physics experiments.

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116 Results
116 Results