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Dive into the research topics where J.F. Benage is active.

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Featured researches published by J.F. Benage.


Physics of Plasmas | 2012

The effects of laser absorption on direct-drive capsule experiments at OMEGA

E.S. Dodd; J.F. Benage; G. A. Kyrala; D. C. Wilson; F.J. Wysocki; W. Seka; V. Yu. Glebov; C. Stoeckl; J. A. Frenje

The yield of an inertial confinement fusion capsule can be greatly affected by the inclusion of high-Z material in the fuel, either intentionally as a diagnostic or from mixing due to hydrodynamic instabilities. To validate calculations of these conditions, glass shell targets filled with a D2 and 3He fuel mixture were fielded in experiments with controlled amounts of pre-mixed Ar, Kr, or Xe. The experiments were fielded at the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using 1.0 ns square laser pulses having a total energy 23 kJ and direct drive illumination of shells with an outer diameter of ∼925 μm and a thickness of ∼5 μm. Data were collected and compared to one-dimensional integrated models for yield and burn-temperature measurements. This paper presents a critical examination of the calculational assumptions used in our experimental modeling. A modified treatment of laser-capsule interaction improves the match to the measured scattered laser light and also improves agreement fo...


Review of Scientific Instruments | 2012

Imaging x-ray Thomson scattering spectrometer design and demonstration (invited).

E. J. Gamboa; Channing Huntington; Matthew Trantham; P.A. Keiter; R. P. Drake; D. S. Montgomery; J.F. Benage; S. Letzring

In many laboratory astrophysics experiments, intense laser irradiation creates novel material conditions with large, one-dimensional gradients in the temperature, density, and ionization state. X-ray Thomson scattering is a powerful technique for measuring these plasma parameters. However, the scattered signal has previously been measured with little or no spatial resolution, which limits the ability to diagnose inhomogeneous plasmas. We report on the development of a new imaging x-ray Thomson spectrometer (IXTS) for the Omega laser facility. The diffraction of x-rays from a toroidally curved crystal creates high-resolution images that are spatially resolved along a one-dimensional profile while spectrally dispersing the radiation. This focusing geometry allows for high brightness while localizing noise sources and improving the linearity of the dispersion. Preliminary results are presented from a scattering experiment that used the IXTS to measure the temperature profile of a shocked carbon foam.


Journal of Physics: Conference Series | 2008

The effects of pre-mix on burn in ICF capsules

D. C. Wilson; G. A. Kyrala; J.F. Benage; F.J. Wysocki; Mark Gunderson; W J Garbett; Vladimir Yu. Glebov; J. A. Frenje; B. Yaakobi; H W Herrman; J.H. Cooley; L Welser-Sherrill; C J Horsfield; S. Roberts

Directly driven implosions at the Omega laser have tested the effects of pre-mix of Ar, Kr, and Xe in D2 + 3 He filled glass micro-balloons. Diagnostics included: D+D and D+T neutron yields, D+ 3 He proton yields and spectra, Doppler broadened ion temperatures, time dependent neutron and proton burn rates, and time gated, high energy filtered, X-ray images. Yields are better calculated by XSN LTE than by non-LTE. Yields with a small amount of pre- mix, atom fractions of ~5e-3 for Ar, 2e-3 Kr, and Xe for 5e-4, are more degraded than calculated, while the measured ion temperatures are the same as without pre-mix. There is also a decrease in fuel ρr. The neutron burn histories suggest that the early yield coming before the reflected shock strikes the incoming shell is un-degraded, with yield degradation occurring afterwards. Adding 20 atm % 3 He to pure D fuel seems to produce a similar degradation. Calculated gated X-ray images agree with observed when the reflected shock strikes the incoming shell, but are smaller than observed afterward. This partially explains yield degradation and both the low fuel and whole capsule ρrs observed in secondary T+D neutrons and slowing of the D+ 3 He protons. Neither LTE on non-LTE captures the degradation by 3 He or at low pre-mix levels, nor matches the large shell radii after impact of the reflected shock.


Japanese Journal of Applied Physics | 2001

The Atlas High-Energy Density Physics Project

H.A. Davis; Rhon K. Keinigs; W. Anderson; W.L. Atchison; R.R. Bartsch; J.F. Benage; Evan O. Ballard; David W. Bowman; J.C. Cochrane; C.A. Ekdahl; Juan M. Elizondo; Rickey J. Faehl; R.D. Fulton; R.F. Gribble; Joyce Ann Guzik; George A. Kyrala; R. Bruce Miller; K. Nielsen; Jerald V. Parker; W. Mark Parsons; C.P. Munson; D. Oro; George Rodriguez; Harold H. Rogers; D.W. Scudder; J.S. Shlachter; J. Stokes; Antoinette J. Taylor; R. James Trainor; P.J. Turchi

Atlas is a pulsed-power facility under development at Los Alamos National Laboratory to drive high-energy density experiments. Atlas will be operational in the summer of 2000 and is optimized for the study of dynamic material properties, hydrodynamics, and dense plasmas under extreme conditions. Atlas is designed to implode heavy-liner loads in a z-pinch configuration. The peak current of 30 MA is delivered in 4 µs. A typical Atlas liner is a 47-gram-aluminum cylinder with ∼ 4-cm radius and 4-cm length. Three to five MJ of kinetic energy will be delivered to the load. Using composite layers and a variety of interior target designs, a wide variety of experiments in ∼ cm3 volumes will be performed. Atlas applications, machine design, and the status of the project are reviewed.


ieee international pulsed power conference | 1995

PROCYON: 18-MJ, 2-/spl mu/s pulsed power system

J.H. Goforth; B.G. Anderson; W. Anderson; W.L. Atchinson; E. Bartram; J.F. Benage; R.L. Bowers; J.H. Brownell; C.E. Findley; C.M. Fowler; O.F. Garcia; G.J. Heltne; D.H. Herrera; T.J. Herrera; M.Y. Hockaday; G. Idzorek; J.C. King; Irvin R. Lindemuth; E.A. Lopez; S.P. Marsh; E.C. Martinez; W. Matuska; G.T. Nakafuji; M.C. Thompson; H. Oona; D.L. Peterson; R.E. Reinovsky; M. Rich; J.S. Shlachter; K.D. Sowder

The Procyon high explosive pulsed power (HEPP) system was designed to drive plasma Z-pinch experiments that produce Megajoule soft X-ray pulses when the plasma stagnates on axis. In the proceedings of the Ninth IEEE Pulsed Power Conference, the authors published results from system development tests. At this time, they have fielded seven tests in which the focus was on either vacuum switching or load physics. Four of the tests concentrated on the performance of a plasma flow switch (PFS) which employed a l/r mass distribution in the PFS barrel. Of the four tests, two had dummy loads and one had an implosion load. In addition, one of the tests broke down near the vacuum dielectric interface, and the result demonstrated what Procyon could deliver to an 18 nH load. The authors summarize PFS results and the 18 nH test which is pertinent to upcoming solid/liquid liner experiments. On their other three tests, they eliminated the PFS switching and powered the Z-pinch directly with the HEPP system. From the best of these direct drive tests, they obtained 1.5 MJ of radiation in a 250 ns pulse, their best radiation pulse to date. They also summarize direct drive test results. More details are given in other papers in this conference for both the PFS and direct drive experiments, and an updated analysis of their opening switch performance is also included. The remainder of this paper describes the parameters and capabilities of their system, and they use the data from several experiments to provide more precise information than previously available.


Journal of Physics: Conference Series | 2008

Constraining fundamental plasma physics processes using doped capsule implosions

Warren Garbett; S James; G. A. Kyrala; D. C. Wilson; J.F. Benage; F.J. Wysocki; Mark Gunderson; J. A. Frenje; R. D. Petrasso; Vladimir Yu. Glebov; B. Yaakobi

A standard technique in inertial confinement fusion research is the use of low levels of spectroscopic dopants as a passive diagnostic of fuel conditions. Using higher dopant levels it becomes possible to modify the plasma conditions. Doped capsule experiments may thus provide a way to control and study fundamental plasma physics processes in the inertial fusion regime. As a precursor to eventual experiments on the National Ignition Facility (NIF) we have performed a series of capsule implosions using the Omega laser. These are intended to guide the modelling of high-Z dopants and explore the feasibility of using such capsule implosions for quantitative physics experiments. We have fielded thin glass shells filled with D-He3 fuel and varying levels of Ar, Kr and Xe dopants. X-ray emission spectroscopy is combined with simultaneous measurements of primary neutron and proton yields and energy spectra in an attempt to fully constrain capsule behaviour.


Review of Scientific Instruments | 1999

One-dimensional x-ray microscope for shock measurements in high-density aluminum plasmas

J. Workman; Thomas E. Tierney; S. C. Evans; George A. Kyrala; J.F. Benage

Accurate experimental measurements of the equation of state for strongly coupled plasmas (Γ⩾1), relevant to astrophysical, geologic and inertial confinement fusion applications, have been extremely difficult. In this pursuit, we have designed a one-dimensional dual-crystal x-ray microscope for making high-resolution measurements of shocks launched by laser pulses in high-density aluminum plasmas. Optical ray-tracing analysis of the design is presented including effects of surface aberrations. The spherically bent mica crystals are arranged at near normal incidence to operate at energies of 1.35 and 4.75 keV using the second and seventh order reflections, respectively. With a magnification of 45×, the microscope’s spatial resolution is predicted to be better than 2 μm when coupled to an x-ray streak camera. The addition of a grazing-incidence optic perpendicular to the imaging direction partially compensates astigmatism. This compensation provides an increase in collection efficiency at the streak camera s...


Physics of Plasmas | 2014

Simultaneous measurements of several state variables in shocked carbon by imaging x-ray scattering

E. J. Gamboa; R. P. Drake; Katerina Falk; P.A. Keiter; D. S. Montgomery; J.F. Benage; Matthew Trantham

We apply the novel experimental technique of imaging x-ray Thomson scattering to measure the spatial profiles of the temperature, ionization state, relative material density, and the shock speed in a high-energy density system. A blast wave driven in a low-density foam is probed with 90∘ scattering of 7.8 keV helium-like nickel x-rays, which are spectrally dispersed and resolved in one spatial dimension by a doubly curved crystal. The inferred properties of the shock are shown to be self-consistent with 1D analytical estimates. These high-resolution measurements enable a direct comparison of the observed temperature with the results from hydrodynamic simulations. We find good agreement with the simulations for the temperature at the shock front but discrepancies in the modeling of the spatial temperature profile and shock speed. These results indicate the challenges in modeling the shock dynamics of structured materials like foams, commonly used in many high-energy density and laboratory astrophysics experiments.


ieee international pulsed power conference | 1997

Pegasus II experiments and plans for the Atlas pulsed power facility

J.S. Shlachter; P.J. Adams; W.L. Atchison; R.R. Bartsch; J.F. Benage; J.C. Cochrane; W.L. Coulter; C.A. Ekdahl; R.J. Faehl; R.D. Fulton; Joyce Ann Guzik; D. Holtkamp; Michael E. Jones; Rhon K. Keinigs; N.S.P. King; George A. Kyrala; H. Lee; Irvin R. Lindemuth; D.V. Morgan; R.W. Moses; A.W. Obst; H. Oona; D. Oro; W.M. Parsons; D. Platts; R.E. Reinovsky; George Rodriguez; D.W. Scudder; Maurice G. Sheppard; D.S. Sorenson

Atlas will be a high-energy (36 MJ stored), high-power (/spl sim/10 TW) pulsed power driver for high energy-density experiments, with an emphasis on hydrodynamics. Scheduled for completion in late 1999, Atlas is designed to produce currents in the 40-50 MA range with a quarter-cycle time of 4-5 /spl mu/s. It will drive implosions of heavy liners (typically 50 g) with implosion velocities exceeding 20 mm//spl mu/s. Under these conditions, very high pressures and magnetic fields are produced. Shock pressures in the 50 Mbar range and pressures exceeding 10 Mbar in an adiabatic compression will be possible. By performing flux compression of a seed field, axial magnetic fields in the 2000 T range may be achieved. A variety of concepts have been identified for the first experimental campaigns on Atlas. Experimental configurations, associated physics issues, and diagnostic strategies are all under investigation as the design of the Atlas facility proceeds. Near-term proof-of-principle experiments employing the smaller Pegasus II capacitor bank have been identified, and several of these experiments have now been performed. This paper discusses a number of recent Pegasus II experiments and identifies several areas of research presently planned on Atlas.


ieee international pulsed power conference | 1995

Comparison and analysis of 2-D simulation results with two implosion radiation experiments on the Los Alamos Pegasus I and Pegasus II capacitor banks

D.L. Peterson; R.L. Bowers; C.F. Lebeda; W. Matuska; J.F. Benage; George C. Idzorek; H. Oona; J. Stokes; N.F. Roderick

Two experiments, PegI-41, conducted on the Los Alamos Pegasus I capacitor bank, and PegII-25, on the Pegasus II bank, consisted of the implosions of 13 mg (nominal), 5 cm radius, 2 cm high thin cylindrical aluminum foils resulting in soft X-ray radiation pulses from the plasma thermalizion on axis. The implosions were conducted in direct-drive (no intermediate switching) mode with peak currents of about 4 MA and 5 MA respectively, and implosion times of about 2.5 /spl mu/s and 2.0 /spl mu/s. A radiation yield of about 250 kJ was measured for PegII-25. The purpose of these experiments was to examine the physics of the implosion and relate this physics to the production of the radiation pulse and to provide detailed experimental data which could be compared with 2-D radiation-magnetohydrodynamic (RMHD) simulations. Included in the experimental diagnostic suites were Faraday rotation and dB/dt current measurements, a visible framing camera, an X-ray stripline camera, time-dependent spectroscopy, bolometers and XRDs. A comparison of the results from these experiments shows agreement with 2-D simulation results in the instability development, current, and radiation pulse data, including the pulsewidth, shape, peak power and total radiation yield as measured by bolometry. Instabilities dominate the behavior of the implosion and largely determine the properties of the resulting radiation pulse. The 2-D simulations can be seen to be an important tool in understanding the implosion physics.

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F.J. Wysocki

Los Alamos National Laboratory

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George A. Kyrala

Los Alamos National Laboratory

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D. S. Montgomery

Los Alamos National Laboratory

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Michael S. Murillo

Los Alamos National Laboratory

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H. Oona

Los Alamos National Laboratory

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J.C. Cochrane

Los Alamos National Laboratory

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Thomas E. Tierney

Los Alamos National Laboratory

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Katerina Falk

Los Alamos National Laboratory

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J. Workman

Los Alamos National Laboratory

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J.S. Shlachter

Los Alamos National Laboratory

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