320 results on '"R. P. Drake"'
Search Results
2. Scaled laboratory experiments explain the kink behaviour of the Crab Nebula jet
- Author
-
C. K. Li, P. Tzeferacos, D. Lamb, G. Gregori, P. A. Norreys, M. J. Rosenberg, R. K. Follett, D. H. Froula, M. Koenig, F. H. Seguin, J. A. Frenje, H. G. Rinderknecht, H. Sio, A. B. Zylstra, R. D. Petrasso, P. A. Amendt, H. S. Park, B. A. Remington, D. D. Ryutov, S. C. Wilks, R. Betti, A. Frank, S. X. Hu, T. C. Sangster, P. Hartigan, R. P. Drake, C. C. Kuranz, S. V. Lebedev, and N. C. Woolsey
- Subjects
Science - Abstract
The periodical change of the Crab nebula’s jet direction challenges our understanding of astrophysical jet dynamics. Here the authors use high-power lasers to create a jet that can be directly compared to the Crab nebula’s, and report the detection of plasma instabilities that mimic kink behaviour.
- Published
- 2016
- Full Text
- View/download PDF
3. Laboratory analogue of a supersonic accretion column in a binary star system
- Author
-
J. E. Cross, G. Gregori, J. M. Foster, P. Graham, J. -M. Bonnet-Bidaud, C. Busschaert, N. Charpentier, C. N. Danson, H. W. Doyle, R. P. Drake, J. Fyrth, E. T. Gumbrell, M. Koenig, C. Krauland, C. C. Kuranz, B. Loupias, C. Michaut, M. Mouchet, S. Patankar, J. Skidmore, C. Spindloe, E. R. Tubman, N. Woolsey, R. Yurchak, and É. Falize
- Subjects
Science - Abstract
Stationary radiative shocks are expected to form above the surface of highly-magnetized white dwarves in binary systems, but this cannot be resolved by telescopes. Here, the authors report a laboratory experiment showing the evolution of a reverse shock when both ionization and radiative losses are important.
- Published
- 2016
- Full Text
- View/download PDF
4. CLEAR – clozapine in early psychosis: study protocol for a multi-centre, randomised controlled trial of clozapine vs other antipsychotics for young people with treatment resistant schizophrenia in real world settings
- Author
-
C. Casetta, P. Santosh, R. Bayley, J. Bisson, S. Byford, C. Dixon, R. J. Drake, R. Elvins, R. Emsley, N. Fung, D. Hayes, O. Howes, A. James, K. James, R. Jones, H. Killaspy, B. Lennox, L. Marchant, P. McGuire, E. Oloyede, M. Rogdaki, R. Upthegrove, J. Walters, A. Egerton, and J. H. MacCabe
- Subjects
Clozapine ,Treatment resistant psychosis ,Children and young people ,Early onset schizophrenia ,Clinical trial ,Psychiatry ,RC435-571 - Abstract
Abstract Background Clozapine is an antipsychotic drug with unique efficacy, and it is the only recommended treatment for treatment-resistant schizophrenia (TRS: failure to respond to at least two different antipsychotics). However, clozapine is also associated with a range of adverse effects which restrict its use, including blood dyscrasias, for which haematological monitoring is required. As treatment resistance is recognised earlier in the illness, the question of whether clozapine should be prescribed in children and young people is increasingly important. However, most research to date has been in older, chronic patients, and evidence regarding the efficacy and safety of clozapine in people under age 25 is lacking. The CLEAR (CLozapine in EARly psychosis) trial will assess whether clozapine is more effective than treatment as usual (TAU), at the level of clinical symptoms, patient rated outcomes, quality of life and cost-effectiveness in people below 25 years of age. Additionally, a nested biomarker study will investigate the mechanisms of action of clozapine compared to TAU. Methods and design This is the protocol of a multi-centre, open label, blind-rated, randomised controlled effectiveness trial of clozapine vs TAU (any other oral antipsychotic monotherapy licenced in the British National Formulary) for 12 weeks in 260 children and young people with TRS (12–24 years old). Aim and objectives The primary outcome is the change in blind-rated Positive and Negative Syndrome Scale scores at 12 weeks from baseline. Secondary outcomes include blind-rated Clinical Global Impression, patient-rated outcomes, quality of life, adverse effects, and treatment adherence. Patients will be followed up for 12 months and will be invited to give consent for longer term follow-up using clinical records and potential re-contact for further research. For mechanism of action, change in brain magnetic resonance imaging (MRI) biomarkers and peripheral inflammatory markers will be measured over 12 weeks. Discussion The CLEAR trial will contribute knowledge on clozapine effectiveness, safety and cost-effectiveness compared to standard antipsychotics in young people with TRS, and the results may guide future clinical treatment recommendation for early psychosis. Trial registration ISRCTN Number: 37176025, IRAS Number: 1004947. Trial status In set-up. Protocol version 4.0 01/08/23. Current up to date protocol available here: https://fundingawards.nihr.ac.uk/award/NIHR131175# /.
- Published
- 2024
- Full Text
- View/download PDF
5. Magnetized Disruption of Inertially Confined Plasma Flows
- Author
-
M. J.-E. Manuel, A. B. Sefkow, C. C. Kuranz, A. M. Rasmus, S. R. Klein, M. J. MacDonald, M. R. Trantham, J. R. Fein, P. X. Belancourt, R. P. Young, P. A. Keiter, B. B. Pollock, J. Park, A. U. Hazi, G. J. Williams, H. Chen, and R. P. Drake
- Published
- 2019
- Full Text
- View/download PDF
6. Electron acceleration in laboratory-produced turbulent collisionless shocks
- Author
-
Anatoly Spitkovsky, Yoichi Sakawa, George Swadling, Stefan Funk, C. K. Li, Wojciech Rozmus, Anna Grassi, B. B. Pollock, Drew Higginson, H.-S. Park, C. Bruulsema, Gianluca Gregori, Scott Wilks, Dmitri Ryutov, Siegfried Glenzer, H. G. Rinderknecht, James Ross, Frederico Fiuza, Bruce Remington, and R. P. Drake
- Subjects
Physics ,Astrophysics::High Energy Astrophysical Phenomena ,General Physics and Astronomy ,Electron ,Plasma ,01 natural sciences ,010305 fluids & plasmas ,Shock (mechanics) ,Relativistic particle ,Computational physics ,Interstellar medium ,Supernova ,0103 physical sciences ,010306 general physics ,Supernova remnant ,Astrophysics::Galaxy Astrophysics ,Fermi Gamma-ray Space Telescope - Abstract
Astrophysical collisionless shocks are among the most powerful particle accelerators in the Universe. Generated by violent interactions of supersonic plasma flows with the interstellar medium, supernova remnant shocks are observed to amplify magnetic fields1 and accelerate electrons and protons to highly relativistic speeds2–4. In the well-established model of diffusive shock acceleration5, relativistic particles are accelerated by repeated shock crossings. However, this requires a separate mechanism that pre-accelerates particles to enable shock crossing. This is known as the ‘injection problem’, which is particularly relevant for electrons, and remains one of the most important puzzles in shock acceleration6. In most astrophysical shocks, the details of the shock structure cannot be directly resolved, making it challenging to identify the injection mechanism. Here we report results from laser-driven plasma flow experiments, and related simulations, that probe the formation of turbulent collisionless shocks in conditions relevant to young supernova remnants. We show that electrons can be effectively accelerated in a first-order Fermi process by small-scale turbulence produced within the shock transition to relativistic non-thermal energies, helping overcome the injection problem. Our observations provide new insight into electron injection at shocks and open the way for controlled laboratory studies of the physics underlying cosmic accelerators. In laser–plasma experiments complemented by simulations, electron acceleration is observed in turbulent collisionless shocks. This work clarifies the pre-acceleration to relativistic energies required for the onset of diffusive shock acceleration.
- Published
- 2020
7. Design of a single-mode Rayleigh–Taylor instability experiment in the highly nonlinear regime
- Author
-
C.C. Kuranz, Laura Elgin, Dov Shvarts, Guy Malamud, R. P. Drake, A. Shimony, Timothy Handy, and Channing Huntington
- Subjects
Physics ,Nuclear and High Energy Physics ,Radiation ,Scale (ratio) ,Design of experiments ,Single-mode optical fiber ,Mechanics ,Laser ,01 natural sciences ,Instability ,Measure (mathematics) ,010305 fluids & plasmas ,law.invention ,Nonlinear system ,law ,0103 physical sciences ,Rayleigh–Taylor instability ,010306 general physics - Abstract
An experimental design, intended to investigate the evolution of the single mode Rayleigh–Taylor (RT) instability in the late time regime is proposed and theoretically analyzed. The goal of the experiment is to directly measure the evolution of the shape of the interface in time, for both low and high-Atwood numbers (A ∼ 0.0.15 and A ∼ 0.6). An objective of this study is to assess the degree to which, using 10-kJ-class lasers, one can expect to observe the predicted re-acceleration of the height of structures produced by RT, which occurs in low-A simulations. The specific design presented here shows no effects of x-ray preheat, and tolerable effects of 2D rarefactions. Observation of the reacceleration effect, at the 10-kJ scale, appears marginal for the design presented here. Experiments could serve to test and validate the numerical results, and determine whether a larger-scale laser would be needed to actually observe the reacceleration effect.
- Published
- 2019
8. Phase contrast imaging of irradiated foils through Talbot Lau X ray Deflectometry on OMEGA EP
- Author
-
Sean Regan, Christian Stoeckl, S. Muller, Carolyn Kuranz, K Matsuo, Ildar A. Begishev, Raul Melean, J. Zou, V. Bouffetier, F. N. Beg, Chad Mileham, C. Sorce, Dan Stutman, W. Theobald, Sallee Klein, Alexis Casner, Paul Keiter, Matthew Trantham, M Bailly-Grandvaux, R. P. Drake, Jeffrey Fein, Marilyn Schneider, and M. P. Valdivia
- Subjects
Nuclear magnetic resonance ,Materials science ,Phase-contrast imaging ,X-ray ,Irradiation ,Omega - Published
- 2020
9. Implementation of a Talbot-Lau x-ray deflectometer diagnostic platform for the OMEGA EP laser
- Author
-
J. R. Fein, Matthew Trantham, K. Kaiser, Dan Stutman, M. P. Valdivia, J. Zou, Christian Stoeckl, R. P. Drake, S. Muller, Chad Mileham, Paul Keiter, Susan Regan, and C. Sorce
- Subjects
010302 applied physics ,Materials science ,business.industry ,medicine.medical_treatment ,X-ray ,Moiré pattern ,Grating ,Ablation ,Laser ,01 natural sciences ,Omega ,010305 fluids & plasmas ,law.invention ,Optics ,law ,0103 physical sciences ,Moire deflectometry ,medicine ,business ,Instrumentation ,FOIL method - Abstract
A Talbot-Lau X-ray Deflectometer (TXD) was implemented in the OMEGA EP laser facility to characterize the evolution of an irradiated foil ablation front by mapping electron densities >1022 cm-3 by means of Moire deflectometry. The experiment used a short-pulse laser (30-100 J, 10 ps) and a foil copper target as an x-ray backlighter source. In the first experimental tests performed to benchmark the diagnostic platform, grating survival was demonstrated and x-ray backlighter laser parameters that deliver Moire images were described. The necessary modifications to accurately probe the ablation front through TXD using the EP-TXD diagnostic platform are discussed.
- Published
- 2020
10. How high energy fluxes may affect Rayleigh–Taylor instability growth in young supernova remnants
- Author
-
Kirk Flippo, W. C. Wan, Channing Huntington, A. Shimony, R. P. Drake, Forrest Doss, H.-S. Park, Kumar Raman, Sallee Klein, Timothy Handy, Steve MacLaren, C.C. Kuranz, A. R. Miles, Bruce Remington, Daniel H. Kalantar, Dov Shvarts, E. M. Giraldez, Tomasz Plewa, D. C. Marion, C. M. Krauland, Shon Prisbrey, Michael Grosskopf, R. J. Wallace, Guy Malamud, Eric Harding, John Kline, Matthew Trantham, and Harry Robey
- Subjects
Science ,Astrophysics::High Energy Astrophysical Phenomena ,General Physics and Astronomy ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Radiation ,01 natural sciences ,Instability ,Article ,General Biochemistry, Genetics and Molecular Biology ,010305 fluids & plasmas ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Rayleigh–Taylor instability ,Ejecta ,Supernova remnant ,lcsh:Science ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Physics ,Multidisciplinary ,Radiant energy ,General Chemistry ,Thermal conduction ,Supernova ,lcsh:Q - Abstract
Energy-transport effects can alter the structure that develops as a supernova evolves into a supernova remnant. The Rayleigh–Taylor instability is thought to produce structure at the interface between the stellar ejecta and the circumstellar matter, based on simple models and hydrodynamic simulations. Here we report experimental results from the National Ignition Facility to explore how large energy fluxes, which are present in supernovae, affect this structure. We observed a reduction in Rayleigh–Taylor growth. In analyzing the comparison with supernova SN1993J, a Type II supernova, we found that the energy fluxes produced by heat conduction appear to be larger than the radiative energy fluxes, and large enough to have dramatic consequences. No reported astrophysical simulations have included radiation and heat conduction self-consistently in modeling supernova remnants and these dynamics should be noted in the understanding of young supernova remnants., Radiation and conduction are generally considered as the main energy transport mechanisms for the evolution of early supernova remnants. Here the authors experimentally show the role of electron heat transfer on the growth of Rayleigh–Taylor instability in young supernova remnants.
- Published
- 2018
11. The design of a photoionization front experiment using the Z-Machine as a driving source and estimated measurements
- Author
-
M. Springstead, Roberto Mancini, R. P. Drake, Heath LeFevre, Paul Keiter, C.C. Kuranz, Guillaume Loisel, and K. Kelso
- Subjects
Physics ,Radiation flux ,Attenuation ,Atomic model ,Front (oceanography) ,Flux ,Photoionization ,Condensed Matter Physics ,Reionization ,Line (formation) ,Computational physics - Abstract
Radiation-driven heat fronts are present in the early universe during reionization, the circumstellar medium of supernovae, and in high-energy-density physics experiments. Dedicated experiments to observe and diagnose the behavior of these types of heat fronts can improve our understanding of these phenomena. A simulation study of photoionization fronts using the HELIOS-CR radiation hydrodynamics code provides an experimental design for the Z-Machine at Sandia National Laboratory using a measurement-calibrated input radiation flux to drive the photoionization front. The simulations use detailed atomic physics and non-diffusive radiation transport in 1D to determine an optimal gas pressure of 0.75 atm for an experiment in N gas as well as the effects of increasing the thickness of the window that seals the gas cell. Post-processing of these simulations demonstrates that ratios of atomic rate coefficients place the heat front in a physics regime where photoionization dominates the energy deposition. To see the sensitivity of the simulations to changes in the model and spatial grid, this analysis performed resolution, atomic model detail, and radiation transport angular grid studies showing less than 10% deviation from the nominal model for increased complexity, when possible. An effort to emulate 3D geometric effects on the radiation flux using an artificial attenuation scheme has shown that, even for conservative estimates of the flux, simulations still produce a photoionization front. Estimations of a streaked, visible spectroscopy measurement using SPECT3D showed that line emission measurements are present early in time and that later in time thermal emission should become dominant.
- Published
- 2021
12. Accretion shocks in the laboratory: Design of an experiment to study star formation
- Author
-
Rachel Young, Patrick Hartigan, R. P. Drake, and Carolyn Kuranz
- Subjects
Physics ,Nuclear and High Energy Physics ,Jet (fluid) ,Radiation ,Star formation ,Astrophysics::High Energy Astrophysical Phenomena ,Stellar atmosphere ,Astronomy ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Spectral line ,Accretion (astrophysics) ,Stars ,Intermediate polar ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,010306 general physics ,010303 astronomy & astrophysics ,Stellar evolution ,Astrophysics::Galaxy Astrophysics - Abstract
We present the design of a laboratory-astrophysics experiment to study magnetospheric accretion relevant to young, pre-main-sequence stars. Spectra of young stars show evidence of hotspots created when streams of accreting material impact the surface of the star and create shocks. The structures that form during this process are poorly understood, as the surfaces of young stars cannot be spatially resolved. Our experiment would create a scaled “accretion shock” at a major (several kJ) laser facility. The experiment drives a plasma jet (the “accretion stream”) into a solid block (the “stellar surface”), in the presence of a parallel magnetic field analogous to the star’s local field. We show that this experiment is well-scaled when the incoming jet has ρ ∼ 10 − 6 − 10 − 5 g cm − 3 and u ∼ 100 − 200 km s − 1 in an imposed field of B ∼ 10 T. Such an experiment would represent an average accretion stream onto a pre-main sequence star with B ∼ 700 G.
- Published
- 2017
13. Design of laboratory experiments to study radiation-driven implosions
- Author
-
Y. Frank, M. Fraenkel, J. S. Davis, R. P. Drake, Matthew Trantham, Dov Shvarts, E. Raicher, Robert Vandervort, Paul Keiter, Sallee Klein, Guy Malamud, and James M. Stone
- Subjects
Physics ,Nuclear and High Energy Physics ,Radiation ,Photon ,010504 meteorology & atmospheric sciences ,Mean free path ,Astrophysics ,01 natural sciences ,Computational physics ,Interstellar medium ,Stars ,0103 physical sciences ,Irradiation ,Current (fluid) ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Dimensionless quantity - Abstract
The interstellar medium is heterogeneous with dense clouds amid an ambient medium. Radiation from young OB stars asymmetrically irradiate the dense clouds. Bertoldi (1989) developed analytic formulae to describe possible outcomes of these clouds when irradiated by hot, young stars. One of the critical parameters that determines the cloud’s fate is the number of photon mean free paths in the cloud. For the extreme cases where the cloud size is either much greater than or much less than one mean free path, the radiation transport should be well understood. However, as one transitions between these limits, the radiation transport is much more complex and is a challenge to solve with many of the current radiation transport models implemented in codes. We present the design of laboratory experiments that use a thermal source of x-rays to asymmetrically irradiate a low-density plastic foam sphere. The experiment will vary the density and hence the number of mean free paths of the sphere to study the radiation transport in different regimes. We have developed dimensionless parameters to relate the laboratory experiment to the astrophysical system and we show that we can perform the experiment in the same transport regime.
- Published
- 2017
14. Impact of ablator thickness and laser drive duration on a platform for supersonic, shockwave-driven hydrodynamic instability experiments
- Author
-
Matthew Trantham, A. Shimony, C.C. Kuranz, R. P. Drake, Guy Malamud, C. A. Di Stefano, J.D. Soltis, Sallee Klein, Dov Shvarts, and W. C. Wan
- Subjects
Physics ,Shock wave ,Nuclear and High Energy Physics ,Radiation ,business.industry ,Fluid mechanics ,Mechanics ,Laser ,01 natural sciences ,Instability ,010305 fluids & plasmas ,law.invention ,Pulse (physics) ,Data acquisition ,Optics ,law ,0103 physical sciences ,Compressibility ,Supersonic speed ,010306 general physics ,business - Abstract
We discuss changes to a target design that improved the quality and consistency of data obtained through a novel experimental platform that enables the study of hydrodynamic instabilities in a compressible regime. The experiment uses a laser to drive steady, supersonic shockwave over well-characterized initial perturbations. Early experiments were adversely affected by inadequate experimental timescales and, potentially, an unintended secondary shockwave. These issues were addressed by extending the 4x10 13 W/cm 2 laser pulse from 19 ns to 28 ns, and increasing the ablator thickness from 185 µm to 500 µm. We present data demonstrating the performance of the platform.
- Published
- 2017
15. Magnetized Disruption of Inertially Confined Plasma Flows
- Author
-
Patrick Belancourt, Matthew Trantham, B. B. Pollock, Alexander Rasmus, Adam B Sefkow, J. R. Fein, M. J.-E. Manuel, R. P. Drake, Rachel Young, J. Park, C.C. Kuranz, Paul Keiter, A. Hazi, H. Chen, Michael MacDonald, Sallee Klein, and Gerald Williams
- Subjects
Physics ,Jet (fluid) ,Field (physics) ,General Physics and Astronomy ,Flux ,Plasma ,Mechanics ,01 natural sciences ,Collimated light ,Interferometry ,Electrical resistivity and conductivity ,0103 physical sciences ,Supersonic speed ,010306 general physics - Abstract
The creation and disruption of inertially collimated plasma flows are investigated through experiment, simulation, and analytical modeling. Supersonic plasma jets are generated by laser-irradiated plastic cones and characterized by optical interferometry measurements. Targets are magnetized with a tunable $B$ field with strengths of up to 5 T directed along the axis of jet propagation. These experiments demonstrate a hitherto unobserved phenomenon in the laboratory, the magnetic disruption of inertially confined plasma jets. This occurs due to flux compression on axis during jet formation and can be described using a Lagrangian-cylinder model of plasma evolution implementing finite resistivity. The basic physical mechanisms driving the dynamics of these systems are described by this model and then compared with two-dimensional radiation-magnetohydrodynamic simulations. Experimental, computational, and analytical results discussed herein suggest that contemporary models underestimate the electrical conductivity necessary to drive the amount of flux compression needed to explain observations of jet disruption.
- Published
- 2019
16. Focus on high energy density physics
- Author
-
R Paul Drake and Peter Norreys
- Subjects
High-energy-density physics ,warm dense matter ,high-pressure matter ,Science ,Physics ,QC1-999 - Abstract
High-energy-density physics concerns the behavior of systems at high pressure, often involving the interplay of plasma, relativistic, quantum mechanical and electromagnetic effects. The field is growing rapidly in its scope of activity thanks to advances in experimental, laser and computational technologies. This ‘focus on’ collection presents papers discussing forefront research that spans the field, providing a sense of its breadth and of the interlinking of its parts.
- Published
- 2014
- Full Text
- View/download PDF
17. Hybrid Vlasov–Fokker–Planck–Maxwell simulations of fast electron transport and the time dependance of K-shell excitation in a mid-Z metallic target
- Author
-
A G R Thomas, M Sherlock, C Kuranz, C P Ridgers, and R P Drake
- Subjects
Science ,Physics ,QC1-999 - Abstract
Using a hybrid Vlasov–Fokker–Planck–Maxwell code coupled to calculations using a modified relativistic binary-encounter Bethe model of ionizing collisions we study the time and space dependence of K _α photon generation by a fast electron beam injected into a solid density copper plasma target. The electron beam is chosen to be representative of that expected to be generated by a picosecond duration, ∼10 ^19 W cm ^−2 intensity laser. K _α photons are produced as electrons reflux laterally across the target and are slowed and thermalized by collisions with, and Ohmic heating of, the background fluid over a ∼10 ps timescale, which dictates the timescale for K _α emission. The results show reasonable agreement with recent experimental results in terms of both the yield and time dependance. We show how lateral expansion of the electrons can be imaged in the K _α radiation.
- Published
- 2013
- Full Text
- View/download PDF
18. Energetic electrons driven in the polarization direction of an intense laser beam incident normal to a solid target
- Author
-
Gerald Williams, J. F. Seely, Lawrence T. Hudson, C.C. Kuranz, R. P. Drake, Hui Chen, N. R. Pereira, C. A. Di Stefano, and J. Park
- Subjects
Physics ,Nuclear and High Energy Physics ,Radiation ,Bremsstrahlung ,Electron shell ,Electron ,Polarization (waves) ,Laser ,01 natural sciences ,Fluence ,Article ,Spectral line ,010305 fluids & plasmas ,law.invention ,law ,0103 physical sciences ,Atomic physics ,010306 general physics ,Laser beams - Abstract
Experiments were performed at the LLNL Titan laser to measure the propagation direction of the energetic electrons that were generated during the interaction of the polarized laser beam with solid targets in the case of normal incidence. The energetic electrons propagated through vacuum to spectator metal wires in the polarization direction and in the perpendicular direction, and the K shell spectra from the different wire materials were recorded as functions of the distance from the laser focal spot. It was found that the fluence of the energetic electrons driven into the spectator wires in the polarization direction compared to the perpendicular direction was larger and increased with the distance from the focal spot. This indicates that energetic electrons are preferentially driven in the direction of the intense oscillating electric field of the incident laser beam in agreement with the multiphoton inverse Bremsstrahlung absorption process.
- Published
- 2016
19. Measurement of Richtmyer–Meshkov mode coupling under steady shock conditions and at high energy density
- Author
-
Guy Malamud, C. A. Di Stefano, Sallee Klein, C.C. Kuranz, and R. P. Drake
- Subjects
Shock wave ,Physics ,Nuclear and High Energy Physics ,Nonlinear system ,Radiation ,Richtmyer–Meshkov instability ,Bubble ,Mode coupling ,Energy density ,Mechanics ,Statistical physics ,Instability ,Shock (mechanics) - Abstract
We present experiments observing Richtmyer–Meshkov mode coupling and bubble competition in a system arising from well-characterized initial conditions and driven by a strong (Mach ~ 8) shock. These measurements and the analysis method developed to interpret them provide an important step toward the possibility of observing self-similarity under such conditions, as well as a general platform for performing and analyzing hydrodynamic instability experiments. A key feature of these experiments is that the shock is sustained sufficiently long that this nonlinear behavior occurs without decay of the shock velocity or other hydrodynamic properties of the system, which facilitates analysis and allows the results to be used in the study of analytic models.
- Published
- 2015
20. Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility
- Author
-
Rachel Young, Matthew Trantham, Michael MacDonald, B. B. Pollock, J. Park, J. R. Fein, Paul Keiter, R. P. Drake, Gerald Williams, C.C. Kuranz, Patrick Belancourt, A. Hazi, Sallee Klein, Hui Chen, Mario Manuel, and Alexander Rasmus
- Subjects
Physics ,Nuclear and High Energy Physics ,Jet (fluid) ,Radiation ,Dense plasma focus ,business.industry ,Solenoid ,Plasma ,equipment and supplies ,Collimated light ,Magnetic field ,Jupiter ,Interferometry ,Optics ,Physics::Accelerator Physics ,Atomic physics ,business ,human activities - Abstract
Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysical systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. This result is a topic of ongoing investigation.
- Published
- 2015
21. Preliminary characterization of a laser-generated plasma sheet
- Author
-
R. P. Drake, J. R. Fein, Sallee Klein, Paul Keiter, J. S. Davis, Guy Malamud, and Matthew Trantham
- Subjects
Physics ,Nuclear and High Energy Physics ,Radiation ,Binary star ,Plasma sheet ,Cataclysmic variable star ,White dwarf ,Plasma ,Astrophysics ,Mechanics ,Wedge (geometry) ,Blast wave ,Shock (mechanics) - Abstract
We present the results from recent experiments to create a flowing plasma sheet. Two groups of three laser beams with nominally 1.5 kJ of energy per group were focused to separate pointing locations, driving a shock into a wedge target. As the shock breaks out of the wedge, the plasma is focused on center, creating a sheet of plasma. Measurements at 60 ns indicate the plasma sheet has propagated 2825 microns with an average velocity of 49 microns/ns. These experiments follow previous experiments [Krauland et al. 2013], which are aimed at studying similar physics as that found in the hot spot region of cataclysmic variables. Krauland et al. created a flowing plasma, which represents the flowing plasma from the secondary star. This flow interacted with a stationary object, which represented the disk around the white dwarf. A reverse shock is a shock formed when a freely expanding plasma encounters an obstacle. Reverse shocks can be generated by a blast wave propagating through a medium. They can also be found in binary star systems where the flowing gas from a companion star interacts with the accretion disk of the primary star.
- Published
- 2015
- Full Text
- View/download PDF
22. Using simultaneous x-ray diffraction and velocity interferometry to determine material strength in shock-compressed diamond
- Author
-
Emma McBride, T. van Driel, Siegfried Glenzer, Andrew Krygier, R. P. Drake, Michael MacDonald, Abraham Levitan, Luke Fletcher, Eduardo Granados, Dominik Kraus, Eric Galtier, Inhyuk Nam, Jan Vorberger, William Schumaker, Peihao Sun, A. J. MacKinnon, Zhou Xing, and Maxence Gauthier
- Subjects
010302 applied physics ,Diffraction ,Materials science ,Physics and Astronomy (miscellaneous) ,Astrophysics::High Energy Astrophysical Phenomena ,Diamond ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Molecular physics ,Strength of materials ,Linear particle accelerator ,law.invention ,Condensed Matter::Materials Science ,Interferometry ,law ,0103 physical sciences ,X-ray crystallography ,engineering ,Density functional theory ,0210 nano-technology - Abstract
We determine the strength of laser shock-compressed polycrystalline diamond at stresses above the Hugoniot elastic limit using a technique combining x-ray diffraction from the Linac Coherent Light Source with velocity interferometry. X-ray diffraction is used to measure lattice strains, and velocity interferometry is used to infer shock and particle velocities. These measurements, combined with density-dependent elastic constants calculated using density functional theory, enable determination of material strength above the Hugoniot elastic limit. Our results indicate that diamond retains approximately 20 GPa of strength at longitudinal stresses of 150–300 GPa under shock compression.
- Published
- 2020
23. Design and Scaling of an Omega-EP Experiment to Study Cold Streams Feeding Early Galaxies
- Author
-
Adriana A. Angulo, Guy Malamud, R. P. Drake, Yuval Birnboim, Carolyn Kuranz, Shane Coffing, and Matthew Trantham
- Subjects
Shock wave ,Physics ,Galactic halo ,Space and Planetary Science ,Galaxy formation and evolution ,Astronomy and Astrophysics ,STREAMS ,Astrophysics ,Omega ,Scaling ,Galaxy - Published
- 2019
24. Laboratory Photoionization Fronts in Nitrogen Gas: A Numerical Feasibility and Parameter Study
- Author
-
Kenneth G. Powell, J. S. Davis, Heath LeFevre, B. van der Holst, William J. Gray, Paul Keiter, R. P. Drake, and C. R. Patterson
- Subjects
Physics ,Front (oceanography) ,Flux ,FOS: Physical sciences ,Astronomy and Astrophysics ,Photoionization ,Electron ,Thermal conduction ,01 natural sciences ,Astrophysics - Astrophysics of Galaxies ,010305 fluids & plasmas ,Computational physics ,Atmospheric radiative transfer codes ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Ionization ,Astrophysics of Galaxies (astro-ph.GA) ,0103 physical sciences ,Diffusion (business) ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
Photoionization fronts play a dominant role in many astrophysical situations, but remain difficult to achieve in a laboratory experiment. We present the results from a computational parameter study evaluating the feasibility of the photoionization experiment presented in the design paper by Drake, R. P., Hazak, G., Keiter, P. A., Davis, J. S., Patterson, C. R., Frank, A., Blackman, E. G., & Busquet, M. 2016, ApJ, 833, 249 in which a photoionization front is generated in a nitrogen medium . The nitrogen gas density and the Planckian radiation temperature of the x-ray source define each simulation. Simulations modeled experiments in which the x-ray flux is generated by a laser-heated gold foil, suitable for experiments using many kJ of laser energy, and experiments in which the flux is generated by a "z-pinch" device, which implodes a cylindrical shell of conducting wires. The models are run using CRASH, our block-adaptive-mesh code for multi-material radiation hydrodynamics. The radiative transfer model uses multi-group, flux-limited diffusion with thirty radiation groups. In addition, electron heat conduction is modeled using a single-group, flux-limited diffusion. In the theory, a photoionization front can exist only when the ratios of the electron recombination rate to the photoionization rate and the electron impact ionization rate to the recombination rate lie in certain ranges. These ratios are computed for several ionization states of nitrogen. Photoionization fronts are found to exist for laser driven models with moderate nitrogen densities ($\sim$10$^{21}$ cm$^{-3}$) and radiation temperatures above 90 eV. For "z-pinch" driven models, lower nitrogen densities are preferred ($, Comment: 22 pages, 14 figures, comments welcome
- Published
- 2018
25. Conceptual design of an experiment to study dust destruction by astrophysical shock waves
- Author
-
T. Temim, C.C. Kuranz, R. P. Drake, Patrick Belancourt, Adrianna Angulo, Bruce Remington, M. J.-E. Manuel, E. Dwek, and Michael MacDonald
- Subjects
Shock wave ,Physics ,Nuclear and High Energy Physics ,education.field_of_study ,Population ,Astronomy ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Galaxy ,Linear particle accelerator ,Electronic, Optical and Magnetic Materials ,Shock (mechanics) ,Interstellar medium ,Supernova ,Nuclear Energy and Engineering ,0103 physical sciences ,Millimeter ,010306 general physics ,education ,010303 astronomy & astrophysics - Abstract
A novel laboratory experimental design is described that will investigate the processing of dust grains in astrophysical shocks. Dust is a ubiquitous ingredient in the interstellar medium (ISM) of galaxies; however, its evolutionary cycle is still poorly understood. Especially shrouded in mystery is the efficiency of grain destruction by astrophysical shocks generated by expanding supernova remnants. While the evolution of these remnants is fairly well understood, the grain destruction efficiency in these shocks is largely unknown. The experiments described herein will fill this knowledge gap by studying the dust destruction efficiencies for shock velocities in the range ${\sim}10{-}30~\text{km}/\text{s}$ ($\unicode[STIX]{x03BC}\text{m}/\text{ns}$), at which most of the grain destruction and processing in the ISM takes place. The experiments focus on the study of grain–grain collisions by accelerating small (${\sim}1~\unicode[STIX]{x03BC}\text{m}$) dust particles into a large (${\sim}5{-}10~\unicode[STIX]{x03BC}\text{m}$ diameter) population; this simulates the astrophysical system well in that the more numerous, small grains impact and collide with the large population. Facilities that combine the versatility of high-power optical lasers with the diagnostic capabilities of X-ray free-electron lasers, e.g., the Matter in Extreme Conditions instrument at the SLAC National Accelerator Laboratory, provide an ideal laboratory environment to create and diagnose dust destruction by astrophysically relevant shocks at the micron scale.
- Published
- 2018
26. Observations of the Magnetized Disruption of Collimated Plasma Flows
- Author
-
Michael MacDonald, A. U. Hazi, Pat Belancourt, Carolyn Kuranz, Jackson Williams, Alexander Rasmus, Matt Trantham, Rachel Young, B. B. Pollock, Hui Chen, J. Park, Mario Manuel, Jeff Fein, R. P. Drake, Sallee Klein, and Paul Keiter
- Subjects
Physics ,Optics ,business.industry ,law ,Astrophysics::High Energy Astrophysical Phenomena ,Plasma ,business ,Laser ,Accretion (astrophysics) ,Collimated light ,law.invention ,Magnetic field - Abstract
The dynamics of magnetized flows is of great interest to the astrophysics community as the formation and long collimation distances of jets in accretion systems are still open questions. In many of these systems, the background magnetic field is parallel to the jet propagation direction. Recent experiments [1] performed at the Jupiter Laser Facility investigated the effects of imposing a background magnetic field aligned with a collimated jet. Plastic cone targets were irradiated by a long-pulse laser as shown schematically in Fig. 1a. When the shock emerges from the backside of the cone, accelerated material accumulates on axis producing a collimated flow. Figure 1b demonstrates the collimation of the plasma without the background field and the disruption of the flow when applying a 5 T field. Experimental results will be discussed in detail with supporting numerical work describing the mechanisms causing the jet disruption.
- Published
- 2017
27. Conceptual design of a Rayleigh–Taylor experiment to study bubble merger in two dimensions on NIF
- Author
-
R. P. Drake, Guy Malamud, and Michael Grosskopf
- Subjects
Physics ,Nuclear and High Energy Physics ,symbols.namesake ,Radiation ,Multi-mode optical fiber ,Conceptual design ,Bubble ,symbols ,Mechanics ,Rayleigh scattering ,National Ignition Facility ,Instability ,Blast wave - Abstract
A preliminary design of an experiment meant to investigate the evolution of multimode Rayleigh–Taylor instability (RT) is presented. This experiment is intended to provide a direct measurement of the two-dimensional bubble front evolution in the hydrodynamic regime. RT growth for the proposed design has been analyzed using one-dimensional direct numerical simulations in Hyades and models of self-similar behavior. The models predictions are compared to results obtained in two-dimensional Dafna numerical simulations, with good agreement. The proposed design assures a significant bubble-merging process (∼3–4 bubble merger generations). The design takes advantage of the National Ignition Facility (NIF) capabilities to provide a large enough laser spot area (∼0.5–1 cm 2 ), along with a low-enough drive that preheat effects remain small.
- Published
- 2014
28. Spatially-resolved X-ray scattering measurements of a planar blast wave
- Author
-
Katerina Falk, R. P. Drake, E. J. Gamboa, Paul Keiter, D. S. Montgomery, and John F. Benage
- Subjects
Physics ,Nuclear and High Energy Physics ,Radiation ,Scattering ,Astrophysics::High Energy Astrophysical Phenomena ,Rarefaction ,Plasma ,Warm dense matter ,Computational physics ,Shock (mechanics) ,Wavelength ,Ionization ,Atomic physics ,Blast wave - Abstract
We present X-ray scattering measurements characterizing the spatial temperature and ionization profile of a blast wave driven in a near-solid density foam. Several-keV X-rays scattered from a laser-driven blast wave in a carbon foam. We resolved the scattering in high resolution in space and wavelength to extract the plasma conditions along the propagation direction of the blast wave. We infer temperatures of 20–40 eV and ionizations of 2–4 in the shock and rarefaction regions of the blast wave. This range of measured ionization states allows for a detailed comparison between different models for the bound–free scattering. FLYCHK simulations of the temperature-ionization balance generally agree with the experimental values in the shocked region while consistently underestimating the ionization in the rarefaction.
- Published
- 2014
29. Measurement of high-dynamic range x-ray Thomson scattering spectra for the characterization of nano-plasmas at LCLS
- Author
-
R. P. Drake, C. P. O’Grady, Timur Osipov, Dominik Kraus, Ken R. Ferguson, Abraham Levitan, Thomas Fennel, Sebastian Carron, Siegfried Glenzer, Ryan Coffee, B. Bachmann, M. Swiggers, Stefan P. Hau-Riege, Christian Peltz, Karl-Heinz Meiwes-Broer, S. Skruszewicz, Christoph Bostedt, Tais Gorkhover, Tilo Döppner, Luke Fletcher, E. J. Gamboa, Michael MacDonald, T. Pardini, Maximilian Bucher, Sebastian Göde, and Jacek Krzywinski
- Subjects
Physics ,Scattering ,Thomson scattering ,business.industry ,Physics::Optics ,Laser pumping ,Laser ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Optics ,Orders of magnitude (time) ,law ,Ionization ,0103 physical sciences ,Femtosecond ,Atomic physics ,010306 general physics ,business ,Instrumentation ,Ultrashort pulse - Abstract
Atomic clusters can serve as ideal model systems for exploring ultrafast (∼100 fs) laser-driven ionization dynamics of dense matter on the nanometer scale. Resonant absorption of optical laser pulses enables heating to temperatures on the order of 1 keV at near solid density conditions. To date, direct probing of transient states of such nano-plasmas was limited to coherent x-ray imaging. Here we present the first measurement of spectrally resolved incoherent x-ray scattering from clusters, enabling measurements of transient temperature, densities, and ionization. Single shot x-ray Thomson scattering signals were recorded at 120 Hz using a crystal spectrometer in combination with a single-photon counting and energy-dispersive pnCCD. A precise pump laser collimation scheme enabled recording near background-free scattering spectra from Ar clusters with an unprecedented dynamic range of more than 3 orders of magnitude. Such measurements are important for understanding collective effects in laser-matter interactions on femtosecond time scales, opening new routes for the development of schemes for their ultrafast control.
- Published
- 2016
30. Detailed characterization of the LLNL imaging proton spectrometer
- Author
-
C.C. Kuranz, B. B. Pollock, Alexander Rasmus, J. Park, J. R. Fein, Sallee Klein, R. P. Drake, Patrick Belancourt, A. Hazi, Gerald Williams, Mario Manuel, H. Chen, and M. J. MacDonald
- Subjects
010302 applied physics ,Physics ,Range (particle radiation) ,Proton ,Spectrometer ,Laser ,01 natural sciences ,Collimated light ,010305 fluids & plasmas ,law.invention ,Magnetic field ,Computational physics ,law ,Dispersion relation ,Electric field ,0103 physical sciences ,Physics::Accelerator Physics ,Atomic physics ,Nuclear Experiment ,Instrumentation - Abstract
Ultra-intense short pulse lasers incident on solid targets (e.g., thin Au foils) produce well collimated, broad-spectrum proton beams. These proton beams can be used to characterize magnetic fields, electric fields, and density gradients in high energy-density systems. The LLNL-Imaging Proton Spectrometer (L-IPS) was designed and built [H. Chen et al., Rev. Sci. Instrum. 81, 10D314 (2010)] for use with such laser produced proton beams. The L-IPS has an energy range of 50 keV-40 MeV with a resolving power (E/dE) of about 275 at 1 MeV and 21 at 20 MeV, as well as a single spatial imaging axis. In order to better characterize the dispersion and imaging capability of this diagnostic, a 3D finite element analysis solver is used to calculate the magnetic field of the L-IPS. Particle trajectories are then obtained via numerical integration to determine the dispersion relation of the L-IPS in both energy and angular space.
- Published
- 2016
31. Atomic modeling of photoionization fronts in nitrogen gas
- Author
-
Carolyn Kuranz, Paul Keiter, William J. Gray, R. P. Drake, J. S. Davis, C. R. Patterson, Kenneth G. Powell, and Heath LeFevre
- Subjects
FOS: Physical sciences ,chemistry.chemical_element ,Electron ,Photoionization ,Kinetic energy ,01 natural sciences ,010305 fluids & plasmas ,Atmospheric radiative transfer codes ,Ionization ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,Physics::Atomic Physics ,010306 general physics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Electron ionization ,Physics ,Front (oceanography) ,Condensed Matter Physics ,Astrophysics - Astrophysics of Galaxies ,Nitrogen ,Physics - Plasma Physics ,Plasma Physics (physics.plasm-ph) ,Astrophysics - Solar and Stellar Astrophysics ,chemistry ,Astrophysics of Galaxies (astro-ph.GA) ,Atomic physics - Abstract
Photoionization fronts play a dominant role in many astrophysical environments, but remain difficult to achieve in a laboratory experiment. Recent papers have suggested that experiments using a nitrogen medium held at ten atmospheres of pressure that is irradiated by a source with a radiation temperature of T$_{\rm R}\sim$ 100 eV can produce viable photoionization fronts. We present a suite of one-dimensional numerical simulations using the \helios\ multi-material radiation hydrodynamics code that models these conditions and the formation of a photoionization front. We study the effects of varying the atomic kinetics and radiative transfer model on the hydrodynamics and ionization state of the nitrogen gas, finding that more sophisticated physics, in particular a multi-angle long characteristic radiative transfer model and a collisional-radiative atomics model, dramatically changes the atomic kinetic evolution of the gas. A photoionization front is identified by computing the ratios between the photoionization rate, the electron impact ionization rate, and the total recombination rate. We find that due to the increased electron temperatures found using more advanced physics that photoionization fronts are likely to form in our nominal model. We report results of several parameter studies. In one of these, the nitrogen pressure is fixed at ten atmospheres and varies the source radiation temperature while another fixes the temperature at 100 eV and varied the nitrogen pressure. Lower nitrogen pressures increase the likelihood of generating a photoionization front while varying the peak source temperature has little effect., Comment: 17 pages, 10 figures, accepted to physics of plasmas
- Published
- 2019
32. A design of a two-dimensional, supersonic KH experiment on OMEGA-EP
- Author
-
Carolyn Kuranz, W. C. Wan, Paul Keiter, Y. Elbaz, A. Shimony, R. P. Drake, Dov Shvarts, Guy Malamud, and C. A. Di Stefano
- Subjects
Shock wave ,Physics ,Nuclear and High Energy Physics ,Radiation ,Single-mode optical fiber ,Mechanics ,Instability ,Vortex ,Theoretical physics ,symbols.namesake ,Mach number ,Experimental system ,symbols ,Supersonic speed ,Scaling - Abstract
An experiment meant to investigate the evolution of single mode Kelvin–Helmholtz (KH) instability in the supersonic regime is presented and theoretically analyzed. This experiment is intended to provide a direct measurement of the two-dimensional vortex evolution so that the high-Mach-number effects can be measured. The proposed design takes advantage of the ability of OMEGA-EP to drive experiments for up to 30 ns to produce steady conditions for KH that endure long enough to observe substantial growth. KH growth for the proposed design has been analyzed using two-dimensional numerical simulations. The results were compared to synthetic temporal KH numerical simulations using non-dimensional scaling in the low and high Mach number regime. The comparisons show that the growth in the high Mach number regime is expected to be suppressed by up to a factor of two. The effects of two-dimensional rarefactions from the lateral boundaries of the experimental system were also investigated. It was found that they introduce no major uncertainties or hazards to the experiment. We produced simulated radiographs, which show that the proposed experimental system will enable observation of the KH structures. An experiment of this kind has not yet been performed, and therefore would serve to validate numerical results and analytical models presented here and in the literature.
- Published
- 2013
33. Regimes of the Vishniac–Ryu Decelerating Shock Instability
- Author
-
R. P. Drake and F. W. Doss
- Subjects
Physics ,Space and Planetary Science ,Turbulence ,0103 physical sciences ,Astronomy and Astrophysics ,Mechanics ,010303 astronomy & astrophysics ,01 natural sciences ,Instability ,010305 fluids & plasmas ,Shock (mechanics) - Published
- 2018
34. Modeling of aspheric, diverging hydrodynamic instability experiments on the National Ignition Facility
- Author
-
Tomasz Plewa, C.C. Kuranz, Michael Grosskopf, A. R. Miles, and R. P. Drake
- Subjects
Physics ,Nuclear and High Energy Physics ,Work (thermodynamics) ,Radiation ,Optics ,Planar ,business.industry ,Aerospace engineering ,business ,National Ignition Facility ,Instability ,Mixing (physics) - Abstract
One branch of work in the laboratory astrophysics community has been focused on developing the understanding of hydrodynamic mixing in core-collapse supernovae (ccSNe) by the Rayleigh–Taylor instability. Experiments studying these processes in the past have been limited to planar systems in large part due to limitations of drive energy. The National Ignition Facility (NIF) is now capable of providing experiments with far more energy than has been previously available on laser facilities, enabling supernova-relevant hydrodynamics in a diverging system. This paper focuses on a proposed design in which hydrodynamic instabilities develop from an aspheric blast-wave driven through multiple, coupled interfaces in a hemispheric target in which the relative masses of the layers are scaled to those within the ccSNe progenitor star. The simulations investigate the diagnosability and experimental value of different designs using a variety of drive conditions.
- Published
- 2013
35. Simulations of radiative effects on the Rayleigh–Taylor instability using the CRASH code
- Author
-
Matthew Trantham, Bruce Remington, E.S. Myra, Michael Grosskopf, A. R. Miles, H.-S. Park, C.C. Kuranz, R. P. Drake, and Guy Malamud
- Subjects
Physics ,Nuclear and High Energy Physics ,Wavelength ,Radiation ,Radiative transfer ,Radiant energy ,Red supergiant ,Mechanics ,Rayleigh–Taylor instability ,Astrophysics ,National Ignition Facility ,Instability ,Shock (mechanics) - Abstract
Future experiments at the National Ignition Facility will be able to generate diagnosable Rayleigh–Taylor instability growth in the presence of locally generated, high radiation fluxes. This interplay of radiative energy transfer and hydrodynamic instability is relevant to many astrophysical systems, such as core-collapse red supergiant supernovae. Previous simulations of high-energy-density Rayleigh–Taylor instabilities in the presence of a hot environment near a radiative shock demonstrate behavior that differs from that found in non-radiative cases. However, these simulations considered only 1D or single wavelength cases. Here we report simulations of an entire experimental system using the CRASH code. These simulations lead to modified predictions, attributed to the effects of radial energy losses.
- Published
- 2013
36. Comparison between Kelvin–Helmholtz instability experiments on OMEGA and simulation results using the CRASH code
- Author
-
R. P. Drake, Michael Grosskopf, Eric Harding, Paul Keiter, Erica M. Rutter, C.C. Kuranz, and Guy Malamud
- Subjects
Physics ,Nuclear and High Energy Physics ,Radiation ,Adaptive mesh refinement ,Perturbation (astronomy) ,chemistry.chemical_element ,Eulerian path ,Crash ,Mechanics ,Omega ,Instability ,symbols.namesake ,Theoretical physics ,chemistry ,symbols ,Radiative transfer ,Beryllium - Abstract
The Center for Radiative Shock Hydrodynamics (CRASH) at the University of Michigan has developed a Eulerian radiation-hydrodynamics code with dynamic adaptive mesh refinement, CRASH, which can model high-energy-density laser-driven experiments. One of these experiments, performed previously on the OMEGA laser facility, was designed to produce and observe the Kelvin–Helmholtz instability. The target design included low-density carbonized-resorcinol-formaldehyde (CRF) foam layered on top of polyamide–imide plastic, with a sinusoidal perturbation on the interface and with the assembled materials encased in beryllium. The results of a series of CRASH simulations of these Kelvin–Helmholtz instability experiments are presented. These simulation results show good agreement both quantitatively and qualitatively with the experimental data.
- Published
- 2013
37. A design of a two-dimensional, multimode RM experiment on OMEGA-EP
- Author
-
Carolyn Kuranz, Guy Malamud, Y. Elbaz, R. P. Drake, Paul Keiter, C. M. Huntington, and C. A. Di Stefano
- Subjects
Physics ,Shock wave ,Nuclear and High Energy Physics ,Radiation ,Multi-mode optical fiber ,Classical mechanics ,Atwood number ,Bubble ,Mode coupling ,Perturbation (astronomy) ,Mechanics ,Instability ,Omega - Abstract
An experiment, meant to investigate the evolution of Richtmyer–Meshkov (RM) instability in the bubble merger regime and at low Atwood number ( A ∼0.3), is proposed and theoretically analyzed. This experiment is intended to provide a direct measurement of the two-dimensional bubble-front shape and spectrum evolution in time, along with the power-law coefficient for bubble-front growth ( θ b ). It is unique in its use of a well-characterized two-dimensional initial perturbation, allowing controlled initiation and growth of the instability. The proposed design assures a significant time scale of steady RM conditions, taking advantage of the long drive (∼30 ns) available on the OMEGA-EP laser facility, along with neither a Rayleigh–Taylor (RT) component nor shock-proximity effects, due to the use of a light to heavy configuration. Multimode RM growth for the proposed configuration has been analyzed using two-dimensional, direct numerical simulations, showing significant mode coupling and convergence to power-law growth of the bubble front. The effects of two-dimensional rarefactions were also investigated, and it was found that they introduce no major uncertainties or hazards to the physics. An experiment of this kind has not yet been performed, and therefore would serve to validate numerical results and analytical models presented in literature.
- Published
- 2013
38. The production and evolution of multiple converging radiative shock waves in gas-filled cylindrical liner z-pinch experiments
- Author
-
Adam Harvey-Thompson, R. P. Drake, Geoffrey Hall, Marcus Weinwurm, J. Skidmore, J. P. Chittenden, G. C. Burdiak, Sergey Lebedev, Lee Suttle, Simon Bland, Francisco Suzuki-Vidal, Louisa Pickworth, P. de Grouchy, Essa Khoory, and George Swadling
- Subjects
Shock wave ,Nuclear and High Energy Physics ,Radiation ,Materials science ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Implosion ,Moving shock ,Shock (mechanics) ,Interferometry ,Optics ,Z-pinch ,Radiative transfer ,Oblique shock ,business ,Astrophysics::Galaxy Astrophysics - Abstract
A cylindrical liner z-pinch configuration has been used to drive converging radiative shock waves into different gases. On application of a 1.4 MA, 240 ns rise-time current pulse, a series of cylindrical shocks moving at typical velocities of 20 km s −1 are consecutively launched from the inside liner wall into an initially static gas-fill of density ∼10 −5 g cm −3 . The drive current skin depth calculated prior to resistive heating was slightly less than the liner wall thickness and no bulk liner implosion occurred. Axial laser probing images show the shock fronts to be smooth and azimuthally symmetric, with instabilities developing downstream of each shock. Evidence for a radiative precursor ahead of the first shock was seen in laser interferometry imaging and time-gated, spatially resolved optical spectroscopy. The interferometry diagnostic was able to simultaneously resolve the radiative precursor and the density jumps at the shock fronts. Optical streak photography provided information on shock timing and shock trajectories and was used to gain insight into the shock launching mechanisms.
- Published
- 2013
39. Measurements of turbulent mixing due to Kelvin–Helmholtz instability in high-energy-density plasmas
- Author
-
C.C. Kuranz, H.-S. Park, Omar Hurricane, Bruce Remington, Christine Krauland, Dov Shvarts, David Martinez, J. F. Hansen, D. C. Marion, Y. Elbaz, R. J. Wallace, G. Langstaff, Harry Robey, Oleg Schilling, R. P. Drake, C. A. Di Stefano, A. Shimony, V. A. Smalyuk, and Kumar Raman
- Subjects
Shock wave ,Physics ,Nuclear and High Energy Physics ,Radiation ,business.industry ,Turbulence ,Mechanics ,Plasma ,Kinetic energy ,Instability ,Optics ,Surface roughness ,business ,FOIL method ,Mixing (physics) - Abstract
Kelvin–Helmholtz (KH) turbulent mixing measurements were performed in experiments on the OMEGA Laser Facility [T.R. Boehly et al., Opt. Commun. 133 (1997) 495]. In these experiments, laser-driven shock waves propagated through low-density plastic foam placed on top of a higher-density plastic foil. Behind the shock front, lower-density foam plasma flowed over the higher-density plastic plasma. The interface between the foam and plastic was KH unstable. The experiments were performed with pre-imposed, sinusoidal 2D perturbations, and broadband 3D perturbations due to surface roughness at the interface between the plastic and foam. KH instability growth was measured using X-ray, point-projection radiography. The mixing layer caused by the KH instability with layer width up to ∼100 μm was observed at a location ∼1 mm behind the shock front. The measured mixing layer width was in good agreement with simulations using a K–L turbulent mixing model in the two-dimensional ARES hydrodynamics code. In the definition of the K–L model K stands for the specific turbulent kinetic (K) energy, and L for the scale length (L) of the turbulence.
- Published
- 2013
40. Simulating radiative shocks with the CRASH laser package
- Author
-
Ben Torralva, Bruce Fryxell, B. van der Holst, M. Klapisch, M. Busquet, R. P. Drake, Kenneth G. Powell, Gabor Toth, E.S. Myra, and Igor V. Sokolov
- Subjects
Physics ,Shock wave ,Nuclear and High Energy Physics ,Radiation ,Opacity ,Astrophysics::High Energy Astrophysical Phenomena ,chemistry.chemical_element ,Mechanics ,Thermal conduction ,Laser ,law.invention ,Xenon ,chemistry ,law ,Radiative transfer ,Atomic physics ,Shock tube - Abstract
We present the latest improvements in the Center for Radiative Shock Hydrodynamics (CRASH) code, a parallel block-adaptive-mesh Eulerian code for simulating high-energy-density plasmas. The implementation can solve for radiation models with either a gray or a multigroup method in the flux-limited-diffusion approximation. The electrons and ions are allowed to be out of temperature equilibrium and flux-limited electron thermal heat conduction is included. We have recently implemented a CRASH laser package with 3-D ray tracing, resulting in improved energy deposition evaluation. New, more accurate opacity models are available which significantly improve radiation transport in materials like xenon. In addition, the HYPRE preconditioner has been added to improve the radiation implicit solver. With this updated version of the CRASH code we study radiative shock tube problems. In our set-up, a 1 ns, 3.8 kJ laser pulse irradiates a 20 micron beryllium disk, driving a shock into a xenon-filled plastic tube. The electrons emit radiation in the shocked xenon. This radiation preheats the unshocked xenon. Photons traveling ahead of the shock will also interact with the plastic tube, heat it, and in turn this can drive another shock off the wall into the xenon.
- Published
- 2013
41. Late-time breakup of laser-driven hydrodynamics experiments
- Author
-
Sallee Klein, Carolyn Kuranz, Paul Keiter, R. P. Drake, C. A. Di Stefano, and D. C. Marion
- Subjects
Physics ,Nuclear and High Energy Physics ,Work (thermodynamics) ,Radiation ,Richtmyer–Meshkov instability ,Turbulence ,Context (language use) ,Mechanics ,Statistical physics ,Breakup ,Instability ,Blast wave ,Mixing (physics) - Abstract
Laser-driven blast waves are frequently used to explore hydrodynamic instability at high energy density. Experiments are designed such that the instability physics occurs in isolation, but secondary processes will eventually develop within the experimental system and affect the physics. At late times, as the blast wave diminishes in strength, these processes increasingly dominate while the instability physics weakens. The resulting dynamics can appear turbulent, and the root cause is not immediately apparent. In this work, we examine the conditions under which a system can begin to exhibit such behavior and, in this context, consider data from an experiment exploring Rayleigh–Taylor hydrodynamic instability, showing significant turbulent-like structure in the material mixing region.
- Published
- 2012
42. Transition from Collisional to Collisionless Regimes in Interpenetrating Plasma Flows on the National Ignition Facility
- Author
-
Michael Rosenberg, Dustin Froula, Jena Meinecke, Dmitri Ryutov, R. P. Drake, C. K. Li, M. C. Levy, Carolyn Kuranz, B. B. Pollock, Frederico Fiuza, H. Takabe, James Ross, Scott Wilks, M. Koenig, Channing Huntington, Brandon Lahmann, Bruce Remington, H.-S. Park, Alex Zylstra, H. G. Rinderknecht, Youichi Sakawa, Daniel H. Kalantar, Anatoly Spitkovsky, A. Link, David Turnbull, Hong Sio, Gianluca Gregori, R. D. Petrasso, Drew Higginson, Taichi Morita, George Swadling, S. V. Weber, and Robert Hatarik
- Subjects
Nuclear reaction ,Physics ,Shock (fluid dynamics) ,Mean free path ,Astrophysics::High Energy Astrophysical Phenomena ,General Physics and Astronomy ,Plasma ,01 natural sciences ,Instability ,010305 fluids & plasmas ,symbols.namesake ,Mach number ,Filamentation ,Physics::Plasma Physics ,Physics::Space Physics ,0103 physical sciences ,symbols ,Neutron ,Atomic physics ,010306 general physics - Abstract
A study of the transition from collisional to collisionless plasma flows has been carried out at the National Ignition Facility using high Mach number (M>4) counterstreaming plasmas. In these experiments, CD-CD and CD-CH planar foils separated by 6-10 mm are irradiated with laser energies of 250 kJ per foil, generating ∼1000 km/s plasma flows. Varying the foil separation distance scales the ion density and average bulk velocity and, therefore, the ion-ion Coulomb mean free path, at the interaction region at the midplane. The characteristics of the flow interaction have been inferred from the neutrons and protons generated by deuteron-deuteron interactions and by x-ray emission from the hot, interpenetrating, and interacting plasmas. A localized burst of neutrons and bright x-ray emission near the midpoint of the counterstreaming flows was observed, suggesting strong heating and the initial stages of shock formation. As the separation of the CD-CH foils increases we observe enhanced neutron production compared to particle-in-cell simulations that include Coulomb collisions, but do not include collective collisionless plasma instabilities. The observed plasma heating and enhanced neutron production is consistent with the initial stages of collisionless shock formation, mediated by the Weibel filamentation instability.
- Published
- 2016
43. Measurement of radiative shock properties by x-ray Thomson scattering
- Author
-
Gianluca Gregori, Dustin Froula, A. J. Visco, Michael Grosskopf, Siegfried Glenzer, R. P. Drake, and Tilo Döppner
- Subjects
Shock wave ,Physics ,Thomson scattering ,Scattering ,Astrophysics::High Energy Astrophysical Phenomena ,General Physics and Astronomy ,Laser ,law.invention ,Computational physics ,Shock (mechanics) ,Supernova ,law ,Radiative transfer ,Electron temperature ,Astrophysics::Galaxy Astrophysics - Abstract
X-ray Thomson scattering has enabled us to measure the temperature of a shocked layer, produced in the laboratory, that is relevant to shocks emerging from supernovas. High energy lasers are used to create a shock in argon gas which is probed by x-ray scattering. The scattered, inelastic Compton feature allows inference of the electron temperature. It is measured to be 34 eV in the radiative precursor and ∼60eV near the shock. Comparison of energy fluxes implied by the data demonstrates that the shock wave is strongly radiative. © 2012 American Physical Society.
- Published
- 2016
44. Studying astrophysical collisionless shocks with counterstreaming plasmas from high power lasers
- Author
-
Sm M. Pollaine, N L Kugland, Mj J. Grosskopf, Youichi Sakawa, Bruce Remington, Anthony M. T. Bell, Js S. Ross, A. Pelka, Dmitri Ryutov, Sh H. Glenzer, Gianluca Gregori, C. Plechaty, Nigel Woolsey, F. Miniati, C.C. Kuranz, Hideaki Takabe, Hye-Sook Park, Edison Liang, L. Gargate, Alessandra Ravasio, Gennady Fiksel, Taichi Morita, C. D. Murphy, D.H. Froula, R. P. Drake, Yasuhiro Kuramitsu, M. Koenig, and Anatoly Spitkovsky
- Subjects
Shock wave ,Physics ,Nuclear and High Energy Physics ,Radiation ,Shock (fluid dynamics) ,Thomson scattering ,Astrophysics::High Energy Astrophysical Phenomena ,Plasma ,Astrophysics ,01 natural sciences ,010305 fluids & plasmas ,Computational physics ,Particle acceleration ,Weibel instability ,Shock waves in astrophysics ,Filamentation ,Physics::Plasma Physics ,0103 physical sciences ,010306 general physics - Abstract
Collisions of high Mach number flows occur frequently in astrophysics, and the resulting shock waves are responsible for the properties of many astrophysical phenomena, such as supernova remnants, Gamma Ray Bursts and jets from Active Galactic Nuclei. Because of the low density of astrophysical plasmas, the mean free path due to Coulomb collisions is typically very large. Therefore, most shock waves in astrophysics are “collisionless”, since they form due to plasma instabilities and self-generated magnetic fields. Laboratory experiments at the laser facilities can achieve the conditions necessary for the formation of collisionless shocks, and will provide a unique avenue for studying the nonlinear physics of collisionless shock waves. We are performing a series of experiments at the Omega and Omega-EP lasers, in Rochester, NY, with the goal of generating collisionless shock conditions by the collision of two high-speed plasma flows resulting from laser ablation of solid targets using ∼10 16 W/cm 2 laser irradiation. The experiments will aim to answer several questions of relevance to collisionless shock physics: the importance of the electromagnetic filamentation (Weibel) instabilities in shock formation, the self-generation of magnetic fields in shocks, the influence of external magnetic fields on shock formation, and the signatures of particle acceleration in shocks. Our first experiments using Thomson scattering diagnostics studied the plasma state from a single foil and from double foils whose flows collide “head-on”. Our data showed that the flow velocity and electron density were 10 8 cm/s and 10 19 cm −3 , respectively, where the Coulomb mean free path is much larger than the size of the interaction region. Simulations of our experimental conditions show that weak Weibel mediated current filamentation and magnetic field generation were likely starting to occur. This paper presents the results from these first Omega experiments.
- Published
- 2016
45. DESIGN CONSIDERATIONS FOR UNMAGNETIZED COLLISIONLESS-SHOCK MEASUREMENTS IN HOMOLOGOUS FLOWS
- Author
-
Gianluca Gregori and R. P. Drake
- Subjects
Shock wave ,Physics ,Shock (fluid dynamics) ,Linear system ,Astronomy and Astrophysics ,Mechanics ,Plasma ,Dissipation ,Collisionality ,7. Clean energy ,01 natural sciences ,Instability ,Weibel instability ,Theoretical physics ,Space and Planetary Science ,Physics::Plasma Physics ,Physics::Space Physics ,0103 physical sciences ,010306 general physics ,010303 astronomy & astrophysics - Abstract
The subject of this paper is the design of practical laser experiments that can produce collisionless shocks mediated by the Weibel instability. Such shocks may be important in a wide range of astrophysical systems. Three issues are considered. The first issue is the implications of the fact that such experiments will produce expanding flows that are approximately homologous. As a result, both the velocity and the density of the interpenetrating plasma streams will be time dependent. The second issue is the implications of the linear theory of the Weibel instability. For the experiments, the instability is in a regime where standard simplifications do not apply. It appears feasible but non-trivial to obtain adequate growth. The third issue is collisionality. The need to keep resistive magnetic-field dissipation small enough implies that the plasmas should not be allowed to cool substantially. © 2012. The American Astronomical Society. All rights reserved.
- Published
- 2016
46. Laboratory astrophysical collisionless shock experiments on Omega and NIF
- Author
-
Anatoly Spitkovsky, C.C. Kuranz, C. Plechaty, R. D. Petrasso, D. D. Ryutov, M. C. Levy, C. K. Li, Hideaki Takabe, Nathan Kugland, Dustin Froula, R. P. Drake, James Ross, Youichi Sakawa, Jena Meinecke, Gennady Fiksel, Taichi Morita, Channing Huntington, Daniel Casey, Gianluca Gregori, Frederico Fiuza, Hye-Sook Park, Bruce Remington, and Alex Zylstra
- Subjects
Electromagnetic field ,Physics ,History ,Magnetic energy ,Thomson scattering ,Implosion ,Plasma ,Electron ,01 natural sciences ,Electromagnetic radiation ,010305 fluids & plasmas ,Computer Science Applications ,Education ,Magnetic field ,Physics::Plasma Physics ,0103 physical sciences ,Atomic physics ,010306 general physics - Abstract
We are performing scaled astrophysics experiments on Omega and on NIF. Laser driven counter-streaming interpenetrating supersonic plasma flows can be studied to understand astrophysical electromagnetic plasma phenomena in a controlled laboratory setting. In our Omega experiments, the counter-streaming flow plasma state is measured using Thomson scattering diagnostics, demonstrating the plasma flows are indeed super-sonic and in the collisionless regime. We observe a surprising additional electron and ion heating from ion drag force in the double flow experiments that are attributed to the ion drag force and electrostatic instabilities. [1] A proton probe is used to image the electric and magnetic fields. We observe unexpected large, stable and reproducible electromagnetic field structures that arise in the counter-streaming flows [2]. The Biermann battery magnetic field generated near the target plane, advected along the flows, and recompressed near the midplane explains the cause of such self-organizing field structures [3]. A D3He implosion proton probe image showed very clear filamentary structures; three-dimensional Particle-In-Cell simulations and simulated proton radiography images indicate that these filamentary structures are generated by Weibel instabilities and that the magnetization level (ratio of magnetic energy over kinetic energy in the system) is ∼0.01 [4]. These findings have very high astrophysical relevance and significant implications. We expect to observe true collisionless shock formation when we use >100 kJ laser energy on NIF.
- Published
- 2016
47. Turbulent amplification of magnetic fields in laboratory laser-produced shock waves
- Author
-
Alessandra Ravasio, C. D. Murphy, Francesco Miniati, Dongwook Lee, Jena Meinecke, Robert Bingham, Carolyn Kuranz, D. Q. Lamb, A. Pelka, Nigel Woolsey, Gianluca Gregori, Hugo Doyle, W. C. Wan, R. Crowston, M. Koenig, Yasuhiro Kuramitsu, Youichi Sakawa, Michael MacDonald, H.-S. Park, Brian Reville, Roman Yurchak, M. Fatenejad, Petros Tzeferacos, Anthony R. Bell, Anthony Scopatz, R. P. Drake, and Alexander Schekochihin
- Subjects
Physics ,Shock wave ,Field (physics) ,Astrophysics::High Energy Astrophysical Phenomena ,General Physics and Astronomy ,Astronomy ,Astrophysics ,01 natural sciences ,Magnetic field ,Interstellar medium ,Cassiopeia A ,Supernova ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010306 general physics ,Ejecta ,Supernova remnant ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
The origin of the large magnetic fields observed in the interior of the supernova remnant Cassiopeia A is still unclear. Laboratory experiments of laser-produced shocks provide new insights into the mechanisms of magnetic field amplification. X-ray1,2,3 and radio4,5,6 observations of the supernova remnant Cassiopeia A reveal the presence of magnetic fields about 100 times stronger than those in the surrounding interstellar medium. Field coincident with the outer shock probably arises through a nonlinear feedback process involving cosmic rays2,7,8. The origin of the large magnetic field in the interior of the remnant is less clear but it is presumably stretched and amplified by turbulent motions. Turbulence may be generated by hydrodynamic instability at the contact discontinuity between the supernova ejecta and the circumstellar gas9. However, optical observations of Cassiopeia A indicate that the ejecta are interacting with a highly inhomogeneous, dense circumstellar cloud bank formed before the supernova explosion10,11,12. Here we investigate the possibility that turbulent amplification is induced when the outer shock overtakes dense clumps in the ambient medium13,14,15. We report laboratory experiments that indicate the magnetic field is amplified when the shock interacts with a plastic grid. We show that our experimental results can explain the observed synchrotron emission in the interior of the remnant. The experiment also provides a laboratory example of magnetic field amplification by turbulence in plasmas, a physical process thought to occur in many astrophysical phenomena.
- Published
- 2016
48. Tracking the density evolution in counter-propagating shock waves using imaging X-ray scattering
- Author
-
Siegfried Glenzer, Eric Galtier, R. P. Drake, John F. Benage, K. W. Hill, N. A. Pablant, Roger Falcone, Philip Heimann, Dirk O. Gericke, Paul Keiter, Hae Ja Lee, Dominik Kraus, Bob Nagler, Eduardo Granados, J. Lu, A. Schropp, P. C. Efthimion, Benjamin Tobias, Maxence Gauthier, Michael MacDonald, Katerina Falk, Luke Fletcher, E. J. Gamboa, D. S. Montgomery, J. B. Hastings, and Ulf Zastrau
- Subjects
Shock wave ,Physics ,Technology ,Physics and Astronomy (miscellaneous) ,Scattering ,Forward scatter ,Astrophysics::High Energy Astrophysical Phenomena ,Inelastic scattering ,Tracking (particle physics) ,01 natural sciences ,010305 fluids & plasmas ,Shock waves in astrophysics ,Engineering ,0103 physical sciences ,Physical Sciences ,Quasiparticle ,ddc:530 ,Graphite ,Atomic physics ,010306 general physics ,Applied Physics - Abstract
Applied physics letters 109(3), 031108 (2016). doi:10.1063/1.4959256, We present results from time-resolved X-ray imaging and inelastic scattering on collective excitations. These data are then employed to infer the mass density evolution within laser-driven shock waves. In our experiments, thin carbon foils are first strongly compressed and then driven into a dense state by counter-propagating shock waves. The different measurements agree that the graphite sample is about twofold compressed when the shock waves collide, and a sharp increase in forward scattering indicates disassembly of the sample 1 ns thereafter. We can benchmark hydrodynamics simulations of colliding shock waves by the X-ray scattering methods employed., Published by American Inst. of Physics, Melville, NY
- Published
- 2016
49. The Effect of a Dominant Initial Single Mode on the Kelvin–Helmholtz Instability Evolution: New Insights on Previous Experimental Results
- Author
-
R. P. Drake, Guy Malamud, Dov Shvarts, A. Shimony, Carolyn Kuranz, and Carlos Di Stefano
- Subjects
Physics ,Work (thermodynamics) ,Mechanical Engineering ,Single-mode optical fiber ,Mechanics ,Vorticity ,Laser ,01 natural sciences ,Instability ,010305 fluids & plasmas ,law.invention ,Vortex ,Wavelength ,law ,0103 physical sciences ,010306 general physics ,Order of magnitude - Abstract
This paper brings new insights on an experiment, measuring the Kelvin–Helmholtz (KH) instability evolution, performed on the OMEGA-60 laser facility. Experimental radiographs show that the initial seed perturbations in the experiment are of multimode spectrum with a dominant single-mode of 16 μm wavelength. In single-mode-dominated KH instability flows, the mixing zone (MZ) width saturates to a constant value comparable to the wavelength. However, the experimental MZ width at late times has exceeded 100 μm, an order of magnitude larger. In this work, we use numerical simulations and a statistical model in order to investigate the vortex dynamics of the KH instability for the experimental initial spectrum. We conclude that the KH instability evolution in the experiment is dominated by multimode, vortex-merger dynamics, overcoming the dominant initial mode.
- Published
- 2016
50. Scaled laboratory experiments explain the kink behaviour of the Crab Nebula jet
- Author
-
Sv Lebedev, Hong Sio, Tc C. Sangster, R. P. Drake, Nc C. Woolsey, Hg G. Rinderknecht, Gianluca Gregori, Dmitri Ryutov, Mj J. Rosenberg, Ja A. Frenje, Rd D. Petrasso, Patrick Hartigan, C.C. Kuranz, Pa A. Norreys, Ck K. Li, Bruce Remington, Alex Zylstra, M. Koenig, D.H. Froula, Petros Tzeferacos, H-S Park, Pa A. Amendt, Sx X. Hu, Fh H. Seguin, Riccardo Betti, Adam Frank, Sc C. Wilks, Rk K. Follett, D. Q. Lamb, Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Plasma Science and Fusion Center, Li, Chikang, Rosenberg, Michael Jonathan, Frenje, Johan A, Rinderknecht, Hans George, Sio, Hong Weng, Zylstra, Alex Bennett, Petrasso, Richard D, Seguin, Fredrick Hampton, and U.S Department of Energy
- Subjects
Plasma Gases ,Science ,MAGNETOHYDRODYNAMIC SIMULATIONS ,Astrophysics::High Energy Astrophysical Phenomena ,INSTABILITY ,General Physics and Astronomy ,Astrophysics ,01 natural sciences ,Instability ,Article ,General Biochemistry, Genetics and Molecular Biology ,010305 fluids & plasmas ,Astrophysical jet ,Observatory ,0103 physical sciences ,Computer Simulation ,Magnetohydrodynamic drive ,010303 astronomy & astrophysics ,Physics ,Jet (fluid) ,Multidisciplinary ,Science & Technology ,Lasers ,Astronomical Phenomena ,Astrophysics::Instrumentation and Methods for Astrophysics ,General Chemistry ,Plasma ,Mechanics ,Models, Theoretical ,Magnetic field ,Multidisciplinary Sciences ,Crab Nebula ,Magnetic Fields ,Science & Technology - Other Topics ,High Energy Physics::Experiment - Abstract
The remarkable discovery by the Chandra X-ray observatory that the Crab nebula’s jet periodically changes direction provides a challenge to our understanding of astrophysical jet dynamics. It has been suggested that this phenomenon may be the consequence of magnetic fields and magnetohydrodynamic instabilities, but experimental demonstration in a controlled laboratory environment has remained elusive. Here we report experiments that use high-power lasers to create a plasma jet that can be directly compared with the Crab jet through well-defined physical scaling laws. The jet generates its own embedded toroidal magnetic fields; as it moves, plasma instabilities result in multiple deflections of the propagation direction, mimicking the kink behaviour of the Crab jet. The experiment is modelled with three-dimensional numerical simulations that show exactly how the instability develops and results in changes of direction of the jet., United States. Department of Energy (Grant DE-FG03-09NA29553), United States. Department of Energy (Grant DE-SC0007168), University of Rochester. Laboratory for Laser Energetics (414090-G), National Laser User’s Facility (DE-NA0000877), University of Rochester. Fusion Science Center (415023-G), Lawrence Livermore National Laboratory (B580243)
- Published
- 2016
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.