[en] Over the past decade a new genre of laboratory astrophysics has emerged, made possible by the new high energy density (HED) experimental facilities, such as large lasers, z-pinch generators, and high current particle accelerators. (Remington, 1999; 2000; Drake, 1998; Takabe, 2001) On these facilities, macroscopic collections of matter can be created in astrophysically relevant conditions, and its collective properties measured. Examples of processes and issues that can be experimentally addressed include compressible hydrodynamic mixing, strong shock phenomena, radiative shocks, radiation flow, high Mach-number jets, complex opacities, photoionized plasmas, equations of state of highly compressed matter, and relativistic plasmas. These processes are relevant to a wide range of astrophysical phenomena, such as supernovae and supernova remnants, astrophysical jets, radiatively driven molecular clouds, accreting black holes, planetary interiors, and gamma-ray bursts. These phenomena will be discussed in the context of laboratory astrophysics experiments possible on existing and future HED facilities

No abstract available

[en] This is the final year of the 3-year LDRD-ERD involving Lasers, D ampersand NT, Physics, and ILSA to develope astrophysics experiments on intense lasers such as the Nova and Gekko lasers. During this 3 year period, we have developed a highly successful experiment probing the hydrodynamics of the explosion phase of core-collapse supernovae, which occurs during the first 3 hours after core collapse. This was in collaboration with the Univ. of Arizona and CEA/Saclay. We also developed a very successful experiment to probe the hydrodynamics of the later time, young remnant phase, meaning the first 10-20 years after core collapse. This was in collaboration with the Univ. of Michigan and Univ. of Colorado. Finally, we developed during the final year an exquisite experiment to probe the dynamics of radiative, high Mach number astrophysical jets, in collaboration with the Univ. of Maryland and Osaka Univ. Each experiment has received very high visibility, with a multitude of publications, both in the technical journals (most importantly, the astrophysical journals) and in the popular press. The attached publication list shows 25 papers published or submitted to technical journals, 5 articles appearing in the popular press (including a cover story of Sky and Telescope), and 65 conference presentations, 10 of which were invited talks. The most important papers to come out of this effort was a comprehensive theory paper for Ap. J. establishing the rigorous scaling between laboratory laser experiments and the astrophysical subjects of interest: supernovae, supernova remnants, and jets; and a review article for Science covering this emerging subfield of Astrophysics on Intense Lasers. Since there are so many publications that have resulted from this LDRD project, only these two most important papers are attached. The rest are properly referenced, and can be found online or in the library. In anticipation of the closing of the Nova laser, we have successfully proposed transferring the supernova hydrodynamics experiments to the Omega laser at the Univ. of Rochester under the NLUF Program and the radiative jet experiments to the Gekko laser at Osaka University, Japan. The goal of this 3-year endeavor was to technically assess whether intense laser facilities could be used beneficially for astrophysics research. The answer to our progress is best answered by our being asked to supply input to the National Academy of Sciences Decadal Survey for Astronomy and Astrophysics, meaning that this new type of astrophysics research is to be represented in the next 10-yr. plan for astronomy and astrophysics

[en] To make a laboratory experiment an efficient tool for the studying the dynamical astrophysical phenomena, it is desirable to perform them in such a way as to observe the scaling invariance with respect to the astrophysical system under study. Several examples are presented of such scalings in the area of magnetohydrodynamic phenomena, where a number of scaled experiments have been performed. A difficult issue of the effect of fine-scale dissipative structures on the global scale dissipation-free flow is discussed. The second part of the paper is concerned with much less developed area of the scalings relevant to the interaction of an ultra-intense laser pulse with a pre-formed plasma. The use of the symmetry arguments in such experiments is also considered

[en] Lawrence Livermore National Laboratory in Livermore, California, is now performing significant astrophysics experiments on its huge Nova laser facility, and a similar effort has started at the Gekko laser facility at Osaka University in Japan. Our experiments on the Nova and Gekko lasers so far encourage us that our astrophysics work is already leading to a better understanding of the hydrodynamics of supernovae and astrophysical jets. The ability of large inertial confinement fusion lasers to recreate star-like conditions in the laboratory greatly improves our understanding of the heavens; for the first time in our history, we can study the stars up close on Earth

[en] In the laboratory experiments designed to reproduce hydrodynamical phenomena of relevance for astrophysics the Reynolds numbers, although very large, are usually smaller than in real astrophysical systems. If the hydrodynamic flow reaches the turbulent state, it may then happen that differences (related to the difference in Reynolds numbers) would appear in the global-scale motions of the two systems. The difficulty in studying this issue in high energy density laboratory experiments lies in that equations of state and transport coefficients are usually not very well known, so that the subtle effect of the Reynolds number may be easily obscured by experimental uncertainties. An approach has recently been suggested [D.D. Ryutov, B.A. Remington, Phys. Plasmas, 10, 2629, 2003] that allows one to circumvent this difficulty and isolate the effect of the Reynolds number. In the present paper, after presenting a summary of the previous results, we briefly discuss various aspects of possible experiments

[en] Extreme conditions of density and temperature of interest to DNT are similar to conditions of low-altitude atmospheres of neutron stars. Consequently, HED experimental capabilities being developed at LLNL (NIF, petawatt lasers) will open the door to laboratory studies of neutron star atmospheres. This capability will seed a new era in the study of extreme physics generated by strongly radiation dominated flows and laser-plasma interactions for the laboratory study of distant astrophysical phenomena. Indeed as has been noted by the recent Davidsen report on Frontiers of HEDPP (p. 85) ''Accretion disks and atmospheres of neutron stars likely fall in the radiation-dominated regimes, where the radiation pressure dominates the particle pressure. Unique dynamics can ensue in such a radiation dominated plasma, especially in the presence of turbulent flows and magnetic fields. With the next generation of HED facilities such as ZR, NIF, coupled with ultra-intense laser ''heater beams'', it may become possible to create radiation-dominated plasma conditions in the laboratory relevant to neutron star (and black hole) accretion dynamics''. With the recent advent of the Rossi XTE time-resolved x-ray satellite, we have entered a new era in our ability to probe the physics and dynamics of neutron stars and black holes on rapid timescales not previously possible. With RXTE, we have diagnosed the dynamics occurring near the surface of a neutron star on timescales less than a millisecond, and have discovered a new phenomena, photon bubble instabilities, in an a accreting X-ray pulsar Centaurus X-3, some 30,000 light years across the galaxy. (Jerningan, Klein and Arons, ApJ, 2000) We in fact, predicted this instability in simulations with time-dependent 2D radiation-hydrodynamics codes that we had developed. (Klein (and others) ApJ 1996a, 1996b) Strongly magnetized neutron stars accrete mass from a nearby normal star that is in orbit with the neutron star. The mass is transferred by way of an accretion disk and eventually finds its way onto the surface of the neutron star, where it is channeled by the strong magnetic fields (typically dipolar) onto polar caps that occupy a small surface (∼1 km²) area on the neutron star. Photon Bubbles are a violent radiation-hydrodynamic instability whereby low density bubbles (buoyant with respect to the surrounding optically thick plasma flow) fill up with hot 10 keV radiation, grow non-linearly and cause the plasma to become turbulent. The instability occurs when the radiation force on matter exceeds the gravitational force, a regime called super Eddington accretion. As has been shown with a linear stability analysis (Arons ApJ 1992), the low density regions in the midst of surrounding optically thick gas, experience a net flux of radiation and increase in buoyancy. If the magnetic field is appreciable (B > 10⁸ Gauss,) a conductive increase in internal energy gives unstable growth with respect to the optically thick surrounding regions. This instability appears as an entropy mode in the accreting plasma. While some aspects of these flows are peculiar to the strongly magnetized neutron stars, most are not. Much of the phenomenology is expected in all super-Eddington flows, whether in accretion powered pulsars, low mass X-ray binaries or in the disks around black holes in active galactic nuclei. The main purpose of our feasibility grant of $75,000 for FY 2003 was to begin the study of the feasibility of generating, in a laboratory plasma, conditions that would mimic the conditions present in the low lying atmosphere of a magnetized neutron star that could potentially give rise to photon bubble instabilities, and eventually permit us to probe the physics of accreting, magnetized compact objects such as neutron stars and black holes. This would provide a unique way to explore some of the most exotic astrophysical phenomena in the universe, using powerful high energy density lasers such as NIF and petawatt laboratory platforms

[en] The authors are developing a laser-induced fluorescence (LIF) diagnostic for the LEM experiment to measure the evolution of a Rayleigh-Taylor unstable fluid interface into the highly nonlinear regime. The interface will be between two fluids of different density in a 7 x 7 x 14 cm cell that will be accelerated downwards over a distance of ∼100 cm, achieving maximum velocities of order 50 m/s. One of the two fluids will be doped with laser dye and pumped to fluoresce with a 100 Hz pulsed, frequency doubled YAG laser beam spread into a sheet and entering the cell from the bottom. The short pulse duration of the laser (<10 ns) eliminates motional blurring, and the images are recorded from the side with a series of 35 mm static cameras. Aligning the laser sheet to the center of the cell localizes the region of the cell probed and eliminates edge effects in the data. This LIF diagnostic will be described

[en] Arguments are presented in favor of a possible existence of a random, force-free magnetic field. Ponderomotive forces in such a field are small, and the evolutionary time is much longer than Alfven crossing time over the vortex scale, whence the suggested term ''magnetostatic''. The presence of this long-lived random magnetic field provides stiffness with respect to large-scale compressional motions. On the other hand, such a field cannot be detected by techniques involving line-of-sight averaging. It may therefore be a source of stiffness for various astrophysical objects, ranging from plasmas in clusters of galaxies to the interiors of molecular clouds in HII regions, and remaining at the same time undetectable. Analysis of large-scale motions on the background of the magnetostatic turbulence is presented; it is concluded that these large-scale motions can be roughly described by a usual hydrodynamics for the matter with an isotropic pressure; the adiabatic index is 4/3

[en] With the advent of high-energy-density (HED) experimental facilities, such as high-energy lasers and fast Z-pinch pulsed-power facilities, millimeter-scale quantities of matter can be placed in extreme states of density, temperature, and/or velocity. With the commissioning of the NIF laser facility in the very near future, regimes experimentally accessible will be pushed to even higher densities and pressures. This is enabling the emergence of a new class of experimental science, wherein the properties of matter and the processes that occur under the most extreme physical conditions can be examined in the laboratory. Areas particularly suitable to laboratory astrophysics include the study of opacities relevant to stellar interiors, equations of state relevant to planetary interiors, strong shock-driven nonlinear hydrodynamics and radiative dynamics relevant to supernova explosions and subsequent evolution, protostellar jets and high Mach number flows, radiatively driven molecular clouds, nonlinear photoevaporation front dynamics, and photoionized plasmas relevant to accretion disks around compact objects such as black holes and neutron stars. In the area of materials science and condensed matter physics, material properties such as phase, elastic coefficients such as shear modulus, Peierls stress, and transport coefficients such as thermal diffusivity can be accessed at considerably higher densities and pressure than any existing data. In the field of nonlinear optical phenomena, NIF will be an unparalleled setting for studying the nonlinear interactions of a ''statistical ensemble'' of 100 high power beams in large volumes of plasma. In the area of nuclear physics, nuclear reaction rates in dense, highly screened plasmas and on ignition implosions, reactions from excited nuclear states via multi-hit reactions should be possible. A selection from this frontier HED science accessible on NIF will be presented