H.‐S. Park
A5013277182- Laser-Plasma Interactions and Diagnostics
- High-pressure geophysics and materials
- Laser-induced spectroscopy and plasma
- Gamma-ray bursts and supernovae
- Nuclear Physics and Applications
- Magnetic confinement fusion research
- Laser-Matter Interactions and Applications
- Atomic and Molecular Physics
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Ion-surface interactions and analysis
- Ionosphere and magnetosphere dynamics
- Stellar, planetary, and galactic studies
- Advanced X-ray and CT Imaging
- Diamond and Carbon-based Materials Research
- High-Velocity Impact and Material Behavior
- Advanced X-ray Imaging Techniques
- Laser Design and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Fusion materials and technologies
- Energetic Materials and Combustion
- Laser Material Processing Techniques
- Fluid Dynamics and Turbulent Flows
- Combustion and Detonation Processes
Lawrence Livermore National Laboratory
2015-2024
Sandia National Laboratories
2013-2021
SLAC National Accelerator Laboratory
2017-2021
Atomic Weapons Establishment
2006-2021
Los Alamos National Laboratory
2013-2019
Osaka University
2009-2019
Massachusetts Institute of Technology
2013-2019
General Atomics (United States)
2006-2019
Stanford University
2019
University of Michigan–Ann Arbor
2011-2018
In the course of 71 days in lunar orbit, from 19 February to 3 May 1994, Clementine spacecraft acquired just under two million digital images moon at visible and infrared wavelengths. These data are enabling global mapping rock types crust first detailed investigation geology polar regions far side. addition, laser-ranging measurements provided view topographic figure moon. The topography many ancient impact basins has been measured, a map thickness derived gravity.
This Letter reports on a series of high-adiabat implosions cryogenic layered deuterium-tritium (DT) capsules indirectly driven by ``high-foot'' laser drive pulse at the National Ignition Facility. High-foot have high ablation velocities and large density gradient scale lengths are more resistant to ablation-front Rayleigh-Taylor instability induced mixing ablator material into DT hot spot. Indeed, observed spot mix in these was low measured neutron yields were typically 50% (or higher)...
The National Ignition Campaign's [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] point design implosion has achieved DT neutron yields of $7.5\ifmmode\times\else\texttimes\fi{}1{0}^{14}$ neutrons, inferred stagnation pressures 103 Gbar, and areal densities ($\ensuremath{\rho}R$) $0.90\text{ }\text{ }\mathrm{g}/\mathrm{cm}{}^{2}$ (shot N111215), values that are lower than 1D expectations by factors $10\ifmmode\times\else\texttimes\fi{}$, $3.3\ifmmode\times\else\texttimes\fi{}$,...
The characteristics of 22–40keV Kα x-ray sources are measured. These high-energy produced by 100TW and petawatt high-intensity lasers will be used to develop implement workable radiography solutions probe high-Z dense materials for the density experiments. measurements show that source size from a simple foil target is larger than 60μm, too large most applications. total yield independent thicknesses, verifying refluxing plays major role in photon generation. Smaller radiating volumes emit...
Abstract Magnetic fields are ubiquitous in the Universe. The energy density of these is typically comparable to fluid motions plasma which they embedded, making magnetic essential players dynamics luminous matter. standard theoretical model for origin strong through amplification tiny seed via turbulent dynamo level consistent with current observations. However, experimental demonstration mechanism has remained elusive, since it requires conditions that extremely hard re-create terrestrial...
DT neutron yield (Y(n)), ion temperature (T(i)), and down-scatter ratio (dsr) determined from measured spectra are essential metrics for diagnosing the performance of inertial confinement fusion (ICF) implosions at National Ignition Facility (NIF). A suite neutron-time-of-flight (nTOF) spectrometers a magnetic recoil spectrometer (MRS) have been implemented in different locations around NIF target chamber, providing good implosion coverage complementarity required reliable measurements Y(n),...
Abstract Energy-transport effects can alter the structure that develops as a supernova evolves into remnant. The Rayleigh–Taylor instability is thought to produce at interface between stellar ejecta and circumstellar matter, based on simple models hydrodynamic simulations. Here we report experimental results from National Ignition Facility explore how large energy fluxes, which are present in supernovae, affect this structure. We observed reduction growth. In analyzing comparison with...
We report on the first layered deuterium-tritium (DT) capsule implosions indirectly driven by a "high-foot" laser pulse that were fielded in depleted uranium hohlraums at National Ignition Facility. Recently, high-foot have demonstrated improved resistance to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into DT hot spot [Hurricane et al., Nature (London) 506, 343 (2014)]. Uranium provide higher albedo and thus an increased drive equivalent additional 25 TW...
A series of Omega experiments have produced and characterized high velocity counter-streaming plasma flows relevant for the creation collisionless shocks. Single double CH2 foils been irradiated with a laser intensity ∼ 1016 W/cm2. The ablated was 4 mm from foil surface using Thomson scattering. peak flow 2000 km/s, an electron temperature 110 eV, ion 30 density 1018 cm−3 were measured in single configuration. Significant increases temperatures seen geometry. conditions used to calculate...
Probing of electromagnetic fields in high-energy-density experiments is key to understanding questions fusion processes such as how the are compressed, diffuse through plasma, and can seed instabilities. Many kinetic studied, including collisionless shocks, filamentary instabilities, jets, magnetic reconnection, turbulence, all depend on field structure. In this review, an overview experimental techniques underpinning theoretical principles modeling proton-based imaging presented, followed...
We have monitored 8.6 million stars in the Large Magellanic Cloud for 1.1 years and found 3 events consistent with gravitational microlensing. place strong constraints on Galactic halo content form of compact lensing objects mass range $10^{-4} \msun$ to $10^{-1} \msun$. Three is fewer than expected a standard spherical this range, but appears exceed number from known populations. Fitting naive model our data yields MACHO fraction $f = 0.20^{+0.33}_{-0.14}$, which implies total (inside 50...
Measurements of x-ray-driven implosions with charged particles have resulted in the quantitative characterization critical aspects indirect-drive inertial fusion. Three types spontaneous electric fields differing strength by two orders magnitude, largest being nearly one-tenth Bohr field, were discovered time-gated proton radiographic imaging and spectrally resolved self-emission. The views spatial structure temporal evolution both laser drive a hohlraum implosion properties provide...
Hydrodynamic instabilities are a major obstacle in the quest to achieve ignition as they cause preexisting capsule defects grow and ultimately quench fusion burn experiments at National Ignition Facility. Unstable growth ablation front has been dramatically reduced implosions with ``high-foot'' drives measured using x-ray radiography of modulations most dangerous wavelengths (Legendre mode numbers 30--90). These reductions have helped improve performance layered DT reported by O. A....
Integrated radiation hydrodynamic modeling in two dimensions, including the hohlraum and capsule, of layered cryogenic HighFoot Deuterium-Tritium (DT) implosions on NIF successfully predicts important data trends. The model consists a semi-empirical fit to low mode asymmetries drive multipliers match shock trajectories, one dimensional inflight radiography, time peak neutron production. Application across shot series, over range powers, laser energies, wavelengths, target thicknesses yield...
By combining experiments and modeling from three US national laboratories, we explore compressive strength in a well-characterized material, tantalum, across pressures zero to over 350 GPa, strain-rates 10−3/s 108/s temperatures 148 K 3800 K. Strength values 40+ are shown vary by nearly two orders of magnitude, 0.15 GPa 10 GPa. Cross-comparison these results allows pressure strain-rate dependencies be isolated, increases more significantly with than strain rate the range studied. Simulations...
Hydrodynamic instabilities can cause capsule defects and other perturbations to grow degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show first experimental demonstration that a strong unsupported shock indirect drive implosions NIF reduces ablation front instability growth leading 3 10 times higher yield with fuel ρR>1 g/cm(2). This work shows importance of during Campaign may provide path improved high compression necessary for ignition.
Experiments have recently been conducted at the National Ignition Facility utilizing inertial confinement fusion capsule ablators that are 175 and 165 μm in thickness, 10% 15% thinner, respectively, than nominal thickness used throughout high foot most of Campaign. These three-shock, high-adiabat, high-foot implosions demonstrated good performance, with higher velocity better symmetry control lower laser powers energies their ablator counterparts. Little to no hydrodynamic mix into DT hot...