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Suggested Citation:"Appendix B: Tools of High Energy Density Science." National Academies of Sciences, Engineering, and Medicine. 2023. Fundamental Research in High Energy Density Science. Washington, DC: The National Academies Press. doi: 10.17226/26728.

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B
Tools of High Energy Density Science

This appendix is intended as a brief introduction to the experimental and computational tools of high energy density science, with a summary of capabilities in each case.

Page 112 Cite

Suggested Citation:"Appendix B: Tools of High Energy Density Science." National Academies of Sciences, Engineering, and Medicine. 2023. Fundamental Research in High Energy Density Science. Washington, DC: The National Academies Press. doi: 10.17226/26728.

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EXPERIMENTS

Static Compression
Diamond-anvil cells (Figure B-1)	to 0.1-1 TPa, 10³-10⁴ K (0.1-1 eV) continuous to pulsed heating; compression between points of diamonds, arbitrary duration; density measured to 0.1-1 percent, pressure to 1-10 percent

**FIGURE B-1** Schematic cross section (*left*) of diamond anvils compressing a sample (*orange*) contained inside a gasket. Samples may be as small as 1-5 µm and as large as 0.5-2 mm across, with thicknesses of about 1 µm-1 mm. Because they are small in size (*right*), diamond-anvil cells can fit inside many instruments, including cooling and heating chambers.
SOURCES: (*Left*) Courtesy of H.P. Scott. (*Right*) Courtesy of N. Yao, Lawrence Berkeley National Laboratory.

Page 113 Cite

Suggested Citation:"Appendix B: Tools of High Energy Density Science." National Academies of Sciences, Engineering, and Medicine. 2023. Fundamental Research in High Energy Density Science. Washington, DC: The National Academies Press. doi: 10.17226/26728.

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Dynamic Compression
Gas-guns (Figure B-2)	to 0.1-1 TPa, 10⁴ K (1 eV) range over 0.1-1 µs mechanical impact at up to 1-10 km/s, planar compression shock, multiple-shock, ramp loading; density, pressure measured to 0.1-1 percent

**FIGURE B-2** (*Left*) Two-stage light gas gun. (*Right*) Schematic of two-stage light-gas gun in use. Samples are typically millimeters to centimeters in size.
SOURCES: (*Left*) Courtesy of Los Alamos National Laboratory. (*Right*) W.J. Nellis, S. Weir, and A.C. Mitchell, 1999, “Minimum Metallic Conductivity of Fluid Hydrogen at 140 GPa (1.4 Mbar),” *Physical Review B* 59(5), http://dx.doi.org/10.1103/PhysRevB.59.3434, reprinted with permission. Copyright 1999 by the American Physical Society.

Page 114 Cite

Suggested Citation:"Appendix B: Tools of High Energy Density Science." National Academies of Sciences, Engineering, and Medicine. 2023. Fundamental Research in High Energy Density Science. Washington, DC: The National Academies Press. doi: 10.17226/26728.

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Pulsed-power (Figure B-3)	to 1-2 TPa, 10⁴-10⁵ K (1-10 eV) range over 0.1-1 µs mechanical impact to 10 km/s, or magnetic compression (planar); shock, multiple-shock, ramp loading; density, pressure measured to 1 percent
	to PPa, 10⁷-10⁹ K (1-100 keV) range over 10-100 ns magnetic compression (cylindrical shock); density, pressure calculated to 1-10 percent

**FIGURE B-3** (*Left*) Z pulsed-power facility, shown in action at Sandia National Laboratories, is 33 m (110 ft.) across. (*Right*) Schematic cross section of Z pulsed-power machine, with red dashed square indicating location of the sample assembly at the center of the machine. Samples are typically millimeters to centimeters in size.
SOURCES: (*Left*) Courtesy of R. Montoya, Sandia National Laboratories, https://www.flickr.com/photos/departmentofenergy/8056998596. (*Right*) N. Bennett, D.R. Welch, C.A. Jennings, et al., 2019, “Current Transport and Loss Mechanisms in the Z Accelerator,” *Physical Review Accelerators and Beams* 22:120401. CC BY 4.0.

Page 115 Cite

Suggested Citation:"Appendix B: Tools of High Energy Density Science." National Academies of Sciences, Engineering, and Medicine. 2023. Fundamental Research in High Energy Density Science. Washington, DC: The National Academies Press. doi: 10.17226/26728.

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Laser (Figures B-4 to B-6)	Dynamic compression to 100 TPa, 10⁷ K range to 100 TPa, 10⁵ K (10 eV) range over 10-50 ns shock, multiple shock or ramp loading (planar); pre-compression; density, pressure measured to 1 percent
	to 100 TPa, 10⁶ K (10 eV) range over 1-10 ns laser shock or ramp (spherical compression); density, pressure measured to 1-10 percent
	to PPa, 10⁷-10⁹ K (1-100 keV) range over 1-10 ns laser shock (spherical); density, pressure calculated to 5-10 percent

**FIGURE B-4** Schematic of the National Ignition Facility at Lawrence Livermore National Laboratory, with light from two laser bays (*top and bottom at left*) directed into the spherical target chamber (*right*). The building is larger than 3 football fields placed side-by side.
SOURCE: Courtesy of Lawrence Livermore National Laboratory.

Page 116 Cite

Suggested Citation:"Appendix B: Tools of High Energy Density Science." National Academies of Sciences, Engineering, and Medicine. 2023. Fundamental Research in High Energy Density Science. Washington, DC: The National Academies Press. doi: 10.17226/26728.

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**FIGURE B-5** Composite image of the NIF target chamber in blue (*left*), which is three stories high (note person for scale at bottom). In contrast, the target for ICF experiments (*right*) is only a few millimeters across.
SOURCES: Lawrence Livermore National Laboratory, see (*left*) https://lasers.llnl.gov/about/how-nif-works/target-chamber and (*right*) https://str.llnl.gov/content/pages/past-issues-pdfs/1999.07.pdf.

Page 117 Cite

Suggested Citation:"Appendix B: Tools of High Energy Density Science." National Academies of Sciences, Engineering, and Medicine. 2023. Fundamental Research in High Energy Density Science. Washington, DC: The National Academies Press. doi: 10.17226/26728.

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**FIGURE B-6** Image of a laser-driven shock-compression experiment at the University of Rochester’s Laboratory for Laser Energetics. The target is a diamond-anvil cell that is holding a sample already at high pressures, to be further compressed by the laser shock.
SOURCE: B. Bishop, 2018, “First Experimental Evidence for Superionic Ice,” https://www.llnl.gov/news/first-experimental-evidence-superionic-ice. Image by M. Millot/E. Kowaluk/J.Wickboldt/LLNL/ LLE/NIF.

THEORY AND SIMULATIONS

High-performance computers, like those at Los Alamos National Laboratory (see Figure B-7) and in other National Nuclear Security Administration laboratories, enable researchers to carry out a variety of simulations, addressing multiple properties of matter at extreme conditions, including the following:

Quantum mechanical simulations
Density Functional Theory (DFT), pseudopotentials at low/warm T
First Principles Molecular Dynamics (MD) and path integral at warm/high T
Time-dependent DFT
Collisional-radiative non-equilibrium kinetics
Classical molecular dynamics
Reduced models for turbulence and mix
Particle-in-cell (PIC)
Hybrid fluid-PIC
Maxwell Vlasov Fokker Planck
Laser-plasma interaction
Laser wakefield acceleration
Extended magnetohydrodynamics (MHD)
Radiation transport

Page 118 Cite

Suggested Citation:"Appendix B: Tools of High Energy Density Science." National Academies of Sciences, Engineering, and Medicine. 2023. Fundamental Research in High Energy Density Science. Washington, DC: The National Academies Press. doi: 10.17226/26728.

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