Multi-Messenger Measurements of the Static Structure of Shock-Compressed Liquid Silicon at 100 GPa
arXiv:2309.14905
Abstract:
Ionic structure of high pressure, high temperature fluids is a challenging theoretical problem with applications to planetary interiors and fusion capsules. Here we report a multi-messenger platform using velocimetry and in situ angularly and spectrally resolved X-ray scattering to measure the thermodynamic conditions and ion structure factor of materials at extreme pressures. We document the pressure, density, and temperature of shocked silicon near 100 GPa with uncertainties of 6%, 2%, and 20%, respectively. The measurements are sufficient to distinguish between and rule out some ion screening models.
A case study of using x-ray Thomson scattering to diagnose the in-flight plasma conditions of DT cryogenic implosions
Physics of Plasmas 29, 072703 (2022)
Abstract:
The design of inertial confinement fusion ignition targets requires radiation-hydrodynamics simulations with accurate models of the fundamental material properties (i.e., equation of state, opacity, and conductivity). Validation of these models is required via experimentation. A feasibility study of using spatially integrated, spectrally resolved, x-ray Thomson scattering measurements to diagnose the temperature, density, and ionization of the compressed DT shell of a cryogenic DT implosion at two-thirds convergence was conducted. Synthetic scattering spectra were generated using 1D implosion simulations from the LILAC code that were post processed with the x-ray scattering model, which is incorporated within SPECT3D. Analysis of two extreme adiabat capsule conditions showed that the plasma conditions for both compressed DT shells could be resolved.
Multi-Messenger Measurements of the Static Structure of Shock-Compressed Liquid Silicon at 100 GPa
arXiv:2309.14905
Abstract:
Ionic structure of high pressure, high temperature fluids is a challenging theoretical problem with applications to planetary interiors and fusion capsules. Here we report a multi-messenger platform using velocimetry and in situ angularly and spectrally resolved X-ray scattering to measure the thermodynamic conditions and ion structure factor of materials at extreme pressures. We document the pressure, density, and temperature of shocked silicon near 100 GPa with uncertainties of 6%, 2%, and 20%, respectively. The measurements are sufficient to distinguish between and rule out some ion screening models.
A case study of using x-ray Thomson scattering to diagnose the in-flight plasma conditions of DT cryogenic implosions
Physics of Plasmas 29, 072703 (2022)
Abstract:
The design of inertial confinement fusion ignition targets requires radiation-hydrodynamics simulations with accurate models of the fundamental material properties (i.e., equation of state, opacity, and conductivity). Validation of these models is required via experimentation. A feasibility study of using spatially integrated, spectrally resolved, x-ray Thomson scattering measurements to diagnose the temperature, density, and ionization of the compressed DT shell of a cryogenic DT implosion at two-thirds convergence was conducted. Synthetic scattering spectra were generated using 1D implosion simulations from the LILAC code that were post processed with the x-ray scattering model, which is incorporated within SPECT3D. Analysis of two extreme adiabat capsule conditions showed that the plasma conditions for both compressed DT shells could be resolved.
Strong suppression of heat conduction in a laboratory replica of galaxy-cluster turbulent plasmas
Science Advances 8, 10 (2022)
Abstract:
In conventional gases and plasmas, it is known that heat fluxes are proportional to temperature gradients, with collisions between particles mediating energy flow from hotter to colder regions and the coefficient of thermal conduction given by Spitzer’s theory. However, this theory breaks down in magnetized, turbulent, weakly collisional plasmas, although modifications are difficult to predict from first principles due to the complex, multiscale nature of the problem. Understanding heat transport is important in astrophysical plasmas such as those in galaxy clusters, where observed temperature profiles are explicable only in the presence of a strong suppression of heat conduction compared to Spitzer’s theory. To address this problem, we have created a replica of such a system in a laser laboratory experiment. Our data show a reduction of heat transport by two orders of magnitude or more, leading to large temperature variations on small spatial scales (as is seen in cluster plasmas).