R.W. VanDervort, N. Christiansen, T. Coffman, L.M. Green, B.M. Haines, K. Ma, Y. Kim, P.M. Kozlowski, R. Lester, D.W. Schmidt, C. Wong
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引用次数: 0
Abstract
Los Alamos National Laboratory’s Bosque campaign on the National Ignition Facility (NIF) seeks to understand how the mix of shell materials and fusion reactants effects the deuterium-tritium (DT) fusion rate in an inertially confined fusion capsule. The NIF platform uses deuterium in a plastic, 3D-printed, two-photon polymerization (2PP) lattice inside the capsule. The voids between the matrix of lattices is filled by tritium gas. Preheat expands the individual lattice struts, which causes deuterium and tritium to prematurely mix before the capsule converges. This preheat is assumed to be created by either laser plasma interactions (LPI) or radiation from the shock. Capsule initial conditions are sensitive to sources of preheat, which necessitates a comprehensive study of how preheat interacts with the lattice.
In this work, results from a shock-tube campaign conducted on the Omega Laser Facility to study the impacts of preheat on a 2PP, 3D-printed lattice is discussed. In these experiments, OMEGA 60 laser beams directly irradiated a plastic ablator (I W/cm), which created both a source of hot-electrons and a radiative shock to preheat the lattice. Expansion of a witness disk is radiographically imaged due to the small size of the lattice struts. We attempted to isolate the preheat source to only the radiative shock by including a thin-gold foil in select ablators to mitigated hot-electron preheat. However, we found that the gold layer reduced the shock speed in the lattice from a plastic only case of m/ns to /ns. The gold layer is estimated to dramatically reduce the radiative preheat due to slowing of the shock, while the hot electron energy is only mildly reduced. Measurements of the witness disk expansion were likely scattered due to the nearby lattice having a similar average areal density to that of the edge of the witness disk. The uncertainties of these measurements are large and more experimental measurements with target design changes are needed to clarify the impacts of preheat on the lattice expansion.
期刊介绍:
High Energy Density Physics is an international journal covering original experimental and related theoretical work studying the physics of matter and radiation under extreme conditions. ''High energy density'' is understood to be an energy density exceeding about 1011 J/m3. The editors and the publisher are committed to provide this fast-growing community with a dedicated high quality channel to distribute their original findings.
Papers suitable for publication in this journal cover topics in both the warm and hot dense matter regimes, such as laboratory studies relevant to non-LTE kinetics at extreme conditions, planetary interiors, astrophysical phenomena, inertial fusion and includes studies of, for example, material properties and both stable and unstable hydrodynamics. Developments in associated theoretical areas, for example the modelling of strongly coupled, partially degenerate and relativistic plasmas, are also covered.