HYDRODYNAMIC MOTION OF ELECTRON BEAM HEATED WARM DENSE MATTER

The hydrodynamic motion of warm dense matter produced by intense electrons is being experimentally studied on the Dual-Axis Radiographic Hydrodynamic Test Facility (DARHT). Experimental results are compared to hydrodynamic simulation codes for verification. Copper and titanium foils of varying thickness are heated in two stages, the first being isochoric, by an electron bunch with ~100 ns pulse length, energy of 19.8 MeV, current of 1.7 kA, and beam spot size of 2 mm. Aluminum, nickel, and carbon are heated in a similar fashion, but with a current of ~1.44 kA and beam spot size of 1 mm. The corresponding hydrodynamic motion of the foils during energy deposition is measured instantaneously with photonic Doppler velocimetry (PDV). The PDV diagnostic provides time-resolved measurement of the foil velocity, inferred pressure in the foil, and hydrodynamic disassembly time. The 1-D hydrodynamic HELIOS-CR code models the electron energy deposition on these foils. Calculated results of foil velocity and plasma pressure profiles are then compared to experimental results and 2-D hydrodynamics simulations with LASNEX. These parametric studies are crucial in understanding the evolution of warm dense matter during energy deposition, and optimizing electron-target interactions that improve the Bremsstrahlung targets and radiographic spot size capabilities on DARHT.