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  1. Material in HED regimes are at very high pressures and temperatures but can often still be modeled in the plasma-fluid approximation. Historically HED regimes were created using large laser/ion- beam drivers heating solid targets. Exciting data was obtained from these single shot experiments. In recent years there has been a shift to obtain HED related data from a large number of shots by using high-repetition-rate drivers. For high-repetition-rate experiments a series of droplet targets are often used to have a fresh target/droplet for each shot. However, one must make sure that target debris from the previous shot does not degrade the target for subsequent shots. This is a challenging CFD problem as one needs to model the initial dynamics of the heated droplet and the subsequent interaction with the following droplets. We use the CFD modeling code PISALE to study this complex problem. We discuss results for liquid hydrogen droplets heated by an x-ray free electron laser (XFEL). We first show 2D results for single heated droplet then 3D results for a heated droplet interacting with two unheated droplets. 
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  2. Abstract

    Volcanic eruptions are energetic events driven by the imbalance of magmatic forces. The magnitudes of these forces remain poorly constrained because they operate in regions that are inaccessible, either underground or dangerous to approach. New techniques are needed to quantify the processes that drive eruptions and to probe magma storage conditions. Here we present X‐ray microdiffraction measurements of volcanic stress imparted as lattice distortions to the crystal cargo of magma from Yellowstone and Long Valley eruptions. Elevated residual stresses between 100 and 300 MPa are preserved in erupted quartz. Multiple volcanic forces could be culpable for the deformation so we analyzed crystals from pyroclastic falls, pyroclastic density currents, and effusive lavas. Stresses are preserved in all quartz but cannot be attributed to differences in eruption style. Instead, lattice deformation likely preserves an in situ measurement of the deviatoric stresses required for the brittle failure of viscous, crystal‐bearing glass during ascent.

     
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