Showing papers by "T. W. Phillips published in 2009"

Studies on the transport of high intensity laser-generated hot electrons in cone coupled wire targets

Abstract: Experimental results showing hot electron penetration into Cu wires using Kα fluorescence imaging are presented. A 500 J, 1 ps laser was focused at f/3 into hollow aluminum cones joined at their tip to Cu wires of diameters from 10 to 40 μm. Comparison of the axially diminishing absolute intensity of Cu Kα with modeling shows that the penetration of the electrons is consistent with one dimensional Ohmic potential limited transport. The laser coupling efficiency to electron energy within the wire is shown to be proportional to the cross sectional area of the wire, reaching 15% for 40 μm wires. Further, we find the hot electron temperature within the wire to be about 750 keV. The relevance of these data to cone coupled fast ignition is discussed.

Limitation on Pre-pulse Level for Cone-Guided Fast-Ignition ICF

Abstract: The viability of fast-ignition (FI) inertial confinement fusion hinges on the efficient transfer of laser energy to the compressed fuel via multi-MeV electrons. Pre-formed plasma due to laser pre-pulse strongly influences ultra-intense laser plasma interactions and hot electron generation in the hollow cone of an FI target. We induced a prepulse and consequent preplasma in copper cone targets and measured the energy deposition zone of the main pulse by imaging the emitted K{sub {alpha}} radiation. An integrated simulation of radiation hydrodynamics for the pre-plasma and particle in cell for the main pulse interactions agree well with the measured deposition zones and provide an insight into the enrgy deposition mechanism and electron distribution. It was demonstrated that a under these conditions a 100mJ pre-pulse completely eliminates the forward going component of {approx}2-4MeV electrons. Consequences for cone-guided fast-ignition are discussed.