The influence of the plasma density scale length on the production of MeV protons from thin foil targets irradiated at I lambda(2) = 5 x 10(19) W cm(-2) has been studied. With an unperturbed foil, protons with energy >20 MeV were formed in an exponential energy spectrum with a temperature of 2.5+/-0.3 MeV. When a plasma with a scale length of 100 microm was preformed on the back of the foil, the maximum proton energy was reduced to <5 MeV and the beam was essentially destroyed. The experimental results are consistent with an electrostatic accelerating mechanism that requires an ultrashort scale length at the back of the target.

Fast ignition is a two-step inertial confinement fusion concept where megaelectron volt electrons ignite the compressed core of an imploded fuel capsule driven by a relatively low-implosion velocity. Initial surrogate cone-in-shell, fast-ignitor experiments using a highly shaped driver pulse to assemble a dense core in front of the cone tip were performed on the OMEGA/OMEGA EP Laser [

The National Ignition Campaign's [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] point design implosion has achieved DT neutron yields of 7.5×10(14) neutrons, inferred stagnation pressures of 103 Gbar, and inferred areal densities (ρR) of 0.90  g/cm2 (shot N111215), values that are lower than 1D expectations by factors of 10×, 3.3×, and 1.5×, respectively. In this Letter, we present the design basis for an inertial confinement fusion capsule using an alternate indirect-drive pulse shape that is less sensitive to issues that may be responsible for this lower than expected performance. This new implosion features a higher radiation temperature in the "foot" of the pulse, three-shock pulse shape resulting in an implosion that has less sensitivity to the predicted ionization state of carbon, modestly lower convergence ratio, and significantly lower ablation Rayleigh-Taylor instability growth than that of the NIC point design capsule. The trade-off with this new design is a higher fuel adiabat that limits both fuel compression and theoretical capsule yield. The purpose of designing this capsule is to recover a more ideal one-dimensional implosion that is in closer agreement to simulation predictions. Early experimental results support our assertions since as of this Letter, a high-foot implosion has obtained a record DT yield of 2.4×10(15) neutrons (within ∼70% of 1D simulation) with fuel ρR=0.84  g/cm2 and an estimated ∼1/3 of the yield coming from α-particle self-heating.

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17-75 keV one-and two-dimensional high-resolution ͑Ͻ10 m͒ radiography has been developed using high-intensity short pulse lasers. High energy K␣ sources are created by fluorescence from hot electrons interacting in the target material after irradiation by lasers with intensity I L Ͼ 10 17 W / cm 2 . High-resolution point projection one-and two-dimensional radiography has been achieved using microfoil and microwire targets attached to low-Z substrate materials. The microwire size was 10 m ϫ 10 m ϫ 300 m on a 300 m ϫ 300 m ϫ 5 m polystyrene substrate. The radiography experiments were performed using the Titan laser at Lawrence Livermore National Laboratory. The results show that the resolution is dominated by the microwire target size and there is very little degradation from the plasma plume, implying that the high-energy x-ray photons are generated mostly within the microwire volume. There are enough K␣ photons created with a 300 J, 1-, 40 ps pulse laser from these small volume targets, and that the signal-to-noise ratio is sufficiently high, for single shot radiography experiments. This unique technique will be used on future high energy density experiments at many new high-power laser facilities.