Solid deuterium clusters provide a new type of target for laser-matter interactions. We present a theory for the generation of laser driven Coulomb explosions that create a hot fusion-producing ion tail. We derive an initial distribution function for the exploded ions, for an arbitrary cluster-size distribution, and solve for the D-D neutron-production rate during the free expansion of these ions into a vacuum. We find good agreement between the theory and the experiment: the theory suggests an explanation for the observed saturation and drop in neutron yield beyond a definite cluster size, consistent with recent experiments by Ditmire ͓T. Ditmire et al., Nature 398, 489 ͑1999͔͒ and Zweiback ͓J. Zweiback et al., Phys. Rev. Lett. 84, 2634 ͑2000͒; J. Zweiback et al., Phys. Rev. Lett. 85, 3640 ͑2000͔͒.

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Intense beams of protons and heavy ions have been observed in ultra-intense laser-solid interaction experiments. Thereby, a considerable fraction of the laser energy is transferred to collimated beams of energetic ions (e.g. up to 50 MeV protons; 100 MeV fluorine), which makes these beams highly interesting for various applications. Experimental results indicate a very shortpulse duration and an excellent beam quality, leading to beam intensities in the TW range. To characterize the beam quality and its dependence on laser parameters and target conditions we performed experiments using the 100 TW laser system at Laboratoire pour l'Utilisation des Lasers Intenses at the Ecole Polytechnique, France, with focused intensities exceeding 10 19 W cm −2 . We found a strong dependence on the target rear surface conditions allowing to tailor the ion beam by an appropriate target design. We also succeeded in the generation of heavy ion beams by suppressing the proton amount at the target surface.We will present recent experimental results demonstrating a transverse beam emittance far superior to the accelerator based ion beams. Finally, we will discuss the prospect of laser accelerated ion beams as new diagnostics in laser-solid interaction experiments. Special fields of interest are proton radiography, electric field imaging, and relativistic electron transport inside the target.

Shock ignition, a new concept for igniting thermonuclear fuel, offers the possibility for a near-term (~3-4 years) test of high gain inertial confinement fusion on the National Ignition Facility at less than 1MJ drive energy and without the need for new laser hardware. In shock ignition, compressed fusion fuel is separately ignited by a strong spherically converging shock and, because capsule implosion velocities are significantly lower than those required for conventional hotpot ignition, fusion energy gains of ~60 may be achievable on NIF at laser drive energies around ~0.5MJ. Because of the simple all-DT target design, its in-flight robustness, the potential need for only 1D SSD beam smoothing, minimal early time LPI preheat, and use of present (indirect drive) laser hardware, this target may be easier to field on NIF than a conventional (polar) direct drive hotspot ignition target. Like fast ignition, shock ignition has the potential for high fusion yields at low drive energy, but requires only a single laser with less demanding timing and spatial focusing requirements. Of course, conventional symmetry and stability constraints still apply. In this paper we present initial target performance simulations, delineate the critical issues and describe the immediate-term R&D program that must be performed in order to test the potential of a high gain shock ignition target on NIF in the near term.