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We present the development and advancement of the Talbot–Lau X-ray deflectometry (TXD) single-image phase-retrieval technique, for high-energy density (HED) plasma diagnostics. The Talbot–Lau interferometer has been benchmarked as an electron density diagnostic for low- $Z$ objects ( $Z ) at the X-ray energies of 8 and 17 keV. A laser driven X-ray backlighter was used at the multi-tera watt laser facility in order to obtain electron density measurements. We measured X-ray refraction and retrieved sharp and smooth density gradients with source-limited spatial resolution. Since TXD can use extended, incoherent, line, or continuum X-ray sources, a wide range of X-ray backlighters can be used, driven from laser or pulsed power systems. Laboratory results indicate potential for simultaneous retrieval of: electron density maps through refraction and attenuation, material mixing through elemental composition, and instabilities through scatter images. Experiments using a 17-keV backlighter to characterize a planar shock are planned to test the TXD technique on an HED plasma environment.

The OMEGA laser system is being used to investigate several approaches to inertial confinement fusion: the traditional central-hot-spot (CHS) ignition, fast ignition (FI), and shock ignition (SI). To achieve ignition, CHS requires the highly uniform compression of a solid deuterium-tritium (DT)-layered target on a low adiabat (defined as the ratio of the pressure to the Fermi-degenerate pressure) and with an implosion velocity Vimp ≥ 3.5 × 107 cm/s. A laser pulse shape with triple pickets is used to produce this low adiabat by optimally timing multiple shocks launched by the pickets and the main laser. Cryogenic targets that imploded optimally with such pulses have demonstrated near-design compression with an areal density ρR ~ 290 mg/cm2 at Vimp = 3.1 × 107 cm/s. These are, by far, the highest DT areal densities demonstrated in the laboratory. SI experiments, where a shock is launched by a picket at the end of the laser pulse into the compressing capsule, have been performed on low-adiabat warm plastic targets. Both yield and areal density improve significantly when a spike is used at the end of the laser pulse, indicating that the energy from the shock is coupled into the compressing target. Integrated FI experiments have begun on the OMEGA/OMEGA EP laser system.

The time interval between the beginning of the laser pulse and the peak of neutron emission (bang time) is an important characteristic of inertial confinement fusion (ICF) implosions, directly comparable to numerical simulation. For this reason, neutron bang time (NBT) detectors have been successfully operated on ICF facilities such as the Nova and OMEGA lasers, and have been proposed as a core diagnostic for the National Ignition Facility (NIF). Prototypes of the NBT detector suitable for the NIF have been built and tested on the 60-beam OMEGA laser system. These prototypes have three channels. The first, most-sensitive channel consists of a fast plastic scintillator coupled with a microchannel-plate (MCP) photomultiplier tube (PMT). The second and third channels are based on a synthetic polycrystalline diamond produced by chemical vapor deposition (CVD). These three independent channels will be able to cover a wide range of DD and DT neutron yields: from 1/spl times/10/sup 9/ to 1/spl times/10/sup 16/. The signals from the NBT prototype channels are recorded on a fast digital oscilloscope. Absolute timing was accomplished using the OMEGA optical fiducial system. The NIF NBT prototypes show better than 100-ps timing accuracy, satisfying the NIF specification.

The proton probing technique is used to image quasi-static electromagnetic fields present in the wake of a high-intensity short-pulse laser propagating through an underdense plasma. Bubblelike field structures form along the channel filaments and expand in time. © 2006 IEEE.

The characterization of energetic electrons generated in high-energy short-pulse laser-solid interactions is of importance for electron fast ignition. Experiments have been carried out at the OMEGA Extended Performance laser facility to study the properties of fast electrons using a spherically bent crystal to image a stand-alone Cu cone and a Cu wire attached to an aluminum cone.