[en] Electroproduction of the omega meson was investigated in the p(e,e'p)omega reaction. The measurement was performed at a 4-momentum transfer Q2 ∼ 0.5 GeV2. Angular distributions of the virtual photon-proton center-of-momentum cross sections have been extracted over the full angular range. These distributions exhibit a strong enhancement over t-channel parity exchange processes in the backward direction. According to a newly developed electroproduction model, this enhancement provides significant evidence of resonance formation in the gamma* p -> omega p reaction channel

[en] Extreme ultraviolet lithography requires a light source at 13.5 nm to match the proposed multilayer optics reflectivity. The impact of wavelength and power density on the ion distribution and electron temperature in a laser-produced plasma is calculated for Nd:YAG and CO₂ lasers. A steady-state figure of merit, calculated to optimize emission as a function of laser wavelength, shows an increase with a CO₂ laser. The influence of reduced electron density in the CO₂ laser-produced plasma is considered in a one-dimensional radiation transport model, where a more than twofold increase in conversion efficiency over that attainable with the Nd:YAG is predicted

[en] We show that the physical Hastings–McLeod solution of the integrable Painlevé II equation generalizes in a natural way to a class of non-integrable equations, in a way that preserves many of the significant qualitative properties. The Hastings–McLeod solution of Painlevé II is an important and universal example of resurgent relations between perturbative and non-perturbative physics. We derive the trans-series structure of the generalized Hastings–McLeod solutions, demonstrating that integrability is not essential for the resurgent asymptotic properties of the solutions. (paper)

[en] Many next generation lithography schemes for the semiconductor industry are based on a 13.5 nm tin plasma light source, where hundreds of thousands of 4d-4f, 4p-4d, and 4d-5p transitions from Sn⁵⁺-Sn¹³⁺ ions overlap to form an unresolved transition array. To aid computation, transition arrays are treated statistically, and Hartree-Fock results are used to calculate radiation transport in the optically thick regime with a one-dimensional Lagrangian plasma hydrodynamics code. Time-dependent spectra and conversion efficiencies of 2% in-band 13.5 nm emission to laser energy are predicted for a Nd:YAG (yttrium aluminum garnet) laser incident on a pure tin slab target as a function of laser power density and pulse duration at normal incidence. Calculated results showed a maximum conversion efficiency of 2.3% for a 10 ns pulse duration at 8.0x10¹⁰ W/cm² and are compared to experimental data where available. Evidence for the need to include lateral expansion is presented.

[en] The molten pool weld produced during self-shielded flux-cored arc welding (SSFCAW) is protected from gas porosity arising from oxygen and nitrogen by reaction ('killing') of these gases by aluminium. However, residual Al can result in mixed micro-structures of δ-ferrite, martensite and bainite in hardfacing weld metals produced by SSFCAW and therefore, microstructural control can be an issue for hardfacing weld repair. The effect of the residual Al content on weld metal micro-structure has been examined using thermodynamic modeling and dilatometric analysis. It is concluded that the typical Al content of about 1 wt% promotes δ-ferrite formation at the expense of austenite and its martensitic/bainitic product phase(s), thereby compromising the wear resistance of the hardfacing deposit. This paper also demonstrates how the development of a Schaeffler-type diagram for predicting the weld metal micro-structure can provide guidance on weld filler metal design to produce the optimum microstructure for industrial hardfacing applications.

[en] Intense, soft-x-ray pulses, generated from separate laser-irradiated converters, were used to irradiate plane plastic foils. The x-ray heating was investigated by measuring the temperature histories of chlorinated tracer layers buried at different depths in the targets. The temperature diagonistic was a time-resolved extreme-UV absorption spectroscopy technique using chlorine L-shell transitions. The temporal temperature profiles were reasonably well reproduced by radiation-hydrocode simulations

[en] The dynamics of plastic foils of different thicknesses which were irradiated with intense, approximately Planckian soft-x-ray pulses, have been investigated using a high magnification (80x), time-resolving extreme ultraviolet (95 or 205 eV) imaging technique for the first time. The experimental results are discussed and compared with hydrocode simulations

[en] Thin plastic foils, up to 6μm thick, were heated by an intense source of soft X-rays, generated from the rear of a second, thin, bismuth or gold foil when it was irradiated at around 10¹⁴ Wcm^-2 by a green laser pulse, 500--700ps in duration. The soft X-rays transmitted through the plastic foils were time resolved in the 10--70A spectral wavelength region using flat-field XUV spectrometers. Absorption features in the transmitted spectra were clearly observed in the regions of the carbon K-edge. Both the experimental data and interpretations are presented

[en] Impact damage in a composite shaft was studied using Line Scanning Thermography (LST), a novel dynamic thermography technique capable of inspecting large areas in short times. It is expected that projectile impact in a laminate composite will generate a discontinuity that affects heat propagation. Therefore, as heat is deposited over the impacted region, a hot spot will be observed. In this study several impact points were evaluated using UT and LST. Experiments show that assessing impact damage using LST is a dynamic process, which should be accounted for when using dynamic thermography to quantify impact damage extension and severity. The LST images provided information about the region affected by impact damage, which was consistent with the damage region determined using UT. It is seen that the damage areas obtained at early observation time after heat application show small areas with severe damage; and for further times after heat application, the temperature of the hot spots drops and the size of the region affected increases with time following a linear relationship with the observation time.

[en] We report on experimental investigations into strong, laser-driven, radiative shocks in cluster media. Cylindrical shocks launched with several joules of deposited energy exhibit strong radiative effects including rapid deceleration, radiative preheat, and shell thinning. Using time-resolved propagation data from single-shot streaked Schlieren measurements, we have observed temporal modulations on the shock velocity, which we attribute to the thermal cooling instability, a process which is believed to occur in supernova remnants but until now has not been observed experimentally.