Fast ignition by intense laser-accelerated proton beams.

The concept of fast ignition with inertial confinement fusion (ICF) is a way to reduce the energy required for ignition and burn and to maximize the gain produced by a single implosion. Based on recent experimental findings at the PETAWATT laser at Lawrence Livermore National Laboratory, an intense proton beam to achieve fast ignition is proposed. It is produced by direct laser acceleration and focused onto the pellet from the rear side of an irradiated target and can be integrated into a hohlraum for indirect drive ICF.

Photonuclear fission from high energy electrons from ultraintense laser-solid interactions

A new regime of laser-matter interactions in which the quiver motion of plasma electrons is fully relativistic, with energies extending well above the threshold for nuclear processes, is studied using a petawatt laser system. In solid target experiments with focused intensities exceeding 10(20) W/cm(2), high energy electron generation, hard bremsstrahlung, and nuclear phenomena have been observed. We report here a quantitative comparison of the high energy electrons and the bremsstrahlung spectrum, as measured by photonuclear reaction yields, including the photoinduced fission of 238U.

Quantification of N-(glucitol)ethanolamine and N-(carboxymethyl)serine: two products of nonenzymatic modification of aminophospholipids formed in vivo.

Chemical, nonenzymatic modification of protein and lipids by reducing sugars, such as glucose, is thought to contribute to age-related deterioration in tissue protein and cellular membranes and to the pathogenesis of diabetic complications. This report describes the synthesis and quantification of N-(glucitol)ethanolamine (GE) and N-(carboxymethyl)serine (CMS), two products of nonenzymatic modification of aminophospholipids. GE is the product of reduction and hydrolysis of glycated phosphatidylethanolamine (PE), while CMS is formed through reaction of phosphatidylserine (PS) with products of oxidation of either carbohydrate (glycoxidation) or lipids (lipoxidation). Gas chromatography/mass spectrometry procedures for quantification of the N,O-acetyl methyl ester derivatives of the modified head groups were developed. GE and CMS were quantified in samples of PE and PS, respectively, following incubation with glucose in vitro; CMS formation was dependent on the presence of oxygen during the incubation. Both GE and CMS were detected and quantified in lipid extracts of human red blood cell membranes. The content of GE, but not CMS, was increased in the lipids from diabetic compared to nondiabetic subjects. Measurement of these modified lipids should prove useful for assessing the role of carbonyl-amine reactions of aminophospholipids in aging and age-related diseases.

Properties of neodymium laser materials.

The optical properties of neodymium-doped crystalline and glass laser materials have been studied in an attempt to further the development of laser materials (emitting at 1.06 micro) for specific applications. The 1.06-micro fluorescence lifetimes and relative fluorescence conversion efficiencies for the more promising materials such as YAG:Nd and glass:Nd have been measured over the temperature range 300-500 K. Also determined were the effects of sensitization of YAG:Nd by Cr(3+) (the enhancement of 1.06-micro, fluorescence and the Cr(3+) ? Nd(3+) energy transfer times). Further absorption spectra and fluorescence lifetimes have been determined for a large group of crystalline and glass laser media under room temperature conditions. The study of these optical properties and their thermal dependences in this temperature region provide information that is useful in solving laser device problems such as optimization of operating temperature and of pump characteristics. Presented in this paper are the results obtained from the above experimental study of the optical properties together with a collection of data from the literature of optical, thermal, and physical properties of these laser materials.