Measurement of the Lifetime of the Metastable 5d\u3csub\u3e3/2\u3c/sub\u3e26d\u3csub\u3e3/2\u3c/sub\u3e, J=0 Autoionizing State of Barium

We report a measurement of the lifetime of the metastable 5d3/226d3/2, J=0 autoionizing state of barium. We have determined the lifetime to be 190(10) ns

Two-Step Stabilization of Autoionizing States

A two-step process using internal conversion and fluorescence to stabilize the 6P3/211d autoionizing state of barium has been observed. The internal conversion produces very highly excited autoionizing Rydberg states, which then emit fluorescence to produce singly excited, bound states. Inclusion of this process should bring calculations closer to agreement with recent measurements of dielectronic recombination

Laser generated electron transport experiment in a novel wire nail target

The transport of high intensity (2x1020 W/cm2) laser generated relativistic electrons with a solid target has been studied in a novel geometry. The targets were 20 um diameter solid copper wires, coated with ~ 2um of titanium, with an 80 um diameter hemispherical termination. They were illuminated by an ~500fs, ~200J pulse of 1.053um laser light focused to a ~ 20um diameter spot centered on the flat face of the hemisphere. K-alpha fluorescence from the Cu and Ti regions was imaged together with extreme ultraviolet (X-UV) emission at 68 and 256eV. Results showed a quasi exponential decline in K-alpha emission along the wire over a distance of a few hundred microns from the laser focus, consistent with bulk Ohmic inhibition of the relativistic electron transport. Weaker Ka and X-UV emission on a longer scale length showed limb brightening suggesting a transition to enhanced transport at the surface of the wire

Electron Generation and Transport using Second Harmonic Laser Pulses for Fast Ignition Laser Fusion Energy

A team of University of Alberta researchers, in collaboration with an international team of investigators, has spearheaded an experiment to study the generation and transport of MeV electrons produced by ultra-high intensity second harmonic Nd:Glass laser pulses. Intensities of up to 5 x I O’ 9 W cm2 have been used to irradiate a variety of targets to investigate the conversion efficiency into MeV energy electrons, as well as the energy spectrum and angular divergence of such electrons. Their transport through a cone tip simulating the generation of an energetic electron beam for the fast ignition of a laser-compressed fuel core was also measured. The experiments were carried out at the Titan high intensity 1aser facility located at the Lawrence Livermore National Laboratory. The experiment is the first step towards evaluating the potential effectiveness of using prepulse-free shorter wavelength second harmonic laser pulses as ignition sources for Fast Ignition Fusion Energy

Energy Injection for Fast Ignition

In the fast ignition concept, assembled fuel is ignited through a separate high intensity laser pulse. Fast Ignition targets facilitate this ignition using a reentrant cone. It provides clear access through the overlaying coronal plasma, and controls the laser plasma interaction to optimize hot-electron production and transport into the compressed plasma. Recent results suggest that the cone does not play any role in guiding light or electrons to its tip, and coupling to electrons can be reduced by a small amount of preplasma. This puts stringent requirements on the ignition laser focusing, pointing, and prepulse

Energy

The University Archives has determined that this item is of continuing value to OSU's history.This episode introduces the concept of energy by showing that two different types of energy, kinetic and potential, are equivalent in the sense that they can produce the same results. In this case the result is a smashed car, either dropped from a height or run into a wall. Another demonstration takes place at a skateboard park showing that kinetic and potential energy can transform into each other.The Ohio State University Department of PhysicsWOS

Efficient Multiphoton Excitation of Multiply Excited States

It is shown that if an atomic excitation involves the absorption of more than one photon above the ionization limit, then the total population transfer depends not only on the two-photon generalized excitation cross section but also on the one-photon loss cross section. In the limit of large population transfers, the efficiency can be dominated by the one-photon loss cross section