VUV/EUV ionising radiation and atoms and ions: dual laser plasma investigations

The interaction of ionising radiation with atoms and ions is a key fundamental process. This report concentrates on studies of photoexcitation/photoionisation using laser-produced plasmas as continuum sources and synchronised laser plasma plumes to provide the absorbing atom or ion species. Examples from studies of the interaction of ionising radiation with atoms and ions ranging from few-electron atomic and ionic systems to the many-electron high atomic number actinides are reviewed and illustrate the advantages and limitations of the Dual Laser Plasma technique

Elastic Cross Sections for Electron Collisions with Molecules Relevant to Plasma Processing

Absolute electron-impact cross sections for molecular targets, including their radicals, are important in developing plasma reactors and testing various plasma processing gases. Low-energy electron collision data for these gases are sparse and only the limited cross section data are available. In this report, elastic cross sections for electron-polyatomic molecule collisions are compiled and reviewed for 17molecules relevant to plasma processing. Elastic cross sections are essential for the absolute scale conversion of inelastic cross sections, as well as for testing computational methods. Data are collected and reviewed for elastic differential, integral, and momentum transfer cross sections and, for each molecule, the recommended values of the cross section are presented. The literature has been surveyed through early 2010.This work is accomplished as a collaboration through APAN (Asia-Pacific Atomic Data Network: a network for dissemination of collisional data relevant to plasmas, discharges, materials, and biosciences). H.C. acknowledges a support by the National Research Foundation of Korea (Grant No. 20100000035), and M.J.B. and S.J.B. support from the Australian Research Council Center of Excellence for Antimatter-Matter Studies. Collaboration between NIFS and NFRI is also acknowledged for the Korea-Japan exchanges

Development of a mercury free ultraviolet high pressure plasma discharge for disinfection

Ultraviolet (UV) disinfection is a critical and growing application for the disinfection of water. Current UV systems for disinfection applications are designed around the use of Low Pressure (LP) and High Pressure (HP) mercury based lamps. Increasing demand to reduce and ideally remove the use of mercury requires innovative adaptations and novel approaches to current technology. A potential alternative technology could be Light Emitting Diodes (LEDs) however with current low efficiencies, high costs and low operating powers a development gap for a high power mercury source has been identified. A mercury free tellurium based high pressure plasma was developed and assessed. Although relatively low efficiencies were measured compared to current mercury based technology rapid improvements are likely obtainable. Such an approach enables a novel adaptation to current technology utilising established; manufacturing facilities, approaches of UV system design and validation protocols. As a consequence it offers the potential for a rapid low cost transition to mercury free UV disinfection where no alternative is currently available

Radiation Science Using Z-Pinch X-Rays

Present-day Z-pinch experiments generate 200 TW peak power, 5–10 ns duration x-ray bursts that provide new possibilities to advance radiation science. The experiments support both the underlying atomic and plasma physics, as well as inertial confinement fusion and astrophysics applications. A typical configuration consists of a sample located 1–10 cm away from the pinch, where it is heated to 10–100 eV temperatures by the pinch radiation. The spectrally-resolved sample-plasma absorption is measured by aiming x-ray spectrographs through the sample at the pinch. The pinch plasma thus both heats the sample and serves as a backlighter. Opacitymeasurements with this source are promising because of the large sample size, the relatively long radiation duration, and the possibility to measureopacities at temperatures above 100 eV. Initial opacity experiments are under way with CH-tamped NaBr foil samples. The Na serves as a thermometer and absorption spectra are recorded to determine the opacity of Br with a partially-filled M-shell. The large sample size and brightness of the Z pinch as a backlighter are also exploited in a novel method measuring re-emission from radiation-heated gold plasmas. The method uses a CH-tamped layered foil with Al+MgF2 facing the radiationsource. A gold backing layer that covers a portion of the foil absorbs radiation from the source and provides re-emission that further heats the Al+MgF2. The Al and Mg heating is measured using space-resolved Kα absorption spectroscopy and the difference between the two regions enables a determination of the gold re-emission. Measurements are also performed at lower densities where photoionization is expected to dominate over collisions. Absorption spectra have been obtained for both Ne-like Fe and He-like Ne, confirming production of the relevant charge states needed to benchmark atomic kinetics models. Refinement of the methods described here is in progress to address multiple issues for radiation science

Applications of aerospace technology in the electric power industry

An overview of the electric power industry, selected NASA contributions to progress in the industry, linkages affecting the transfer and diffusion of technology, and, finally, a perspective on technology transfer issues are presented

Analysis of long-lived radionuclides produced by proton irradiation in lead targets - γ -measurements

The presented work aims at a radiochemical analysis of the radionuclide inventory of a solid lead target irradiated with high energetic protons in the spallation neutron facility SINQ at Paul Scherrer Institute. Lead samples from the vicinity of the beam entry have been extracted. A detailed γ-analysis shows the radial distribution of selected radionuclides relative to the incoming beam. The concentrations of these nuclides are evaluated in dependence on the proton beam profil

Investigation of Phonon Polaritons in an hBN GaN Heterostructure

There have been many great advances in the generation and manipulation of optics in the visible and near infrared (IR) range over the past decade. This is largely due to plasmonic enhancement, which has led to new technology in biosensing and molecule detection, solid-state lighting, and solar energy harvesting. The field of plasmonics uses quanta of plasma oscillations, plasmons, formed from the interaction between electromagnetic radiation and free electrons to enhance optical near field magnitudes. However, there is still a large region of the electromagnetic spectrum, covering the mid-infrared (MIR) and terahertz (THz) regions, ranging from 3 μm to 1 mm, that has not benefitted from this research. Polaritonics have recently gained attention from the scientific community to access this region and enhance current technologies. Polaritons are an IR alternative to plasmons; these quasiparticles are formed from light coupling to an elementary material excitation, such as phonons, plasmons, magnons, or excitons. In this project, we look at the past, present, and future of terahertz technology and the role phonon polaritons play in their advancement. A hexagonal boron-nitride/gallium nitride superlattice is examined through simulated reflection experiments to identify phonon polariton modes