Idealized Slab Plasma approach for the study of Warm Dense Matter

Recently, warm dense matter (WDM) has emerged as an interdisciplinary field that draws increasing interest in plasma physics, condensed matter physics, high pressure science, astrophysics, inertial confinement fusion, as well as materials science under extreme conditions. To allow the study of well-defined WDM states, we have introduced the concept of idealized-slab plasmas that can be realized in the laboratory via (i) the isochoric heating of a solid and (ii) the propagation of a shock wave in a solid. The application of this concept provides new means for probing the dynamic conductivity, equation of state, ionization and opacity. These approaches are presented here using results derived from first-principles (density-functional type) theory, Thomas-Fermi type theory, and numerical simulations.Comment: 37 pages, 21 figures, available, pdf file only. To appear in: Laser and Particle beams. To appear more or less in this form in Laser and Particle beam

The G protein-coupled receptor subset of the dog genome is more similar to that in humans than rodents

<p>Abstract</p> <p>Background</p> <p>The dog is an important model organism and it is considered to be closer to humans than rodents regarding metabolism and responses to drugs. The close relationship between humans and dogs over many centuries has lead to the diversity of the canine species, important genetic discoveries and an appreciation of the effects of old age in another species. The superfamily of G protein-coupled receptors (GPCRs) is one of the largest gene families in most mammals and the most exploited in terms of drug discovery. An accurate comparison of the GPCR repertoires in dog and human is valuable for the prediction of functional similarities and differences between the species.</p> <p>Results</p> <p>We searched the dog genome for non-olfactory GPCRs and obtained 353 full-length GPCR gene sequences, 18 incomplete sequences and 13 pseudogenes. We established relationships between human, dog, rat and mouse GPCRs resolving orthologous pairs and species-specific duplicates. We found that 12 dog GPCR genes are missing in humans while 24 human GPCR genes are not part of the dog GPCR repertoire. There is a higher number of orthologous pairs between dog and human that are conserved as compared with either mouse or rat. In almost all cases the differences observed between the dog and human genomes coincide with other variations in the rodent species. Several GPCR gene expansions characteristic for rodents are not found in dog.</p> <p>Conclusion</p> <p>The repertoire of dog non-olfactory GPCRs is more similar to the repertoire in humans as compared with the one in rodents. The comparison of the dog, human and rodent repertoires revealed several examples of species-specific gene duplications and deletions. This information is useful in the selection of model organisms for pharmacological experiments.</p

Photoionized plasma calculations using laboratory and astrophysical models

We present numerical simulations from the code GALAXY, frequently employed to model the distribution of excitation and ionization, and the spectral emission from laboratory plasma experiments. In particular, preliminary calculations relevant to the Lawrence Livermore National Laboratory photoionization collaboration are presented, along with results which compare GALAXY with results from the astrophysical code CLOUDY

Measurement of L-shell emission from mid-Z targets under non-LTE conditions using Transmission Grating Spectrometer and DANTE power diagnostics

Producción CientíficaIn this work, we present the measurement of L-band emission from buried Sc/V targets in experiments performed at the OMEGA laser facility. The goal of these experiments was to study non-local thermodynamic equilibrium plasmas and benchmark atomic physics codes. The L-band emission was measured simultaneously by the time resolved DANTE power diagnostic and the recently fielded time integrated Soreq-Transmission Grating Spectrometer (TGS) diagnostic. The TGS measurement was used to support the spectral reconstruction process needed for the unfolding of the DANTE data. The Soreq-TGS diagnostic allows for broadband spectral measurement in the 120 eV–2000 eV spectral band, covering L- and M-shell emission of mid- and high-Z elements, with spectral resolution λ/Δλ = 8–30 and accuracy better than 25%. The Soreq-TGS diagnostic is compatible with ten-inch-manipulator platforms and can be used for a wide variety of high energy density physics, laboratory astrophysics, and inertial confinement fusion experiments

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

Energy Levels and Transition Probabilities for Nitrogen-Like Fe xx

Energies of the 700 lowest levels in Fexx have been obtained using the multiconfiguration Dirac-Fock method. Configuration interaction method on the basis set of transformed radial orbitals with variable parameters taking into account relativistic corrections in the Breit-Pauli approximation was used to crosscheck our presented results. Transition probabilities, oscillator and line strengths are presented for electric dipole (E1), electric quadrupole (E2) and magnetic dipole (M1) transitions among these levels. The total radiative transition probabilities from each level are also provided. Results are compared with data compiled by NIST and with other theoretical work

Modelling, Design And Diagnostics For A Photoionised Plasma Experiment

Photoionised plasmas are common in astrophysical environments and new high resolution spectra from such sources have been recorded in recent years by the Chandra and XMM-Newton satellites. These provide a wealth of spectroscopic information and have motivated recent efforts aimed at obtaining a detailed understanding of the atomic-kinetic and radiative characteristics of photoionised plasmas. The Z-pinch facility at the Sandia National Laboratories is the most powerful terrestrial source of X-rays and provides an opportunity to produce photoionised plasmas in a well characterised radiation environment. We present modelling work and experimental design considerations for a forthcoming experiment at Sandia in which X-rays from a collapsing Z-pinch will be used to photoionise low density neon contained in a gas cell. View factor calculations were used to evaluate the radiation environment at the gas cell; the hydrodynamic characteristics of the gas cell were examined using the Helios-CR code, in particular looking at the heating, temperature and ionisation of the neon and the absorption of radiation. Emission and absorption spectra were also computed, giving estimates of spectra likely to be observed experimentally

Reaching Isochoric States of Matter by Ultrashort-Pulse Proton Heating

The aim of this LDRD is to develop two completely new methods for creating and probing warm dense states of matter (plasmas at several eV at solid density), which will enable the direct measurement of fundamental material properties such as the opacity and equation of state (EOS). There is in this warm dense regime an almost complete lack of quantitative experimental data--primarily because of the difficulty in creating uniform, single temperature/density plasmas on which to make measurements. In an ideal case one would volumetrically heat a target with a very short burst of energy--simultaneously making measurements prior to the subsequent hydrodynamic expansion of the target. However, no mechanism for such rapid, uniform heating of a material currently exists. We propose to develop a completely new technique that has the potential for creating large uniform plasmas in local thermodynamic equilibrium (LTE) at warm dense conditions. This technique is based on volumetric heating of solid density targets with a high energy, high-flux, short-pulse, laser-produced proton beam. We also propose to use this beam of protons to probe high-Z, solid density matter with both 2-dimensional spatial resolution and picosecond temporal resolution. The combination of these two techniques will enable us to make the very first quantitative measurements of the equation of state and opacity of an isochorically heated state of matter

Ionization disequilibrium in K- and L-shell ions

Producción CientíficaTime-gated Sc K-shell and Ge L-shell spectra are presented from a range of characterized thermodynamic states spanning ion densities of 1e19-1e20cm-3 and plasma temperatures around 2000eV. For the higher densities studied and temperatures from 1000 to 3000 eV, the Sc and Ge x-ray emission spectra are consistent with steady-state calculations from the modern atomic kinetics model SCRAM. At the lower ion densities achieved through plasma expansion, however, the model calculations require a higher plasma temperature to reproduce the observed Ge spectrum. We attribute this to ionization disequilibrium of the Sc because the ionization time scales exceed the hydrodynamic timescale when the inferred temperatures diverge.This work has been supported by the Research Grant No. PID2019-108764RB-I00 from the Spanish Ministry of Science and Innovation