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Pablo Martel

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Papers by Pablo Martel

Equation of state for hot dense matter using a relativistic screened hydrogenic model

The study of matter under conditions of high density, pressure, and temperature is a valuable sub... more The study of matter under conditions of high density, pressure, and temperature is a valuable subject for inertial confinement fusion (ICF), astrophysical phenomena, high-power laser interaction with matter, etc. In all these cases, matter is heated and compressed by strong shocks to high pressures and temperatures, becomes partially or completely ionized via thermal or pressure ionization, and is in the form of a dense plasma. The thermodynamics and the hydrodynamics of hot dense plasmas cannot be predicted without the knowledge of the equation of state (EOS) that describes how a material reacts to pressure and how much energy is involved. Therefore, the equation of state often takes the form of pressure and energy as functions of density and temperature. Furthermore, EOS data must be obtained in a timely manner in order to be useful as input in hydrodynamic codes. By this reason, the use of fast, robust and reasonably accurate atomic models, is necessary for computing the EOS of a...

Analytical Potential for Core and Si ngle Excited Configurations Including Plasma Effects to Obtain Atomic Properties for Ions in Dense and Hot Plasmas

Study of the solar opacity using the ATMED code

Calculation of LTE Spectral Opacities for ICF Plasma Mixtures using an Average Atom Model

Fast calculation of LTE opacities for ICF plasmas

Using spar se matr ices techniques and it er ative solver s in the calculation of level populations for NLTE plasmas

1. Intr oduction Calculations of populations of ion species existing in plasmas comprise an impor... more 1. Intr oduction Calculations of populations of ion species existing in plasmas comprise an important research area for laboratory and astrophysical plasmas from low to high electron density regime. Ionic charge distribution is required for the determination of average ionizations, emissivities and opacities, both for hydro-simulations and spectroscopic diagnostics. In this work, we present a steady-stat e CR model for

Radon in Groundwater of the Northeastern Gran Canaria Aquifer

Water, 2015

222 Rn has been detected in 28 groundwater samples from the northeast of Gran Canaria (Canary Isl... more 222 Rn has been detected in 28 groundwater samples from the northeast of Gran Canaria (Canary Islands, Spain) utilizing a closed loop system consisting of an AlphaGUARD monitor that measures radon activity concentration in the air by means of an ionization chamber, and an AquaKIT set that transfers dissolved radon in the water samples to the air within the circuit. Radon concentration in the water samples studied varies between 0.3 and 76.9 Bq/L. Spanish radiological protection regulations limit the concentration of 222 Rn for drinking water to 100 Bq/L, therefore the values obtained for all the analyzed samples are below this threshold. The hydrogeological study reveals a significant correspondence between the radon activity concentration and the material characteristics of the aquifer. For a selected group of samples with high radon concentrations, gross alpha activity has been determined to have values higher than the prescriptive screening level (0.1 Bq/L).

Spectrally resolved intensities of ultra-dense hot aluminum plasmas

We present a first study of spectroscopic determination of electron temperature and density spati... more We present a first study of spectroscopic determination of electron temperature and density spatial profiles of aluminum K-shell line emission spectra from laser-shocked aluminum experiments performed at LULI. The radiation emitted by the aluminum plasma was dispersed with an ultra-high resolution spectrograph (A/AA ~ 6000). From the recorded films one can extract a set of time-integrated emission lineouts associated with the corresponding spatial region of the plasma. The observed spectra include the Lya, Hej3, Hey, Lyj3 and Lyy line emissions and their associated He-and Li-like satellites thus covering a photon energy range from 1700 eV to 2400 eV approximately. The data analysis rely on the ABAKO/RAPCAL computational package, which has been recently developed at the University of Las Palmas de Gran Canaria and takes into account non-equilibrium collisional-radiative atomic kinetics. Stark broadened line shapes and radiation transport calculations.

Collisional-Radiative Calculations of Optically Thin and Thick Plasmas Using the Computational Package ABAKO/RAPCAL

Communications in Computational Physics, 2010

Non-local thermodynamic equilibrium (NLTE) conditions are universal in laboratory and astrophysic... more Non-local thermodynamic equilibrium (NLTE) conditions are universal in laboratory and astrophysical plasmas and, for this reason, the theory of NLTE plasmas is nowadays a very active subject. The populations of atomic levels and radiative properties are essential magnitudes in the study of these plasmas and the calculation of those properties relies on the so-called collisional-radiative (CR) models. However, the complexity of these models has led to the development of numerous collisionalradiative codes and this is a current research topic in plasmas. In this work is presented a versatile computational package, named ABAKO/RAPCAL, to calculate the populations of atomic levels and radiative properties of optically thin and thick, lowto-high Z, NLTE plasmas. ABAKO/RAPCAL combines a set of analytical approximations which yield substantial savings in computing running time, still comparing well with more elaborated codes and experimental data. In order to show the capabilities of the code and the accuracy of its results, calculations of several relevant plasma magnitudes for various plasma situations are shown and compared.

Atomic Physics Modeling and Applications for ICF Plasmas

Plasma and Fusion Research, 2013

The Atomic Physics Group at the Institute of Nuclear Fusion (DENIM) in Spain has accumulated expe... more The Atomic Physics Group at the Institute of Nuclear Fusion (DENIM) in Spain has accumulated experience over the years in developing a collection of computational models and tools for determining some relevant microscopic properties of, mainly, ICF and laser-produced plasmas in a variety of conditions. In this work several applications of those models in determining some relevant microscopic properties are presented.

Modelling of spectral properties and population kinetics studies of inertial fusion and laboratory-astrophysical plasmas

Plasma Physics and Controlled Fusion, 2012

Fundamental research and modelling in plasma atomic physics continue to be essential for providin... more Fundamental research and modelling in plasma atomic physics continue to be essential for providing basic understanding of many different topics relevant to high-energy-density plasmas. The Atomic Physics Group at the Institute of Nuclear Fusion has accumulated experience over the years in developing a collection of computational models and tools for determining the atomic energy structure, ionization balance and radiative properties of, mainly, inertial fusion and laser-produced plasmas in a variety of conditions. In this work, we discuss some of the latest advances and results of our research, with emphasis on inertial fusion and laboratory-astrophysical applications.

Developments and comparison of two denim opacity models

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1998

... The Unresolved Transition Array (UTA) developed by Bauche et al. [10] , [11] and [12] , and t... more

Scaling law of radiative opacities for ICF elements

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2001

This work is focused on the determination of Rosseland and Planck mean analytical formulas for se... more This work is focused on the determination of Rosseland and Planck mean analytical formulas for several single elements used in ICF targets. A scaling law of these mean opacities is given as a function of the plasma parameters: electron temperature and plasma density. These opacities have been tested with numerical results from other codes and with available experimental results.

Opacity calculations of plasmas by using parametric potentials

Laser and Particle Beams, 1996

A numerical model for opacity calculations by using a family of analytical potentials for each co... more

Determination of corona, LTE, and NLTE regimes of optically thin carbon plasmas

Laser and Particle Beams, 2008

In this work is accomplished the determination of the corona, local and non-local thermodynamic e... more In this work is accomplished the determination of the corona, local and non-local thermodynamic equilibrium regimes for optically thin carbon plasmas in steady state, in terms of the plasma density and temperature using the ABAKO code. The determination is made through the analysis of the plasma average ionization and ion and level populations. The results are compared whit those obtained applying Griem's criterion. Finally, it is made a brief analysis of the effects of the calculation of level populations assuming different plasma regimes in radiative properties, such as emissivities and opacities.

Analysis of the influence of the plasma thermodynamic regime in the spectrally resolved and mean radiative opacity calculations of carbon plasmas in a wide range of density and temperature

Journal of Quantitative Spectroscopy and Radiative Transfer, 2013

In this work the spectrally resolved, multigroup and mean radiative opacities of carbon plasmas a... more In this work the spectrally resolved, multigroup and mean radiative opacities of carbon plasmas are calculated for a wide range of plasma conditions which cover situations where corona, local thermodynamic and non-local thermodynamic equilibrium regimes are found. An analysis of the influence of the thermodynamic regime on these magnitudes is also carried out by means of comparisons of the results obtained from collisional-radiative, corona or Saha-Boltzmann equations. All the calculations presented in this work were performed using ABAKO/RAPCAL code.

Multifrequential and mean opacity calculation of carbon plasmas in a wide range of density and temperature

Journal of Physics: Conference Series, 2008

The purpose of this work is to calculate the multifrequential and mean opacity of optically thin ... more

Analytical opacity formulas for low Z plasmas

Journal of Physics: Conference Series, 2008

The accurate computation of radiative opacities is basic in the ICF target physics analysis, in w... more The accurate computation of radiative opacities is basic in the ICF target physics analysis, in which the radiation is an important feature to determine in detail. For this reason, accurate analytical formulas for giving mean opacities versus temperature and density of the plasma seem to be a useful tool. In this work we analyse some analytical expressions found in the literature for the opacity low Z plasmas in a wide range of temperature and densities. The validity of these formulas for computing the opacity under NLTE conditions is investigated using the new code ABAKO.

A new set of relativistic screening constants for the screened hydrogenic model

High Energy Density Physics, 2011

A new Relativistic Screened Hydrogenic Model has been developed to calculate atomic data needed t... more A new Relativistic Screened Hydrogenic Model has been developed to calculate atomic data needed to compute the optical and thermodynamic properties of high energy density plasmas. The model is based on a new set of universal screening constants, including nij-splitting that has been obtained by fitting to a large database of ionization potentials and excitation energies. This database was built with energies compiled from the National Institute of Standards and Technology (NIST) database of experimental atomic energy levels, and energies calculated with the Flexible Atomic Code (FAC). The screening constants have been computed up to the 5p¡/2 subshell using a Genetic Algorithm technique with an objective function designed to minimize both the relative error and the maximum error. To select the best set of screening constants some additional physical criteria has been applied, which are based on the reproduction of the filling order of the shells and on obtaining the best ground state configuration. A statistical error analysis has been performed to test the model, which indicated that approximately 88% of the data lie within a ±10% error interval. We validate the model by comparing the results with ionization energies, transition energies, and wave functions computed using sophisticated self-consistent codes and experimental data.

Determination of the average ionization and thermodynamic regimes of xenon plasmas with an application to the characterization of blast waves launched in xenon clusters

High Energy Density Physics, 2011

Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This f... more Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shock propagates. In this work the average ionization and the thermodynamic regimes of xenon plasmas are determined as functions of the matter density and temperature in a wide range of plasma conditions. The results obtained will be applied to characterize blast waves launched in xenon clusters.