Marco Gigosos

University of Valladolid | UVA · Facultad de Ciencias

Classical molecular dynamics simulations of hydrogen plasmas have been performed with an emphasis on the analysis of the equilibration process. The theoretical basis of the simulation model as well as numerically relevant aspects, such as the proper choice and definition of simulation units, are discussed in detail, thus proving a thorough implemen...

We report experimental determination of plasma-induced Stark widths and shifts of the He II Pα line and a comparison of the results with calculations performed by several computational approaches. The measurements were carried out in a small compressing plasma channel device, reaching electron densities in excess of 10 18 cm −3 and temperatures of...

We report experimental determination of plasma-induced Stark widths and shifts of the He II P α line and a comparison of the results with calculations performed by several computational approaches. The measurements were carried out in a small compressing plasma channel device, reaching electron densities in excess of 10 18 cm − 3 and temperatures o...

Powerful laser-plasma processes are explored to generate discharge currents of a few $100\,$kA in coil targets, yielding magnetostatic fields (B-fields) in excess of $0.5\,$kT. The quasi-static currents are provided from hot electron ejection from the laser-irradiated surface. According to our model, describing qualitatively the evolution of the di...

The conformational landscape of the bicyclic molecule 2-decalone has been studied in a jet-cooled expansion by using rotational spectroscopy. The investigation covered the frequency region 7–19 GHz using broadband fast-passage IMPACT Fourier-transform microwave techniques. The introduction of the asymmetric carbonyl substituent in the double-chair...

Sparteine is a quinolizidine alkaloid used as a chiral auxiliary in asymmetric synthesis. We examine whether hydration by a single molecule can flip sparteine from the most stable trans conformation to the bidentate cis arrangement observed in catalytic complexation to a metal center. Sparteine and the sparteine-water dimer were generated in a supe...

The Plasma diagnostics through the analysis of spectral line shapes is a widely known tech- nique which gives very reliable values of the electron density. This technique is based on the comparison of the experimental data with the theoretical calculations of the line profile, which, in many cases, is mainly due to the Stark effect. Currently there...

The local electric field created by free electrons and free ions in a plasma alter the emission spectra giving rise to the appearance of forbidden transitions and to which is called Stark shift and Stark broadening. The analysis of these spectra is the basis of one of the most efficient diagnostics techniques to determine the electron density in a...

A review of the models used for the calculation of the Stark broadening spectrum for plasmas is presented. The aim is to provide an overview of the related theories using a simple formalism, useful for an introduction to the study of this phenomenon, which is encountered in plasma diagnostics. A historical development is followed and some of the pr...

Modeling the Stark broadening of spectral lines in plasmas is a complex problem. The problem has a long history, since it plays a crucial role in the interpretation of the observed spectral lines in laboratories and astrophysical plasmas. One difficulty is the characterization of the emitter’s environment. Although several models have been proposed...

Spectral line shapes of neutral helium 3889 Å(23S–33P) transition line are calculated by using several theoretical methods. The electronic contribution to the line broadening is calculated from quantum statistical many-particle theory by using thermodynamic Green's function, including dynamic screening of the electron-atom interaction. The ionic co...

In the framework of the Spectral Line Shapes in Plasmas Code Comparison Workshop (SLSP), large discrepancies appeared between the different approaches to account for ion motion effects in spectral line shape calculations. For a better understanding of these effects, in the second edition of the SLSP in August, 2013, two cases were dedicated to the...

In this work, we briefly summarize the theoretical aspects of isolated line broadening. We present and discuss test run comparisons from different participating lineshape codes for the 2s-2p transition for LiI, B III and NV.

We present the results of an experimental study of the He I 492.1 nm line with forbidden components emitted by low-electron temperature high electron number density plasma. The laser interferometry at 632.8 nm and shape of the He I 447.1 nm line were used to measure electron number density in the range (1 – 7) x 10 23 m-3 , while electron temperatu...

Context. The Stark broadening of the spectral lines of the wavelengths 501.6, 667.8, 728.1, 388.9, 587.6, and 706.5 nm from neutral helium in plasmas are studied theoretically and experimentally. Aims: The aim of this work is to provide information about the connection between the shape and width of spectral lines and the electron density and tempe...

The emitting ions and atoms in a plasma are under strong local electric fields created by the other particles in the plasma and thus the emission process is altered, giving rise to the widely known Stark effect. Due to the fact that this phenomenon depends strongly on the density of charged particles in the plasma and on the temperature, the study...

The tables contain the area normalized Stark broadened spectral profiles of the HeI 492.2nm line. Doppler effect has not been included in the profiles. The first column of each table is the wavelength detuning, measured in nanometers, from the unperturbed wavelength. The other columns give the spectral profiles for different cases of perturber mas...

We present a study of statistical static and dynamic properties of local electric fields in moderately coupled hydrogen plasmas. In this regime new molecular dynamics simulations of neutral hydrogen, protons and electrons are now well controlled. They provide new insight into the statistical properties of the microfield. Taking advantage of such ca...

The Silences of the Archives, the Reknown of the Story. The Martin Guerre affair has been told many times since Jean de Coras and Guillaume Lesueur published their stories in 1561. It is in many ways a perfect intrigue with uncanny resemblance, persuasive deception and a surprizing end when the two Martin stood face to face, memory to memory, befor...

The broadening of the He I 447.1 nm line and its forbidden components in plasmas is studied using computer simulation techniques and the results are compared with our and other experiments. In these calculations wide ranges of electron densities and temperatures are considered. Experimental measurements are performed with a high electron density pu...

Research lines of the Plasma Spectroscopy Group at the University of Valladolid are presented in this work. The first one is devoted to atomic parameters determination, the second to laser spectroscopy, and the third is calculation and spectral analysis by computer simulation.

The broadening of the HeI 447.1 nm line in plasmas has been studied using computer simulations and the results compared with our and previous experiments. Wide ranges of electron density and temperature were considered in the simulations. Different plasma compositions as well as plasmas with different electronic and gas temperatures were also taken...

An experimental study on the asymmetry of the Balmer Hβprofile in plasmas produced by microwaves at atmospheric pressure is presented. The study is based on the definition of several functions and parameters that quantify the asymmetry and different shape aspects of the profile. The study shows the experimental dependence of these characteristics o...

The results of an experimental study of the He I 447.1 nm line and its forbidden component at high electron number density are presented and compared with profiles calculated using computer simulation method. Michelson interferometer at 632.8 nm was used to measure plasma electron number density in the range (1–7) × 1023 m− 3 while electron tempera...

In this paper the results of an experimental study of the He I 447.1 nm line and its forbidden component at high electron number density are presented and compared with profiles calculated using computer simulation method. Michelson interferometer at 632.8 nm was used to measure plasma electron number density in the range (1 - 7) x 10^23 m-3 while...

This paper presents a study on the asymmetry of the Balmer H(beta) profile in plasmas produced by microwaves at high pressure with the help of some functions of asymmetry for the whole profile, as well as by means of some specific parameters characterizing only its central dip. The study shows how this asymmetry--very low in our case--depends on th...

Ion dynamics is revisited in the presence of a magnetic field. This problem is of interest for the characterization of the ITER divertor plasmas, where Zeeman-Stark line shapes are both a diagnostic tool and an ingredient in the transport codes used for radiative transfer simulations. Comparisons between ab initio simulations of Zeeman-Stark profil...

Context: Stark broadening of the 447.1 line of neutral helium in a weakly coupled plasma has been studied. This spectral line has a very close forbidden component. This means it is very sensitive to the plasma electron density, which is similar to hydrogen lines, for which the Stark effect is linear. Aims: The aim of this work is to supply informat...

Computer simulations permit one to calculate Stark broadened profiles for non-equilibrium plasma conditions. In this work, the dependences of some line parameters on the unbalance between electrons and ions temperatures in the plasma are shown. This method can be applied in some cases to analyze experimental conditions by comparing experimental and...

In this talk a short description of line profile calculations will be given. Several calculation models will very briefly reviewed, and a special attention will be paid to computer simulations. Finally, different results of line profiles obtained using computer simulations will be shown, together with several applications in plasma diagnostics.

Tables contain the are anormalized Stark broadened spectral profiles of the He I 447.1nm line. Doppler effect has not been included in the profiles. For a fixed electron density, ranging from 10+21m-3 to 10+24m-3, data corresponding to three different reduced masses of the emitter perturber pair, {mu}, are given. The values of mu are {mu}=0.8, 2.0...

Experimental measurements of the center of the H-beta Stark profile on three different installations have been done to study its asymmetry in wide ranges of electron density, temperature, and plasma conditions. Theoretical calculations for the analysis of experimental results have been performed using the standard theory and computer simulations an...

An experimental study on the asymmetry of the Balmer Hbeta profile in plasmas produced by microwaves at atmospheric pressure is presented. The asymmetry of the whole profile is studied with the help of one function that quantified this characteristic. The asymmetry and shape of the central valley is also studied with the definition of several param...

The hydrogen Balmer beta line is used as a plasma diagnostics tool for a long time. It is well known that the experimental profiles of Hbeta line exhibit an asymmetry while some of most commonly used theoretical models, due to the employed approximations, give unshifted and symmetrical profiles [1, 2]. In the present work the central part of Hbeta...

Absorption and fluorescence excitation spectra of Xe/CF4 mixtures in the Vac UV region display numerous bands coinciding with energies of the Xe atom states increased by the energy of one v3 vibrational quantum of CF4. Satellites of the resonance and dipole-forbidden states are essentially differ in spectral shape and intensity implying different i...

An experimental study on the asymmetry of the Balmer Hβ profile in plasmas produced by microwaves at atmospheric pressure is presented. The study is based on the definition of several functions that quantify the asymmetry aspects of the profile. Apart from the asymmetry aspects of the flanks also form-functions are defined that characterize the cen...

One of the most commonly used methods to do plasma diagnosis is the analysis of the Stark broadened line profiles emitted by the atoms or ions in the plasma. The shapes of these lines strongly depend on the density of charges in the plasma. This permits to use some the line characteristics, as its width at half maximum, as a diagnostic tool to obta...

The study of the local stochastic electric fields at neutral or charged points in an homogeneous infinite plasma is of interest for several domains. For instance they can be used as external perturbations within semiclassical models designed to synthesize line spectra for diagnostic purposes [1, 2, 3, 4]. This work addresses the simpler problem of...

The hydrogen Balmer beta line is used as a plasma diagnostics tool for a long time. It is well known that the experimental profiles of Hβ line exhibit an asymmetry while some of most commonly used theoretical models, due to the employed approximations, give unshifted and symmetrical profiles [1, 2]. In the present work the central part of Hβ profil...

The statistical properties of local electric fields in an classical plasma are investigated by molecular dynamics (MD) simulation. Two‐component plasma simulations of neutral hydrogen, protons and electrons for intermediate plasma coupling conditions, typically Ne ≈ 1018cm−3,Te ≈ 1eV, have been carried out. These simulations appear as a possible an...

The modeling of edge plasma of present and future magnetic confinement devices requires the knowledge of accurate line shapes. For instance, spectroscopic diagnostics using detailed line profiles may be used for obtaining the main plasma parameters. Detailed lines shapes also enter in the study of the radiation transfer in the divertor plasma by us...

The aim of this work is the investigation of the statistical properties of local electric fields in an ion-electron two component plasmas for coupled conditions. The stochastic fields at a charged or at a neutral point in plasmas involve both slow and fast fluctuation characteristics. The statistical study of these local fields based on a direct ti...

In this note we want to clarify the applicability of the SO(4) symmetry of the hydrogen atom for the calculation of line broadening for emitters in a plasma with magnetic fields.

Aims:Recent measurements on the Stark broadening of radio recombination lines show values and trends in disagreement with conventional theories. Different attemps to explain those disagreements have not been successfull for any of the employed theoretical models. In particular, the impact model that describes well the physical conditions at which t...

A study of hydrogen lines emitted in warm (Te∼1eV) and dense (Ne≥1018cm−3) plasmas is presented. Under such plasma conditions, the electronic and the ionic contributions to the line width are comparable, and the general question related to a transition from impact to quasi-static broadening arises not only for the far wings but also for the core of...

Direct integration of the semi‐classical evolution equation based on Molecular Dynamics simulations (MD) and the Frequency Fluctuation Model (FFM) have long been used to synthesize spectra accounting for ion dynamics. Cross comparisons of these approaches generally show results in good agreement. Recently, interest in low temperature (Te ∼ 1eV) and...

A comparison between computer simulated Balmer lines and recent experimental profiles is shown in this work. The influence of different effets on the calculated profiles is discussed. Though several points must still be clarified a little deeper, the agreement between experimental and calculated profiles guarantees a good understanding of the relev...

The influence of electron temperature in the broadening of spectral lines dominated by strong collisions has been studied. Computer simulation allows us to study the effects of strong and weak collisions separately. Results shown here are focused on some Sr+ and Ba+ resonance lines as examples of lines broadened dominantly by strong collisions. The...

We report results of the Stark broadening calculations for Sr+ and Ba+ resonance lines in ultracold plasmas using semiempirical formulas and numerical computer simulation technique. The simulation results show that strong collisions dominate Stark broadening at very low electron temperatures and weak collision approximation used recently by Vrincea...

Studies of charge-charge (ion-ion, ion-electron, and electron-electron) coupling properties for ion impurities in an electron gas are carried out on the basis of a regularized electron-ion potential without short-range Coulomb divergence. This work is motivated, in part, by questions arising from recent spectroscopic measurements revealing discrepa...

The computer simulated Stark broadened spectral line profiles in a plasma which are useful for plasma diagnostics were analyzed. Computer simulation techniques for wide ranges of plasma electron density, electron temperatures and plasma compositions were used to obtain the spectral line profiles. The total electric field suffered by the emitter due...

Electron broadening for ion emitters is investigated with a molecular dynamics based spectral line shape simulation. A regularized Coulomb potential that removes the divergence at short distances is used for the ion–electron interaction. The method presented here allows one to account for all the correlations between charged particles, which is in...

Balmer-alpha, -beta and -gamma lines have been calculated using computer simulations including ion dynamics effects for equilibrium and non-equilibrium conditions. The results obtained allow us to supply diagnostic maps based on the widths of those lines, as well as the Stark broadened full line profiles and the dipolar correlation functions obtain...

The ion-electron coupling properties for a ion impurity in an electron gas and for a two component plasma are carried out on the basis of a regularized electron-ion potential removing the short-range Coulomb divergence. This work is largely motivated by the study of radiator dipole relaxation in plasmas which makes a real link between models and ex...

A program for the determination of plasma electron number density, 1020≤(Ne)≤1023 m-3, from the comparison of experimental and theoretical hydrogen Balmer beta (Hβ) line profiles is described in detail. Three theoretical data sets (one set is calculated within the framework of this paper) are included with the program and may be selected as a user'...

Electron broadening for ions in plasmas is investigated in the framework of a simplified semi‐classical model involving an ionic emitter imbedded in an electron gas. A regularized Coulomb potential that removes the divergence at short distances is postulated for the ion‐electron interaction. Line shape simulations based on Molecular Dynamics for th...

We present a general review of computer simulation methods used in spectral line shape calculations, in particular for hydrogen dipolar transitions (one photon) and two-photon polarization profiles. We describe the characteristics and the requirements that the simulation techniques must satisfy and we cite the main results obtained. © 2001 American...

The purpose of this work is to show a suitable plasma source and experimental arrangement for high accuracy measurement of atomic parameters developed in the Optics Department of Valladolid University. It is important to remark the careful plasma diagnostics procedures followed, and as an example we present a NII emission experiment where a very ex...

Computer simulation techniques have been employed to calculate hydrogen Balmer-alpha Stark broadened profiles over an electron density range between 1018 m-3 and 4.6.1022 m-3. Fine structure effects have been taken into account because of the low perturber densities considered. These calculations have allowed us to compile tables of the Balmer-alph...

In this work, the scope of the hypothesis of the physical and statistical independence between ionic (slow variation) and electronic (fast variation) microfields applied to spectral lines calculation in plasmas is analyzed. This hypothesis is used in some spectral profiles calculation methods. This analysis has been done by computer simulation.

This paper shows the results of calculations, obtained by computer simulation, of the Stark broadening of the dipolar Lyman$-\alpha$ line of hydrogen considering fine structure, of two–photon absorption profiles for the transition 1S$\to$2S of hydrogen and of the profiles that could be obtained using two–photon polarization spectroscopy techniques...

Computer simulation techniques have been used to calculate the Stark broadening profiles of the hydrogen dipolar Lyman-alpha transition and of two-photon absorption, dispersion and polarization profiles in the 1S->2S transition. The calculations have considered electron densities in the range between 4.64*1019(m-3) and 1*1023(m-3), and temperatures...

This work reports an extensive collection of 108 transition probabilities of NII lines in the visible spectral region, all of them measured in an emission experiment. Relative intensity measurements have been made on a pulsed discharge lamp and the absolute $A_{ki}$ values have been obtained by using the literature available data. Electron density...

This work reports information about Stark broadening and shift parameters of a very extensive collection of visible singly ionized nitrogen lines. All of them were measured in a linear discharge lamp from a mixture of nitrogen and helium. Electron density and temperature range in this experiment from 0.2 to 1.1 × 1023 m-3 and from 17 000 to 29 000...

This work reports information about the temporal evolution of theexcitation equilibrium departure in a high current pulsed arc.An argon plasma has been created in a linear lamp by discharging a capacitorbank on its electrodes. Spatially and temporally-resolved measurementshave allowed us to determine electron density Ne and excitation temperatureT...

In this article we present the different groups of investigation which work at the Department of Optics and Applied Physics of the University of Valladolid (Spain). The areas covered by these groups are the following: (1) optical diagnostic techniques in plasmas, (2) calculation of spectral line shapes, (3) atmospheric optics, (4) radiometry and ph...

This work reports information about the temporal evolution of the equilibrium departure in a high current pulsed arc. An argon plasma has been created in a linear lamp by discharging a capacitor bank on its electrodes. Very careful diagnostics techniques have allowed us to determine electron density Ne (2.0 - 9.5 X 1022 m-3) and ArII excitation tem...

Hydrogen lines of low principal quantum number have been recently measured for high densities and low temperatures. For such conditions, the use of a binary collision electronic impact operator is shown to overestimate the width of the line.

A set of tables of the Stark width of the first three lines of Lyman and Balmer series of hydrogen, useful for plasma diagnosis purposes, is presented in this work. These tables have been obtained by means of a fully recognized computer simulation technique. Computer experiments have been carried out for density values between and . Simulation temp...