Modelling of spectral properties and population kinetics studies of inertial fusión and laboratory astrophysical plasmas
Abstract: 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.
Summary (2 min read)
- The authors will focus on some of the latest advances and results of their research, with emphasis on ICF and, also, laboratory-astrophysical applications.
- In the following section the authors briefly describe the most recently developed models and codes, i.e. ABAKO/RAPCAL [3, 4] and ATMED  .
- ABAKO/RAPCAL was designed to perform detailed atomic kinetics and radiative properties calculations over a wide range of temperature and density, including the coronal, LTE and non-LTE regimes.
- Meanwhile, the new averageatom screened hydrogenic model, ATMED, was aimed for providing fast estimates and potential in-line hydrodynamical calculations of emissivities and opacities for plasmas under LTE conditions.
- In the first one, connected to laboratory astrophysics, radiative properties calculated from RAPCAL are used to characterize the radiative blast waves launched in xenon clusters.
2. ABAKO/RAPCAL and ATMED computational packages
- Furthermore, the ATMED code was aimed for providing fast calculations of the photon energy dependent opacity as well as the Rosseland and Planck mean opacities for single element and mixture hot dense plasmas under LTE.
- Typical ATMED running times are of the order of seconds.
- The needed atomic data are computed using a relativistic screened hydrogenic model based on a new set of universal screening constants including j-splitting  .
- The opacity calculations take into account the bound-bound, bound-free, free-free contributions, as well as scattering processes.
- Line shapes include natural, Doppler and electron collisional Frequency-dependent opacity for a Be(99.1%)-Cu(0.9%) plasma mixture at 250 eV and 0.1 g cirT 3 .
3. An application to laboratory-astrophysical plasmas: characterizing radiative blast waves created in the laboratory
- Measurements indicate that blast waves in clustered xenon reached the needed conditions to enter the radiative flux regime-defined as the situation in which the radiative energy flux is greater than the material energy flux, thus playing an important role in the evolution of the blast wave.
- The results discussed so far were obtained assuming steady state.
- Therefore, for them to be meaningful, the validity of this assumption for the case of study must be checked and possible time-dependent effects discarded.
- An accurate study would require full time-dependent calculations.
4. An application to ICF plasmas: spectroscopic diagnosis of shock-ignition implosions
- Fitting the observed spectrum by means of a weighted least-squares minimization procedure yields both core and shell temperature and density conditions.
- Details of this procedure and comparisons with hydro-simulations and experimental data can be found in  .
- Uncertainties in the parameters were determined from a confidence interval statistical study that takes into account the correlations between model parameters  .
- Furthermore, the spectroscopic analysis also provides an estimate of pR = 0.17 ± 20%gcirr 2 for the target's areal density at the collapse of the implosion, which is consistent consistent with the results of early experiments based on particle diagnostics  .
- Fundamental research and modelling in plasma atomic physics play an important role to understand different phenomena in a wide variety of laboratory and astrophysical plasmas.
- The codes and models developed by the Atomic Physics Group at the Institute of Nuclear Fusion combine accuracy and celerity in a proper balance and can be a valid tool to design and/or interpret experiments.
- As illustration, the authors discuss the use of the ABAKO/RAPCAL computational package, first, for the characterization of radiative blast waves launched in xenon clusters and, second, as part of the physical model for the spectroscopic diagnosis of shockignition implosions.
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