Calculation of Plasmas with Relativistic Collisional Radiative Average Atom Code ATMED CR

Calculation of Plasmas with Relativistic Collisional Radiative Average Atom Code ATMED CR

The paper illustrates the computational capability of the collisional-radiative model ATMED CR for calculating the temporal evolution of accurate atomic populations including nlj-splitting, mean charge and atomic processes rates. The present work contains computed time-dependent plasmas with the average atom code ATMED CR of neon and aluminium created with X-ray Free Electron Lasers proposed in the 10th Non-LTE Code Comparison Workshop. The results for plasma properties can be considered as very precise, according to the electronic temperature profiles registered in experiments of laser-created plasmas with duration times of picoseconds and femtoseconds. As a consequence, the Crank-Nicholson implicit numerical iterative temporal module of ATMED CR can be considered a new rapid method for simulating this type of plasmas, avoiding some of the typical difficulties that appear in interpreting results of free electron laser experiments, as very different temporal scales in NLTE regime, enormous matrices of detailed collisional radiative codes, etc. In this paper, it is also presented a representative sample of steady state iron plasmas focusing the attention on two issues. First, the huge computation capability extension up to millions of plasmas with the implementation of a collisional radiative balance in the relativistic average atom model ATMED. Second, it will be addressed the good agreement of atomic and radiative properties not only with respect to very recent experimental measurements of laboratories and High Energy Density facilities, but also to the last theoretical developments in quantum mechanics of statistical methods, as new codes based on the self consistent Hartree-Fock-Slater model for the average atom which in turn solve the Schrödinger’s or Dirac’s equations of radial wave functions. The new codes have been validated with some state of the art models as OPAL, SCO-RCG, STA, CASSANDRA, LEDCOP, THERMOS, etc. The results for plasma properties can be considered as relatively precise and optimal, being checked fundamentally the high sensitivity of calculations to changes in regime, local thermodynamic equilibrium (LTE) or non-LTE (NLTE), electronic and radiation temperatures, dilution factor, matter or electronic density and plasma length. The systematic theoretical investigation is carried out through comparison of calculations performed with a wide set of atomic collisional radiative codes with detailed configurations or codes of the average atom formalism. Some transmissions computed with ATMED CR using UTA (Unresolved Transition Array) formalism are also checked with respect to very recent experimental measurements of laboratories.

Read full article: http://bp.bookpi.org/index.php/bpi/catalog/view/19/21/142-1

Editor

leave a comment

Create Account



Log In Your Account