Numerical simulation of plasma implosion under radiative heating of the inlet hole walls of hohlraum target

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Caractérisation de jets d'agrégats d'argon pour l'étude de l'interaction laser-agrégats

Argon clusters jets were produced at the output of supersonic nozzles and used as targets for intense laser - clusters interaction experiments. They were fully characterized combining two optical diagnostics (Mach-Zehnder interferometry and Rayleigh Scattering) with the support of a numerical simulation. This study was performed with Laval and conical nozzles. Homogeneous clusters size profiles were observed at the output of the conical nozzle. Clusters mean radius was measured in the range from 200 to 300 Å, increasing with the input Argon pressure varying from 20 to 60 bars

Coupled magnetogasdynamics: Radiative transfer computing using unstructured meshes

We present a new object-oriented radiative-magnetogasdynamics (RMHD) code based on unstructured grid technology which is expected to be a convenient tool for investigations of plasma dynamics in various pulsed-power facilities. High-performance computing is a proper tool for simulations of complex multiscale nonlinear processes like transient flows of strongly radiative multicharged plasmas. The first tests of this new code have showed promising results. The code performs calculations in (r-z) and (x-y) coordinates. We accept a single-fluid MHD model [1]. The MHD-equations are written in a 2.5D approximation, i.e. the main flowfield vectors are presented by all three components. Anisotropy of dissipative processes in the presence of magnetic field is accounted. The electron-ion energy relaxation is included. Radiative energy transfer is described by the equation for spectral radiation intensity. To overcome the inhomogeneity of magnetically-driven plasmas we solve the radiative transport equation by means of semi-analytical characteristic algorithm. An additional grid of rays is necessary for its implementation. A modified FE-DSN-method [2] as well as the method based on the adjoint radiative transfer problem solution [3] are also developed and put into practice. The radiative energy transfer is calculated via multigroup spectral approximation. For practical applications the datatables of plasma properties as to thermodynamics, ionisation state, opacities and emissivities are used. The MHD equations written as conservation laws are discretized by means of a finite-volume method. The set of finite volumes is built for basic unstructured triangular mesh. All the physical variables are located in the triangular grid nodes. A splitting scheme is applied to the full MHD system. The procedure of time-advance is an explicit second-order predictor-corrector. A general monotonous reconstruction of mesh-defined functions was designed with respect to the dependence on two variables and a generalized quasi-monotonous Lax-Friedrichs-Tadmor scheme was developed [4]. The explicit difference scheme allows quite natural parallel implementation for distributed computer systems. A technique of margins was suggested for data exchange between subdomains with unstructured grids located at different processors. The designed code was applied to simulations of a dense strongly radiative Z-pinches formed of an exploded multiwire array. Comparisons with experimental data obtained in Sandia National Laboratory (USA) are presented

The Numerical Modelling of Stressed-Strained States for Medium with Strained Depended Elastic Parameters.

Abstract: Some models of medium (rocks) with strained depended elastic parameters are de-scribed. Two-dimensional finite element code for elastic stress analysis is presented. The results of numerical computations are discussed.Note: Research direction:Mathematical modelling in actual problems of science and technic

Stable algorithm for matching the fluxes of momentum and kinetic energy during remeshing

Abstract: The paper describes a numerical method for solving a non-linear system of equations used in the technique of matching the fluxes of mass and momentum in the remeshing procedure. The quadratic convergence of the algorithm on the kinetic energy balance is analytically shown and demonstrated on the model example.Note: Research direction:Mathematical problems and theory of numerical method