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The work is devoted to some problems in numerical modelling plasma generated in the course of magnetic implosion of multiwire arrays (liners) in Z-pinch discharge mode, including numerical and theoretical analysis of quasispherical imploding conical wire arrays. Experiments were performed at ANGARA-5-1 facility (TRINITI) with the discharge current up to 3 MA. The numerical simulations were carried out on the base of 2D RMHD code MARPLE (IMM RAS). An appropriate description of the early phase of plasma generation during the electrical explosion of wires is a real challenge in MHD modeling of these experiments, in our computations we used the plasma ablation model, which allows to obtain more realistic results as compared with the models where the entire wires are considered to be initially already in plasma state. According to the experimental data we assume that the wire skeleton is stable during the overall time of the plasma generation as its density is significantly more than that of the surrounding plasma. Besides that the skeleton carries essentially less electric current than the plasma. The plasma ablation process lasts until the total wire skeleton evaporation. Experiments show that in the case of current pulse matched load the plasma generation is finished soon after the current maximum. Taking into account small diameter of the wires as compared with interwire gaps and the array dimensions plasma production is simulated by a steady source surface placed inside the computational domain. The mass ablation rate at the unit of the source surface is calculated with respect to the local distribution of the magnetic field induction. The numerical experiments showed that the plasma ablation model has a significant effect on both the entire scheme of plasma dynamics and such values as voltage drop at the load and soft X-ray yield power. The improvement of the ablation model parameters based on experimental and theoretical estimations is an issue of the day in 2D and 3D Z-pinch simulations.

MHD numerical simulations are applied for multiparameter studies of quasi-spherical magnetic compression of plasma liners created by conical multiwire arrays electrical explosion at ANGARA-5-1 facility (TRINITI) with the discharge current 2 to 3 MA and the pulse rise time about 100 ns. The description of the plasma dynamics at different stages of implosion is reproduced as a result of simulation. Numerical and experimental time profiles of voltage drop at the load and soft X-ray yield power are compared. The effect of the geometry changes upon the implosion process is studied. Numerical simulation is based on 2D RMHD code MARPLE (IMM RAS) using unstructured triangular grids. The code implements one-fluid two-temperature MHD model, grid-characteristic method for radiative energy transfer and the model of prolonged plasma ablation to simulate plasma source. The governing MHD system of is completed by electrical equation for the full circuit including the generator itself, leading-in systems and the discharge chamber with the plasma in it. Equations of state, transport and kinetic coefficients, opacity and emissivity coefficients are taken from the tables. The behavior of the discharge is satisfactorily described in general by the above RMHD model. The plasma ablation model appeared to have a significant effect on both the entire scheme of plasma dynamics and such values as voltage drop at the load and soft X-ray yield power. The improvement of this model based on experimental and theoretical estimations is an issue of the day in 2D and 3D Z-pinch simulations. The MARPLE code calibrated against the conical liners simulations proved to be a useful tool for computations aimed to optimization of the experimental setup for 3D implosion of plasma.