In this work, we effectuated the numerical simulations of the phase dynamics of an array of Josephson junctions taking into account the capacitive coupling between the neighboring junctions and the diffusion current in the stack. We observed that, if we increase the coupling and the dissipation parameters, the IV characteristic changes qualitatively from the IV characteristics studied before. For currents greater than the critical one, we obtained an additional branch in the IV characteristics. This branch is characterized by a lower voltage than the outermost one. Moreover, we obtained an additional charging of the superconducting layers in the IV region for currents greater than the critical one. We studied the time evolution of this charging by the means of Fast Fourier Transform. We proved that the charge density wave associated with this charging has a complex spectral structure. In addition, we analyzed the behavior of the system for different boundary conditions, appropriate to different experimental setups.

In this article, we compare laser prepulse interactions with flat and periodic 1D grating aluminum targets. We describe the cases of normal and oblique radiation incidence. The choice of an appropriate radiation incidence angle and target geometry reduces back-reflection and increases the performance of laser-driven experiments due to more uniform target heating. We studied preplasma generation in front of the targets and described its temporal evolution for different angles of radiation incidence. The electron density has a symmetric periodic distribution in front of grating targets and an irregular distribution in front of flat targets. It varies from $0.3\times {10}^{22}{\mathrm{cm}}^{-3}$ to $3.5\times {10}^{22}{\mathrm{cm}}^{-3}$ for grating targets, and from $1\times {10}^{22}{\mathrm{cm}}^{-3}$ to $2.5\times {10}^{22}{\mathrm{cm}}^{-3}$ for flat targets. The generation of overcritical density regions occurs before the end of the prepulse stage. We developed a semi-analytical model based on the effective refractive index and Bloch wave approximation to describe changes in reflectivity during the simulations. During the preplasma expansion, the reflectivity varies from 0.1 to 0.8. The numerical simulation results align well with the analytically predicted behavior of the preplasma–target ensemble. Grating targets are more suitable for experiments compared with flat ones. The most convenient angle of radiation incidence is about 15°.