Vacuum Breakdown in Multibeam Configuration of a Magnetic Dipole Wave

In this work we investigate vacuum breakdown in multipetawatt laser fields of the multibeam configuration corresponding to a converging magnetic dipole wave. Three-dimensional numerical simulation via the particle-in-cell method was used to determine the threshold total laser radiation power required for vacuum breakdown depending on the number of laser beams. It is shown that the minimal vacuum breakdown threshold power of 14 PW is attained when there are 12 beams while for a lower number of beams (from two to six) the threshold increases to 18 PW. The dependence of the growth rate of the quantum-electrodynamic cascade on the number of laser beams is determined in a wide range of total radiation power. Fluctuations in the power of each of the beams are shown to have little effect on both the breakdown threshold and the cascade growth rate.