Generation of electron – positron pairs by laser-ion implosion of a target with a spherical microbubble inside

Laser targets with microbubbless have recently been intensely studied, including with the aim of generating superintense electromagnetic fields. Under the action of laser radiation, ion beams are formed in the target, converging to the centre of the microbubbles. In the central region, the ion density can be several times higher than the target density, leading to the generation of an extremely intense electric field and high-energy ions. Using PIC simulation, the dynamics of target electrons is investigated taking into account the effects of quantum electrodynamics (QED) and the development of a QED cascade in the intense field region. It is shown that an increase in the electron temperature leads to a much more efficient formation of electron – positron pairs. The contribution of bremsstrahlung to the generation of photons in the central region of the microbubbles is analysed. It is found that the contribution of bremsstrahlung is insignificant in comparison with the synchrotron mechanism of electron emission in the collective field of ions.