Short laser pulses with relativistic intensity allow to efficiently accelerate electrons and ions of a plasma target to high energies, which opens up prospects for creating compact charged particle accelerators with a wide range of practical applications. In this case, the accumulated energy and the number of accelerated particles are determined not only by the laser pulse, but also by the parameters of the target, its structure and density. One of the ways to optimize such sources is associated with the possibility of controlling the plasma of a solid target by changing the plasma density gradient on the irradiated side.
Short laser pulses with relativistic intensity allow to efficiently accelerate electrons and ions of a plasma target to high energies, which opens up prospects for creating compact charged particle accelerators with a wide range of practical applications. In this case, the accumulated energy and the number of accelerated particles are determined not only by the laser pulse, but also by the parameters of the target, its structure and density. One of the ways to optimize such sources is associated with the possibility of controlling the plasma of a solid target by changing the plasma density gradient on the irradiated side.
In this work, we simulated the expansion of plasma under the action of an additional nanosecond laser pulse synchronized with the main pulse. The simulation was carried out using the hydrodynamic code FRONT, which solved a system of two-temperature hydrodynamics, including the equation of continuity and the equation of motion of plasma density, as well as equations for the internal energy of electrons and ions. The calculations were carried out in three-dimensional (cylindrical) geometry. The preplasm density profile can be roughly represented as the sum of two exponentials, one of which describes the plasma near the target, and the other describes the sub-critical plasma.
We examined the influence of target thickness and material, laser pulse duration and intensity on plasma formation. The calculations compared the results of target expansion for targets with a thickness of 6 microns, 10 microns and 30 microns at different laser pulse laser pulses with energies up to several millijoules. Aluminum, iron and tungsten were investigated as target materials.
The results of hydrodynamic modeling allowed to take into account the formation of preplasma on the front side of the target in kinetic modeling. Using the kinetic code VSim, calculations were made on particle acceleration and optimal parameters of preplasma were found. This allows to increase the efficiency of particle acceleration.
The work was carried out with the support of the Russian Science Foundation (Grant No 24-22-00119)

preplasma,laser acceleration of ions,laser acceleration of elecrtons