Efficient laser acceleration of electrons and ions from targets with controlled preplasma

Compact sources of high-energy particles and secondary radiation based on the interaction of high-power laser pulses with plasma targets are of interest due to a possibility of their application in a wide range of practical problems. One of the ways to optimize such sources is related to the possibility of controlling the preplasma of a solid target by changing the density gradient of the expanding plasma plume on the irradiated side. The problem of accelerating charged particles by a short laser pulse from targets with a preplasma generated by a nanosecond prepulse (additional pulse) of different intensity and duration is considered. Using self-consistent hydrodynamic/kinetic simulation, the efficiency of electron acceleration is shown to depend not only on the gradient of the preplasma density profile, but also on the focusing point of the laser pulse on this profile.