Studying and surveying proton acceleration in high power laser interaction with foam targets

Acceleration of high energy charged particles is one of the most important applications of high-power lasers interaction with plasma. Using targets with densities close to critical densities, because of better laser-plasma coupling, the transferred energy from the laser to plasma will be increased. Today, due to the construction of foam-structured targets, with a density close to critical density, it is possible to use such targets in order to study more about the acceleration process of particles with densities close to the critical density. In this paper, using particle simulation in a cell, a realistic form of foam structure of laser interaction with targets has been studied in more detail. The optimal state for porous foam in terms of dimensions and distances between holes is proposed based on the maximum energy of the protons produced after the laser pulse is completed and it is found out that for a foam with a density of 3.6 critical density and 16-micrometer length, the existence of holes with 0.5-micrometer radius and 1.5-micrometers for the distance between the centers can produce protons with 40 MeV energy but if the holes are not in proper conditions, protons’ maximum energy will be decreased about 20 percent relative to the condition without porous foam.