Numerical investigation on the heat deposition characteristics of femtosecond laser pulses undergoing multiple filaments

Abstract In this study, the heat deposition characteristics of laser filaments formed by femtosecond laser pulses with different initial energy under influences of external focusing are numerically investigated by means of (3 D + 1)-dimensional numerical simulations. The results indicate that the numbers and intensity of filaments increase with growth of the input energy. The formation of multiple filaments limits the increase of filament length. When fixing the input energy, radius of the filament becomes narrow while its numbers and intensity are both enhanced under strong focusing. Under stronger focusing, the filaments can also deposit higher laser energy and result in larger energy deposition rate for laser beams with a given input energy, which further leads to dramatic increase in local temperature and pressure. These are likely to affect the filament induced airflow velocity and eventually the mass of formed snow in the cold supersaturated cloud chamber.