Dual pulse laser generated plasma for controllable energy deposition

We study temporal dynamics of plasma generated by a combination of the low energy 800 nm femtosecond laser pulse and high energy nanosecond pulse of 1064 nm. A three-dimensional model is developed which includes multiphoton and tunneling ionization by the first pulse and three-temperature model for the second pulse, combined with the refractive index calculations and Navier-Stokes equations. A numerical study was conducted to examine different patterns formed by the laser pulses, energy exchange mechanisms and optimal pairing depending on spatial beam shaping. It was shown, that electron dynamics is controlled by the first seeded pulse and depends on the initial laser intensity profile. Analysis includes Gaussian and flat top laser intensity profiles.