Pic Simulations Of Ultrashort Pulse Laser Solid Target Interactions PDF Download

The precision and reproducibility of ultrashort pulse laser damage makes it amenable to a wide variety of applications, with a temporal separation between laser incidence and ablation of material resulting in a clean damage pattern that minimally affects the surrounding area. Additionally, as increasingly intense laser systems continue to be developed, the prevention or mitigation of laser damage becomes increasingly important. A number of numerical techniques have been developed for studying the dynamical processes involved, but each typically sacrifices either resolution on the atomic scale or the ability to model processes on the spatial scale of the laser. This work utilizes an ultrashort pulse laser damage algorithm built upon the framework of the particle-in-cell (PIC) method which is capable of resolving the complete damage process from laser incidence on the femtosecond scale to ablation and resolidification on the nanosecond scale. Moreover, it is capable of resolving the entire laser affected area while still capturing physics on the few nanometer scale. To prepare this algorithm for accurate application to real metals, I first modify a well established particle collision algorithm that kinetically evaluates short range deflections, enabling a PIC based laser target interaction to capture established material properties like absorption and skin depth without sacrificing the ability to model nonthermal velocity distributions and ballistic particles. With this advancement, the algorithm as a whole is validated by directly comparing copper craters experimentally produced over a range of fluences against craters produced via simulation with the same laser parameters. With experimental confirmation, the algorithm is then refined and expanded to allow better handling of physics like the quantum statistics affecting electron behavior during the laser target interaction and the influence of temperature on the nature of particle-particle interactions governing the ablation process. These advancements are then used to study the phenomena of laser induced periodic surface structure and the formation of transient warm dense matter produced by an ultrashort pulse on aluminum. Finally, I extend the applicability of the laser-target interaction portion of the algorithm to dielectrics by incorporating into it photoionization and impact ionization models appropriate for solid density materials. I then analyze the dynamics of these ionization processes in Zinc Selenide for pulses in the near-mid infrared regime.