Modeling of ultrafast laser ablation into vacuum

Laser-matter interaction is a very complicated phenomenon. There exist three principal regimes for laser pulses, namely long, short, and ultrashort pulse lasers. In the ultrashort regime, the target material is ionized more rapidly than the thermal relaxation time, and the material is ablated without signi.cant transfer of heat to the surrounding lattice. The absence of heat transfer to the surrounding lattice provides important advantages to micromachining: reducing both the material property change due to heating and slag deposition. To further understand the ablation process, a solver using the Space-Time Conservation Element Solution Element (CE/SE) Method is used to describe the material removal based on a gas dynamics model. The model uses a coordinate transformation with an immobilized boundary, .xing the size of the computational domain in time. The expanding computational domain facilitates the use of vacuum boundary conditions. The immobilized boundary is used to explore the expansion the ionized gas into a vacuum. In addition, exploration of the equation of state highlights some shortfalls and errors that require future attention.