  In pulsed laser deposition, thin film growth is mediated by a laser-generated
plasma, whose properties are critical for controlling the film microstructure.
The advent of 2D materials has renewed the interest in how this ablation plasma
can be used to manipulate the growth and processing of atomically thin systems.
For such purpose, a quantitative understanding of the density, charge state,
and kinetic energy of plasma constituents is needed at the location where they
contribute to materials processes. Here we study laser-induced plasmas over
expansion distances of several centimeters from the ablation target, which is
the relevant length scale for materials growth and modification. The study is
enabled by a fast implementation of a laser ablation/plasma expansion model
using an adaptive Cartesian mesh solver. Simulation outcomes for KrF excimer
laser ablation of Cu are compared with Langmuir probe and optical emission
spectroscopy measurements. Simulation predictions for the plasma-shielding
threshold, the ionization state of species in the plasma, and the kinetic
energy of ions, are in good correspondence with experimental data. For laser
fluences of 1-4 J/cm$^2$, the plume is dominated by Cu$^0$, with small
concentrations of Cu$^{+}$ and electrons at the expansion front. Higher laser
fluences (e.g., 7 J/cm$^2$) lead to a Cu$^{+}$-rich plasma, with a fully
ionized leading edge where Cu$^{2+}$ is the dominant species. In both regimes,
simulations indicate the presence of a low-density, high-temperature plasma
expansion front with a high degree of ionization that may play a significant
role in doping, annealing, and kinetically-driven phase transformations in 2D
materials.
