Expansion Dynamics of a Laser Produced Zn Plasma: Short-Pulse and Ultrafast Excitations

Abstract

The hydrodynamical characteristics of ultrafast (100 fs) and short-pulse (7 ns) laser produced plasmas (LPP) generated by ablating a Zinc target, for a background pressure of 100 Torr Nitrogen, are reported. Velocities of the plume front indicate a deceleration in both the femtosecond and nanosecond excitation domains, where the plume velocity decreases exponentially with time. Plume aspect ratios indicate that initially the nanosecond plasma plume expands more radially, then it expands more axially, and thereafter the radial and axial expansion rates become similar. On the other hand the femtosecond plasma plume expands preferably in the axial direction throughout its expansion. Results are analyzed and discussed in detail.