Laser-produced carbon plasma evolution and lifecycle

Summary form only given. Laser produced plasmas (LPPs) have been the focus of extensive basic research which have led to a diverse range of applications in many domains including extreme ultraviolet lithography, cellular microsurgery, laser-induced breakdown spectroscopy, nanocluster and nanotube production, laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICP-MS) etc.. Studies of LPPs have been necessary to understand the physical and chemical processes associated with the ablation of a target material and the hydrodynamic target response to the intense heating induced by nanosecond and femtosecond lasers. While numerous materials have been studied using various laser beams, carbon has received particular attention due to its applications in fullerene production, deposition of diamond-like thin films, and choice for the design of plasma facing components in magnetic and inertial fusion reactors. However, though much effort has been expended to characterize carbon plasmas with laser ablation through the investigation of emission spectra, a thorough understanding of the entire cycle of carbon produced plasmas is lacking. In this study we analyzed the entire lifecycle of laser-produced carbon plasma in vacuum using fast imaging employing fast gated intensified CCD camera and optical emission spectroscopic diagnostic tools. Plasmas are produced by heating graphite targets either using fundamental radiation from a Nd:YAG laser (1064 nm, 6 ns FWHM) or using a Ti Sapphire ultrafast laser (800 nm, 40 fs FWHM). Our results show that continuum emission dominates in the earliest time of plasma evolution. As time evolves, visible line emission dominates during the time window of 100 ns -5 μs. At later times, a Planckian-type emission is also observed caused by particle/cluster-like emission. Details of the carbon plasma lifecycles of both nanosecond and femtosecond laser-produced plasmas are studied and discussed.