@article{25198,
  keywords = {Model, Target, Measurements, Measurement, USA, Surface, Emission, Pulse, Velocity, Experimental, Algorithm, Interferometry, Material, Ablation, Laser, Laser ablation, Laser ablation, Breakdown, Time-resolved, Time, Ca, E, Form, Plasma, Solids, Number, Pulses, Vapor, C, Metals, Ionization, Electron number densities, Plasmas, Picosecond, Picosecond laser, Picosecond laser ablation, Density, Pulsed laser, Pulsed laser, Targets, Electron, Electron number density, Number density, Order, Ha, Metal, Dynamics, Results, Expansion, Plume, Atmosphere, Physics, Air, Air breakdown, Electron emission, Electron-emission, Forms, Heat transfer, Laser plasma, Laser plasmas, Pulsed laser ablation (PLA), Pulsed laser ablation (PLA), Theoretical-model, Vapor plume},
  author = {Samuel S Mao and Xianglei Mao and Ralph Greif and Richard E Russo},
  title = {Initiation of an early-stage plasma during picosecond laser ablation of solids},
  abstract = {<p>Picosecond time-resolved images of plasma initiation were recorded during pulsed-laser ablation of metal targets in an air atmosphere. An early-stage plasma was observed to form before the release of a material vapor plume. Close to the target surface, interferometry measurements indicate that the early-stage plasma has an electron number density on the order of 10<sup>20</sup> cm<sup>-3</sup>. The longitudinal expansion of the ionization front for this plasma has a velocity 10<sup>9</sup> cm/s, during the laser pulse. In contrast, a material-vapor plume forms approximately 200 ps after the laser pulse, and it moves away from the target at 10<sup>6</sup> cm/s. The experimental observations of the early-stage plasma were simulated by using a theoretical model based on a two-fluids description of laser plasmas. The results indicate that the initiation of the plasma is due to air breakdown assisted by electron emission from the target.</p>},
  year = {2000},
  journal = {Applied Physics Letters},
  volume = {77},
  pages = {2464-2466},
  month = {10/2000},
  doi = {10.1063/1.1318239},
  language = {eng},
}