Dynamics of an air breakdown plasma on a solid surface during picosecond laser ablation

摘要: Using picosecond time-resolved shadowgrams and interferograms, we measured the lateral expansion of an early stage ablation plasma induced by a 1064 nm, 35 ps laser pulse on copper target. The was found to have electron density order 1020 cm−3 near target surface. Prior expanding material vapor plume, this high originates from breakdown air, assisted laser-induced emission longitudinal suppressed due development strong space-charge region. At postpulse times, relation r∼t1/2 for temporal radius plasma. Measurements energy absorption provide interpretation experimentally reduction in efficiency as fluence increases beyond approximately 100 J/cm2.