Near-Surface Plasma Formed by Dual-Pulse Laser Action at Two Wavelengths on Titanium in Air

摘要： Spectra and structures of near-surface plasma torches were studied experimentally by measuring the speci? c mass loss and plume luminosity caused by dual-pulse laser radiation at wavelengths 1064 and 532 nm on titanium in air as functions of the time between laser pulses and their sequence. Dependences of the laser-plasma temperature and concentration of charged particles on the paired laser pulse parameters were established at laser radiation power densities q1064 ≤ 3.1·109 and q532 ≤ 2.7·109 W/cm2 for λ = 1064 and 532 nm. The optimal conditions for recording erosion plasma spectra had the initial effect from second-harmonic radiation with a time interval between pulses of 4–5 μs; for speci? c mass loss, 3–6 μs. The results were important for enhancing the ef? ciency of laser emission spectral analysis and laser-plasma processing of materials.