Metallic surface temperature at the very beginning of the laser-induced breakdown obtained from black-body radiation.

ABSTRACT

We present experimental results of cooper surface temperature measured nanosecond by nanosecond at the very beginning of the laser-induced breakdown experiment. The experiment is conducted by NdYAG laser for three irradiances 1.4×10^{9}, 3.2×10^{11}, and 3.7×10^{12} W/cm^{2}. The temperatures of the metal surface, before plasma is created, are in the interval 7 400-11 200 K. These values are close to most estimates for the critical temperature of copper. The moment when plasma was created is recognized applying a bifurcated optical cable. After creation, temperature of the plasma increases attaining values over 50 000 K. All temperatures are derived relying on continuous spectra emitted from the bright spot illuminated by the laser.