[Spatial profile of radiation from the plasma induced by laser-ablated aluminum]

The plasma was acquired with a pulsed Nd:YAG laser beam ablating aluminum. The pulse energy was set up to 145 mJ per pulse. Ar was used as surrounding gas with the pressure of 100 kPa. The radiation of the plasma was recorded with time- and space-resolved technique, so we obtained time-resolved, in 10(-9) s, spectra of the plasma radiation in front of the surface at 0.5 mm, 1.5 mm, 2.5 mm and 3.5 mm, respectively. Based on the spectra, we briefly discussed the characteristics of the plasma radiation in each zone, and studied the behavior of the continuum and aluminum radiation in detail, so the spatial profile of the plasma was obtained. As we found, at the beginning of the plasma coming into being, the radiation of the plasma was dominated by continuum radiation, but aluminum radiation became dominant later. Characteristic and ion radiation was much weaker than continuum radiation. The aluminum radiation lasted much longer than continuum and ion radiation. As a result, it was suggested that the absorption of continuum radiation of plasma by aluminum atoms should be the main mechanism for the formation of the aluminum double lines and the broad absorbtion spectra.