After the multiphoton ionization of sodium-argon mixture, time-resolved atomic emission spectrum is used to experimentally study the unusual phenomenon of the obviously different broadening between Na D<sub>1</sub> and D<sub>2</sub> lines spectra. The primary reason for the unusual broadening of Na D<sub>2</sub> line is that the spectral line of Ar I 588.9 nm overlays with Na D<sub>2</sub> line (589.0 nm) after ionization, and the serious self-absorption on Na D<sub>2</sub> line is the secondary reason. Although there is difference of population between 3<sup>2</sup>P<sub>3/2</sub> and 3<sup>2</sup>P<sub>1/2</sub> states, the experiment result demonstrates that the difference between Na D lines in radiation channel will not affect the broadening of spectral profile.
The kinetic behaviors of 6p[1/2]<sub>0</sub>, 6p[3/2]<sub>2</sub> ,and 6p[5/2]<sub>2</sub> were examined under the ultrahigh pumped power. These processes were detected by the way of time-resolved fluorescence and ASE spectra. A theory of energy-pooling is presented under the focused condition. There are three types of energy-pooling processes. The first type is energy-pooling ionization. The obvious ionization can be observed whenever the laser prepared state is the 6p[1/2]<sub>0</sub>, 6p[3/2]<sub>2</sub>, or 6p[5/2]<sub>2</sub> state. The second type is energy-pooling with big energy difference. The energy-pooling collision between the two 6p[1/2]<sub>0</sub> atoms can produce one 5d[3/2]<sub>1</sub> atom and one 6s’[1/2]<sub>0</sub> atom when the prepared state is 6p[1/2]<sub>0</sub>. The third type is energy-pooling with small energy difference. The way of generation of five secondary 6p states is energy-pooling instead of collision relaxation.