The Role of Sub-Target in the Transversely Excited Atmospheric Pressure CO₂ Laser-Induced Shock-Wave Plasma

A transversely excited atmospheric pressure (TEA) CO 2 laser pulse (50 mJ, 100 ns) was focused on silicon grease which is painted on a copper plate as a subtarget with a power density of 6 GW/cm 2 under reduced pressure. The comparison of the characteristics of the induced laser plasma between two cases, with subtarget and without subtarget was made. It is proved that the emission spectrum assigned to the silicon atom can be detected only for the case with the subtarget. It is also proved that in the absence of the subtarget, the gushing speed of the atom is very low, while for the case with subtarget, the gushing speed of atoms becomes very fast. It is shown that the setting of subtarget is very effective for producing laser-induced shock wave plasma and it is very effective for the realize quantitative analysis of a soft material.