Dynamics of laser produced carbon plasma expanding in low pressure ambient atmosphere

The laser produced carbon plasma expanding in vacuum (P<10−3 Torr) and low pressure ambient atmosphere (P<10−2 Torr and P=10−1 Torr) has been studied by emission spectroscopy and fast photography using intensified charged coupled device (ICCD). The double peak structure is observed in the temporal profile of C I transition 2p3 D30−8f F(5/2) at 399.7 nm, C II transition 3d D2−4fF20 at 426.7 nm, and C III transition 3s S2−3pP20 at 465.0 nm as the plasma expands in ambient atmosphere. The stratification of the plasma into slow and fast components is imaged using ICCD. A compression wave model is proposed to explain the occurrence of a double peak structure.