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

The laser produced carbon plasma expanding in vacuum (P${\text{<10}}^{\text{−3}}$ Torr) and low pressure ambient atmosphere (P${\text{<10}}^{\text{−2}}$ Torr and P${\text{=10}}^{\text{−1}}$ 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 2p${}^3$ ${}^3$ D${}^0$ –8f F $\text{(5/2)}$ at 399.7 nm, C II transition 3d ${}^2$ D–4f ${}^2$ F${}^0$ at 426.7 nm, and C III transition 3s ${}^3$ S–3p ${}^3$ P${}^0$ 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.