DYNAMICS OF LASER-PRODUCED CARBON PLASMA EXPANDING IN LOW-PRESSURE AMBIENT ATMOSPHERE

The laser produced carbon plasma expanding in vacuum (P<10(-3) Torr) a nd low pressure ambient atmosphere (P<10(-2) Torr and P=10(-1) Torr) h as been studied by emission spectroscopy and fast photography using in tensified charged coupled device (ICCD). The double peak structure is observed in the temporal profile of C I transition 2p(3) D-3(0)-8f F ( 5/2) at 399.7 nm, C II transition 3d D-2-4f F-2(0) at 426.7 nm, and C III transition 3s S-3-3p P-3(0) at 465.0 nm as the plasma expands in a mbient 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. (C) 1998 Americ an Institute of Physics.