Abstract
In this paper, the plume expansion dynamics of an ablated Sm2O3, Nd2O3 and NiO mixture oxides target by KrF laser into background oxygen atmosphere has been investigated using a fast ICCD imaging. The laser fluence was fixed at 2 J cm−2 and the surrounding ambient gas pressure was varied from vacuum to 50 mbar. Some effects as double plume splitting, plume sharpening and plume stopping were observed. The imaging data were used to create position–time plots of the luminous front. The plume behaviour was found to be influenced by the gas pressure above a certain threshold. Exceeding this pressure threshold, in earlier time the expansion was almost linear independently of the background gas pressure used. However, as time evolves, the plume is decelerated and comes to rest. The plasma plume dynamics was analysed in the framework of a shock-wave model and a drag model. It was found that the shock-wave model is valid in distances range which depends on the gas pressure. At later time, it is rather the drag model which is valid since it predicts exactly the stopping distance observed at high pressures. Using the dimensionless variables, a general description of the plasma plume dynamics was given. Finally, the plasma plume width-time evolution was studied.
Published Version
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