Parametric study of expanding plasma plume formed by laser-blow-off of thin film using triple Langmuir probe

The triple probe technique has been used to study the parameters of flowing plasma plume formed by laser-blow-off (LBO) of a multicomponent LiF-C target. The advantages of triple Langmuir probe over the single probe have been discussed with regard to the present study. Our results show that triple probe is better suited for parametric measurements close to the target. The spatiotemporal evolutions of electron density and temperature were measured in different ambient environments and for various laser fluences. The angular distribution of electron density and temperature was also measured. It was found that the presence of ambient gas drastically affects the electron density and temperature of the LBO plume. Large enhancement in n(e) and T-e at intermediate pressures (10(-2) Torr) is expected due to increase in collisional processes. On the other hand, laser fluence does not affect the observed n(e) and T-e significantly. In vacuum, a new phenomenon, i.e., an oscillation in the trailing portion of the plasma plume at a closer distance from the target, is also reported. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3204946]