The Langmuir probe as a diagnostic of the electron component within low temperature laser ablated plasma plumes

A Langmuir probe has been used as a diagnostic of the temporally evolving e lectron component within a laser ablated Cu plasma expanding into vacuum, f or an incident laser power density on target similar to that used for the p ulsed laser deposition of thin films. Electron temperature data were obtain ed from the retarding region of the probe current/voltage (I/V) characteris tic, which was also used to calculate an associated electron number density . Additionally, electron number density data were obtained from the saturat ion electron current region of the probe (I/V) characteristic. Electron num ber density data, extracted by the two different techniques, were observed to show the same temporal form, with measured absolute values agreeing to w ithin a factor of 2. The Langmuir probe, in the saturation current region, has been shown for the first time to be a convenient diagnostic of the elec tron component within relatively low temperature laser ablated plasma plume s. (C) 1999 American Institute of Physics. [S0034-6748(99)01503-8].