ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The spatial and temporal distribution of neutral and singly ionized lithium atoms has been investigated when slab targets are irradiated by ∼1 μs pulses of both resonant and nonresonant radiation from a flashlamp pumped dye laser. The ion population is enhanced when the laser is tuned to resonance with the 2s–2p line of neutral lithium and there is evidence for efficient ion production at distances up to 7.5 mm from the target surface. In particular, the rate of ionization is increased and the maximum ion population is attained between 120 and 200 ns earlier in the resonant case depending on distance above the target surface. However, the on-resonance ion population close to the surface is found to decrease significantly some 200 ns into the laser pulse. Ion and neutral drift velocities were measured by direct observation of the surface of the expanding plasma plume at a laser flux close to 8×108 W cm−2 and were consistent with the value predicted by a dynamic source model for accelerated plasma expansion, as was the value for the electron temperature derived from line intensity ratios. Power density thresholds for ion production have been studied and in particular, the threshold for Li2+ production is established. © 1999 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.371160
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