Spatio-temporal inhomogeneities of laser induced plasma on surface solutions
✍ Scribed by J. Ben Ahmed; Z. Ben Lakhdar; G. Taïeb
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 195 KB
- Volume
- 1
- Category
- Article
- ISSN
- 1612-2011
No coin nor oath required. For personal study only.
✦ Synopsis
A transient plasma created by focusing a nanosecond
laser pulse on the surface of ionic solutions of Ca^++^ and
Mg^++^ is studied spectroscopically. This kind of plasma has a
properties which vary significantly with time and over its
extended volume. The emissions of ionic and atomic line of calcium
and magnesium are analyzed to get information on the electronic
temperature, the electronic density and on the kinetics of the
population of low atomic and ionic states: 4P~1~ of CaI,
5S~1/2~ of CaII, 3P~1~ of MgII and 3P~1/2~ of MgII. The
temperature is maximal at the plasma center and it drops at the
edges. The study of the term T(r ≠ 0)/T(r = 0) as a
function of time, where r is the radial position, shows a
continue decreasing with time, which implies that the
inhomogeneity of the temperature develops with time. On the
another side, the electronic density deceases exponentially with
time and does not vary significantly with space. These
measurements allow us to follow the kinetics of the transformation
of calcium (magnesium) from Ca^++^Mg^++^ to
Ca^+^(Mg^+^) to give at the end Ca (Mg) and to understand
the behavior of self-absorption phenomena which is observed in the
resonance line of CaII at t ≈ 2000 ns to increase with
time. The experimental results are simulated by a kinetics model
of LTE laser induced plasma in its late relaxation period.