| Autor: |
Pathak, Kedar, Povitsky, Alex |
| Předmět: |
|
| Zdroj: |
Journal of Applied Physics; Dec2008, Vol. 104 Issue 11, p113108, 10p, 10 Graphs |
| Abstrakt: |
The behavior of ablated plumes produced by nanosecond scale multiple laser pulses typical for carbon ablation is studied in order to understand the plume expansion dynamics and shielding effect of plume with special interest to ionization of plumes. The patterns of a planar plume (typical for channel cutting) and an axisymmetric plume (typical for hole drilling) appear to be quite different. Ionization in carbon plume is estimated using the Saha equation. An iterative procedure is developed to determine the local equilibrium temperature affected by ionization. It is shown that though shielding due to the presence of ionized particles in carbon plume is small, the effect of ionization on plume temperature can be considerable. Shielding effect is calculated for laser pulses with different time intervals between pulses. The effects of high temperature and low density of plume are conflicting and cause shielding behavior to be nonmonotonic. It is shown that the nonmonotonic dependence of the delivered laser energy, the pulse number, and the difference in shielding characteristics between planar and axisymmetric formulations increase with the time duration between two consecutive pulses. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
