Break-Up Dynamics of Polymer Beads under Laser Bombardment.
NAVAL RESEARCH LAB WASHINGTON D C
Pagination or Media Count:
Spherical polymer beads approximately 1 mm diameter, have been irradiated with a 100 J, 40 nsec Q-switched Ndglass laser. This is not enough energy to dissociate and ionize all the atoms contained in the polymer bead. Instead a small fraction about 1 of the material is ablated from the irradiated side of the bead accounting for about 60 of the laser pulse energy. The remainder of the polymer bead subsequently disintegrates in a symmetric, reproducible manner. Approximately 15 of the laser pulse energy is used in this disintegration to dissociate about 30 of the molecules in the polymer bead. The balance of the laser pulse energy about 25 is lost in reflection at glass surfaces and at the target itself. If the laser pulse is preceded by a prepulse containing about 15 of the total pulse energy, the gas released by molecular dissociation is mostly released within 1 microsecond of the peak laser power. Also the disintegration and gas release are both approximately spherically symmetric about the initial target point. However with no prepulse approximately the same amount of gas is released over a longer time period and this gas and the debris of the target are ejected away from the laser. Author
- Lasers and Masers
- Plasma Physics and Magnetohydrodynamics