Laser Induced Plasmas in Liquid Water: From Single Pulse Breakdown to Repetitive Breakdown [thesis]

Rashedul Haydar
Optical breakdown in water created by 10ns pulsed Nd:YAG laser operating at λ=1064 nm was studied. Spatial and temporal information was obtained with two intensified CCD cameras while spectral data were recorded using a time-integrating spectrometer. We have studied three water samples with different impurity content (ultrapure, distilled, and tap water) and followed the plasma evolution over a timespan of a few hundred nanoseconds. Images taken by the two synchronized cameras, systematically
more » ... layed relative to each other, show that the center of emission intensity in single plasma events moves toward the incoming laser beam. For repetitive breakdown, the center of intensity of the pulse moves beyond the focal point away from the laser beam. The emission of both single pulse plasmas as well as repetitive breakdown plasmas are dominated by a broad, blackbody-like spectral feature with corresponding temperatures generally exceeding 20,000 K.
doi:10.14418/wes01.1.1031 fatcat:lczyhrxbpje4fog2qk7kdeh3vm