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Optical Water Breakdown by Nanosecond Nd : Yag Laser and Detection Optoacoustical Effects
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bulanov, Alexey Nagorny, Ivan G. |
| Copyright Year | 2012 |
| Abstract | Different mechanisms of plasma fronts supersonic expansion are known at the present time: a fast ionization wave (FIW), laser supported radiation wave (LSRW), laser supported detonation wave (LSDW), breakdown and electronic thermal conductivity mechanism. The study of mechanisms of laser plasma expansion is caused by different reasons including specially the research of laser plasma spectral characteristics and plasma fronts interaction for different mechanisms. We have determined the mechanism of plasma expansion for the case of an optical breakdown and low-threshold breakdown by laser wavelength λ = 1.06 μm within intensities range of 5·108 – 1011 W cm-2 in a normal atmosphere. In a case of near-threshold laser intensities close to breakdown threshold of air, I ~ (5 10)·1010 W cm-2, we have restricted to reviewing of a case of sharp-focused laser beam. In whole, the determination of plasma expansion mechanism have produced by comparison of velocities of three mechanisms: the FWI, the LSDW and the LSRW. Besides the experimental data for speeds of laser fronts were compared wth theoretical calculations. Plasma experiments were performed by using 532 nm (180 mJ) and 1064 nm (360 mJ) pulses from Brilliant B Nd:YAG laser. The spectral features of breakdown (including time-dependent intensities of absorption, molecular and atomic lines) have beenperformed. Researches of the acoustic effects accompanying optical breakdown in a liquid, generated by the focused laser radiation have been carried out at interaction with a liquid surface. Researches have been spent on the first and the second harmonics of Nd:Yag laser. Time laser radiation in a mode of the modulated quality was equal to 10 nanoseconds. Density of power for laser impulse was 1011 W/cm2. Various modes of movement of plasma fronts have simultaneously been investigated at various focusings of laser radiation. On the fig.1 the frequence shift of the peaks of optical breakdown, depending on the energy pulse are presented. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.spsl.nsc.ru/FullText/konfe/LO-2012/R7.%20Lasers%20in%20environmental%20monitoring/0435_Bulanov.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
