| Original Articles |
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Reduce of Threshold of Laser Inducing Breakdown in Atmosphere by Introducing an Electric Spark |
| ZHANG Xian-Bin1;SHI Wei1;LI Hua2 |
| 1Department of Applied Physics, Xi’an University of Technology, Xi’an 710048
2Xi’an Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Xi’an 710068 |
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| Cite this article: |
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ZHANG Xian-Bin, SHI Wei, LI Hua 2005 Chin. Phys. Lett. 22 2885-2887 |
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Abstract We report laser-generated plasmas in atmosphere with electrical spark generated by a synchronization circuit. The breakdown thresholds under the conditions that the electrical spark is used and not used are compared. The breakdown threshold has a distinct decrease after the electrical spark is used. Breakdown thresholds as a function of atmosphere pressure have also been measured at laser wavelengths 532nm and 1064nm for the laser pulse width of 15ns. We also discuss the principle and performances of the ionized atmosphere by Nd:YAG laser under the condition of electrical spark introduction. Multiphoton ionization and cascade ionization play important roles in the whole process of atmosphere ionization. The free electron induced by electrical spark can supply the initialization free electron number for multiphoton ionization and cascade ionization. A model for breakdown in atmosphere, which is in good agreement with the experimental results, is described.
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| Keywords:
52.20.-j
52.50.Jm
42.62.-b
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Published: 01 November 2005
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| PACS: |
52.20.-j
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(Elementary processes in plasmas)
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52.50.Jm
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(Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.))
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42.62.-b
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(Laser applications)
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