Laser produced plasma in crystalline &agr;‐Al2O3and aluminum metal
作者:
Joshua E. Rothenberg,
Gad Koren,
期刊:
Applied Physics Letters
(AIP Available online 1984)
卷期:
Volume 44,
issue 7
页码: 664-666
ISSN:0003-6951
年代: 1984
DOI:10.1063/1.94870
出版商: AIP
数据来源: AIP
摘要:
A comparative study of the laser produced plasma (LPP) in vacuum at the surface of transparent crystalline &agr;‐Al2O3(sapphire) and Al metal generated by 248‐nm excimer laser pulses of 15‐ns duration is reported. It was found that the threshold fluence for strong LPP emission in sapphire is 0.55 J/cm2, which is significantly lower than that needed for the same process in clean Al (1.7 J/cm2). At fluences higher than 4 J/cm2the LPP emission from both targets is similar. The results obtained in sapphire require that its absorption coefficient increase by many orders of magnitude during the laser pulse. A possible explanation for the observed threshold difference is that the greater thermal diffusivity of Al more than compensates for its greater volatility; hence, a greater fluence is necessary to create the LPP in Al.
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