Energy penetrated and inverse bremsstrahlung absorption co-efficient in laser ablated germanium plasma

Abstract

In the present experimental conditions, at Nd:YAG laser in fundamental (1064) nm, at laser irradiance 1.0 × 1011 Wcm−2 the (IB) absorption αib is approximately equal to (0.0204 cm-1). In present work irradiance is varied from 1.0 × 1011 to 1.8 × 1011Wcm−2 and inverse bremsstrahlung varies from 2.0 × 10−3 to 1.2 × 10−2 cm−1. The power absorbed by germanium target surface is found to be Pabs = 2.07 × 108 Wcm−2 and 1.04 × 103 Wcm−2 is reflected back from germanium surface. Whereas at highest laser irradiance 1.8 × 1011 Wcm−2 the power absorbed by surface is found to be Pabs = 3.67 × 108 Wcm−2 and 1.84 × 103Wcm−2 is reflected back from germanium surface. In present work we have calculated laser absorbance and percentage which is estimated by absorbed light throughout the original irradiance I0 at target surface, in present work absorbance at germanium surface is 0.2 where as reflectivity R of germanium sample which is found to be 0.39 for 1064 nm wavelength. At irradiance I0 1.0 × 1011 Wcm−2 the energy penetrated is E∼5.05 × 1010 Wcm−2 and for high laser irradiance at I0 1.8 × 1011 Wcm−2 the energy penetrated is E∼8.95 × 1010 Wcm−2 respectively.