Interaction of intense Ti:sapphire laser with solid targets has been studied experimentally by measuring hard x-ray and hot electron generation. Hard x-ray ͑8 -100 keV͒ emission spectrum and K␣ x-ray conversion efficiency ͑ K ͒ from plasma have been studied as a function of laser intensity ͑10 17 -10 19 W/cm 2 ͒, pulse duration ͑70-400͒fs, and laser pulse fluence. For intensity I Ͼ 1 ϫ 10 17 W/cm 2 , the Ag K increases to reach a maximum value of 2 ϫ 10 −5 at an intensity I =4 ϫ 10 18 W/cm 2 . Hot electron temperature ͑KT h ͒ and K scaling laws have been studied as a function of the laser parameters. A stronger dependence of KT h and K as a function of the laser fluence than on pulse duration or laser intensity has been observed. The contribution of another nonlinear mechanism, besides resonance absorption, to hard x-ray enhancement has been demonstrated via hot electron angular distribution and particle-in-cell simulations.

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