Hot electron diagnostic in a solid laser target by K-shell lines measurement from ultraintense laser-plasma interactions (3x10(20) W/cm(2),<= 400 J)

Characterization of hot electron production from an ultraintense laser-soli d target plasma interaction by using a buried molybdenum K-shell fluor laye r technique has been reported. Laser energy was typically 400 J and its int ensity was from 2 x 10(18) up to 3 x 10(20) W cm(-2) at 20 TW to 1 PW laser power by changing pulse duration from 20 ps down to 0.5 ps. X-ray backgrou nd noise level was significantly greater, i.e., gamma flash, in the shorter pulse experiments. Data analysis procedures for the experiments were devel oped. The conversion efficiency from the laser energy into the energy, carr ied by hot electrons, has been estimated to be similar to 50% at 3 x 10(20) W cm(-2) laser intensity, higher than similar to 18% at 10(19) W cm(-2) an d similar to 12% at 2 x 10(18) W cm(-2) intensity. (C) 2001 American Instit ute of Physics.