Experimental scaling laws for mass-ablation rate, ablation pressure in planar laser-produced plasmas with laser intensity, laser wavelength, and target atomic number

Layered-target experiments at 1.06 μm for carbon and silicon materials have been carried out to measure mass-ablation rate ṁ and ablation pressure Pa as a function of absorbed laser intensity Ia, laser wavelength λL, and target atomic number Z at irradiances of 1013–1015 W/cm2. The results can be put in the forms ṁ(kg/s cm2)≂55 [Ia(W/cm2)/1014]1/3λL−4/3(μm) Z3/8 and Pa(Mbar)≂7.4 [Ia(W/cm2)/1014]2/3λL−2/3(μm) Z3/16. The experimental data are compared with one-dimensional hydrodynamic calculations (code medusa) using different values of electron heat-flux limitation. An indication of laser intensity, target atomic number dependent on flux inhibition was found: 0.06≤f≤0.08 for silicon targets and f=0.015–0.03 for carbon targets. These flux limitations are discussed in terms of a small lateral transport and an eventual presence of intense magnetic fields.