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Simultaneous experimental measurements of copper Kα imaging and the maximum target normal sheath acceleration proton energies from the rear target surface are compared for various target thicknesses. For the T-cubed laser (≈4 J, 400 fs) at an intensity of ≈2 × 1019 W cm-2, the hot electron divergence is determined to be θHW HM≈22° using a Kα imaging diagnostic. The maximum proton energies are measured to follow the expected reduction with increasing target thickness. Numerical modeling produces copper Kα trends for both signal level and electron beam divergence that are in good agreement with the experiment. A geometric model describing the electron beam divergence reproduces the maximum proton energy trends observed from the experiment and the fast electron density and the peak electric field observed in the numerical modeling. [ABSTRACT FROM AUTHOR]

We studied the transport of an intense electron beam produced by high intensity laser pulses through metals and insulators. Targets were irradiated at two different intensities, 1017 W/cm2 and 1019 W/cm2, at the laser facility Xtreme Light XL-III in Beijing, a Ti:Sa laser source emitting 40 fs pulses at 800 nm. The main diagnostic was Cu-Kα fluorescence imaging. Images of Kα spots have been collected for those two laser intensities, for different target thickness, and for different materials. Experimental results are analyzed taking into account both collisional and collective effects as well as refluxing at the edge of the target. The target temperature is evaluated to be Tc ∼ 6 eV for intensity I = 1017 W/cm2 (for all the tested materials: plastic, aluminium, and copper), and Tc ∼ 60 eV in aluminium and 120 eV in titanium for intensity I = 1019 W/cm2. [ABSTRACT FROM AUTHOR]