Spectral line profiles, broadened mostly by Stark effects from electric fields produced by charge particles, and diélectronic satellite line intensities have recently been used for determining electron densities in the dense region of laser-created plasmas. We present here a direct comparison of electron density measurements in the conduction region of laser created plasmas on a plane target using these two techniques.
Experiments were carried at the GRECO laser facility, using the Nd phosphate glass laser at its second harmonic (0.53 μm) and 600 ps pulse length. The laser was focused on a 160 μm focal spot in which was centered a 25 or 50 μm diameter aluminum dot implanted on a carbon substrate. Laser intensities were in the range 1 × 1014−3 × 1014 W/cm2. The ls4p−ls2 He-like transition, the 4p−ls H-like transition and the Ly c satellites were recorded on the same spectrum with a PET flat crystal spectrograph. Spot spectroscopy provided quasi-homogeneity and low reabsorption along the line of sight which was tilted 7° out the target surface. 3 μm resolution along the laser axis was obtained with an imaging knife-edge placed 1 mm apart from the target.