Collision and interpenetration of plasmas created by laser‐illuminated disks

Supersonic, counterstreaming plasmas were produced by ablating plasma from the inside surfaces of two parallel disks made of aluminum and magnesium, respectively, with a 0.53 μm laser at an intensity of 101 4 W/cm2 for 1.3 nsec. Diagnostics included holographic interferometry, a time‐integrated x‐ray pinhole camera and a gated x‐ray crystal spectrograph with imaging slits. The plasmas interpenetrate for the first half of the laser pulse but stagnate once the electron density exceeds 5×102 0 cm− 3. Spectroscopic measurements suggest a coronal electron temperature of ∼800 eV and an ion temperature of ∼15 keV in the stagnated plasma. The observations are in good agreement with a two ion fluid model of interpenetrating plasmas in which the dominant slowing down process is ion–ion collisions.