Now showing 1 - 3 of 3
  • Publication
    Emission characteristics and dynamics of the stagnation layer in colliding laser produced plasmas
    The expansion dynamics of ion and neutral species in laterally colliding laser produced aluminium plasmas have been investigated using time and space resolved optical emission spectroscopy and spectrally and angularly resolved fast imaging. The emission results highlight a difference in neutral atom and ion distributions in the stagnation layer where, at a time delay of 80 ns, the neutral atoms are localised in the vicinity of the target surface (< 1 mm from the target surface) while singly and doubly charged ions lie predominantly at larger distances, < 1.5 mm and < 2 mm respectively. The imaging results show that the ions were found to form a well defined, but compressed, stagnation layer at the collision front between the two seed plasmas at early times (Δt < 80 ns). On the other hand the excited neutrals were observed to form a V shaped emission feature at the outer regions of the collision front with enhanced neutral emission in the less dense, cooler regions of the stagnation layer.
    Scopus© Citations 37  290
  • Publication
    Ion emission in collisions between two laser-produced plasmas
    Measurements of the total ion emission from a pair of colliding laser-produced aluminium plasmas were obtained with the aid of a Faraday cup detector. The energy profile width at half height of the kinetic energy distribution for ions emitted normal to the target was found to be 30% narrower for colliding plasmas compared to a single plasma. Similar to ion emission from single plumes, the mean ion kinetic energy is observed to increase with the energy of the incident laser pulse. However, the width of the ion energy distribution increases at a significantly slower rate than in the single plume case.
    Scopus© Citations 19  490
  • Publication
    Electron and ion stagnation at the collision front between two laser produced plasmas
    We report results from a combined optical interferometric and spectrally resolved imaging study on colliding laser produced aluminium plasmas. A Nomarski interferometer was used to probe the spatio-temporal distribution of the electron density at the collision front. Analysis of the resulting interferograms reveals the formation and evolution of a localised electron density feature with a well defined profile reminiscent of a stagnation layer. First signs of electron stagnation are observed at a time delay of 10 ns after the peak of the plasma generating laser pulse. The peak electron density was found to exceed 1019 cm−3 and the layer remained well defined up to a time delay of ca. 100 ns. Temporally and spectrally resolved optical imaging was also undertaken to compare the Al+ ion distribution, with that of the 2D electron density profile. This revealed nascent stagnation of singly charged ions at a delay time of 20 ns. We attribute these results to the effects of space charge separation in the seed plasma plumes.
    Scopus© Citations 37  442