Atomic mass dependent electrostatic diagnostics of colliding laser plasma plumes

Abstract

The behaviours of colliding laser plasma plumes (C p ) compared with single plasma plumes (S p ) are investigated for 14 different atomic mass targets. A Faraday cup, situated at the end of a drift tube (L ¼ 0.99 m), is employed to record the time-of-flight (TOF) current traces for all elements and both plume configurations, for a fixed laser intensity of I p ¼ 4.2 Â 10 10 W cm À2 (F ¼ 0.25 kJ cm À2 ). The ratio of the peak current from the C p relative to twice that from the S p is designated as the peak current ratio while the ratio of the integrated charge yield from the C p relative to twice that from the S p is designated as the charge yield ratio. Variation of the position of the Faraday cup within the drift tube (L ¼ 0.33, 0.55, and 0.99 m) in conjunction with a lower laser fluence (F ¼ 0.14 kJ cm À2 ) facilitated direct comparison of the changing TOF traces from both plasma configurations for the five lightest elements studied (C, Al, Si, Ti, and Mn). The results are discussed in the frame of laser plasma hydrodynamic modelling to approximate the critical recombination distance L CR . The dynamics of colliding laser plasma plumes and the atomic mass dependence trends observed are presented and discussed. V C 2013 AIP Publishing LLC.

Expansion Dynamic and Characterization of Stagnation Layer in Laterally Colliding Plasmas: Dependence of Observation Bandwidth and Plasma Plume Separation

“…Earlier work by Min et al [30] measured velocities of 9.46•10 6 cm/s in Si plasmas irradiated by two collinear pulses. Yeates et al [31] used electrostatic diagnostics to infer velocities of 10 6 for silicon. The current work uses filters to isolate specific groups of ions and also employs different geometries to investigate the stagnation layer and its expansion velocity.…”

“…Another study by Yeates et al [31] investigated ion emission dynamics of laser-produced plasma from several elements, comprised of metals and non-metals (C, Al, Si, Cu, Mo, Ta, W), under vacuum conditions using a Faraday cup. This study of plasma properties employing fast photography, time, and space resolved optical emission spectroscopy, and electron analysis showed that there existed different mechanisms for generating ions in laser ablation plumes.…”