Diagnostics of laser plasma plume dynamics within an electrically biased confining cavity

Abstract

The dynamics of laser generated plasma plumes expanding within confining surfaces display a two-phase nature. Early phase enhancement due to hydrodynamic containment results in higher temperatures, densities, and average charges states in comparison to freely expanding plasma plumes. Later phase dynamics result in rapid decay of the plasma plume due to lossy plasma—surface interactions. This paper examines laser plasma generation and expansion within rectangular aluminium cavities biased to high voltages (Vbias = ±9 kV). “Hydro-electro-dynamic” confinement of the laser plasma plumes and the expansion dynamics were studied via space and time resolved visible emission spectroscopy. The charged confining cavities displayed enhanced emission, higher electron densities (Ne) and longer emission durations compared to those of an unbiased cavity. This behavior is attributed to the influence of the electric fields in the cavity on the charged particle dynamics within the cavity volume. The degree of enhancement depended strongly on the applied polarity.

Dynamics of spatially confined ns laser induced atmospheric air plasma and shock waves: visualization vis-à-vis validation

“…One of the major beneficiaries of the confined plasma in a cavity is laser induced breakdown spectroscopy (LIBS) [9, 12-17, 27, 29-33]. Different aspects of the confined laser ablated plasma from various solid targets such as plume dynamic geometries [8, 9, 12-17, 27, 29-36], plasma density measurements [8,29,31], shock wave confinement [8,17,27,36,37], role of cavity geometry [10,12,15,[31][32][33]38], spatial and magnetic confinements [27,29,34], role of laser energy [29], confinement up to few ns using a metallic micro-hole of 100 µm diameter [13,38], etc, were studied independently for enhanced spectroscopic signals of LIBS. LIBS is one of the applications in which the cavities with mm dimension are regularly used.…”