Effect of double pulse irradiation on the morphology of a picosecond laser produced chromium plasma

TL;DR

This study investigates how double-pulse laser irradiation influences the morphology of chromium plasma plumes, revealing control mechanisms that could enhance applications like high harmonic generation and thin film fabrication.

Contribution

It introduces a novel approach to controlling plasma plume morphology using double-pulse schemes with adjustable delay and spatial separation parameters.

Findings

Aspect ratio decreases with increased pressure, delay, and second pulse energy.

Higher pressure conditions for single-pulse plumes can be mimicked at lower pressures using double pulses.

Potential applications include high harmonic generation and high-quality thin film production.

Abstract

We describe the measurements to control the morphology and hence the characteristics of a picosecond laser produced chromium plasma plume upon double-pulse (DP) irradiation compared to its single-pulse (SP) counterpart. DP schemes are realized by employing two geometries wherein the inter-pulse delay ($\tau_p$) in the collinear geometry and the spatial separation ($\Delta x$) are the control parameters for schemes DP$_1$ and DP$_2$ respectively. The aspect ratio (plume length/plume width) decreases upon increasing parameters such as pressure, delay between pulses and the energy of the second pulse in DP1 scheme. Interestingly, the expansion conditions of the plume which occurs at higher pressures for SP scheme could be recreated in DP1 scheme for a lower pressure $\sim$ 10$^{-6}$ Torr. This could be potentially applied for immediate applications such as high harmonic generation and quality thin film production.