Eur. Phys. J. Spec. Top. (2021) 230: 4035-4044
https://doi.org/10.1140/epjs/s11734-021-00029-9

Regular Article

On the resonance absorption in laser-driven deuterium cluster

Institute for Plasma Research, HBNI, Bhat, 382 428, Gandhinagar, Gujarat, India

^b mkundu@ipr.res.in

Received: 28 August 2020
Accepted: 24 December 2020
Published online: 15 April 2021

Abstract

In a laser-irradiated atomic cluster linear resonance absorption occurs when Mie-plasma frequency (${\omega }_{\text{M}}$) matches the laser frequency ($\omega$); and laser absorption is unconditionally presumed to be maximum here for the collisionless interaction. To judge it, we study interaction of short laser pulses of various intensity, polarization, and pulse duration with a deuterium cluster using molecular dynamics simulation. For a given laser energy and pulse duration, we show that absorption peak is red-shifted from the expected Mie-resonance condition $\omega ={\omega }_{\mathrm{M}}$, irrespective of linear polarization (LP) and circular polarization (CP) of laser. Increasing the intensity, red-shift of absorption peak increases; and above an intensity, it disappears (sometimes followed by a growth in absorption) when outer ionization saturates at 100% which also holds true for fixed pulse energy and increasing pulse duration. Laser absorption and red-shift of the absorption peak for LP and CP are found to be almost equal.