Charged Particle Oscillations in Transient Plasmas Generated by Nanosecond Laser Ablation on Mg Target

• Published in: Symmetry (Basel) Vol. 12; no. 2; p. 292
• Main Authors: Agop, Maricel, Mihaila, Ilarion, Nedeff, Florin, Irimiciuc, Stefan Andrei
• Format: Journal Article
• Language: English
• Published: MDPI AG 01-02-2020
• Subjects: charged particle oscillations; fractal analysis; joint invariant functions; langmuir probe; laser ablation; lie groups
• ISSN: 2073-8994; 2073-8994
• DOI: 10.3390/sym12020292

The dynamics of a transient plasma generated by laser ablation on a Mg target was investigated by means of the Langmuir probe method and fractal analysis. The empirical data showcased the presence of an oscillatory behavior at short expansion times (<1 μs) characterized by two oscillation frequencies and a classical behavior for longer evolution times. Space- and time-resolved analysis was implemented in order to determine main plasma parameters like the electron temperature, plasma potential, or charged particle density. In the motion fractal paradigm, a theoretical model was built for the description of laser-produced plasma dynamics expressed through fractal-type equations. The calibration of such dynamics was performed through a fractal-type tunneling effect for physical systems with spontaneous symmetry breaking. This allows both the self-structuring of laser-produced plasma in two structures based on its separation on different oscillation modes and the determination of some characteristics involved in the self-structuring process. The mutual conditionings between the two structures are given as joint invariant functions on the action of two isomorph groups of SL(2R) type through the Stoler-type transformation, explicitly given through amplitude self-modulation.