Laser-plasma instabilities driven by 1 ω 0 pulses at shock ignition conditions

Year: 2025

Authors: Gosling B., Arber T.D., Cristoforetti G., Nicolai P., Gizzi L.A.

Autors Affiliation: Univ Warwick, Ctr Fus Space & Astrophys, Coventry CV4 7AL, England; CNR, Ist Nazl Ott, I-56124 Pisa, Italy; Univ Bordeaux, CNRS, Ctr Lasers Intenses & Applicat, UMR 5107,CEA, F-33400 Talence, France.

Abstract: Recent experiments using 1 omega(0) ( lambda(0) = 1.314 mu m) laser pulses at the PALS facility have demonstrated the excitation of multiple parametric instabilities. At peak intensities ( I similar to 10(16) W cm(-2)), the combination of high irradiance ( I lambda(2) ) and electron temperatures ( similar to 3-4 keV) creates plasma conditions relevant to shock ignition. We present two-dimensional particle-in-cell simulations of laser-plasma instabilities at both low ( similar to 10(15) W cm(-2)) and high ( similar to 10(16) W cm(-2)) intensities. The simulations incorporate flow, density, and temperature profiles obtained from hydrodynamic modeling, as well as the effects of Coulomb collisions. In both regimes, stimulated Brillouin scattering emerges as the primary mechanism for backscattered electromagnetic radiation. At low intensity, two-plasmon decay (TPD) drives electron plasma wave activity, while stimulated Raman scattering (SRS) is suppressed by the short density scale length ( L-n ), limiting convective gain. At higher intensity, the onset of laser beam filamentation leads to a reduction in TPD activity, while the increased L-n facilitates the excitation of SRS within the resulting filaments. The resulting hot-electron populations follow thermal-like distributions with effective temperatures ranging between 17 and 37 keV with respect to laser intensity. The fraction of laser energy converted into electrons with E > 100 keV increases from 0.2% to 0.7% between low and high intensity. In the low-intensity regime, resonance absorption near the critical density also enhances the hot-electron flux at the simulation boundary, especially for electrons with E <= 100 keV. This contribution diminishes at higher intensities, where SRS near the quarter-critical density becomes the dominant source of hot-electron generation. Journal/Review: PHYSICS OF PLASMAS

Volume: 32 (9)      Pages from: 92705-1  to: 92705-18

More Information: B. Gosling is supported by a studentship within the Engineering and Physical Sciences Research Council (EPSRC) supported Centre for Doctoral Training in Modelling of Heterogeneous Systems, Grant No. EP/S022848/1. We acknowledge using ARCHER2 through the Plasma HEC supported by UKRI Grant EP/X035336/1. We also acknowledge the use of the Sulis Tier 2 supported by the EPSRC Grant EP/T022108/1. In addition, we gratefully acknowledge the use of the computational facilities provided by the University of Warwick Scientific Computing Research Technology Platform. This work has also been carried out within the framework of the EURO-fusion Enabling research projects AWP24-ENR-IFE-02-CEA-02. Finally, we wo uld like to acknowledge the reviewers for providing insightful feedback that has improved the quality of this work.
KeyWords: Stimulated Raman-scattering; 2-plasmon Decay Instability; Hot-electron Generation; Ion-acoustic-waves; Parametric-instabilities; Electromagnetic-waves; Intensities Relevant; Relativistic Plasma; Langmuir; Frequency
DOI: 10.1063/5.0251431