Mitigation of hot electrons from laser-plasma instabilities in high-Z, highly ionized plasmas
Abstract
Hard x-ray measurements are used to infer production of hot electrons in laser-irradiated planar foils of materials ranging from low- to high-Z. The fraction of laser energy converted to hot electrons, fhot, was reduced by a factor of 103 going from low-Z CH to high-Z Au, and hot electron temperatures were reduced from 40 to ∼20 keV. The reduction in fhot correlates with steepening electron density gradient length-scales inferred from plasma refraction measurements. Radiation hydrodynamic simulations predicted electron density profiles in reasonable agreement with those from measurements. Both multi-beam two-plasmon decay (TPD) and multi-beam stimulated Raman scattering (SRS) were predicted to be above threshold with linear threshold parameters that decreased with increasing Z due to steepening length-scales, as well as enhanced laser absorption and increased electron plasma wave collisional and Landau damping. The results add to the evidence that SRS may play a comparable or a greater role relative to TPD in generating hot electrons in multi-beam experiments.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 01, 2017
- Source ID
- 10.1063/1.4978625
Entities
People
- D. H. Edgell
- D. Haberberger
- D. Shvarts
- Dustin Froula
- E. Raicher
- J. P. Holloway
- J. R. Fein
- M. Fraenkel
- M. R. Trantham
- P. A. Keiter
- R. Paul Drake
- Y. Frank
Organizations
- Defense Threat Reduction Agency
- Laboratory for Laser Energetics
- United States Department of Energy
- University of Michigan