Cross-beam energy transfer saturation by ion trapping-induced detuning
- Univ. of Rochester, NY (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Laboratory for Laser Energetics, University of Rochester
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Univ. of Rochester, NY (United States)
The performance of direct-drive inertial confinement fusion implosions relies critically on the coupling of laser energy to the target plasma. Cross beam energy transfer (CBET), the resonant exchange of energy between intersecting laser beams mediated by ponderomotively driven ion-acoustic waves (IAW), inhibits this coupling by scattering light into unwanted directions. Furthermore, the variety of beam intersection angles and varying plasma conditions in an implosion results in IAWs with a range of phase velocities. Here we show that CBET saturates through a resonance detuning that depends on the IAW phase velocity and that results from trapping-induced modifications to the ion distribution functions. For smaller phase velocities, the modifications to the distribution functions can rapidly thermalize in the presence of mid-Z ions, leading to a blueshift in the resonant frequency. For larger phase velocities, the modifications can persist, leading to a redshift in the resonant frequency. Ultimately, these results may reveal pathways towards CBET mitigation and inform reduced models for radiation hydrodynamics codes to improve their predictive capability.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Univ. of Rochester, NY (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP)
- Grant/Contract Number:
- 89233218CNA000001; NA0003856
- OSTI ID:
- 1819165
- Alternate ID(s):
- OSTI ID: 1829650
- Report Number(s):
- LA-UR--21-23580; NA0003865
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 28; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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