Nonlinear cross-beam energy transfer model for ICF/HED design codes
POSTER
Abstract
Cross-beam energy transfer (CBET) allows crossing laser beams to exchange energy and is critically important for ICF/HED experiments. The nonlinear physics of CBET for multi-speckled laser beams is examined using particle-in-cell simulations for a range of plasma conditions, laser intensities, and crossing angles relevant to indirect-drive ICF experiments.
Ion trapping induces nonlinear processes such as changes to the plasma response function, the IAW dispersion, and nonlinearities (e.g., bowing and self-focusing), which, together with pump depletion, oblique forward stimulated Raman scattering (FSRS), and backward stimulated Brillouin scattering (BSBS), determine the time-dependent nature and level of CBET gain as the system approaches steady state. Using VPIC simulations, we construct a nonlinear CBET model that computes the CBET gain (including effects from ion trapping and secondary instabilities) from local quantities such as plasma density and laser intensity, the IAW wavenumber kλD, and the electron-to-ion temperature ratio Te/Ti.
Ion trapping induces nonlinear processes such as changes to the plasma response function, the IAW dispersion, and nonlinearities (e.g., bowing and self-focusing), which, together with pump depletion, oblique forward stimulated Raman scattering (FSRS), and backward stimulated Brillouin scattering (BSBS), determine the time-dependent nature and level of CBET gain as the system approaches steady state. Using VPIC simulations, we construct a nonlinear CBET model that computes the CBET gain (including effects from ion trapping and secondary instabilities) from local quantities such as plasma density and laser intensity, the IAW wavenumber kλD, and the electron-to-ion temperature ratio Te/Ti.
*This work was supported by the Los Alamos National Laboratory Directed Research and Development (LDRD) Program. VPIC simulations were run on LANL Institutional Computing Clusters. This work was performed under the auspices of the U.S. Department of Energy by Triad National Security, LLC, operator of the Los Alamos National Laboratory under Contract No. 89233218CNA000001.
Presenters
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Lin Yin
- Los Alamos Natl Lab