Initial experimental results on magnetized cross-beam energy transfer

Cross-beam energy transfer (CBET) is a laser-plasma interaction process which transfers power between two laser beams and is active in both indirect and direct drive inertial confinement fusion implosions.  The presence of a seed magnetic field can both modify the plasma conditions in the CBET region and may also introduce additional plasma modes which mediate the power transfer.  Interest in magnetized CBET arises from recent NIF experiments on magnetized implosions [1] which show slight hot spot shape changes with a 26 T applied B-field.  We have performed experiments on the Omega laser to study magnetized CBET.  In one experimental configuration a laser-coil introduces a 100 – 200 T B-field to an exploding foil Carbon plasma where two lasers cross and experience CBET.  Thomson scattering measurements in the magnetized plasma may show evidence of electron-cyclotron resonances due to the B-field.  We show the experimental data and review the Thomson scattering and CBET predictions from magnetized plasma wave kinetic theory. 

[1]  J. D. Moody et al., Phys. Rev. Lett. 129, 195002 (2022).

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and by the LLNL-LDRD program under Project Number 23-ERD-025.