![]() ![]() The effects of frequency detuning laser beams in direct-drive symmetric implosions were investigated with a 3-D cross-beam energy transfer (CBET) model. Furthermore, the presence of the CBET gain multiplier required to match the data in all of the configurations tested suggests that additional physics effects, such as intensity variations due to diffraction, shortcomings of extending the 1-D Randall model to 3-D, or polarization effects, should be explored to explain the differences in observed and predicted drive. These measurements were performed on both OMEGA and the National Ignition Facility to access a wide range of plasma conditions, laser intensities, and laser beam geometries. The simulated mass ablation rates and ablation front trajectories were in excellent agreement with the measurements at all angles when a CBET model based on Randall’s equations was included into the simulations with an optimized multiplier on the CBET gain factor. Hydrodynamic simulations more » performed without CBET reproduced the measured ablation rate and ablation front trajectory at the pole of the target, verifying that the other laser-coupling physics effects are well-modeled when CBET effects are negligible. The combination of low- and high-CBET conditions in the same implosion allowed the effects of CBET on the ablation rate and ablation pressure to be decoupled from the other physics effects that influence laser-coupling. A polar-direct-drive laser configuration was used, where the equatorial laser beams were dropped from a symmetric direct-drive configuration to suppress CBET at the pole, while allowing it to persist at the equator. The angularly-resolved mass ablation rates and ablation front trajectories for Si-coated CH targets were measured in direct-drive inertial confinement fusion experiments to quantify crossbeam energy transfer (CBET) while constraining the hydrodynamic coupling. (LLNL), Livermore, CA (United States) Sponsoring Org.: USDOE National Nuclear Security Administration (NNSA) OSTI Identifier: 1444067 Alternate Identifier(s): OSTI ID: 1439134 OSTI ID: 1873239 Report Number(s): LLNL-JRNL-836148 Journal ID: ISSN 1070-664X 2017-123, 1406, 2362 Grant/Contract Number: NA0001944 AC52-07NA27344 Resource Type: Accepted Manuscript Journal Name: Physics of Plasmas Additional Journal Information: Journal Volume: 25 Journal Issue: 5 Journal ID: ISSN 1070-664X Publisher: American Institute of Physics (AIP) Country of Publication: United States Language: English Subject: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY CBET ICF NIF LPI wavelength detuning Physics - Plasma physics, Physics - Nuclear physics and radiation physics, Physics - Condensed matter physics for Laser Energetics Lawrence Livermore National Lab. ![]() Publication Date: Fri May 25 00:00: Research Org.: Univ. of Rochester, Rochester, NY (United States). ![]()
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