54 / 2020-02-24 16:07:11

The influence of driven asymmetry on yield degradation in triple-shape indirect-drive implosion on the 100kJ laser facility

driven asymmetry,,Indirect-drive

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The driven asymmetries of P2/P4 is the most important issue on yield degradation in NIF’s recent experiments. Meanwhile, a middle compression ratio(20~25) implosion experiments using tripleshape indirect driven were performed on the 100kJ level laser facility in China to investigate the influence of driven asymmetry.
In this work, total 48 laser beams with 80kJ laser energy injected into the cylindrical hohlraum. The hohlraum with a length of 4680um and a diameter of 2600um. There were two laser-entrance holes with diameter 1500um at the two ends. In our design, the hohlraum driven asymmetries were significantly changed through the variation of hohlraum gas-fill from 0.3atm to 0.4atm and the inner diameter of capsule from 750um to 850um(changing the CCR). The DD neutron yield in all configuration experiments were from 1.8х109 to 7.6х109. Meanwhile, the YOC1D were only 4.3% to 15.6%（calculated by LARED code）.LARED code also proposed the 2D calculated neutron yield based on the consideration of the influence of P2/P4 and the YOC2D were increased obviously (49% to 81%).Furthermore, based on the hot-spot energy balance analyze, the efficiency of pdV works were decreased sharply due to the P2 driven asymmetry.
In summary, the main reason of degradation of neutron yield in 20~25 compression ratio implosions on the 100kJ level laser facility were driven asymmetry, especially is P2