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The experimental investigation of the <i>hohlraum</i> energetics of two-entrance holes spherical <i>hohlraum</i> at the 100 kJ level laser facility
摘要： The two-laser entrance hole (LEH) spherical hohlraum energetic experiments with all 48 laser beams and two laser pulse shapes at the 100 kJ level laser facility were investigated. In this work, the time-resolved radiation temperature measured by multi-angle x-ray diodes agreed well with LARED simulations, and the peak radiation temperature was up to 260 eV with the laser power of 45 TW. Meanwhile, the backscattered laser energy fraction was less than 5% in the majority of shots, which proposed a low level of laser–plasma interaction (LPI) effect in the spherical hohlraum. However, in the shaped pulse shots with capsules, the stimulated Raman scattering (SRS) of smaller incident angle lasers was signi?cantly increased to 15%. The measured SRS spectrum and LARED simulations showed that the increase in the LPI effects caused by the ablated CH plasma was around 0.1Nc (Nc is the critical density). In summary, according to the experimental results, the x-ray conversion ef?ciency of the vacuum spherical hohlraum was 85%–88% in 3 ns square pulses and 89%–93% in 3.6 ns shaped pulses. It was closer to that of the two-LEH cylindrical hohlraum at the Shen-Guang and NIF facilities.
关键词： LARED simulations,laser-plasma interaction,x-ray conversion efficiency,hohlraum energetics,spherical hohlraum
更新于2025-09-19 17:13:59
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Note: Radiochemical measurement of fuel and ablator areal densities in cryogenic implosions at the National Ignition Facility
摘要： A new radiochemical method for determining deuterium-tritium (DT) fuel and plastic ablator (CH) areal densities (ρR) in high-convergence, cryogenic inertial confinement fusion implosions at the National Ignition Facility is described. It is based on measuring the 198Au/196Au activation ratio using the collected post-shot debris of the Au hohlraum. The Au ratio combined with the independently measured neutron down scatter ratio uniquely determines the areal densities ρR(DT) and ρR(CH) during burn in the context of a simple 1-dimensional capsule model. The results show larger than expected ρR(CH) values, hinting at the presence of cold fuel-ablator mix.
关键词： cryogenic inertial confinement fusion,neutron down scatter ratio,National Ignition Facility,areal densities,fuel-ablator mix,plastic ablator,deuterium-tritium fuel,radiochemical method,Au hohlraum
更新于2025-09-04 15:30:14