First inertial confinement fusion implosions in the compressive regime at the Laser MegaJoule facility

Since 2022, the Laser MegaJoule facility (LMJ) has reached a sufficient number of laser beams to allow for a symmetrical inertial confinement fusion (ICF) platform : up to 270 kJ of laser light can now be delivered on target, using four irradiation rings consisting of five laser quads each.

We report here on a recent indirect-drive campaign, in which the compressive regime was explored. In this experiment, D₂-filled sillicon-doped plastic capsules were imploded by 2-shock pulses using vacuum or gas-filled rugby-shaped gold hohlraums. The continued commissioning of new plasma diagnostics has allowed measuring the laser backscattered energy, radiative drive, LEH closure, hot-spot symmetry and neutron yield.

Increasing the capsule convergence ratio (~15x), the neutron yield over simulation (YoS) did not exceed ~10%. 3D integrated simulations and highly resolved 2D simulations including the capsule support tent are performed to investigate the performance degradation.