Study and design of hohlraum shape on Shenguang-Ⅲ facility

The time dependence of irradiation drive symmetry and intensity on the capsule in different shaped hohlraums and laser arrangement is investigated by a 3D view-factor code called IRAD3D. The simulation results show that the loss of energy by the wall of hohlraum is reduced for a much smaller hohlraum area in the ellipsoidal-shaped hohlraum, resulting in an increase in the fraction of energy absorbed by the capsule. The time-integrated Legendre mode P2 of asymmetry can be controlled in a low level in a validated length of hohlraum. The hohlraum can be shorter in ellipsoidal-hohlraum with two-cones irradiation. A smaller Legendre mode P4 is attained in a four-cones irradiation system but a worse mode M4 of azimuthal asymmetry appears. All of the asymmetry modes are in a good level in the ellipsoidal-hohlraum with two-cones irradiation, meanwhile there is a 25%-27% increase in the irradiation drive flux onto the capsule compared with the cylindrical hohlraums.