Progress in octahedral spherical hohlraum study

Abstract

In this paper, we give a review of our theoretical and experimental progress in octahedral spherical hohlraum study. From our theoretical study, the octahedral spherical hohlraums with 6 Laser Entrance Holes (LEHs) of octahedral symmetry have robust high symmetry during the capsule implosion at hohlraum-to-capsule radius ratio larger than 3.7. In addition, the octahedral spherical hohlraums also have potential superiority on low backscattering without supplementary technology. We studied the laser arrangement and constraints of the octahedral spherical hohlraums, and gave a design on the laser arrangement for ignition octahedral hohlraums. As a result, the injection angle of laser beams of 50°–60° was proposed as the optimum candidate range for the octahedral spherical hohlraums. We proposed a novel octahedral spherical hohlraum with cylindrical LEHs and LEH shields, in order to increase the laser coupling efficiency and improve the capsule symmetry and to mitigate the influence of the wall blowoff on laser transport. We studied on the sensitivity of the octahedral spherical hohlraums to random errors and compared the sensitivity among the octahedral spherical hohlraums, the rugby hohlraums and the cylindrical hohlraums, and the results show that the octahedral spherical hohlraums are robust to these random errors while the cylindrical hohlraums are the most sensitive. Up till to now, we have carried out three experiments on the spherical hohlraum with 2 LEHs on Shenguang(SG) laser facilities, including demonstration of improving laser transport by using the cylindrical LEHs in the spherical hohlraums, spherical hohlraum energetics on the SGIII prototype laser facility, and comparisons of laser plasma instabilities between the spherical hohlraums and the cylindrical hohlraums on the SGIII laser facility.

Stimulated Brillouin scattering behaviors in multi-ion species plasmas in high-temperature and high-density region

“…Backward stimulated Brillouin scattering (SBS) is a three-wave interaction process where an incident electromagnetic wave (EMW) decays into a backscattered EMW and a forward propagating ion-acoustic wave (IAW). Backward SBS leads to a great energy loss of the incident laser and is detrimental in inertial confinement fusion (ICF) [1][2][3], including indirect-drive ignition [4,5], direct-drive ignition [6,7], shock ignition [8,9], and hybrid-drive ignition [1] with a spherical hohlraum [10][11][12][13] where indirect-drive and direct-drive processes are combined. Therefore, SBS plays an important role in the successful ignition goal of ICF.…”

Numerical Simulation on the Influence of the Longitudinal Fins on the Enhancement of a Shell-and-Tube Ice Storage Device

“…With phase change materials (PCMs) they can absorb energy in the evening and regenerate the thermal energy in the daytime, which fills the gap of the energy load between day and night [10,11]. Among the various thermal energy storage system types, the so-called cold energy storage system using water as PCMs, which is also known as the ice storage system, has been utilized in applications such as advanced energy systems [12,13], food cold chain [14], peak load shifting [15] and building air conditioning systems [16].…”

Simulation of the Gas Filling and Evacuation Processes in an Inertial Confinement Fusion (ICF) Hohlraum

“…In inertial confinement fusion (ICF), a capsule filled with deuterium-tritium is imploded to ignition and burns under appropriate conditions, which bring clean and sustainable energy [1][2][3][4][5]. In particular, the indirect drive approach of ICF relies on the efficient conversion of laser power to X-rays that heat and symmetrically drive the capsule implosion embedded in a cylindrical hohlraum [6,7].…”