First Investigation on the Radiation Field of the Spherical Hohlraum

Abstract

The first spherical hohlraum energetics experiment is accomplished on the SGIII-prototype laser facility. In the experiment, the radiation temperature is measured by using an array of flat-response x-ray detectors (FXRDs) through a laser entrance hole at four different angles. The radiation temperature and M-band fraction inside the hohlraum are determined by the shock wave technique. The experimental observations indicate that the radiation temperatures measured by the FXRDs depend on the observation angles and are related to the view field. According to the experimental results, the conversion efficiency of the vacuum spherical hohlraum is in the range from 60% to 80%. Although this conversion efficiency is less than the conversion efficiency of the near vacuum hohlraum on the National Ignition Facility, it is consistent with that of the cylindrical hohlraums used on the NOVA and the SGIII-prototype at the same energy scale.

A novel superconducting magnetic levitation method to support the laser fusion capsule by using permanent magnets

“…In the six LEHs spherical hohlraums scheme [4], one LEH is set right under the capsule, making it impossible to put a solid magnet underneath. However, a thin cylinder with a coaxial hole is doable if the radius of the hole is large enough.…”

“…Symmetry plays a crucial role in inertial confinement fusion (ICF) experiments, because any perturbation to the spherical symmetry will be strongly amplified through ablative hydrodynamic instabilities [1,2]. To improve the radiation symmetry, indirect drive has been developed decades ago, spherical hohlraum has been reintroduced in recent years [3,4,5]. Capsule support is another important link in ICF experiments, which influences the symmetry around the capsule directly.…”

“…Y. Ishigaki et al developed an accurate position control system for superconducting ICF capsule using three electromagnet coils [9,10]. But technically, it does not seem possible to put three coils around the capsule without interfering with the laser paths, especially in the octahedral spherical hohlraums scheme where there are six laser entrance holes (LEHs) [4]. There are also relative ideas such as using negative feedback digital circuits to control the capsule position [11], using magnetic levitation to build a capsule transport system [12], which we do not intend to comment too much on.…”

Ladder climbing and autoresonant acceleration of the spherical plasma density wave

“…The spherical plasma is an interesting subject of studying and it is significant for the injection and acceleration of the electrons [20,21]. In addition, the most of the laboratory facilities about the inertial confinement fusion are spherically symmetric [22,23]. Clearly, the existence of the LC and AR in the spherically symmetric plasma has important impact on the electrons acceleration and inertial confinement fusion.…”

Growth rate and gain of stimulated Brillouin scattering considering nonlinear Landau damping due to particle trapping

“…PACS numbers: 52.38.Bv, 52.35.Fp, 52.35.Mw, 52.35.Sb 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), which will lead to a great energy loss of the incident laser and is detrimental in inertial confinement fusion (ICF) [1][2][3]. In the indirect-drive ICF [2,3] or the hybrid-drive ignition [1,[4][5][6], CH was chosen as the standard ablator material for ICF ignition capsules due to its low atomic number, high density, and a host of manufacturing considerations. Thus, the inside of hohlraum will be filled with low-Z plasmas, such as H or CH plasmas from the initial filled material or from the ablated material off the capsule.It is one of the key issues for the success of laser fusion to control backward SBS.…”