Study On Interface Instability In ICF Polymer Microsphere Target Preparation

Inertial Confinement Fusion (ICF) is one of the most attractive frontiers in the scientific field all over the world, which has been investigated by multinational researchers. ICF will supply much cleaner and more enough energy to human beings if it is tackled. As one of the most important parts in ICF experiments, the nuclear fuel container, known as ICF target, must be of high sphericity and surface finish to meet the strict requirements on its geometric symmetry. Many kinds of ICF targets are fabricated based on hollow polymer spheres (i.e., the so-called mandrel) with higher geometric symmetry.Among the several ways fabricating hollow polymer capsules for ICF targets, solvent evaporation based on microencapsulation technique is the most straightforward and the state-of-the-art one. However, comprehensive fundamental research on this specific topic is far from sufficient. This dissertation focuses on the surface finish research on the emulsification and solidification steps of the microencapsulation technique on hollow polymer capsules. The main factors affecting the surface roughness of PAMS ball were investigated and stability of interface of emulsion droplet was concerned. This should be helpful to prepare polymer hollow spheres and master the basic control technology.Because of the complexity of the interface of double emulsion curing, the gas-liquid interface of polymer curing process and interfacial mass transfer of liquid-liquid were invstigated. Based on this work, the main factors affecting the member surface roughness and mechanism resulting in the member defects were demonstrated.The main factors affecting the PAMS microspheres surface roughness were revealed by studying the emulsion droplet solidification steps. The factors include the osmotic pressure difference between the inside water phase (W1) and outside water phase (W2), the viscosity of the polymer solution, miscibility of oil and water, temperature of emulsion droplet curing. Chemical potential among the W1/O/W2 double emulsions could be balanced by adding salts in W1 phase and W2 phase, and macro vacuoles can be eliminated effectively via suppression of the water migration. Sphercity and wall thickness uniformity were improved at low temperature because diffusion rate of Fluorobenzene was decreased. Besides, the surface roughness of middle modulus and high modulus can be effectively reduced.The simulation of polymer member curing is studied. The free volume theory of polymer solution diffusion was described with the thermodynamics of polymer solution, and the theoretical model for preparing ICF membranes by casting was established. With the simulation results, the regularity of influence by external conditions on curing behavior can be controlled. The factors as optimizing solidification process, the phase separation, and interfacial instability, which may affect the quality of membranes that can be founded.