Fabrication of polystyrene hollow microspheres as laser fusion targets by optimized density-matched emulsion technique and characterization

Abstract

Inertial confinement fusion, frequently referred to as ICF, inertial fusion, or laser fusion, is a means of producing energy by imploding small hollow microspheres containing thermonuclear fusion fuel. Polymer microspheres, which are used as fuel containers, can be produced by solution-based micro-encapsulation technique better known as density-matched emulsion technique. The specifications of these microspheres are very rigorous, and various aspects of the emulsion hydrodynamics associated with their production are important in controlling the final product. This paper describes about the optimization of various parameters associated with density-matched emulsion method in order to improve the surface smoothness, wall thickness uniformity and sphericity of hollow polymer microspheres. These polymer microshells have been successfully fabricated in our lab, with 3-30 µm wall thickness and 50-1600 µm diameters. The sphericity and wall thickness uniformity are better than 99%. Elimination of vacuoles and high yield rate has been achieved by adopting the step-wise heating of W 1 /O/W 2 emulsion for solvent removal.

Synthesis of millimeter-scale Al2O3 ceramic hollow spheres by an improved emulsion microencapsulation method

“…In general ICF requires high quality hollow sphere as fuel container, for example, (1) the hollow sphere must be translucent; (2) it can be used at high temperature; (3) the diameter should be several hundred micrometers to several millimeters. In addition, hollow spheres with smooth surface, high uniformity and sphericity (higher than 99%) need to be fabricated [1,2]. Currently, the main candidate target pellets are hollow glass microspheres (HGM), metal alloy or metal-coated spheres.…”

An easily assembled double T-shape for the preparation of submillimeter-sized hollow polyacrylonitrile (PAN) microcapsules for inertial confinement fusion (ICF) project

“…The materials used for target fabrication are mainly metal, nonmetal inorganic, porous foam material and organic macromolecule polymer [11,12]. Beryllium (Be) is the most commonly used metal for low-Z, high intensity, and thermal conductivity [13].…”

“…Micro emulsion enclosure method shows the remarkable advantages of simple equipment, easy operation, low cost and fabricated micro-balloons appear better concentricity than the ones from the other methods, and it is easy to obtain large-size microballoons [26][27][28][29]. This method is very suitable to fabricate polymer hollow micro-balloons [30,31].…”

Design and Application of a Laser Confocal Probe

“…[1] The goal of ICF research is to simulate the controlled laboratory implosion of fusible material to a condition of ignition and burning. The micro-sphere capsule is the key element in the ICF system.…”

“…[2] The surface finish is in the order of 10 nanometers. [1] Position measurement of the target micro-sphere must rely on a non-contact probe with a measurement accuracy ,1 mm.…”