Temperature Effects on the Behavior of Liquid Hydrogen Isotopes Inside a Spherical-Shell Inertial Confinement Fusion Target

An important task in the inertial confinement fusion (ICF) research is to fabricate targets which will result in high fusion yield. A spherical shell containing a uniform liquid (or solid) deuterium-tritium (D-T) layer on the inner surface represents one of the most popular high-gain ICF target configurations. The uniformity of the D-T layer is a must to achieve the desired high gain. The present work studies the temperature effects on the formation of a uniform liquid hydrogen layer inside a spherical glass shell (SGS). The profile of the liquid layer is first investigated for an isothermal case. An equation suitable for describing the profile is derived by including the London-van der Waals attractive forces between the liquid and substrate molecules. Two theoretical models are then established to explain the changes in the liquid layer profile under the influence of a vertically applied temperature gradient. It is found that a uniform liquid layer of single-component hydrogen can be created and maintained by an appropriate negative temperature gradient, namely, a temperature gradient which will keep the top of the SGS cooler than the bottom. The liquid layer is kept uniform dynamically: there are continuous fluid flows in the regions of the vapor and liquid. The characteristics of the fluid flows are obtained by solving the fluid equations under the low-Reynolds-number approximations. The effect of the component separation both in the liquid layer and the vapor region, which is induced by the temperature gradient, is studied when the enclosure inside the SGS is a mixture of hydrogen isotopes. A uniform layer can also be formed for the mixture liquid except that the required temperature gradient is now positive in direction, unlike the case of the single-component liquid. The heating effect due to the radioactive decay of tritium is also evaluated. An experimental apparatus capable of generating a desired temperature gradient across the SGS at liquid hydrogen temperatures is described. The profiles of the liquid layer are observed for different temperature gradients and the results are in qualitative agreement with the theoretical predictions.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Nuclear Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Mok, Lawrence Shung-Wei

• Engineering, Nuclear

Identifier

(UMI)AAI8422137

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/70897