A New Layering Method for Indirect Drive IFE Targets Progress Report for the Periods August 15, 2000 through December 14, 2001

Layering is the process whereby condensed deuterium tritium (DT) fusion fuel at 18-19 K is very uniformly distributed on the inside wall of an Inertial Fusion Energy (IFE) target. The quality and uniformity of the DT layer has a profound effect on the performance (gain) of the target. It would be a great advantage for indirect drive targets to carry out layering with the capsule already assembled in the hohlraum. One concept to accomplish this is to layer targets in controlled temperature, cryogenic tubes while they are being staged for feeding to the injection system. In this report we have demonstrated through extensive analysis that in-hohlraum layering is possible, but that variations in dimensions, alignments and material properties can easily cause the capsule temperature nonuniformity to exceed values needed to assure proper fuel layering. The concept shows sufficient promise to warrant continued investigation. Analysis alone cannot demonstrate the feasibility of in-hohlraum layering. One of the most basic and important experiments is the measurement of the properties of hohlraum materials. Such measurements must be performed with sufficient accuracy to demonstrate predictability and repeatability to the level of precision needed to maintain thermal control. Continued close interaction between target designers and target fabricators is needed to ensure development of a cost-effective target design