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In inertial fusion energy (IFE) power plant designs, the fuel is a spherical layer of frozen DT contained in a target that is injected at high velocity into the reaction chamber. For direct drive, typically laser beams converge at the centre of the chamber (CC) to compress and heat the target to fusion conditions. To obtain the maximum energy yield from the fusion reaction, the frozen DT layer must be at about 18.5 K and the target must maintain a high degree of spherical symmetry and surface smoothness when it reaches the CC. During its transit in the chamber the cryogenic target is heated by radiation from the hot chamber wall. The target is also heated by convection as it passes through the rarefied fill-gas used to control chamber wall damage by x-rays and debris from the target explosion. This article addresses the temperature limits at the target surface beyond which target uniformity may be damaged. It concentrates on direct drive targets because fuel warm up during injection is not currently thought to be an issue for present indirect drive designs and chamber concepts. Detailed results of parametric radiative and convective heating calculations are presented for direct-drive targets during injection into a dry-wall reaction chamber. The baseline approach to target survival utilizes highly reflective targets along with a substantially lower chamber wall temperature and fill-gas pressure than previously assumed. Recently developed high-Z material coatings with high heat reflectivity are discussed and characterized. The article also presents alternate target protection methods that could be developed if targets with inherent survival features cannot be obtained within a reasonable time span.

A central feature of an inertial fusion energy (IFE) power plant is a target that has been compressed and heated to fusion conditions by the energy input of the driver. This is true whether the driver is a laser system, heavy ion beams or Z-pinch system. The IFE target fabrication, injection and tracking programmes are focusing on methods that will scale to mass production. We are working closely with target designers, and power plant systems specialists, to make specifications and material selections that will satisfy a wide range of required and desirable target characteristics. One-of-a-kind capsules produced for today's inertial confinement fusion experiments are estimated to cost about US$2500 each. Design studies of cost-effective power production from laser and heavy-ion driven IFE have suggested a cost goal of about $0.25-0.30 for each injected target (corresponding to ∼10% of the 'electricity value' in a target). While a four orders of magnitude cost reduction may seem at first to be nearly impossible, there are many factors that suggest this is achievable. This paper summarizes the design, specifications, requirements and proposed manufacturing processes for the future for laser fusion, heavy ion fusion and Z-pinch driven targets. These target manufacturing processes have been developed-and are proposed-based on the unique materials science and technology programmes that are ongoing for each of the target concepts. We describe the paradigm shifts in target manufacturing methodologies that will be needed to achieve orders of magnitude reductions in target costs, and summarize the results of 'nth-of-a-kind' plant layouts and cost estimates for future IFE power plant fuelling. These engineering studies estimate the cost of the target supply in a fusion economy, and show that costs are within the range of commercial feasibility for electricity production.

The long-range goal of the Z-Pinch IFE program is to produce an economically-attractive power plant using