Developing target injection and tracking for inertial fusion energy power plants

Fuelling of a commercial inertial fusion energy (IFE) power plant consists of supplying about 500 000 fusion targets each day. The most challenging ty pe of target in this regard is that for laser driven direct drive IFE power plants. Spherical capsules with cryogenic DT fuel must be injected into th e centre of a reaction chamber operating at temperatures as high as 1500 de grees C and possibly containing as much as 0.5 torr of xenon fill gas. The DT layer must remain highly symmetric: have a smooth inner ice surface fini sh and reach the chamber centre (CC) at a temperature of about 18.5 K. This target must be positioned at the centre of the chamber with a placement ac curacy of +/-5 mm. The accuracy of alignment of the laser driver beams and the target in its final position must be within +/-20 mum. All this must be repeated six times per second. The method proposed to meet these requireme nts is to inject the targets into the reaction chamber at high speed (appro ximate to 400 m/s). track them, and hit them in Right with steerable driver beams. The challenging scientific and technological issues associated with this task are being addressed through a combination of analyses, modelling , materials property measurements and demonstration tests with representati ve injection equipment, Measurements of relevant DT properties are planned at Los Alamos National Laboratory. An experimental target injection and tra cking system is now being designed to support the development of survivable targets and demonstrate successful injection scenarios. Analyses of target heating are under way. Calculations have shown that a direct drive target must have a highly reflective outer surface to prevent excess heating by th ermal radiation. In addition. heating: by hot chamber fill gas during injec tion far outweighs that by the thermal radiation. It is concluded that the dry wall, gas filled reaction chambers must have gas pressures and wall tem peratures less than previously assumed in order to prevent excessive heatin g in current direct drive target designs. An integrated power plant systems study to address this issue has been initiated.