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Deep geologic repository progress—2025 Update
Editor's note: This article has was originally published in November 2023. It has been updated with new information as of June 2025.
Outside my office, there is a display case filled with rock samples from all over the world. It contains a disk of translucent, orange salt from the Waste Isolation Pilot Plant near Carlsbad, N.M.; a core of white-and-bronze gneiss from the site of the future deep geologic repository in Eurajoki, Finland; several angular chunks of fine-grained, gray claystone from the underground research laboratory at Bure, France; and a piece of coarse-grained granite from the underground research tunnel in Daejeon, South Korea.
Osamu Mitarai, Akira Hirose, Harvey M. Skarsgard
Fusion Science and Technology | Volume 19 | Number 2 | March 1991 | Pages 234-250
Technical Paper | Plasma Engineering | doi.org/10.13182/FST91-A29362
Articles are hosted by Taylor and Francis Online.
The concept of a generalized ignition contour map, showing , and T, is used to study the ignition criterion for a D-3He fusion reactor with plasma temperature and density profiles. Direct heating scenarios to the D-3He ignition regime without the help of deuterium-tritium burning are considered. The machine size and enhancement factor for the confinement time required to reach D-3He ignition can be simply determined by comparing the height of the operation path with Goldston L-mode scaling and the height of the generalized saddle point. A confinement enhancement factor of 2 to 3 is required in the case of a large plasma current (30 to 80 MA) in a small-aspect-ratio tokamak. On the other hand, for a small plasma current (≲10 MA), large-aspect-ratio tokamak, an enhancement factor of 5 to 6 is necessary to reach ignition. Fuel dilution effects by fusion products and impurities, the confinement degradation effect due to 14-MeV protons, and the operation paths are also considered. To lower the height of the saddle point, and hence the auxiliary heating power, we optimize the fuel composition and examine operation in the hot ion mode.
