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In transition: Commercializing fusion power
Commercial fusion power is closer than ever. There are now around 30 U.S. fusion companies, several of which claim to be on track to connect to the grid as early as the 2030s.
Tokamak and laser inertial confinement approaches benefit from decades of research at facilities such as the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory and ITER, with alternative concepts including stellarator, magnetic mirror, and Z-pinch confinement also making notable progress as private and government funding for fusion increases.
G. C. Pomraning
Nuclear Science and Engineering | Volume 127 | Number 2 | October 1997 | Pages 182-198
Technical Paper | doi.org/10.13182/NSE97-A28596
Articles are hosted by Taylor and Francis Online.
The problem of describing steady-state transport of a perpendicularly incident particle beam through a thin slab of material is considered. For a scattering kernel sufficiently peaked in momentum transfer to allow a Fokker-Planck description of the scattering process in both energy and angle, an approximate closed form solution to this problem was obtained almost 50 yr ago and is referred to as the Fermi-Eyges formula. It is shown that a Fermi-Eyges-like formula can be derived for a broader class of scattering kernels. This class consists of scattering described by the continuous slowing-down approximation (the Fokker-Planck description in energy), but not sufficiently forward peaked in angle to allow an angular Fokker-Planck representation. This generalized formula reduces to the classic Fermi-Eyges result for scattering operators with a valid Fokker-Planck limit and also describes problems that, while involving a forward-peaked scattering kernel, do not possess a Fokker-Planck description. A classic example of such a kernel is the Henyey-Greenstein kernel, and the Fermi-Eyges-like solution in this case exhibits more beam spreading than that predicted by the classic Fermi-Eyges formula. In particular, the scalar flux is non-Gaussian in the radial coordinate, as contrasted with the Gaussian Fermi-Eyges result.