The actual limitations for the trapped field in
YBa2Cu3O7−δ
(YBCO) monoliths are discussed. The influence of the sample geometry and of the critical
current density on the trapped field is investigated by numerical calculations. The field
dependence of the critical current density strongly influences the trapped field. A nonlinear
relationship between the sample size, the critical current density and the resulting
trapped field is derived. The maximum achievable trapped field in YBCO at
77 K is found to be around 2.5 T. This limit is obtained for reasonable geometries
and high but realistic critical current densities. Such high fields have not been
reached experimentally so far, due to non-optimized flux pinning and material
inhomogeneities. These inhomogeneities can be directly assessed by the magnetoscan
technique, and their influence is discussed. Significant differences between the
a- and
the c-growth sectors were found. Limitations due to cracks and non-superconducting inclusions
(e.g. 211 particles) are estimated and found to be candidates for variations of
Jc
on a millimetre length scale, as observed in experiments.
Keywords: Nuclear fusion Inertial confinement Magnetic confinement Radiation damage Materials DiagnosticsThis work aims at identifying common potential problems that future fusion devices will encounter for both magnetic and inertial confinement approaches in order to promote joint efforts and to avoid duplication of research. Firstly, a comparison of radiation environments found in both fusion reaction chambers will be presented. Then, wall materials, optical components, cables and electronics will be discussed, pointing to possible future areas of common research. Finally, a brief discussion of experimental techniques available to simulate the radiation effect on materials is included.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.