“…Other electron microscopes equipped with superconducting lenses but with somewhat poorer resolution are or were available at the following institutions: Cornell University, Ithaca [106], Enrico Fermi Institute, Chicago [77,78], Collège de France, Paris [112], Faculté des Sciences, Rheims, France [89], Hitachi, Tokyo [87], Laboratoire d'Optique Electronique de CNRS, Toulouse, France [93], Oak Ridge National Laboratory, Oak Ridge [89], Institute fur Experimentalle Kernphysik, Karlsruhe Germany [113], and Academy of Sciences, USSR [114]. The accelerating voltages of these electron microscopes range from 50 to 5000 kV [113], the consumption of helium is typically ~1 liter/h, and in most cases the superconducting lenses, operate in the persistent mode.…”