Abstract: A vaporizer and extractor apparatus for a laser isotope separation process is arranged as an assemblage of modular components in which equipment subject to maintenance is replaceable via vacuum casks while the apparatus is operational or briefly shut down without loss of vacuum. A vacuum transfer cask is provided for modular extractor substrate assemblies. The substrate assemblies are nestable and are mounted on extensible probes which permit them to be nested in the vacuum transfer cask for transport. During use the substrates extend from the cask, through a vacuum lock and are placed side by side in the vacuum chamber. A vacuum transfer cask is also provided for the vaporizer assembly which is mounted on an extensible arm which in turn positions the assembly in the chamber or retraces the vaporizer assembly from the chamber into the transfer cask, rotating it during the process in order to permit it to fit into the cask.