Nuclear fusion
In the same period the laboratory spectroscopy of MIA becomes relevant as a diagnostic tool for hot plasmas of thermonuclear devices (see [[Nuclear fusion]]) which begun with building [[Stellarator]] in 1951 by Spitzer, and continued with [[tokamak]]s, z-pinches and the laser produced plasmas. Progress in ion [[Accelerator physics|accelerators]] stimulated beam-foil spectroscopy as a means to measure lifetimes of exited states of MIA. Many various data on highly exited energy levels, [[autoionization]] and inner-core ionization states were obtained.