The invention relates to a method for the real-time determination of the filling level of a cryogenic tank intended to house a two-phase liquidgas mixture, in which at least one of the the level, volume or mass contained in the tank is calculated for the liquid or the gas at each time step. One example embodiment include vertical routing of test nest assembly cooling lines in order to minimize the test nest footprint and increase available test sites on a single test card. The middle region is arranged to shift the peak of plasma density to the outside of the peripheral edge of the target substrate.