The main part of this thesis is devoted to the derivation and study of formulas for the probability of survival of the haploid and diploid yeast cell, based on models proposed by Zirkle and Tobias. Some properties of so-called completely monotonic functions are developed, and the results are applied to the investigation of some of the more complicated formulas. Finally the theoretical expressions are compared with the experimental data obtained by Tobias.

"The object of this note is to outline an Omnitron source scheme where the sheath voltage of the Omnitron is not carried over into the reactor region."