Relation between ion spot growth and gas ratio in storage tubes

In a recording Storage tube, the relation between the rate of growth of the central maximum of the ion spot and the gas content is shown to be strongly non-linear. However, by integrating over the entire ion spot, it is possible to calculate the positive ion current and, from that, the gas ratio and gas content. It is concluded that, whenever possible, gas content should be determined by gas ratio measurements rather than by ion spot growth. The effects of an excessive gas content are discussed briefly.