Some problems in the design of a direct view storage tube

The direct view storage tube here described has a multi-grid target assembly and two separate electron guns, one for writing and another for viewing. One problem in developing this tube was to study viewing duration, or time of continuous display of information previously written as a function of pressure. Residual gas within the tube is ionized by passage of the electron beams. Positive ions from within the target structure land on the storage layer, and erase the stored picture. This very good vacuum is necessary for long viewing duration.