The 2AP1 is a 2 inch electro-statically focused and deflected oscilloscope tube. It features a green P1 phosphor.
The anodes are assembled on ceramic rod supports. The individual elements are crimped to provide a friction fit to the support.
The electron gun is also put together on to the ceramic support rods.
The screen is typical of the period in that it is not completely flat. This slightly domed surface is stronger than a flat sheet and reduces the risk of implosion. True flat screen CRT's were developed much later when improved and laminated glass became available. With a vacuum inside a CRT the glass screen is subjected to a pressure of 15 pounds per square inch and glass is strong in compression and not tension. A domed surface generates compressive forces. The screen is 51 mm in diameter.
The end window envelope is 36 mm in diameter, and excluding the 11 base pins is 175 mm tall.
Reference: Data-sheet. Type 2AP1 was first introduced in 1944. See also1944 adverts.