This experimental valve from RCA has the Type designation of R6241 and we can find no specific details about it. However, it is visually identical to just one valve that we know of and that is the commercial Thyratron 3D22 and CV2851.
The metal base shell carries the development tube label and this exhibit is number 178.
The heater is in the foreground. The locating pip is on the base shell.
The valve is a tetrode Thyratron with two grids. The screen grid is probably the central electrode.
The box anode and the central electrode that is held in a clip attached to the inside of the dome.
The top mica with circular structure above. Looking at the base shows the electrode supports passing through the glass foot.
The seven base pins held in a ceramic disc.
The wide glass tube envelope is 51 mm in diameter, and excluding the B7D base pins is 95 mm tall.
Reference: Datasheet. Type R6241 was first introduced in 1958.