The 6GE5 from General Electric is part of their Compactron range of television valves. The 6GE5 is designed to operate as a line timebase output valve with peak anode voltages of 5kV and a maximum anode dissipation of 17.5 Watts.
The anode with side flanges formed at the point of maximum heat generation. The bright beam plate can be seen below the top mica. The control grid is fitted with a heat radiating fin at the top.
The dome carries the Type designation. The Control grid heat sink is U shaped.
The wide glass tube envelope is 38 mm in diameter, and excluding the base pins is 61 mm tall.
Reference: Datasheet. Type 6GE5 was first introduced in 1961.