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BELL SYSTEM TECHNICAL JOURNAL 



Straight lines normal to the cathode surface. A hole in the anode electrode 

 will allow the beam to emerge from the gun. Because of the change in 



Fig. 7 — Electron gun utilizing rectilinear flow. 



CATHODE ANODE SPACING, d/rQ 

 Fig. 8 — Relation between perveance, angle of cone of flow, and cathode-anode spacing. 



field near the hole, the hole acts as a diverging electron lens. Figure 7 

 illustrates such a gun.^^ The curves shown in Fig. 8 relate to this sort of 



