ELECTRON GUN

electrode structure that produces and may control, focus, and deflect a beam of electrons, as in a television picture tube, where the beam produces a visual pattern on the tube's screen. At one end of the gun is the cathode, a flat metal support covered with oxides of barium and strontium. When heated by a coil behind the support, these oxides emit electrons, which are drawn toward a positively charged sleeve (first anode) and partially intercepted by a flat disk (the control electrode).