Electron Beams and Their Applications in Low Voltage Devices

A study has been made of the segregation into beams of the space current in devices of the over-all size of commercial receiver tubes and at potentials less than 300 volts. Electrode coatings of luminescent material were used to make the beam traces apparent on any or all electrodes. Qualitative relationships between beam formations and relative electrode potentials are stated. Space currents of a few milliamperes have been concentrated into beams less than 0.010 inch wide in simple structures. Special control grids associated with conventional cathodes have been found to combine good space current control with effective beam formation. These effects together with control of beam width and direction can be obtained in a single device. Simple structures are used to segregate the electron discharge from a single cathode into a few or many similar electron beams. Between such structures and the outermost electrodes are placed perforated positive electrodes with their openings disposed to receive and pass the electron beams. Such electrodes are found to receive as little as two per cent of the current computed from their projected area. Such perforated electrodes include conventional type grids. The relationships between beam widths and electrode potentials have been found to be such that mutual volt-ampere relations can be radically different from those hitherto utilized. Linear, saturation type, or special volt-ampere relations can be obtained.