Abstract :
In considering the function of initial concentration and ray focusing it is found, for tubes using slow electrons (up to 4000 volts), that both a Wehnelt cylinder and a molecular concentrator are necessary. The action of molecular concentration has been studied thoroughly, and the static relation between pressure, beam current, and anode potentials are explained. The use of plate potentials higher than about 5000 volts was found to be unsuitable. Special phenomena accompanying such concentration are taken up, including the effect of ionic oscillations and the problem of lack of sharpness with high-frequency deflections. A remedy for the former was found in a grounded metallic outside coating, and for the latter an improvement was found by filling with light gas (hydrogen, helium). The processes in the gas space and the deflection of electrons were then investigated. The various methods for reducing secondary illumination are described. In conclusion, the reaction of the Braun tube upon the circuit was taken up and the avoidance of distortion and origin displacements by means of circuit precautions are described.
