Electron Optical System of Two Cylinders as Applied to Cathode-Ray Tubes

The electron beam of a cathode-ray tube is usually focused by means of an electron optical system of two coaxial cylinders. This paper presents a detailed treatment of such a focusing system and is divided into two parts. Geometric electron optics of axially symmetric electrostatic fields is presented in Part I. This part deals with (1) the analogy between light and electron optics, (2) motion of electrons in axially symmetric electrostatic fields, (3) definition and determination of positions of cardinal points due to axially symmetric electrostatic fields, and (4) thick and thin lenses. The lenses equivalent to the electrostatic fields of two coaxial cylinders are discussed in Part II. This part deals with (1) positions of cardinal points due to two coaxial cylinders of various diameters and at various voltages, (2) use of such cardinal points, (3) experimental determination of positions of cardinal points, and (4) spherical aberration of electrostatic field due to two cylinders. The results are applied to the cathode-ray tube, throughout the discussion.