Spiral focusing for cathode-ray tubes

This paper describes a resistive lens or spiral lens, which uses a controlled voltage distribution on the inside of a cylinder for focusing. Electron-optically, this long electrostatic lens shares many of the features of a magnetic solenoid. These include a low degree of spherical aberration, high beam transmission, and a capability to operate as an immersion lens with an ultimate magnification of unity. An application of the spiral lens is presented, including lens design, circuit features, and performance testing of a radar indicator tube with spiral focusing.