X-rays from Radio Tubes

Abstract

The radiographic illustrations which are presented in this article prove that x-rays can be produced for experimental purposes with a unit which can be built for a very small fraction of the cost of installation of a standard x-ray unit. The apparatus consists essentially of a 1/10 hp. motor which operates a rotor whose function is to raise the frequency of the current; a set of brushes for conducting the current from the rotor to the block of condensers (0.16 MF) ; a “kick coil” of 24-ohm capacity; a resonator for building up the voltage, and an old 01-A radio tube. The schematic plan of the apparatus is given in Figure 1. The construction of the apparatus is very simple. A “kick coil” consisting of one and one-quarter pound of No. 24 silk covered wire is wound on a bakelite core five-eighths inch in diameter and three inches long. The purpose of this coil is to excite the primary circuit of an Oudin resonator which consists of six turns of No. 10 cotton-covered space-wound wire which is connected to two ounces of No. 32 double cotton-covered space-wound wire which composes the secondary. The primary of the resonator is further excited by the use of a block of condensers which are connected as indicated in Figure 1. The tube used is of the familiar 01-A type, the four prongs being shorted. A copper cap is placed on the tube and connected to the resonator, the prongs being connected to a suitable high resistance. The rotor used to raise the frequency of the current is driven by a 1/10 hp. variable-speed motor and consists of a brass disk four inches in diameter and one-half inch thick in which are placed at one-inch spaces, one-quarter inch mica segments. A rear view of the assembly is shown in Figure 2. Its total weight is 28 pounds. The machine, when in operation, will produce a beam of x-rays easily detected for a distance of several feet in all directions. With r meter measurements the writers determined the intensity of the rays to be three-fourths of an r unit per minute, at a distance of three feet.