The Cathode Ray Tube—a Development of the General Electric Research Laboratory

Abstract

HomeRadiologyVol. 8, No. 1 PreviousNext EditorialThe Cathode Ray Tube—a Development of the General Electric Research LaboratoryPublished Online:Jan 1 1927https://doi.org/10.1148/8.1.77bMoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In AbstractA vacuum tube which produces as many electrons per second as a ton of radium— and there is only a pound of that rare substance in the world—was announced by Dr. W. D. Coolidge of the Research Laboratory of the General Electric Company at a meeting of the Franklin Institute of Philadelphia, on the occasion of the award to him of the Howard N. Potts gold medal of the Institute for his outstanding work in the development of X-ray tubes.Radium is constantly disintegrating, and in so doing is bombarding electrons—infinitely small particles of matter or electricity—into space at very high velocities. The rate at which radium disintegrates is beyond human control; nothing that man can do seems to affect the rate at which the element breaks down. The cathode ray tube likewise bombards high speed electrons into space, but at a rate that can be controlled by man, and in quantities far greater than by all the radium in the world. The electrons given off by radium are of higher average velocity than those so far produced with the cathode ray tube, but otherwise the two are alike.So much more concentrated are the rays from the tube that many startling experiments have been conducted with the new device. Crystals of the mineral calcite apparently become red hot coals when exposed for a moment to the rays, but they are glowing with cold light; ordinary salt is turned brown, and considerable time elapses before it again becomes the colorless substance it usually is; bacteria and small flies are almost instantly killed by exposure to the rays; ordinarily colorless acetylene gas is transformed into a yellow solid which cannot be dissolved; and a rabbit's gray hair has been destroyed, to be replaced later by a profuse growth of longer, snow-white hair.Cathode rays have been known to some extent for many years. At first, however, thev were known only within vacuum tubes, but about thirty years ago a European scientist, Lenard, succeeded in making the electrons pass through a tiny piece of extremely thin aluminum foil cemented to the glass wall of the tube. Improvements have been numerous since then, but with previous tubes the metal "windows" were much smaller and the operating voltages much lower than with the new tube.Several unusual features have been incorporated in the new tube. There is a “window” three inches in diameter, of nickel foil the thickness of which is measured in thousandths of an inch and which is capable of withstanding a total atmospheric pressure of more than a hundred pounds. A heated tungsten filament, originally used by Dr. Coolidge in the X-ray tube and now known to all as an essential part of radio tubes, furnishes the supply of electrons.Article HistoryPublished in print: Jan 1927 FiguresReferencesRelatedDetailsRecommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 8, No. 1 Metrics Altmetric Score PDF download