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File:Braun cathode ray tube.jpg

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Description
English: Drawing of the first cathode ray tube invented by German scientist Ferdinand Braun in 1897. It was a cold cathode tube, developed from the Crookes tube and so did not have a heated filament to produce electrons. Instead it produced electrons by ionization of residual gas in the tube with a high voltage. The tube contains a platinum cathode electrode (right end), an anode electrode consisting of an open tube in the neck to focus the electrons into a narrow beam (center right), a pair of flat deflection plates (center left), and a paper screen (left) painted on the inner side with a fluorescent chemical like zinc sulfide or calcium tungstate. When a high voltage is applied between the cathode and anode, it creates positive ions which are attracted to the negative cathode. When they strike the cathode they knock out electrons (cathode rays) which are accelerated down the tube to the left, through the anode tube, between the deflection plates, and strike the fluorescent screen at the left end, producing a glowing spot. If a second voltage is applied between the deflection plates the electron beam will be repelled by the positive plate and attracted toward the negative plate, so the spot on the end screen will move toward the positive plate.

The small curved side tube attached to the neck (right) is called a "softener". The residual air in the tube, necessary for ionization, tended to be absorbed by the walls over time, making the vacuum "harder", so the tube would eventually stop functioning. The softener tube contained a pellet of chemical that would release gas when heated. If the tube stopped producing cathode rays, a flame would be played over the softener tube, releasing gas to "soften" the vacuum so it would work again.
Date
Source Retrieved on 11 October 2013 from Eugen Nesper 1921 Handbuch der Drahtlosen Telegraphie und Telephonie, Julius Springer, Berlin, p. 78, fig. 46 on Google Books
Author Eugen Nesper

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This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.

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Date/TimeThumbnailDimensionsUserComment
current15:28, 7 May 2017Thumbnail for version as of 15:28, 7 May 20171,084 × 216 (47 KB)Quibikdenoise a bit
15:21, 7 May 2017Thumbnail for version as of 15:21, 7 May 20171,084 × 216 (49 KB)Quibikremove halftone noise
20:59, 11 October 2013Thumbnail for version as of 20:59, 11 October 20131,084 × 216 (38 KB)ChetvornoUser created page with UploadWizard

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