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Cold Cathode Ray Tube, c. 1902
Inventory Number: 25358
Number of documents: 1
Document Type: Miscellaneous Note
Document Heading: Cold Cathode Tube
Text:
Discovery of the properties of cathode rays started with the work on electrical discharges in low-pressure gases between 1875 and 1900 by many scientists including Crookes, Perrin, and J.J. Thomson (later Lord Kelvin). The first use of a cathode ray beam as an oscillograph was by F. Braun of Strasburg in 1897, and in Germany the cathode ray tube is known as the Braun Tube. The original tube used unheated electrodes to which a high voltage was applied to give a discharge through the residual gas in the tube. In 1905, A. Wehnelt introduced the cylinder round the cathode to which a bias was applied to concentrate the beam through the hole in the anode, and he also used the heated cathode with an emitting coating which made possible the lower voltage tubes.
The Braun tube was used to investigate the damped wavetrains used for early radio spark transmissions (i.e. the American early radio pioneer and theoretician, J.S. Stone), and several such tubes survive in museums and universities. It is known that A.C. Cossor made early cathode tubes in the UK.
In 1902, a tube such as this one was used by MacGregor-Morris in England; this tube also conforms closely to the design shown in Nesper, Handbuch der Drahtlosen Telegraphie und Telephonie (Berlin, 1921).
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