File:Glow-discharge-tubes.gif

Figure 1 shows what can happen when an electric current passes through a gas discharge tube. A number of visual phenomena may appear, depending on the gas pressure, voltage across the tube, tube length, gas type, and other factors. It should be noted that at the cathode (the source of electrons), the electron density is the same as at the anode.

Figure 2 shows a hypothetical "funnel-shaped" glow discharge tube, in which the cathode is much larger than the anode; the electron density increases towards the anode.

Figure 3 shows a spherical glow discharge tube. The cathode has become a "virtual cathode", and some the glow discharge phenomena have disappeared. The electron density at the anode is much greater than at the virtual cathode.

This work is licensed under the Creative Commons Attribution 2.5 License. https://creativecommons.org/licenses/by/2.5/CC-BY-2.5Creative Commons Attribution 2.5truetrue

Image created by Ian Tresman on July 13th, 2005, based on an images by Hannes Alfvén in his book Cosmic Plasma (1981), p.55

This media file is either in the public domain or published under a free license, and contains no inbound file links. If this media file is useful, then it should be transferred to the Wikimedia Commons. If this media is not useful, then please propose it for deletion or list it at files for discussion.

This file is a candidate to be copied to Wikimedia Commons. Any user may perform this transfer; refer to Wikipedia:Moving files to Commons for details. If this file has problems with attribution, copyright, or is otherwise ineligible for Commons, then remove this tag and DO NOT transfer it; repeat violators may be blocked from editing. Other Instructions Endorse this file for transfer by adding |human=<your username> to this Template. If this file is freely licensed, but otherwise unsuitable for Commons (e.g. out of Commons' scope, still copyrighted in the US), then replace this Template with {{Do not move to Commons|reason=<Why it can't be moved>}} If you think that a local copy of this file should be retained, then replace this Template with {{Keep local|reason=<Why a local copy is needed>}} Please ensure that the file has a properly descriptive and unambiguous name before transferring; see Wikipedia:File mover#What files should be renamed? for details.

This file was suggested for transfer by a bot (User:Fbot). Please verify that this file is suitable for Commons before transferring it.