Talk:X-ray tube

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This article is surreptitious advertising and not a scientific paper! Take this page with a pinch of salt!

It is also highly limited in scope; to medical imaging.192.25.144.225 15:32, 5 May 2006 (UTC)[reply]

Advertising? How? Yes, the wording is a bit strange in places, and it is overly concerned with medical matters, but I don't see any advertising. Crooks and Coolidge aren't collecting revenues any more, and haven't been for some decades. --Speedevil 11:47, 6 September 2007 (UTC)[reply]

This page suffers from horrible duplication. Much of the comment on each variant tube is simple rewording of the others. --Speedevil 12:34, 17 September 2007 (UTC)[reply]

Hazards, X-ray tubes?[edit]

Under this heading is: "CRT's running at 30 to 40 kV"...They run at about 15-20 kV. Substantial X-rays aren't produced until 40 kV is dropped between the anode-cathode. Even then, most glass had lead in it, and few X-rays would be emitted unless cathode current was high. A rectifier tube usually runs in a saturation region--high filament/cathode current--and, hence, the potential drop is usually only a few kV. Otherwise, the rectifiers wouldn't be efficient.68.231.189.108 (talk) 15:01, 16 October 2009 (UTC)[reply]

Somewhat late but: the CRT in the last CRT TV that I had ran at 33kV. Further the projection tubes used in early projection TVs (circa 1950-1955) were found to emit significant amounts of X-rays when they were operated outside of their optical unit (i.e. the hazard was to service engineers, not the users. They operated at 25kV, but it was the rather high beam current that contributed to the x-ray production. 86.177.111.9 (talk) 17:21, 10 August 2011 (UTC)[reply]
I'm in the 25kV team. Of course, I can't prove that someone didn't use higher. The source (11) quoted in the article gives a max value of 35kV, so it does not justify the 40kV stated in the article. That source does not look very reliable to me ("Edited by Glenn Elert -- Written by his students" and taken from yet another source, which I cannot trace at all.)
The final sentence seems odd. The threshold for radiation production at any frequency is completely defined by the voltage. The current affects only the intensity of the radiation, not the frequency. If you needed 40kV to produce x-rays, then you would not get any x-rays however much current was passed at 25kV.
What energy corresponds to x-rays is a bit arbitrary. https://en.wikipedia.org/wiki/X-ray says soft x-rays start at 100eV! And hard x-rays at less than 10keV. By that standard vitually all thermionic valves would emit x-rays and, because even small power valves run at 100's of mA, significant quantities.--Merlin3189 (talk) 20:13, 25 November 2016 (UTC)[reply]
Most sources seem to give a figure for CRT anode voltage of 25 kV [1] but the McGraw-Hill Encyclopedia of Science and sci.electronics FAQ says up to 35 kV. These were for color CRTs; the 15-20 kV range 68.231.189.108 quotes was for earlier black & white CRTs. The projection tubes mentioned by 86.177.111.9 are an x-ray hazard because they operate at a higher voltage of 50-100 kV. [2], [3] As Merlin3189 says, x-rays can be produced by voltages as low as 100 V; the issue is how much can penetrate the glass envelope of the tube to become a hazard. The soft x-rays produced by voltages below 10 kV cannot penetrate even the thin glass envelope of ordinary vacuum tubes [4] and so tubes operating at voltages below this are safe. --ChetvornoTALK 16:34, 26 November 2016 (UTC)[reply]

Crookes' Tube[edit]

It is not clearly stated, that Röntgen used a Crookes' Tube when he discovered X-rays. In fact, he stated in his very first letter here, that all kinds of discharge tube are equally suited. Dschoni (talk) 17:09, 30 March 2017 (UTC)[reply]

You picture is of an early; self-rectified, vacuum-regulated X-Ray tube; not a Crookes' tube. They are pear-shaped, with only two electrodes.68.231.189.108 (talk) 15:12, 16 October 2009 (UTC)[reply]

Also, you mentioned X-Ray power supplies were "rectified high-voltage transformers" (until switching power supplies became more practical/affordable with solid state devices.)Rectified hi-voltage was used, for a short while, but then most tubes went to beefier electrodes to become the "Self-rectified" type. Unless for very high currents, these are still generally used for exposures of one second or less.68.231.189.108 (talk) 15:12, 16 October 2009 (UTC)[reply]

I am not an expert and don't want to put misinformation in the article if I'm wrong. But I think the first caption has "left" and "right" mixed up. If someone more knowledgeable could look at this I would be greatful. Specifically, I think:

Coolidge X-ray tube, from early 1900s. The heated cathode is on the right, and the anode is left. The X-rays are emitted downwards.

should be

Coolidge X-ray tube, from early 1900s. The heated cathode is on the left, and the anode is right. The X-rays are emitted downwards.

207.172.220.9 (talk) 22:41, 20 January 2008 (UTC)[reply]

You're right. I screwed up the description when I added the picture. Thanks for catching my dislexia! --ChetvornoTALK 16:23, 15 June 2008 (UTC)[reply]

Grid Controlled X-Ray Tubes[edit]

Hi, it will be a great value add for having a section covering Grid Controlled X-ray tubes in this article. This technique is useful in reducing continuous X-ray dosage to patients in Fluoroscopy. I will be grateful if someone knowledgeable looks into this. — Preceding unsigned comment added by SirajIssani (talk • contribs) 05:29, 19 March 2011 (UTC)[reply]

Rotating Anode Type[edit]

What is the purpose of the rotating anode type? Probably it's a better thermal restistance, but it is not mentioned. So we rather should explain the benefits of this setup, then how a induction motor works. 46.5.54.206 (talk) 17:20, 14 December 2015 (UTC)[reply]

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