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Proud Mary

Sun Jun 21 2009, 05:45PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

I may be biased by my own interest in micro-power miniature soft X-ray sources, but I can't see much of a role for a tube like this in amateur X-radiography.

The greedy power supply, and the problems of shielding will be enough to put off most who think about it.

Much the most interesting X-ray studies are (in my view!

) subjects like insects and fish, which may be done very well with a micro-focus tube with 5-20kV anode voltage at 1 or 2mA. Safe, effective shielding of such soft rays can be done with 1mm or less lead sheet, or even a piece of glass with the softer rays. It's true that the soft rays are much the most dangerous, since they are completely absorbed by the body, but the cost and labour of shielding them is negligible compared with something like your huge Siemens tube., whose use is far more limited than it might first appear.

Unless you are TC freak, more is not always better!

BradStockdale

Mon Jun 22 2009, 12:49AM

Registered Member #2119 Joined: Mon May 11 2009, 04:30PM
Location:
Posts: 15

This tube would be considered a pretty powerful source of x-rays? I misled myself into thinking it wasn't an incredibly powerful tube.My other x-ray tube is a huge rotating anode beast. About a foot long, probably 10" wide at the largest spot. So I thought a 6" x 1.5" tube (approx) would be a 'small' tube... I guess I made a bad assumption.

I'll have to post some pics of my other tube sometime. It is a beautiful specimin. Filaments are still intact and the vacuum is intact as well. The anode doesn't show much wear at all. All in all, a gorgeous tube.

Thank you for letting me know that this is a more powerful tube than I was giving it credit for. As mentioned before, I used to be into nuclear physics much more than I am now, and I'm not planning on getting back into that field anytime in the near future. Already been exposed to enough radiation -- I don't need to add insult to injury. Lol.

Proud Mary

Mon Jun 22 2009, 01:09AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Well now Brad, whether it is 'big' or not is rather subjective - but to give you some idea, I have some excellent tubes with silver, germanium, cobalt, nickel and iron anodes, and none use more than 30kV at 3mA - some of my microfocus tubes use ony 5 - 15 kV @ 500uA - 1.5mA.

If you think about the radiography of living human beings, then absorption must be as little as possible consistent with getting a picture (and that means high kVa) and the exposure must be brief as a camera snap-shot or the patient will surely move, if even ever so slightly, and blur the image. And such things as the cooling of the anode at such power, and operator safety, are other reason for having short, high energy expsoures exposures.

But if I am making an X-radiograph of a small beetle, I can have an exposure as long as I like. A flimsy metal sheet is enough to block all the radiation, whereas your big tubes would require lead and concrete between the machine and the operator station.

There is a lot more to it than that, but unless you are trying to find cracks in steel pipes or concrete castings, less power, rather than more, is the way to go in amateur radiography.

Think of the difference between a shoe-box size desk-top apparatus and the huge assemblies from which those tubes have been taken.

X-rays are very dangerous indeed! So the less power the better. Much amateur radiography could be done more safely if the experimenter paid greater attention to the different methods of image production - intensifying screens, electronic image intensifiers, and so on.

BradStockdale

Wed Jun 24 2009, 12:49AM

Registered Member #2119 Joined: Mon May 11 2009, 04:30PM
Location:
Posts: 15

I've mentioned my other x-ray tube several times in this thread. Thought I would post a few images of it. I'm not sure what it came out of, nor any of the specs. Filaments are good. In the image where it is standing up, it is held by a glass stand with some white silicone sealant 'dots' to protect the glass.

Regards,
Brad

uzzors2k

Wed Jun 24 2009, 09:29AM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

Nice. You've never fallen for the temptation of trying it?

BradStockdale

Wed Jun 24 2009, 01:42PM

Registered Member #2119 Joined: Mon May 11 2009, 04:30PM
Location:
Posts: 15

While I definitely want to try out both of my x-ray tubes, I haven't let myself for a number of reasons:

1) I didn't have an appropriate power supply until I received the flouroscopy system recently
2) I have not the proper shielding materials
4) I do not have the stator windings used to rotate the anode on that big tube. (I'm sure, though, that the tube could be used at lower power levels and for short intervals without the anode rotation in place.)

So, the tubes are meant more for display purposes than anything else...

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