Re: Neon Transformer Question

On Sat, 22 Aug 2009 12:43:32 -0400, default <default@xxxxxxxxxxxxx>
wrote:

On Fri, 21 Aug 2009 17:36:20 -0500, "bw" <bwegher@xxxxxxxxxxx> wrote:

Jon
P.S. Problem with higher voltages, which do make for great ladders, is
that you also may wish to worry about x-rays and view the ladder from
some distance. A dentist's machine will operate often at around 70kV
and produce quite useful levels of hard x-rays. At 7.5kV or less, I
wouldn't be nearly as worried but just keep it in mind. (Old TVs were
required by the FDA to limit exposures to about 0.5 mRem/hr, but they
use accelerating voltages that vary from around 12-15kV for smaller
ones to maybe 25kV or more for larger sets. Color TV uses higher
voltages [from my experience, anyway] than monochrome, as well.)

Yes, all people need to be CAREFUL with any of this, especially the casual
usenet reader.

No disagreement to that last. There are lots of ways to kill yourself
(without ever owning a motorcycle, or swimming with sharks, ocean
kayaking, or other interesting things)

BUT from my own experience: leaving undeveloped film around the TC:
It takes roughly 10KV (with a vacuum tube) and over, to produce
X-rays, and at the lower voltages it helps to have a heated cathode to
produce "soft" X-rays.

At 100 KV, the technique is a lot less particular. A TC operating at
100KV, just ionizing air, will produce tons of ozone (which can kill
you just as dead) but no X-rays. Put any evacuated tube on the top
terminal and you get X-rays of some sort. Most of the time it is just
enough to fluoresce the glass of the bulb and fog film placed next to
it, but put a two element high vacuum diode from an old color TV on
the top terminal and you have X-rays in abundance - for fogging film
at a distance.

Its my understanding that the vacuum toobe manufacturers eventually
started adding lots of lead to the glass formula to decrease X
radiation. Older TV's used steel boxes to house the damper diode and
rectifier diode.

My conclusion is: you have to want to produce X-rays to do it, but
there are lots of ways to kill yourself that don't include ionizing
chromosomal damage and a slow death to cancer - like ozone and a slow
death to cancer, or instant electrocution.

Play safe

Priorities: Be Safe, Have Fun, Don't Get Caught (in that order)

As a first-draft hack at your list, I'd insert:

Learn new stuff, ... then your list

Some things cannot be learned well without some risk-taking involved.
And some of those things which are exciting and energizing enough to
provide enough motivation to get over the hurdles of study or hard
work involved in the learning experience also happen to be risky, as
well. The balancing act between motivation, risk, and educational
rewards is complex, of course, and depends also in part on the
maturity of those getting the education and the partners they can find
to help mitigate risks in the process without losing sight of what's
being learned.

And despite all of the above sometimes exploring new territory is
still going to be injurious. Everyone knows about the Curie family
example. But basic research isn't always safe, nor should it be.
Risks need to be taken at times. It's just that all known sources of
risk should be accounted for and balanced with other goals as well as
possible. How well that is done will depend on the skills and
experience of those involved. And nothing is perfect in that regard,
either.

If I were a sign-carrier on this topic, it would read:

Yes! to risk mitigation
No! to risk avoidance
Learn! Explore! Do!

It was wonderful to read that you used film to test out x-ray
generation. Your demarcation of 10kV is roughly consistent with
numbers I have in my head from very vague theory and some metals
(tungsten, in particular.) I don't know, though, if you went to the
trouble of securing film that is uniquely sensitive to x-rays. Did
you? (There is pretty good film around, these days. Variations of
sensitivity across the surface of xray film is on the order of a few
percent, probably well below any hobby level of repeatability.)

By the way, there are some nifty experiments to be performed with
x-rays. The usual diffusion equations applied to electrons striking a
point in the metal (and here again that infinite resistor grid comes
to mind as an image to me) don't work well, partly because it is only
valid when the electrons are near enough in speed and dissimilar
enough in their direction that they that they all behave very close to
the mean case. That isn't the case. The mean free path depends on
the span between the eV of the source beam and the excitation energy
required/allowed by the K shell of the target atoms. So I think the
simplifying rule doesn't work and the actual function needs to be
explored, experimentally. Okay. Probably has been. But it would be
interesting to do it on as-yet unexplored materials, if any. Or gases
like air (which you say doesn't appear to generate xrays at the
voltages you've tried.)

There's a world out there to poke at!

Jon
.

Relevant Pages

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