Re: lightning, Xrays

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>


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From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, February 28, 2003 4:29 PM
Subject: Re: lightning, Xrays


 > Original poster: "Malcolm Watts by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
 >
 > Hi Jim,
 >
 > On 26 Feb 2003, at 18:02, Tesla list wrote:
 >
 >  > Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>"
 > <jimlux-at-earthlink-dot-net>
 >  >
 >  > I see from the news
 >  > http://www.napa.ufl.edu/2003news/lightxray.htm
 >  >
 >  > that there has been experimental measurement of Xray emission from
 >  > lightning strokes.
 >  >
 >  > It's historically been the case that you needed both HV and High Vacuum
to
 >  > get Xrays.  Therefore, there's no radiation hazard from, e.g., a tesla
coil.
 >  > Here's a case (not likely to be duplicated by the casual amateur) where
you
 >  > get Xrays with HV, but no vacuum.
 >  > I was aware that you can get Xrays from very fast rise time sparks
(>1E9
 >  > A/microsecond, as I recall), but this is something new...
 >  >
 >  > It's also in Science, vol 299, page 694-697 "Energetic Radiation
Produced
 >  > by Rocket-Triggered Lightning", J.R.Dwyer, et.al.
 >
 > The key word there might be "triggered". Question is, do X-rays occur
 > if there is no metal present in the discharge path? All those man-
 > made devices that produce X-rays "in a vacuum" are firing energetic
 > electrons at metal targets.
 >

I've read the article in Science now.. apparently, various and sundry forms
of energetic radiation have been detected in connection with lightning and
thunderstorms before, but they never had "detected events" well correlated
with a particular stroke, which the UF lightning lab does quite nicely. They
took some reasonable precautions to insure that the huge EMP didn't throw
off the measurement, which was basically made with a NaI(Tl) scintillator on
a PMT.  Many photons at once, so they don't have a good measurement on
energy.

There is also some other literature (cited in the Science paper) which talks
about how the other measurements (non-triggered) had been theorized to be be
part of the stepped leader process, but, since the triggered lightning
doesn't work the same way, it might not.