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Re: Using X-rays to Measure Tesla Coil Voltage



---------- Forwarded message ----------
Date: Fri, 26 Sep 1997 13:19:29 -0400
From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Using X-rays to Measure Tesla Coil Voltage



> From: 	Greg Leyh[SMTP:lod-at-pacbell-dot-net]
> Sent: 	Tuesday, September 23, 1997 5:00 AM
> To: 	Tesla List
> Subject: 	Re: Using X-rays to Measure Tesla Coil Voltage
> 
> Fr. Tom McGahee wrote:
> 
> 
> 
> > > > The unit was our standard model M-150 running with a 14.4 kV 
> > > > pole xmfr as the power source.  As to the measurement
equipment, 
> > > > well, lets just say I have some friends at a local university
who 
> > > > "borrowed" (unofficially of course --- and for only a 4 day
period) 
> > > > some unique test equipment from a well equipped physics dept
and 
> > > > they took the measurements. Can't say much more without
shooting 
> > > > myself in the foot in case I might need some more equipment
for 
> > > > short term use in the future.
> > > > DR.RESONANCE
> > >
> > > Can you at least mention the general principle behind the
> > > measurement?
> > > -GL
> > 
> > Greg,
> > When I was in high school in the mid 1960's I built (among other
> > things) a number of homemade x-ray machines. These ranged all the
way
> > from 40KV to 250KV units. The intensity of the x-rays produced
was a
> > function of current. The penetrating ability of the x-rays was a
> > function of voltage. I was able to "calibrate" my machines
through
> > the use of a set of stepped wedges that were made of strips of
> > aluminum and steel. The higher the KV, the greater the thickness
> > through which the x-rays could penetrate. I was able to get the
> > radiology department of the local hospital to x-ray my step wedge
in
> > 25KV increments. Then I used the negatives to calibrate my step
> > wedge.
> 
> Thumbs up!!  I'll bet that the folks at the radiology dept didn't
> get too many requests like that, especially from HS students.
> 
> Did your stepped wedge seem fairly linear, that is could you just
> stack up four 50kV wedges to get a 200kV wedge?
> 
> 
> -GL
> 
> 

Greg,
As I recall, it was pretty linear. I know that there was a certain
ammount of non-linearity when I was dealing with the LOWER KV ranges,
but I believe that that was probably attributable to my not taking
into account the initial KV level required to penetrate through the
glass envelope of the x-ray tube and air absorbtion (which is greater
for the low KV range). In fact, at the really low KV range where
x-ray production was just beginning to show itself, the rays had very
little penetrating ability and so the chance for error in making
measurements was greater. If I remember correctly, when going from
100KV to 200KV the step was quite linear. But I may be wrong... it
was more that 30 years ago and I don't have my written notes on that
stuff available any more. But check with a radiologist to make sure.

Hope this helps.
Fr. Tom McGahee