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RE: [TCML] current limit system and X-rays



It depends on the mean free path of electrons in the tube, hence the high vacuum. If the mean free path is 1/4 the distance between the 2 electrodes in a tube rated 120KV then you will get mostly 30KeV X rays. you might get some X ray production with an AC power supply at TC frequencies, but I think that output will be minimal. These tubes were designed to operate on HVDC.

> Date: Mon, 27 Sep 2010 07:10:10 -0700
> From: jimlux@xxxxxxxxxxxxx
> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] current limit system and X-rays
> 
> David Rieben wrote:
> > Hi,
> > 
> > snipperzz:
> > 
> > ----- Original Message ----- From: "Frank" <fxrays@xxxxxxxxxx>
> > To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> > Sent: Sunday, September 26, 2010 6:00 PM
> > Subject: Re: [TCML] current limit system and X-rays
> > 
> > 
> > 
> >> Almost the universal voltage for most X ray work is 40-60 KV.
> >>
> >> Using an NST will not work unless you can series them, even a 15KV 
> >> transformer will be pushed.
> >>
> > 
> > Actually, dental x-rays typically run 60 to 70 kV at only
> > a few mAs. However, medical x-rays can run >100 kV at hundreds of mAs, 
> > depending on how much soft tissue that
> > must be pentrated to get a clear image of the target "innards".
> > Of course, exposure time is nearly always in the fractions of
> > a second.
> > 
> 
> and it gets trickier than that, because a standard accelerating voltage 
> for medical x-rays is 110kV.. BUT, the actual energy of the xrays coming 
> out is quite a bit less  ( peaking at around 30keV), but a typical x-ray 
> machine will use an aluminum "hardening" filter that filters out the 
> lower energy photons, leaving the remainder averaging up around 50-60 keV.
> 
> But.. it would be unusual to get significant xray production from NST 
> voltages, even in a hard vacuum.  After all, the maximum energy would be 
> the 21kV peak voltage from a 15kVrms NST, and just as with the 110kVp 
> xrays, the vast majority of photons will be much lower energy, and not 
> even make it out of the tube.
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