RE: vacuum tube construction. (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 13 Aug 2007 22:06:39 -0700
From: Anthony R. Mollner <penny831@xxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: vacuum tube construction. (fwd)

I would be interested in seeing that article.
Tony

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Monday, August 13, 2007 7:45 PM
To: tesla@xxxxxxxxxx
Subject: RE: vacuum tube construction. (fwd)



---------- Forwarded message ----------
Date: Mon, 13 Aug 2007 16:23:27 -0700
From: Frank <fxrays@xxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: vacuum tube construction. (fwd)

Hi,
  X ray production begins with voltages above 20KV, a tube running at 
600 V as stated will not produce any  X rays.
X rays at the lower level are called soft X rays and will easily pass 
thru soft tissue. This level is radiation is not as dangerous as 
harder X rays but one still has to pay attention to it!

For sure, if you have a vacuum system good enough to overcome leaks, 
you can get to an X ray vacuum, a Lenard's tube is a good example of this.

If a tube does not have X ray element construction, it will generate 
X rays but they are so diffused and scattered it is very hard to get 
any serious exposure from them.
A Maltese cross tube was the first unfocused X ray tube and very 
difficult to obtain useable results.
After Jackson made the focus tube, X rays then became a useable 
medical tool. Even the Coolidge tube is a focus type tube.

A Tesla type X ray tube is a single element tubes that generates X 
rays in an unfocused manner much like a Maltese tube.

Believe it or not, an old radio tube can be turned into an X ray tube.
If anyone likes, I can send then an antique article on making an X 
ray machine. It uses a high frequency Tesla coil to excite a radio 
tube and there are complete instructions on how to make the HF coil.

Frank



At 03:33 PM 8/13/2007 -0600, you wrote:

>---------- Forwarded message ----------
>Date: Mon, 13 Aug 2007 14:21:12 -0700
>From: Jim Lux <jimlux@xxxxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: RE: vacuum tube construction. (fwd)
>
>At 12:28 PM 8/13/2007, you wrote:
>
> >---------- Forwarded message ----------
> >Date: Mon, 13 Aug 2007 12:13:06 -0700
> >From: Frank <fxrays@xxxxxxxxxx>
> >To: Tesla list <tesla@xxxxxxxxxx>
> >Subject: RE: vacuum tube construction. (fwd)
> >
> >All this tube is is a simple Geissler tube.
> >The vacuum levels are not high enough to ever generate X rays.
>
>Not entirely true.. More if the mean free path is greater than the
>distance from electron source to electron target, and the voltage is
>high enough, you can get x-rays.
>
>There's also soft x-ray sources using fast rising edges that I think
>can tolerate higher pressures.  An example might be a z-pinch device
>
>
>  >You need a hard vacuum and a diffusion or turbine pump along with a
> >scavenging method to pump the tube down hard enough to be able to
> >generate X rays.
>
>Or a sorption pump (you only have to pump once, and then you getter it).
>
>
> >   Tubes that can be taken apart for cleaning will not
> >have seals good enough to hold an X ray vacuum.
>
>Not precisely true.. There are continuously pumped tubes that are
>dismantleable.
>
>
>
>
> >Large mercury arc rectifiers will work as a switch with some
> >additional circuitry but are not available anymore. Those were used
> >on some of the early wireless transmitters.
>
>They were used far more recenly than that in high voltage DC converters.
>
>As recently as 2005, they completed an upgrade of the Sylmar
>Converter station at the southern end of the Pacific HVDC Intertie ,
>replacing the mercury arc valves with thyristors.
>
>They normally serviced the mercury arc valves on a 7 year cycle,
>however the 1994 Northridge earthquake interrupted the service cycle,
>and encouraged replacement with more modern thyristors.
>
>Interestingly, the mercury arc based converters work just fine, it's
>just that they require a larger maintenance crew and require more
>servicing, so they have an availability of 92% as opposed to 98% for
>thyristors.  There's also the environmental hazard of a system with
>many pounds of mercury.
>
>
> >Dosimeters are a device to measure radiation over time, basically a
> >charged capacitor that is discharged by radiation. Usually they are
> >calibrated in REMS and if they ever register, the amount of radiation
> >is enormous and you better run!
> >
> >A CD Geiger counter, Model CDV 700-XX is a good counter to measure
> >radiation in small amounts and can be used to detect X rays. These
> >are on Ebay all the time.
>
>I've been given to understand that CD type geiger counters have a
>severe failing in that they don't detect low energy soft x-rays very
>well (ones that can't penetrate the GM tube envelope).  If you're
>working at lowish voltages (tens of kV), one could have a fairly high
>X-ray flux that wouldn't register.
>
>I'm not a X-ray dosimetry expert  by any means, but it's probably
>worth consulting someone who is, and, in particular, someone who's
>familiar with low energies.
>
>
> >Frank
> >
> > >Quoting Tesla list <tesla@xxxxxxxxxx>:
> > >
> > > >
> > > > ---------- Forwarded message ----------
> > > > Date: Mon, 13 Aug 2007 07:52:30 -0400