RE: vacuum tube construction. (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- 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.
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.  Tubes that can be taken apart for cleaning will not 
have seals good enough to hold an X ray vacuum.
Since the tube conducts, it will not work as a spark gap at all, 
basically it is a neon tube type effect and it will just glow as the 
voltage is applied and then turn into a voltage regulator and get 
brighter with more current until the electrodes start to get hot and 
they will out gas and lower the vacuum until the tube stops conducting.

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.

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.

Frank

>Quoting Tesla list <tesla@xxxxxxxxxx>:
>
> >
> > ---------- Forwarded message ----------
> > Date: Mon, 13 Aug 2007 07:52:30 -0400
> > From: Jeff Fink <revtec@xxxxxxx>
> > To: 'Tesla list' <tesla@xxxxxxxxxx>
> > Subject: RE: vacuum tube construction. (fwd)
> >
> > I am new to this list and ironically this is the first post I have read.
> >
> > Over the years I have been experimenting with massive cold cathode vacuum
> > tube diodes, looking at the phenomena of PAGD (pulsed abnormal glow
> > discharge).  I was wondering if the tube could be used as the 
> spark gap on a
> > TC.  I understand there could be X-ray production, but would it be
> > dangerous?  Another question: Would the X-rays register on 60's vintage
> > Civil Defense radiation dosimeters?
> >
> > My tube design is incredibly easy to build when you consider that there is
> > no grid or filament, though some machine shop work is 
> required.  They can be
> > easily disassembled for cleaning and modification.
> >
> > My largest is 12" diameter, using a 12" by 3" long by 1/2" wall 
> pyrex tube.
> >
> > The anode and cathode are 3/4" aluminum plates.  The tube sets into a
> > circular groove on each plate and is sealed with a 3/16" O'rings 
> coated with
> > vacuum grease.  A hole and fitting on the cathode plate provides connection
> > to a refrigeration vacuum pump sold by Grainger, which developes 
> a very nice
> > vacuum.  The tube lights off on only 600 volts.
> >
> > Jeff
>
>It wouldn't work so well for a TC because TCs have discharge currents in the
>hundreds to thousands of amps and I don't think a discharge tube would handle
>that too well for long. Also the 600V firing is kind of low so you
>wouldn't get
>much energy output from the coil.