From: "Christopher R. Carlen"
Subject: Re: X-Rays in the garage?
Date: Tue, 01 Oct 2002 17:17:50 -0700
Organization: Sandia National Laboratories, Albuquerque, NM USA
NNTP-Posting-Date: Wed, 2 Oct 2002 00:16:48 +0000 (UTC)
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James Meyer wrote:
> On Tue, 01 Oct 2002 23:01:45 GMT, NightRunner
>>Along those lines... I had noticed once some time ago when I was into
>>collecting tubes, that I had some tv diode tubes marked with warnings
>>about x-rays. Could one simply drive the holy hell out of a diode at
>>very high voltages and achieve a reasonable result? That would be
>>easiest to implement since the diodes have just a cathode and anode
>>complete with a handy terminal on top :-)
> The old 1B3 color TV rectifier tubes -will- produce X-rays. Unless you
> get one of the late model versions which were built with glass in which a large
> percentage of lead was added. Your wife would probably cherish "lead crystal"
> glassware, but for your purposes lead loaded glass would be something to avoid.
> In order to get much in the way of X-rays out of a 1B3, you will need to
> feed it with at least 30,000 volts on the plate.
But those tubes were for rectifying CRT HV, which was only a few mA,
thus you will have trouble getting many X rays with only a few mA, and
at that current anyway, the voltage drop across the tube probably won't
be anywhere close to that, but rather something like a few hV to a few
kV. To get the 30kV across the tube, you'd force massive current
through it. The tube wouldn't survive this continuous mode, but it
might be able to do it with very narrow pulses.
But then the cathode wasn't designed for high current anyway, so even
low duty high current pulses would probably tear it up in short order.
I'd think one would have not too much trouble building an X ray tube, if
they had a decent vacuum cleaner.
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA