Re: [Phys-l] Microwave door. Was: Re: About the "why" and "how" questions.

[chuck britton <cvbritton@mac.com>]

Recent magnetrons are ceramic with metal endcaps. Enough ceramic is 
required to hold off the 4000  volt accelerating potential.
Recent disassemblies has shown ceramic ring magnets around the 
ceramic midsection of the tube.

Have not yet attacked one of the newer 'Inverter' designed circuits.
The older circuit was pretty much straight forward brute force 60 Hz 
step-up transformer power supply. Large high voltage capacitor and 
diode to feed the anode.

A large capacitor COULD have held pcb's (in olden days).
Burning insulation can still produce toxic gases.

The door was undoubtedly glass. Tempered perhaps?
Could have been a 'Rupert's Drop' explosion?

My bet would be on the glass door relieving internal stress since a 
catastrophic failure in the electronics would have likely vented 
outside the cavity of the oven.
.
At 9:10 PM -0800 12/24/10, Bernard Cleyet wrote:
> What toxic output?
>
> I'm quite disappointed -- except for e. feed thrus, all the 
> magnetrons I've seen are metal.   What a shame; your chance to add 
> experimental physicist to you personality and your "friend" "blew 
> it". 
>
> bc does have a magnetron w/ ceramic containing Be.  Unlikely in a 
> domestic one.
>
> p.s. Was the door glass?
>
>
>
>
> On 2010, Dec 23, , at 08:24, Moses Fayngold wrote:
>
> cut
>
> >   I personally have no idea of "Why" and "How" this happened. Of 
> > course, I could
> >  resort to considering this as a divine message from some 
> > mysterious headquarters
> >  that it is time for me to switch from pure theoretical to applied 
> > physics, but I
> >  so far decided to keep such possibility as a last resort.
>
>
> >  Meanwhile, I
> >  immediately called to a colleague - a professional experimental 
> > physicist with
> >  30 year experience. He came over, looked at the scene and said 
> > that he has never
> >  encountered or heard of this kind of event. His only suggestion was that the
> >  cause might be a gradually  accumulated strain or stress in the 
> > microwave door,
> >  or explosion (rather, implosion?) of the vacuum tube in the 
> > internal magnetron.
> >  Neither of which explains much to me.
>
>
> >  On his insistence (he said there might be
> >  some toxic output) we wrapped the thing into a plastic bag and 
> > disposed of it,
> >  and now I regret this since I cannot anymore do a more thorough 
> > examination.  
> >   I have done some search on the Internet, but did not find anything similar
> >  except for SHC (spontaneous human combustion) (never before heard 
> > about that,
> >  either), and again, without any satisfactory explanation or even 
> > proof that all
> >  described cases were not some artifacts.
> >   So my question to this Forum is: Has anyone any viable idea or information
> >  about this kind of effect? If yes, that would be a good answer to 
> > the "Why" and
> >  "How" question.
> >
> >  Thanks,
> >
> >   Moses Fayngold,
> >   NJIT
> >
> >
> >
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