Re: Capacitor charge, were is it?

To: tesla-at-pupman-dot-com
Subject: Re: Capacitor charge, were is it?
From: Richard Hull <hullr-at-whitlock-dot-com>
Date: Mon, 04 Nov 1996 16:01:54 -0800
Tesla List wrote:
> 
> >From music-at-triumf.caSun Nov  3 22:31:43 1996
> Date: Sun, 03 Nov 1996 09:27:56 PST
> From: "Fred W. Bach, TRIUMF Operations" <music-at-triumf.ca>
> To: tesla-at-pupman-dot-com
> Cc: music-at-triumf.ca
> Subject: Re: Capacitor charge, were is it?
> 
> >Message-ID: <199611020526.WAA06948-at-poodle.pupman-dot-com>
> >Date: Fri, 1 Nov 1996 22:26:04 -0700
> >Subject: Re: Capacitor charge, were is it?
> 
> >Date: Fri, 1 Nov 1996 09:53:14 -0500 (EST)
> >From: Steve Roys <sroys-at-umabnet.ab.umd.edu>
> >To: tesla-at-pupman-dot-com
> >Subject: Re: Capacitor charge, were is it?
> 
>   [snip]
> 
> >Conductors pass the electrons on easily between atoms, insulators hold
> >onto their electrons and don't let them go as easily.  The better the
> >insulator, the stronger the hold on the electrons. Vacuum has nothing to
> >retard the electrons.  Once the electron breaks free, it's free to go,
> >governed only by it's initial momentum and the surrounding electric and
> >magnetic fields.
> >
> >So in a sense, it seems like once an electron breaks away from a conductor
> >into the vacuum, a perfect vacuum could actually be considered a perfect
> >conductor.
> 
>    ... you mean as is there isn't any loss to heating the vacuum?  OK.
> 
>    But there is one property of a conductor that vacuum doesn't have:
>    confinement of the charge.   When you talk about particles moving
>    in a vacuum you're into the realm of particle accelerators.  Here
>    we have a special problem of energy 'loss' with electrons or
>    low-energy ions: space charge.  The energy isn't really lost it
>    just goes into a useless form, the electrons repel each other and
>    accelerate away from each other in random directions.  Think of the
>    electron bundle as an expanding foam.   Theoretically this energy
>    is recoverable.
> 
>    As Steve mentions, in a strong magnetic field the electrons lose
>    energy to synchrotron radiation.
> 
>  Fred W. Bach ,    Operations Group        | Internet: music-at-triumf.ca
>  TRIUMF (TRI-University Meson Facility)    | Voice:  604-222-1047 loc 6327/7333
>  4004 WESBROOK MALL, UBC CAMPUS            | FAX:    604-222-1074
>  University of British Columbia, Vancouver, B.C., CANADA   V6T 2A3
>  "Accuracy is important. Details can mean the difference between life & death."
>  These are my opinions, which should ONLY make you read, think, and question.
>  They do NOT necessarily reflect the views of my employer or fellow workers.

Fred,

Conductors are incapable of confining charge.  They can only conduct it 
from one place to another.  When the charge flow (current) stops in a 
conductor, it is dead!  When it stops in a dielectric, it is charged. 
Only dielectrics can confine and contain charge.  The structure and 
nature of metals are such that they are not capable of confining charge 
only transporting it from one place to the next.

You are right in that a vacuum is an insulator so far as conducting 
charge, but it can definitely confine and contain charge, for it is a 
dielectric medium.  Charged particles are the only way that charge can be 
transported through a vacuum unless we down-convert EM radiation to 
electrical energy.

Richard Hull