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Re: Skin Effect & Primary Current?
Tesla List wrote:
>
> >From jim.fosse-at-bdt-dot-comSat Jul 27 20:12:49 1996
> Date: Sat, 27 Jul 1996 08:27:08 GMT
> From: Jim Fosse <jim.fosse-at-bdt-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Skin Effect & Primary Current?
>
> >From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
> >To: tesla-at-pupman-dot-com
> >Subject: Re: Skin Effect & Primary Current?
> >
> Huge snip
>
> " The cathode substances also fall into two groups when the
> restriking time is investigated: a circuit containing a carbon arc can
> be interrupted for up to about 1 sec at applied voltages of several
> hundred V and will restrike without change of the electrode
> separation, while a Cu arc when interrupted for 10^-3 sec or less will
> not restrike. Hg arcs at low pressure have restriking times of less
> than 10^-8 sec."
>
> WHAT? Mercury at 10nS. !!!! ????? Why are Mercury Thyratrons So Slow?
> If low pressure mercury arcs quench in 10nS. why use blown Cu/N2
> gaps;) I think von Engel is off here (pun intended)
>
> Although, if the 10^-3 sec number is correct for Cu, maybe we should
> consider a different electrode material? (or at least determine if we
> are close to the arc region of operation instead of just the glow
> discharge region).
>
> as always; thoughts, comments, snide remarks?
>
> jim
Jim,
That was "RESTRIKE" time wasn't it? That I can believe low pressure
mercury ionizes very quickly as its atoms are everywhere in a weak
vacuum! It is the "QUENCH" time that is real poor. The only real atoms
in a mercury rectifier/thyratron are metal atoms! These are real hard to
quiet down or "un-excite" as they conduct lots of current.
This is why they are far better from a number of bullet-proof aspects
than any silicon diode. If I remember correctly the "arc drop" of a
mercury tube is 13 volts.
Richard Hull, TCBOR