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Re: Observations - Gaps and Arcs (fwd)



---------- Forwarded message ----------
Date: Wed, 08 Jul 1998 23:26:55 -0500
From: Bert Hickman <bert.hickman-at-aquila-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Observations - Gaps and Arcs (fwd)

Terry, CW, and all,

As long as the dissipation PER GAP is kept to a reasonable level, and
the resulting heat carried away from the gap, there's really no reason
why this approach shouldn't be scalable to higher power levels. 

For example, in the days of spark radio, very efficient quenching gaps
were made by using a series of relatively heavy copper disks, separated
by thin mica washers, in a sealed atmosphere (to reduce gap fouling from
electrode oxidation). Per-gap spacing was typically 10 mils or less.
Operation quickly resulted in an operating atmosphere consisting
primarily of nitrogen, since the initial free oxygen combines to form
copper oxides. 

By providing outside cooling, substantial power could be handled. Per
Morecroft (Principles of Radio, 1921, John Wiley & Sons), these gaps
were used to handle up to 600 H.P.[400 KW!] of input power (Telefunken's
Nauen Station). A similar quenching gap, called the Chaffee gap,
consisted of alternating copper and aluminum electrodes in a moist
hydrogen atmosphere, and was used on systems operating off a HV DC
source, but it was limited to about 200 watts/gap. 

The old Spark Radio engineers really knew their stuff...!

-- Bert --

Tesla List wrote:
> 
> ---------- Forwarded message ----------
> Date: Wed, 8 Jul 1998 12:12:16 -0600
> From: terryf-at-verinet-dot-com
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: Observations - Gaps and Arcs (fwd)
> 
> Hi CW,
> 
>         I am working on a gap that has up to 60 gaps at 0.004 inch (900 watt neon
> coil) but haven't gotten it together yet.  10000 watts is a lot of power.
> However, with air cooling and proper quenching I think it will work but I
> really don't know for sure.  In my case with 60 pipe sections, there is a
> huge area for cooling.  Proper quenching is extremely important!  It keeps
> the power dissipation in the gap much lower.
>         I simply epoxy pipe sections to a board with spacers (like thick paper) in
> between the sections.  This is fast and cheap.  When we find the "perfect"
> system, we can worry about aesthetics more.
>         If anyone has any other information on a very large number of very small
> gaps we would love to know about it.
> 
>         Terry Fritz
> 
> At 10:44 PM 7/7/98 -0600, you wrote:
> >
> >
> >---------- Forwarded message ----------
> >Date: Tue, 7 Jul 1998 22:36:02 -0500 (CDT)
> >From: Larry Bud Melman <gasman-at-althea.a-line-dot-net>
> >To: Tesla List <tesla-at-pupman-dot-com>
> >Subject: Re: Observations - Gaps and Arcs (fwd)
> >
> >> My employer made electrosurgery equipment back in the 40's (which used a
> >> static gap).  I've dug through the old log books and discovered that
> >> much research was performed pertaining to the number and size of the
> >> spark gaps.
> >>
> >> One final design contained a series of 8 tungsten - tungsten gaps, 3/8
> >> inch diameter, set for (I think) 0.012 inch each.  A clever mechanical
> >> device would reset the spacings of each gap once the machine was turned
> >> on - thus compensating for erosion.
> >>
> >> I've also discovered that the Miller part numbers (posted in the recent
> >> tesla resource list from R. Hull) for the tungsten TIG contact points,
> >> heat sinks, and ceramic base are still valid and stocked at most
> >> locations. :)  They also want to charge the ludicrous price of 98..89 for
> >> the p/n 096761 HF/HV 10KV 0.002 uf capacitor!
> >
> >
> >       Since this talk about multi-static gaps has been propagating on
> >this listserv, I've been wondering about the feasibility of such a gap,
> >carried to the Nth degree, on a hi-power coil.  Like ten or twenty gaps
> >divided equally, made with big pieces of material acting as big heat sinks,
> >and lots of airflow with a big fan.
> >
> >       You see, I fear I am destined to have to build a RSG, and am actually
> >seeking parts to do so.  However, as long as it is possible, I'm going to
> >continue to delude myself into believing it's possible to consider
> alternatives.
> >(for my about 10,000 watt, 27,000v, 16-20inch coil).
> >
> >
> >
> >       Yeah, I know - I'm nuts        ;-o
> >
> >
> >                                                               CW.
> >
> >