Re: Magnet Design for Tesla Coils

To: tesla-at-poodle.pupman-dot-com
Subject: Re: Magnet Design for Tesla Coils
From: Tesla List <tesla-at-stic-dot-net>
Date: Fri, 14 Mar 1997 14:16:09 -0600
Approved: tesla-at-stic-dot-net
Subject: 
        (Fwd) Re: Magnet Design for Tesla Coils
  Date: 
        Fri, 14 Mar 1997 13:09:37 -0500
  From: 
        "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
    To: 
        tesla-at-pupman-dot-com

> In a message dated 97-03-12 00:38:21 EST, you write:
> 
> Bert (and all):
> 
> No, I didn't see a significant difference in performance as compared to
> series gap, for example, but based on what follows, I think magnetic
> quenching is a viable method to investigate.  I have not tried a "high
> velocity vacuum gap" as you mentioned.  One problem I introduced (yea, I
> screwed up due to my ignorance) was the electode geometry in the magnetic
> field.  I built an enclosed spark gap so I could evacuate it with a vacuum
> pump;  the electrode geometry closely resembled the World War II vintage
> RADAR spark gap tubes, i.e, an cylindrical aluminum cathode that was
> concentric to a tungsten anode (the design minimizes electrode erosion).  
> 
> The spark gap worked great (at atmospheric pressure) without a magnetic
> field,  its performance was equal to a series gap. With a magnetic field
> applied, there was no discernible diference in performance.  However, I
> placed the tube in a magnetic field so the tubes' axis was perpendicular to
> the magnetic field.  Gee, sounds good!  But, with the electrode geometry I
> described, the spark propagates perpendicular to the tube axis.  In other
> words, the spark path was parallel to the magnetic field and does not aid in
> quenching the spark.   Live and learn!
> 
> So, can't comment on higher fields based on my erroneous set-up, but I think
> it's worth looking into.   In using an enclosed spark gap, the glass envelope
> acted as an insulator when the spark gap was placed within the magnets' gap;
>  with an open air gap, I used mica sheets with some success, but they don't
> always hold up when using a 15KV, 60mA sign transformer.  The other idea is
> to perhaps adapt the ceramic nozzle assemblies used in MIG welding equipment
> (check out a local welding supply store for things other than tungsten TIG
> rods) as insulators.  
> 
> Hope this helps, Bert and that my mistakes might benefit others.  But hey,
> how else do we learn?  Too bad there wasn't an easier way!
> 
> TIMOTHY RANEY, TCBOR

Check out the ceramic nozzles sold at equipment rental places for 
standard sandblasters.  One that is popularly available has a 1/4 
inch hole down the middle.  Just the right size for a 1/4 inch 
tungsten tig electrode.

rwstephens