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Re: Skin Effect & Primary Current?

Hi Jim,
         Nice thinkin', and thanks for the information. The gap 
electrodes were specifically chose to be tungsten carbide with this
thought in mind (v. high melting/sublimation point). Pre-apology for 
the various snips....

>     At this current density your gaps are in the glow-discharge
> region (don't believe me? look at the light emitted. Is it blue:
> indicating a Nitrogen glow discharge? or Green: copper? ?/iron. =>
> arc)

Bright blue.
 
> On page 274 A. von Engel states: (which goes against "common"
> knowledge)
> 
>     " 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)

I have it on good authority that specially built thyratrons can indeed
operate at moderately high break rates and but require special 
internal construction in the form of baffles and the anode must be 
made of a particular type of material. I'm sorry, I don't have the 
particulars handy. 

> 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).

I think high m.p. is certainly the way to go. I have had no trouble 
with power arcs or quenching with the coil in question. To some extent
this is alleviated because in throwing an attached arc, the system 
loses energy very quickly indeed. I have scoped the loss as occurring 
in less than 10 cycles (very conservative).

Malcolm