Re: Primary Heating

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Robert,
           I really am moved to comment on this piece:

On 5 Mar 2002, at 12:37, Tesla list wrote:

> Original poster: "rheidlebaugh by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>
> 
> As I read this subject I see current is every where the same. No current is
> not every where the same. Yes it is a series circuit, but the load is not
> all places the same. The load is distributed in a log distrabution into the
> secondary and surounding areas and across the resonant length of the primary
> starting at 22 ohms to over 6oo meg at the 1/4 wave resinant point at the
> moment of time of firing. Yes the average current is low, but the
> instantanious current is often well over 400 amps traveling as a slow movind
> standing wave pulse along the conductor decresing as the impedance
> increases. Keeping in mind in a TC we are not dealing with a uniform sign
> wave current, but a multi harmonic pulse burst of intense current. The
> heating effect of 400 amps in 22 ohms is more than 40ua in 600meg.This is
> just my minds view of what should be happening in the primary.AMATURE RADIO
> OPERATORS HAVE FOUND IT NESSISARY to use larger tubing at the feed point of
> an antenna to carry the input power.
>   Robert  H 

It is well established that the current at the feed point of an 
antenna is orders of magnitude larger than currents at the tip. 
Furthermore, coupling between various sections of a whip is minimal 
compared with coupling between turns of a spiral. I think the 
equivalences you are trying to use are invalid.
     The current in the primary is sinusoidal, at least on a 
timescale that compares with the frequency it resonates at. I think 
the point about impedance scaling is completely invalid. The primary 
has a pretty large chunk of capacitance hooked straight across it 
when the gap fires. It also has far more coupling from inside to 
outside than a typical secondary does top to bottom. If it is highly 
questionable to associate wirelength with free space wavelength for 
the secondary at the resonant frequency of the secondary, it is out 
of the question for the primary (consider how short the conductor 
is). Tesla himself realized that. I read his musings on this very 
thing (I will dig out a reference to the work and page if you 
require). In effect, he said it would be desirable (he didn't exactly 
say why if I recall) but that it couldn't be done which was a rather 
pragmatic concession to nature considering he was trying to transform 
a low voltage to a high one.
      I've no doubt we'll be able to craft an experiment which will 
give the answer to this problem. We've managed to dispel other 
"mysteries" in this fashion.
 
Regards,
Malcolm
<snip>