Re: slow-wave helical resonator

["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 Gary,

On 5 Aug 2002, at 12:20, Tesla list wrote:

> Original poster: "Gary Peterson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <glpeterson-at-tfcbooks-dot-com>
> 
> > > > . . . what is meant by a 'slow-wave' resonator? . . .
> 
> I would appreciate the list's critical comments regarding the accuracy of
> the following definition:
> 
> slow-wave helical resonator
> A resonant circuit consisting of a single-layer cylindrical inductor wound
> in the form of a helix, usually including capacitive end loading.  The speed
> of a wave disturbance along the axis of the helix is significantly less than
> the propagation of an electromagnetic wave in free space.  A Tesla coil's
> secondary and a magnifying transmitter's base-driven extra coil can both
> behave as a slow-wave helical resonators, the latter propagating the wave at
> around 17% the speed of light in free space.
> 
> Gary

Or alternatively, in the time it takes for a disturbance to travel 
the height (so as not to confuse with wirelength!) of the coil, it 
would have travelled (at the speed of light) some millions of km in 
free space. I haven't quantified the distance because the speed of 
propagation in a helix depends on the characteristics of the helix. 
17% is by no means a hard figure.

Regards,
malcolm