Re: Primary resonators with very low L/C ratio

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:

 > Original poster: "Paul Nicholson by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>
 >
 > How do we construct a primary tuned circuit which has a very low L/C
 > ratio?   We come up against this question when we try to take an
 > OLTC and either raise the frequency or raise the power level.
 >
 > As a target for discussion, how would a bang size of 50 Joules,
 > firing at 300V, and resonating at 100kHz be dealt with?

A simple calculation leads to: L=(V/(2*pi*f))^2/(2*E)
V=voltage, f=frequency, E=energy.
In the example: L=2.28 nH
With a single turn, this would be a loop with about 0.7 mm of radius,
with 0.1 mm wire...

The formula says that better values can be easily obtained by
increasing the voltage or decreasing the frequency.
3000V and 10 kHz multiply the inductance by 10000, to more confortable,
maybe too big, 22.8 uH.

It's possible to decrease the inductance of a single loop coil by
connecting several stacked loops in parallel.

Ex: A single loop with 10 cm of radius made with wire with 1 cm of
diameter has L=0.418 uH.
Stacking loops in 10 cm of height:
2 loops:  L=0.234 uH.
3 loops:  L=0.199 uH.
4 loops:  L=0.187 uH.
10 loops: L=0.177 uH.
Calculations with the Inca program.
(http://www.coe.ufrj.br/~acmq/programs)

Antonio Carlos M. de Queiroz