Wire length,resonance, and Q (fwd)
From: Mark S Graalman [SMTP:wb8jkr-at-juno-dot-com]
Sent: Friday, May 29, 1998 5:00 AM
Subject: Re: Wire length,resonance, and Q (fwd)
Yes that's true Greg, but (lets see if say this right)
looking at the charging of Cterm the current will lag
the voltage by 90 degrees, Maximum I-term and
Maximum E-term don't occur at the same time.
I would think the phase relationship between the two
would be much closer at the coil base.
On Thu, 28 May 1998 23:36:05 -0500 Tesla List <tesla-at-pupman-dot-com> writes:
>From: Greg Leyh [SMTP:lod-at-pacbell-dot-net]
>Sent: Thursday, May 28, 1998 7:17 AM
>To: Tesla List
>Subject: Re: Wire length,resonance, and Q (fwd)
>Mark S Graalman wrote:
>> I have to wonder here if there isn't a simple
>> misunderstanding of 1/4 wave resonance, the fact
>> that we are talking about an ELECTRICAL 1/4 wave
>> and not a PHYSICAL 1/4 wave. That a 'monopole'
>> tesla secondary is a ELECTRICAL 1/4 wave from
>> the bottom to the top, and any situation where one
>> has a current node at one end and a voltage node
>> at the other is being operated as a 1/4 wave electrically
>> regardless of its physical length.
>This is true, and devices such as waveguide stubs and antennas
>often operate in this 1/4 wave mode. However, a TC secondary
>_does not_ behave in this way, for the following simple reason:
>There is no actual voltage node (max V, min I) at the top.
>Although there is a current node at the base (max I, min V),
>the top winding carries both the maximum voltage _and_ nearly
>the maximum current, just like in a standard HV transformer.
>This current at the top simply goes into charging the top
>electrode, which has a lumped capacitance back to ground.
>The current going into the arc is typically only 30 to 40%
>of the total current being delivered to the top electrode.
>If you change the "electrical length" of the TC secondary,
>this will still be the case.