Re: This phase shift stuff...

To: tesla-at-pupman-dot-com
Subject: Re: This phase shift stuff...
From: Terry Fritz <twf-at-verinet-dot-com>
Date: Thu, 18 Feb 1999 17:51:30 -0700
Approved: twf-at-verinet-dot-com
At 08:07 AM 2/18/99 -0800, you wrote:
>Tesla List wrote:
>> 
>> Original Poster: Terry Fritz <twf-at-verinet-dot-com>
>> 
>> Hi Jim,
>> 
>>         One could build a TC in a can which would increase the
capacitance along
>> the seconday greatly and push the system into more of a transmission line
>> type of system.  However, would this be a realistic system to compared to
>> the regualar kinds of Tesla coils we all use?  I am really looking for the
>> effects in the standard type of system with no tricks.
>> 
>>         Terry
>
>Perhaps that is the goal of the experiment: to determine where the
>lumped model breaks down and the transmission line is more appropriate? 
>One analysis of the conventional self C considers it as a can that has
>been opened up and flattened out (a conical can with 180 degree included
>angle). I was thinking of something where you had, say, 50 to 100
>turns... more than a helical resonator which often only has less than
>10.. but less than a classical TC with several hundred.  We know the
>lumped mechanism works: use a big L and a big C so that parasitic C is
>neglible and you still get big voltages. The idea here is to build
>something that has distributed L and C, but is still small in terms of
>wavelength (although, given that loaded LC structures have slow
>propagation speeds, you are getting to a slow wave phenomena, and it
>isn't small compared to a wavelength anymore).
>
>I know some students who are starting out in a class on FDTD (finite
>difference, time domain) electromagnetic analysis and might be
>interested in a project. Could we formulate some questions to ask them?
>
>-- 
>Jim Lux                               Jet Propulsion Laboratory
>ofc: 818/354-2075     114-B16         Mail Stop 161-213
>lab: 818/354-2954     161-110         4800 Oak Grove Drive
>fax: 818/393-6875                     Pasadena CA 91109
>
>

If I can find an extreme case of a real Tesla coil and I don't see
significant phase shifts, then the rest of the lesser cases would also be
free from phase shift.  I think we are fairly well with the low phase shift
case according to computer models but it it time to test the real world
sitiuation to check to be sure that the real world is correct (of course,
the computer models ARE correct :-))
	The real trick is to be sure that I am measuring the coil's behavior and
not the test equipment's influences.

	Here is a question for the students.  If you have a coil 12 inches in
diameter close wound with #24 wire with a sine signal is applied to the
base.  How long must the coil be the get a top to bottom phase shift of 45
degrees in the voltage or current at resonance?  I am not sure all the
tools exist to answer that question (perhaps they have the high dollar
software available that could tackle this..), but if they want a
challenge...  
	If they figure this out, a written report would be very useful to us!!

It's just a coil of wire, so how hard could it be... :-))

	Terry