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Re: Propagation velocity in long helical coils.



Hi! This is really a question for anybody who can help. I've seen references
to "bipolar coil" setup several times on the list, and my good friend Mr. Z
has a bipolar. Before I start building, can anyone explain the advantages
and disadvantages of a bipolar coil? Appreciate your input. I might add that
the discussions of power, energy, and mathematical derivations, etc,
relating to circuit analysis of "the coil" have been both fascinating and
helpful. Please keep at it! Best Regards, Noah

----- Original Message -----
From: "Tesla List" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, May 17, 2000 9:36 PM
Subject: Re: Propagation velocity in long helical coils.


> Original Poster: "Robert Jones" <alwynj48-at-earthlink-dot-net>
>
> Hi Terry and all,
>
> As you can read my mathcad files thats going to be helpful.  I suggest you
> start with the zero internal C version as thats the one I have the
equations
> for.   Also I have not included ground reflections or top load mag
> reflections. The ground reflections may be important for end effects at
> least thats what Malcolms measurements indicate.  When you or Malcolm has
> some comparative L measurements on the ground and isolated we will know
more
> about it.  You will also need inverse FFT.  As in many of these types of
> problems you solve the transformed equation then convert back to get the
> answer you wanted. One more thing I assume you have complex FFT routines
> i.e. unless its a symmetric bipolar coil you need the sin and cos terms.
Or
> I can add the ground reflection for symetry that probaly best but a bit
more
> work on the equations and we need those measurments as a check on the
> reflection equation.
>
> Could Malcolm get hold of Wheeler's paper for his L formula so we can
check
> its got no inapprorate assumptions ie it is valid for short coils.
>
> I will need to tidy up the work sheet and put it in an algoritmic form.
Can
> I assume the resusltant programme will be freely distibuted?   I am
looking
> forward to seeing the current profile of a short coil.  Do we have any
> volinters for some anamated graphic output rotines.
>
> Ultimatly we need the transiant solution so we can watch the current and
> voltage profiles build.  That may require an FFT for each element of the
> current and voltage profile.  Or we could build a finite element
simulation.
> Thinking about that it would have the mega advantage of showing how the I
> and V build and it may be possible to patch it into microsim.  Even a 100
> element one would be good and  the distibuted coupling to the primary
would
> be a relatively simple. So which one do you want the equations for ?
>
> Need to do the sums on the computation time for the simulation.  You have
> the self C and current flow in and out and voltage across each element
then
> the mL and C to every other element. Just 5 equations per element So 3N +
> 2N**2 calculations per run cycle. Say 50 run cycles per coil cycle
(depends
> on the integration and diff algorithms).  So for one cycle and 100
elements
> its one million equations. Say 10 million floating point operations.   How
> does this compare to the self C program.  Both  would be a nice cross
check
> and the maths one normally provides more insight.  I think ground
> reflections are simple for both due to symmetry.
>
> Regards Bob
>
> -----Original Message-----
>
>
> >Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
> >
> >Hi Bob,
> >
> > Let me know what needs to be done and I'll get to it.  I wrote an FFT
> >thing in school once that worked and Bert sent me some info tonight too
on
> >FFTs.
> >
> >At 07:06 PM 05/16/2000 -0400, you wrote:
> >>Hi Terry,
> >>
> >>I can now include end effects because I have solved the boundary problem
> but
> >>I don't have an equation for the end C (except  Med).  However the
method
> >>could be included in your program but it would need FFT routines.  It
> would
> >>have the advantage I think of accurately predicting the output voltage
and
> >>coil profile voltage (for long coil).  The later would be useful for
flash
> >>over prediction at the lower end.  It is also valid for shorter coils
> until
> >>internal self C starts to produce errors. i.e. insight into current
> >>profiles.
> >>This method could have internal C added then it would be valid for very
> >>short coils.
> >>
> >snip...
> >
> >
>
>