Re: Designing High-Gain Triple Resonance Tesla-Transformers

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

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 



Going to a solenoid coil will give you a lot of "insulation headaches".  You
can wrap a lot of polypropylene around the lower part of sec, but high freq.
currents can "capacitively couple" right thru insulation due to displacement
currents.

Since you are at present only in the design stage, it would be better to
consider a much larger coil radius thus providing better coupling and still
using a flat spiral for the pri.

Use Antonio's program and run a lot of "what-ifs" until you get the result
you need.

Dr. Resonance

 >
 >  >It's possible, however, to make a magnifier driver with quite
 >  >high coupling by using a flat primary coil and a short
 >  >solenoidal coil. To increase the effective coupling, the bottom
 >  >of the secondary coil can be connected to the top of the primary
 >  >coil (ground the outer end of the primary coil, and connect the
 >  >inner end to the bottom of the secondary coil, both wound in the
 >  >same direction). Make the primary coil conical, and coupling
 >  >coefficients around 0.7 can be easily obtained.
 >
 > Most solenoid coils that I have seen having such high coupling
 > coefficients appear to be vulnerable to HV breakdown at the final
 > turns of the secondary windings.
 >
 > The spiral strip transformer, on the other hand, produces
 > uniform voltage grading through the thickness of the secondary
 > winding.  The equal potential lines outside the windings, however,
 > bend sharply around the edges of the thin winding conductors
 > creating highly enhanced electric fields which results in electrical
 > breakdown.  The function of the ring cages is to maintain the coaxial
 > field distribution across the margin which is nearly parallel to the
 > uniform field throughout the thickness of the winding.
 >
 > The outer cage appears to be connected to the primary turn.  FIG. 7 of
 > U.S. patent No. 5,079,482 provides a clear illustration of an outer
 > cage.  It is not clear to me how an inner ring would be connected.
 >
 >   >> To date, the only resonant transformers that I have seen having
 >   >> such high coupling coefficients have been of the spiral strip
 >   >> design that include inner and outer ring cages to shape the
 >   >> electric field in the margins of the transformer.  (See, for
 >   >> example, IEEE Transactions on Nuclear Science, Vol. NS-26, No.
 >   >> 23, June 1979, pp4211-4213.)  What is not clear to me in the
 >   >> spiral strip design is how the ring cages are connected.  That
 >   >> is, are the ring cages connected to their respective inner and
 >   >> outer winding?
 >
 >  >Couldn't find the article. Too old to be on the IEEE site.
 >
 > The article gives the best description I could find.  The description
 > would indicate that the inner cage rings have significant differences from
 > the outer rings.  I have other references that illustrate ring cages in
 > pulse transformers, however, they do not provide much of a description.
 >
 > If the inner ring cage is merely to control the equipotential lines in
 > the transformer margin, then might they not be left floating?
 >
 > Mike Day
 >
 >
 >