AC vs DC and Toroid Question

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <MFRYML-at-aol-dot-com>

Hello everyone,

I have a relatively large secondary coil-about 2500 ft., 12.5" dia, 50" high.
  Have a small (14 dia duct pipe toroid but planning a larger one.

I have several questions, please:

1)  Given a .15 mfd primary capacitor, a rotary spark gap, and a set of four
120v/7500v neon transformers in parallel producing 240 ma together, would
there be a performance difference (1) operating the system AC versus  (2)
rectifying the current to produce DC, and slowing the spark gap down to 
allow the
capacitor to charge fully between firing ?

I never really understood the mechanics of AC vs DC in a Tesla coil.  With
AC, doesn't the capacitor spend a large percentage of the time actually 
draining
the charge at the point the current changes polarity.  If the gap fires, say,
300 pps, at least 2 pulses in 5 will have the polarity change occur and have
little or no charge stored in the capacitor, assuming a normal sine wave 60 hz
AC frequency.  Am I in left field ?
Since the polarity changes twice per cycle, does the reverse current flow in
the primary coil have the same effect on the oscillation as the forward flow
(like pushing a swing from the front instead of the back every second push) ?

With the rectified DC, however, you only get current flow 50 % of the time.
The "pushes" may come less often, but they will be stronger.

So, which gives better performance ?

2)  I used the Java Script TC designer to see the effect of a larger toroid
on frequency and hopefully spark length. Great Program !   I was thinking of a
30" or 36" dia aluminized drain pipe toroid.  Is there a law of diminishing
returns here ?  Do you start to have too much (pink) discharge to the air
compared to the charge collection effect? I presume I would still need a 
breakout
point attached.

3) The program also indicates a power factor correction capacitor of 291 mfd.
  Is this to be at 500v or is a higher voltage recommended.  Do these really
make a difference on transformer performance ?

4)  The info on toroid construction describes a metal or metallized plate in
the center.  Does this serve some purpose and affects performance, or can one
simply have the "plain doughnut without the hole" ?

Thanks for reading.  I appreciate input on any of the points.

Martin